An Evaluation of the Applicability of Upland Buffers for the Wetlands of the Wekiva Basin

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Title:
An Evaluation of the Applicability of Upland Buffers for the Wetlands of the Wekiva Basin Final Report
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iv, 163 p. : ill. ; 28 cm.
Language:
English
Creator:
Brown, Mark T ( Mark Theodore ), 1945-
Schaefer, Joseph M
Center for Wetlands
St. Johns River Water Management District (Fla.)
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Center for Wetlands, University of Florida
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Gainesville, Fla
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Subjects / Keywords:
Wetland ecology -- Florida -- Wekiva River Watershed   ( lcsh )
Wetlands -- Management -- Florida -- Wekiva River Watershed   ( lcsh )
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buffer zones
bibliography   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )

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Statement of Responsibility:
Mark T. Brown and Joseph M. Schaefer, principal investigators, with K.H. Brandt ... et al..
Bibliography:
Includes bibliographical references (p. 145-163).
General Note:
"October, 1987."
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Series taken from label.

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Final Report


AN EVALUATION OF THE APPLICABILITY OF
UPLAND BUFFERS FOR THE WETLANDS OF THE WEKIVA BASIN



Mark T. Brown and Joseph M. Schaefer, Principal Investigators

with

K. H. Brandt, S. J. Doherty, C. D. Dove, J. P. Dudley,
D. A. Eifler, L. D. Harris, R. F. Noss, and R. W. Wolfe


October, 1987








Center for Wetlands
University of Florida
Gainesville, Florida 32611
(904) 392-2424
















Acknowledgements


The authors wish to express their appreciation to the staff of the Center

For Wetlands, for their dedication and service way beyond the call of duty.

Their attitude made completion of this report so much easier. Specifically,

Jenny Carter, Staff Assistant, coordinated personnel and somehow managed to get

the report finalized under difficult odds. Linda J. Crowder processed all the

words over and over again as we edited and polished. Carol Cox proofread each

draft. Stephen Roguski, our expert draftsperson, drafted the figures. Karla

Brandt not only helped with research and writing, but did a fantastic job of

final editing. Steven Tennenbaum devoted two days to derivations of the Theis

Equation. We thank you for your energy.

Ms. Sidney Brinson, spent a day in the field with the authors explaining

the Districts methodology for wetlands determination. Staff from the Florida

Department of Natural Resources, especially Ms. Deborah Shelly, provided

support and transportation.

Glenn Lowe, Chief Environmental Specialist a the St. Johns River Water

Management District was project manager for the District and was extremely

patient and effective in his support.










Preface


This document is the product of a contract between the St. Johns River

Water Management District and the Center for Wetlands, University of Florida to

evaluate the applicability of upland buffers to the wetlands of the Wekiva

River Basin. The purpose of this report is to develop critical insight

concerning the need for, potential applicability of, and criteria for

delineating upland buffers in the Wekiva Basin. In this report, we have

reviewed the literature related to buffers, wetlands, wildlife habitat,

transition zones, water quality and quantity, and other models and criteria for

determining buffer zones. We have reviewed this information as a means of

evaluating the need for an upland buffer to protect the water resources of the

Wekiva River System.

Whether an upland/wetland buffer zone is desirable and/or necessary for

the Wekiva River System is not a question in the minds of the authors. Our

review of the literature; our understanding of the unique character of the

Wekiva River System; our knowledge of the limitations of the criteria for

issuing of permits for construction, operation, and maintenance of stormwater

systems; the limits of jurisdiction under current wetlands regulation; and the

expressed policies of the Governing Board of the St. Johns River Water

Management District suggest that an upland buffer is desirable and necessary if

the wetlands, waters, and wildlife of the Wekiva River Basin are to be

preserved.

Two issues have surfaced during our study which need clarification as a

prelude to the report. Both are related to the language in Chapter 373,







Florida Statutes. In 373.413 and 373.416 a distinction is drawn between

permits for construction and permits for operation and maintenance of water

management systems. Both kinds of permits require that such systems cannot be

harmful to the water resources of the District. Operation and maintenance

permits are subject to an additional criterion: such activities cannot be

inconsistent with the overall objectives of the District. Using one standard

for construction and two for operation and maintenance is confusing. Operation

and maintenance cannot be separated from construction, since once constructed,

a system normally will be operated. Or to put it another way, if constructed,

it seems backwards to then evaluate a permit for operation and find a system

inconsistent with District objectives. Such a finding should be made prior to

construction so that the project may be altered or redesigned to conform to

District objectives. Thus, in our view, the review process for construction

permit applications must also include operation and maintenance concerns. The

District needs to review whether the constructed system will be harmful to the

water resources and whether it will be consistent with the District's overall

objectives during the construction permit review process.

The second issue is related to the definition of "water resources." We

believe that one cannot separate the waters of the District from the overall

aquatic system when determining harm to the resource. The water resource must

include not only the abiotic substance (H20), but also the other abiotic

substances and the biotic organisms that are carried and sustained by it. The

water resource cannot be artificially dissected into parts which are regulated

separately (although it is attempted quite often, much to the detriment of the

resource); for as the water goes, so the organisms, and vice-versa.












TABLE OF CONTENTS

Acknowledgements . . . ii

Preface .. . . . .iii


I. INTRODUCTION . . .


A. The Concept of Buffer Zones . .

B. Buffers for Wetlands, Wildlife, and Water Quality. .

C. Intent and Scope of the Report . .

II. REVIEW OF THE LITERATURE .. . .

A. Significance of Buffer Zones . .

1. Ecological Significance of Transition Zones .
2. Physical and Ecological Significance of Wetland For
3. Water Quality Benefits of Buffer Zones .
4. Water Quantity Benefits of Buffer Zones .
5. Edge Effects on Wildlife . .
6. Regional Habitat Needs of Wildlife: Corridors .
7. Between-Habitat Needs of Wildlife . .
8. Within-Habitat Needs of Wildlife . .

B. Review of Buffer Zone Regulations . .

C. Summary: Resource Buffer Zones .. .

III. LANDSCAPE ECOLOGY OF THE WEKIVA RIVER BASIN.. .

A. Landscape Perspective . .

1. Physical Description . .
2. Biological Description . .


B. Wetland Communities .


. .1


.1

.2


.5

.7

.7

7
est Edges.. 11
.... 14
23
S. 26
S 33
S. 38
S 44

S 50

59

S 67

67

67
S 74
74


. . . .82


1. Aquatic/Marsh Communities. . . .82
2. Mixed Hardwood Swamp Community . .. .. 84
3. Hydric Hammock Community .... . .86

Transitional Communities: Mesic Hammock and Scrubby Flatwoods. 87

Upland Communities . . 87

1. Pine Flatwoods Communities. .. . ... 88
2. Wet Prairie Communities . . .. 90







3. Pine Sandhill Communities . . 90
4. Sand Pine Scrub Communities .. . 92

IV. STATUTORY & DISTRICT CRITERIA RELATED TO BUFFER ZONES .. 95

A. Statutory Criteria, Sections 373.413 & 373.416, FS .. 96

B. Rule Criteria, 40C-4, 40C-41 and 40C-42, FAC... 98

V. DETERMINATION OF BUFFER ZONE REQUIREMENTS.. .. .11

A. Overview of the Methodology for Determination of Buffer Zones. .111

B. Determining Buffer Zone Requirements . ... .118

C. Illustration of Buffer Zone Determinations . .. ... 128

LITERATURE CITED .. . . . .145

APPENDIX A. WILDLIFE ASSOCIATED WITH WEKIVA RIVER BASIN .. ...169














I. INTRODUCTION


I.A. The Concept of Buffer Zones


The landscape is a mosaic of uplands and wetlands, developed lands and

natural lands, and forests and fields. Somehow, without complete knowledge

about how these pieces fit together, society must make decisions concerning how

best to assemble the puzzle. Some decisions are easier than others, especially

when there are no conflicting elements. Unlike a puzzle, however, the ease of

adding a new land use to the landscape is inversely related to the number of

pieces already on the board. As more and more land uses are added to the

landscape, the decisions concerning placement require more and more thought.

The more pieces there are on the board, the more conflicts there will be

between pieces. Most often, it is at the borders between pieces where

conflicts arise. Decisions are easier to make when adjoining uses are not

significantly different, i.e., when the existing land uses abutting the

boundaries of a decision piece are similar to the proposed use of the piece in

question. However, when adjoining uses are significantly different,

consideration must be given to the interrelationships that are being created

and to how one piece might affect surrounding pieces.

When uses are significantly different, or where the potential for conflict

is serious, it is common practice to create a buffer between them. Thus we

have buffers around airports, nuclear power plants, and bombing ranges. De-

militarized zones (DMZ's) between warring nations are often used to maintain

peace. Zoning in urban areas uses successively lower-density districts to make

1







2

transitions between high-density land uses and low-density residential

districts. Buffer zones can be relatively narrow, like the grassed shoulders

of highways which separate high-energy roads from forested landscapes, or quite

wide, like the DMZ between North and South Korea. Generally, as the density of

activity or the potential for conflict increases, the width of the buffer

necessary to contain the negative effects increases proportionally. In

addition, as the difference in activity level between bordering land uses

increases, the width of the border must increase, since it is not the absolute

magnitude of activity but rather the relative magnitudes of activity between

neighboring uses that require buffering.



I.B. Buffers for Wetlands, Wildlife, and Water Quality

The differences between developed lands and wild lands are significant;

the more intensely developed, the more the differences. Frequently, on

developed lands the native vegetation is removed and replaced with exotics,

drainage is improved, soil is compacted or covered with impervious materials,

wildlife habitat is replaced with human habitat, and activity levels increase

10 to 100 times those found in the wild. The gradient in the intensity of

noise, wastes, temperature, light, structure, and activity from undeveloped to

developed lands is remarkable. It is this gradient that affects the edge

between developed and wild lands, creating a new environment unlike the

original and not at all similar to the developed land.

The edge between wild lands and developed lands is characterized by

overflows of materials and energy that "flow" from high density to low. Water

runs off developed land, carrying sediments and nutrients. Noise from

developed land intrudes into the edge, disrupts natural activity, and

interferes with the less intense communications of wildlife that are cues for









3

territorial protection and breeding. Increased temperatures caused by removing

tree canopy and paving the ground surface have marked effects on the forest

microclimate.

Edges are common in the landscape, with or without development. In the

wild landscape, however, sharp edges are hard to find. The lake edge is not a

clean line; as the water level rises and falls throughout the year, it creates

a littoral zone that is neither open water nor dry land, but somewhere in

between. The sea edge is buffered by estuaries and coastal wetlands, which

are neither open ocean nor dry land. The forest edge is a transition from the

mature canopy with moist soils and minimal understory through a zone of more

open canopy, with drier soils and dense understory, to the prairie with its

xeric soils and lack of woody vegetation.

As the landscape is developed, the wild lands that surround cities

retreat. If the world was a homogeneous flat plain and development happened as

a simple outward progression from the central city, the edge would constantly

be moving and little need would be generated for buffer zones between developed

lands and undeveloped lands. However, the world is not homogeneous, but

heterogeneous, having many differences, many patches, and many obstructions to

development. The development process becomes patchy, areas are skipped,

wetlands left, and parks created. Areas are set aside as wildlife habitat, or

protected for water quality purposes, or left undeveloped as remnants to remind

us of what the landscape was once like. The patches that are created in this

manner undergo constant change as they "evolve" or succeed toward ecological

communities that are islands in the developed landscape.

In Florida, under continuing growth pressure, the wild landscape has been

mostly developed, leaving behind large and small islands of managed national,

state, and local parks, along with many wetlands. Wetlands were first left








4

behind because their development required a relatively greater commitment of

funds and time than they were worth. Where the demand was high, in coastal

areas for instance, wetlands were converted into dry lands and developed.

Development skirted the swamps and marshes of inland areas not as a result of

comprehensive planning, but because of piecemeal decisions made on a project-

by-project basis. As land became more valuable and wetlands were threatened,

state and local governments responded to increased pressure by enacting laws to

protect the special values of wetlands recognized by society. Of primary

concern was their function for maintaining clean, productive surface water and

their value as very productive wildlife habitat.

In the minds of many, wetlands are now "protected." The Warren S.

Henderson Wetlands Protection Act of 1983 established state permitting

authority over activities in wetlands by virtue of the fact that they were

defined as waters of the state. A methodology for determining state waters,

developed as a rule (Ch. 17-4 FAC) by the Florida Department of Environmental

Regulation, was required by the Henderson Act. The rule uses vegetation as a

means of determining landward extent of state waters. Plant species normally

found in wetlands are sorted into three broad categories: submerged species,

transitional species, and "invisible" species. All plants not found on these

plant lists are considered upland species. The rule then uses simple formulas

that relate dominance of these species to determine the upland edge of "state

waters." It is important to note that at no time does the rule or the original

legislation (except in the name of the Act) delineate "wetlands". It only

refers to a selective list of plant species. The intent of the rule and

legislation is to protect state waters, which include areas that are dominated

by certain plant species that indicate regular and periodic inundation.

Wetlands can, and do, extend landward of this jurisdictional line.









5

The area immediately adjacent to and upland of the jurisdictional line is

often a transition zone between wetlands and uplands. It is a zone that is

wetland at times and upland at times, exhibiting characteristics of each and

vegetated by species that are found in each. It is important to both the

wetland and the upland as a seed reservoir, as habitat for aquatic and wetland-

dependent wildlife species, as a refuge to wildlife species during high-water

events, and as a buffer to the extreme environmental conditions of sharp

vegetated edges.

To protect the values and functions of areas that are waterward of the

jurisdictional line, attention must be given to the area immediately upland of

the line. Wholesale alteration of this edge has immediate and potentially

large-scale permanent impacts on the waterward area. Wetland-dependent

wildlife species that are frequent users of this area are excluded, silt laden

surface waters are no longer filtered, the microclimate is greatly affected and

groundwaters may be diverted or drained. In the natural state the transition

zone is a buffer zone both for the adjacent wetland and state waters and for

the wildlife species that inhabit them. It should be recognized as such, and

afforded some degree of development control.



I.C. Intent and Scope of the Report

This report is intended to provide a detailed review of the existing

scientific understanding of upland buffer zones, their importance to the

adjacent wetlands and waters, and the effects of alterations of these

transitional areas on downstream water quality and quantity, and wetland

wildlife habitat values. As we researched the topic, we found a dearth of

information directly addressing buffer zones. However, there has been much

recent interest in the literature concerning the impacts of edges on wildlife








6

habitat values, and some recent investigations of the extent and species

composition of transitional zones between wetlands and uplands.

The habitat values of transitional areas are related to between and within

habitat needs of wildlife, the water quality values of buffer zones are related

to protection of surface and groundwater, and their value related to water

quantity issues is in their ability to mitigate adverse drainage impacts.

The report is organized in five parts with an appendix that gives lists of

aquatic and wetland-dependent wildlife species that are characteristic of the

Wekiva Basin. After the Introduction, the second section reviews the

literature and summarizes and relates it to the concept of a resource buffer

zone. The third section gives a brief physical and ecological description of

the Wekiva Basin. The fourth section reviews the Water Management District's

statutory criteria (Chapter 373 FS) and permit criteria in 40C-4, 40C-41, and

40C-42 FAC and relates them to protection of the water resources of the Basin.

The fifth section develops a methodology for determining buffer zone

requirements.














II. REVIEW OF THE LITERATURE


II.A. Significance of Buffer Zones


II.A.1. Ecological Significance of Transition Zones

The zone that lies between what are unconditionally identified as uplands

and wetlands is a zone of transition (sometimes called an ecotone). In this

zone, environmental conditions resemble neither the true wetland nor upland,

but fluctuate and may resemble each during different times of the year or from

one year to the next. Plant species that characterize transition zones may be

an assemblage of both wetland species and upland species and may contain

species that are not found in either of the two adjacent zones. It has long

been held that highest species diversity occurs in areas of habitat overlap

(MacArther and Pianka 1966, Allen 1962, Ranney 1977).

The Florida Department of Environmental Regulation (FDER), in its rules

concerning the delineation and definition of landward extent of waters of the

state, recognizes three main categories of plants: submerged, transitional, and

"invisible" species (Ch. 17-4.022 FAC). In an area dominated by transitional

species, a preponderance of evidence that indicates it is regularly inundated

is necessary before the area is considered a state water. In other words,

without regular inundation, an area dominated by transitional species is not

considered state waters, and by inference, therefore not a wetland.

Under 17-4.022 FAC, Florida does not recognize purely transitional areas

as state waters, and as a result does not recognize them as important or

necessary for protection under the Warren S. Henderson Wetlands Protection Act

7







8

(Chapter 430 Florida Statutes). However, their ecological significance as

wildlife habitat and seedbanks, as well as their role in maintaining the

integrity of the adjacent wetland community, is unrelated to their

classification under 17-4.022 FAC. The FDER has chosen a cut-off based on

dominance of "submerged" species to delineate state waters. The line so

determined in most cases classifies all vegetation to the landward side as

uplands. Most transition zones are to the landward side of the FDER

jurisdictional line.

The role of transition zones as wildlife habitat for wetland-dependent

species will be reviewed in subsequent sections, as well as their role as

seedbanks. Generally, their ecological value stems from (1) direct use by

wildlife and (2) seed sources for plant species that are more upland in growth

requirements, yet are found within wetlands and are an important component of

the community. Transition zones occupy the key upland fringe and as a result

are the main source for seed material that contributes to the spatial

heterogeneity of wetlands.

Wetland communities are not homogeneous. They are heterogeneous

communities whose spatial variation in species composition is probably

controlled by topography and ultimately by periods of inundation. Higher areas

sometimes referred to as hummocks range in size from a few meters to several

hectares. Hummocks have fewer periods of inundation and water depths are

shallower, resulting in conditions that favor more mesicc" species. Lower

areas are favored by those species that are to7':ant of flooding. This

heterogeneity of the wetland landscape is oce of the key factcrs that gives it

its diversity and wildlife value. Wildlife values are greatly enhanced as a

result of the increased diversity of vegetation and undulating topography.








9

Studies of the Florida landscape indicate that the plant species diversity

in transition zones is higher than the diversity of either the adjacent wetland

or upland. Clewell (1982) found five community types on the Alafia River in

central Florida along a gradient from wet to dry of which the "Moist Mesic

Forest" seems to occupy that area that is transitional. The number of plant

species found in this community exceeded all others by 25%. In Gross's (1987)

study of 12 small-stream floodplain ecosystems in north and central Florida, 12

vegetation types were distinguished, using cluster analysis of which the three

most diverse appeared to occur most often in the transitional areas. Studying

methods for determining transition zones, Hart (1984) documented species

composition of the wetland to upland continuum of eight wetland community types

of north central Florida. She found that the transition zones were more

diverse than either the wetland or upland and were different physiognrmically

from adjacent wetlands, yet were "....aligned more closely with wetlands than

with uplands and were composed of species that tended to alternate between

wetland and transition zones." The width of transition zones varied from a

minimum of 10 m to a maximum of 30 m depending on the method used to delineate

the zone and the type of wetland.

Wildlife species richness shows direct spatial relationships to the

increased diversity of transition zones. Studies of forest edges (see Edge

Effects on Wildlife) have documented increases in species richness and density

of individuals within ecotones between habitats. Vickers et al. (1985) found

that species richness and abundance of herpetofauna were greater along the

edges of six wetlands in north central Florida than in either the wetland or

upland habitat. Harris and Vickers (1984) found that virtually all mammals,

because of their cursorial mode of locomotion and frequently herbivorous food

habits, reside in "peripheral" areas, i.e., the transition zones. When water







10

levels were increased, the movement of wildlife to the peripheral areas was

also increased, suggesting the important role that transition zones play in

providing refuge from wet-season increases in water levels in wetlands. The

ecotone seems to play an even more important role when surrounded by clearcuts.

Harris and McKlveen (1982) found a greater abundance and diversity of breeding

birds in the ecotone between cypress wetlands and clearcut areas than in the

ecotone between cypress and pinelands.

Classifying the bottomland hardwood ecosystem into five classes, Wharton

et al. (1981) represented the transition to upland communities as the fifth

class. They listed the importance of environmental factors to fauna in each

zone. Of the five classes, the transitional zone ranked highest in importance

overall and highest in 18 of 27 factors, among which are:

1. Retardation of "side flooding,"
2. Detritus source,
3. Diversity of oaks,
4. Availability of large variety of flora and fauna.
5. Diversity of forest strata,
6. Refuge from high water, and
7. Forage and cover for upland species.

The importance of the highest zones (transitional zones) of bottomland

hardwoods to detrital food chains of downstream systems has been documented

(Livingston et al. 1976, White et al. 1979). These studies showed that the

infrequent pulses of organic matter and detritus form the higher zones in the

floodplain after extreme flood and rainfall events correspond to peaks in fish

production.

Topography plays an important role in controlling the width of transition

zones. The transition zone between wetland and upland may be only a few meters

in width or may extend for several hundred meters. In areas of very low

relief, where the landscape has little or no slope, the transition zone may be

extensive and ill-defined; yet, in landscapes where slopes are more prominent,








11

the transition from upland to wetland may be far more abrupt. In studies of

the central Florida landscape (Brown et al. 1984, 1985, and 1986), transition

zones as wide as 30 m were delineated using species composition as the

controlling variable. Gross (1987) found community types using cluster

analysis that were dominated by transition zone vegetation on central Florida

streams as wide as 80 m, but 40-m zones were more common.



II.A.2. Physical and Ecological Significance of Wetland Forest Edges

When forest is cleared and some forested remnants are left, as when the

landscape is developed for agriculture or urban uses or clearcut during

silviculture operations, the remaining forested patches contain induced edge

where there once was a forest continuum. These forested tracts develop

characteristic edge habitats that differ from habitat of interior forests.

Ranney (1977), in a review of the literature on forest island edges, suggested

that edge habitat differed from interior forests in at least six ways:

1. Tree species composition,
2. Primary production,
3. Structure,
4. Development,
5. Animal activity, and
6. Propagule dispersal capabilities.

The importance of edge is in its effects on the forested habitat and

eventually on the suitability of the habitat for indigenous fauna. The

conditions created when the forest continuum is cleared have detrimental long

term consequences on the remaining forest system. Using current jurisdictional

lines (Ch. 17-4.022 FAC) to determine the landward extent of state waters and

given current development practices, the forest edge created between wetland

and developed upland will coincide with the jurisdictionally determined line of

regularly inundated wetland. In most instances this does not include

transitional zones to the landward side of the jurisdictional line. The








12

creation of an edge at this wetland/"upland" boundary opens the wetland to the

many changes associated with edge conditions.

When a forested edge is created through clearing and/or partial removal of

the forest canopy, steep gradients of solar radiation, temperature, wind speed,

and moisture are incurred between the relative extremes of the open land and

the forest interior (Wales 1967, 1972). Studies of characteristics of newly

created edges (Gysel 1951, Swift and Knoeerr 1973, Trimble and Tryson 1966,

Wales 1972, 1976) suggest that solar radiation is probably the most important

physical parameter influencing conditions at the forest edge. The forest edge

environment is characterized by increased solar radiation which in turn

increases temperatures and decreases moisture content of soils and relative

humidity when combines with effects of increased wind flows. Physical and

structural manifestations of these changes include increase of shade-

intolerant, xeric tree and shrub species and an increase of species associated

with early stages of succession (Gysel 1951, Trimble and Tryson 1966, Wales

1972).

Of particular importance is the effect of increased wind speed on the

newly created forest edge; especially when the edge is created at the

wetland/upland interface. A major consequence of clearcutting is the loss of

buffering of destructive wind speeds by the adjacent tree canopy. Tree wind-

throws are common along newly created edges since edge trees not exposed to

wind velocities of the open landscape are not structurally prepared for them.

Wetland trees do not have deep-rooted growth habits, but instead rely on a root

mat very near the soil surface to provide structural support in the relatively

low bearing-capacity soils of most swamps. Windthrows are relatively more

common in the deep organic soils of wetland ecosystems than in forested upland











communities because of soil instability and difficulty of trees to anchor

sufficiently.

The spatial effects of forest edge conditions are variable and are highly

dependent on the way the edge is maintained. Ranney (1977) summarizes the

spatial influences of newly created edges as between 5 and 20 m deep from the

forest edge toward the interior. In a study of microclimate on Ft. George

Island near Jacksonville, Florida, Hart (1985) determined that most of the

microclimatic change between cleared areas and a forest interior in north and

south directions occurred within 10 m of the edge, although on western facing

edges, 25 m was often required for equivalent microclimatic change. Hart notes

that the eventual closure of newly created edges by shrubs and vines will

ameliorate negative microclimatic conditions and suggests the planting of fast-

growing shrub species in some instances to speed up edge closure. Harris

(1984) discusses the "three-tree-height" rule of thumb for the distance over

which climatic effects of a surrounding clearcut will penetrate into an old-

growth stand. Related to average tree heights of Florida wetland ecosystems,

the three-tree-heights rule would suggest the penetration of influences as deep

as 70 m.

Conceptually, to maintain the integrity of the wetland community and to

insure faunal habitat for wetland-dependent species, buffers from 5 to 70 m in

depth are necessary. Clearing at the wetland edge opens the wetland to

significant changes. However, with a buffer that encompasses the transitional

zone on the landward side of the wetland, negative impacts can be avoided.

Changes in abiotic parameters (due especially to increased solar radiation

and wind) towards more xeric conditions along edges lead to corresponding

changes in plant and animal communities (see Table 9 in Lovejoy et al. 1986)

and in system properties such as nutrient cycling (Ranney 1977). Studies by








14

Levenson (1981) and Ranney et al. (1981) in Wisconsin have documented major

edge effects on the vegetation of forest islands. They found that climatic

structural edge influences extend at least 10 to 15 m into a forest on the

east, north, and south sides and 30 m on the west side. Once established,

characteristic edge associations composed of xeric-adapted and shade-intolerant

species act as sources of propagules that invade the forest interior; forest

islands below a certain size (about 5 ha in Wisconsin) may be entirely edge

habitat in terms of their flora and vegetation structure (Ranney et al. 1981).

Such changes may be essentially permanent. In Ohio, Whitney and Runkle (1981)

found that small but persistent environmental differences associated with

forest edges have greater long-term effects on tree species composition and

structure than did severe but relatively brief disturbances associated with

logging.



II.A.3. Water Quality Benefits of Buffer Zones

The water quality benefits of buffer zones are related to the ability of

the zone to abate destructive water velocities and quantities of pollutants

carried by surface runoff from uplands that may have a negative impact on

downstream water quality, flora, and fauna. Soils of transitional areas are

generally characterized by a low accumulation of organic matter (Gross 1987,

Clewell 1982) but have accumulations of organic debris on the order of 1 to 5

tons per ha, depending on vegetative cover (Hewlett 1982). This organic debris

can absorb about 98% of rainfall energy, miiiinizing erosion potential. Known

as litter detention storage, it disperses the energy of water that would

otherwise break bonds of soil materials and produces a slurry of mud and eroded

soil. The kinetic energy of sediment transport increases rapidly as the second

power of water velocity (Hewlett 1982) suggesting that as a slope increases or











loses obstructions (such as vegetation) to uninterrupted flow, erosion

potential increases dramatically.

Occupying topographic lows in the landscape, wetlands are particularly

susceptible to erosional deposition from higher grounds and to erosional

scouring as a result of increased water velocities from mismanaged upland

surface waters. Maintaining undisturbed vegetation in transition zones can

help to minimize these destructive forces. The Florida Division of Forestry's

Silviculture Best Management Practices (BMP) Manual 1979) recommends a

Discretionary Zone (DZ) for land occurring within 300 ft of a watercourse.

This 300-foot-wide strip of land is considered the zone most influential to

surface water quality. Recommendations are given for varying site

sensitivities regarding the intensity level of activities such as construction

of roads, site preparation, and harvesting practices. Within the DZ, two

Streamside Management Zones (SMZ) are further delineated: a fixed primary and a

variable secondary zone, each of which has been assigned special management

criteria. The primary zone is 10 m from the edge of the watercourse,l while

the secondary zone is from 10 to about 50 m from the water's edge. The width

of the secondary zone is determined by the soil and topographic characteristics

of the site. Within each of the SMZ's, recommendations for site preparation

and harvesting are given relative to slope and soil erodibility.

Since the main objective of Silviculture BMP's is to minimize negative

impacts on water quality, and since silviculture, by definition, is the


1Sometimes the border of the SMZ's are referred to as "...the edge of the
watercourse or lake..." (Florida Division of Forestry 1979); other times the
SMZ is "adjacent to perennially open waters" (Riekerk and Winter 1982); still
others as a "...strip of forest land surrounding all perennial streams and
lakes 10 acres or larger" or as "a vegetated strip adjacent to a
watercourse..." or as occurring "...along all perennial and intermittent
streams..." (Florida Division of Forestry 1979). A strict definition of the
watercourse's edge as related to 17-4 FAC may be important to help determine
from what point the SMZ should be applied.








16

management of forests for their wood fiber, the BMP's are designed to maximize

the forest area that can be harvested. If the goal was to minimize negative

impacts on state water resources,2 the primary and secondary zones would begin

at the wetland edge and extend upland. In this manner the zones would occupy

the area that is commonly termed the transition zone between upland and wetland

and would insure minimum impacts to state waters.

It is generally agreed that the more sensitive a site is to sediment

production, the wider the undisturbed vegetative buffer should be. Since

sediment production can result in the deposition of materials in locations

where they may have negative impacts, and since sediments provide a major

vehicle by which pollutants are transported, every effort should be made to

encourage the use of vegetative buffers to minimize sediment deposition in

wetlands and water courses. The width and efficiency are variable. Karr and

Schlosser (1977), relying on the work of Trimble and Sartz (1957), suggest a

minimum width of buffers for conditions encountered in "municipal conditions"

as 15 to 20 m for lowest (0 to 3%) slopes and as high as 80 m for slopes of

60%.

There has been much research on the effects of logging in close proximity

to streams, especially in the northwest United States. Erman et al. (1977), in

studies of logged landscapes with and without streamside buffers, found that

buffers were very important in minimizing negative impacts as a result of

erosion from logged lands, and that streams with narrow (less than 30 m)

buffers showed effects comparable to streams with no buffers. Generally, their



2Waters of the state are those lands that are regularly and periodically
inundated as defined by 17-4.022 FAC which includes areas dominated by
"submerged" wetland vegetation. Thus to protect state waters and achieve Best
Management Practices as they relate to these waters, the discretionary zone,
primary zone, and secondary zone should be measured as distance from the edge
of the wetland instead of the edge of the watercourse.








17

research on 62 northern California streams showed a strong correlation between

buffer width and stream community diversity index. Streams with highest

diversity indices had buffers greater than 50 m in width.

Streamside biffers in the high-relief landscapes that characterize most of

the continental United States are generally measured from the channel bank.

Where landscape relief is high, channel slopes are high, and associated

floodplain ecosystems are narrow; and as a consequence, streamside buffers

measured in this way probably adequately protect the resource. However, where

landscape relief is low, as in the Southern Coastal Plain, terrain is flatter,

stream channel slopes are lower, and associated riparian ecosystems are wider.

The measurement of streamside buffers in low relief landscapes needs to reflect

these important differences and begin at the upland edge of the riparian

ecosystem.



Effects of Construction Activities

Darnell et at. (1976) summarized the effects of construction activities on

riparian ecosystems and grouped them into three time related categories:

1. Direct and immediate results which take place during the
construction process;

2. Effects which occur during the period of stabilization
following completion of the construction; and

3. Long-term effects of more or less permanent changes
brought about by the construction itself or by
subsequent human use and environmental management occasioned
by the constructed facilities.

The water quality effects of construction activities within upland

boundaries of riparian ecosystems can be grouped into the same time-related

categories, although for the sake of simplicity, the first two may be combined.

The overall impacts of any construction activity vary depending on

environmental features (e.g., physical characteristics such as slope, soils,







18

and vegetative cover), timing, type of construction activity, and the care

taken during the active construction phases. Long-term impacts associated with

subsequent uses vary depending on environmental features, intensity of uses,

and management practices.

During and immediately following construction the major impacts on water

quality can be grouped into three broad classes:

1. Impacts associated with erosion of loose soils and their
subsequent deposition in downslope wetlands;

2, Suspended sediment increases in surface waters,
resulting in increased turbidity; and

3. Introduction of unusual levels of chemical compounds
that may have negative effects on resident fish and
wildlife populations.

The most obvious results of the deposition of eroded sediments in wetlands

are the impacts associated with filling. When wetland soils are covered with

additional depths of fill material, the most serious impact is loss of oxygen

penetration to the root zone and resulting stress on vegetation. If the accu-

mulation of sediment is deep enough, or if the sediment is fine enough to plug

up soil pores so as to effectively starve roots of oxygen, death of vegetation

results. Secondary impacts are experienced by wildlife as a result of the loss

of habitat.

The authors have on numerous occasions witnessed the results of inad-

vertent filling along wetland edges throughout Florida. In most cases these

results were caused by erosion of unstable soils during clearing and con-

struction activities. The deposition of eroded material resembles a wedge of

sediments where the bigger particles drop out of the sediment stream first and

successively finer materials drop out farther into the wetland system. Depths

of sediment are greatest along the periphery and taper off to shallower and

shallower accumulations as the sediment stream penetrates into the wetland. In







19

most instances the effects are immediate and dramatic. Where sediment depths

are greatest, both understory and canopy plants are killed, and as the sediment

wedge tapers off, tree kills are less noticeable, but the many varieties of

understory vegetation with their shallower root systems are killed. Finally,

at the farthest extreme of the sediment wedge, only the herbaceous vegetation

is affected.

The net result of the deposition of eroded sediments within the limits of

wetland communities is to shift the conditions of the transitional edge farther

into the wetland. Dead and dying vegetation is replaced over time by early

successional upland vegetation. The impacts are less a loss of water storage

capacity (since the volume of sediments may be small compared to the overall

volume of water stored in the wetland) as they are a loss of valuable wetland

function and wildlife habitat.

If the disturbed area is close enough to surface waters, or if the

configuration of the wetland is such that stormwater runoff from the upland

edge can collect and form an intermittent stream, sediments eroded during

construction phases may directly affect aquatic environments. In their review

of impacts of construction activities in wetlands, Darnell et al. (1976)

grouped the biological impacts of suspended and sedimented solids under the

topics of turbidity, suspended solids, and sedimentation. Within each group

they review the biological effects that have been documented in the literature.

Their review is summarized in Table II.A.I.

The final water quality effect during the construction phase is related to

the release of chemicals, the levels of which may be harmful to downstream fish

aand wildlife or negatively affect ecosystem function. When areas are cleared,

runoff increases, carrying with it increased volumes of soil and sediment.

Large quantities of dissolved cations and other minerals are lost from the











Table II.A.1 Biological Effects of Sediments and Suspended Solids on Aquatic
Environments (after Darnell et al. 1976)


Biological Effect


Turbidity






Suspended Solids
















Sedimentation


* Reduction of photosynthesis eliminates
phytoplankton, attached algae, and rooted
vegetation, thus eliminating base of aquatic food
chain
* Decreased visibility interferes with normal
behavior patterns of higher aquatic organisms

* Temperature effects water absorbs more radiant energy,
inhibiting vertical mixing in calm waters or uniformly
heating moving waters modifying oxygen content
* Oxygen reduction through inhibition of photosynthesis,
heating, or increased COD and BOD
* Reduction of primary production inhibits light
penetration, absorption of critical nutrients, removal of
algae and zooplankton from suspension through adherence to
particles
* Effects on respiration oxygen reduction can selectively
eliminate aquatic animals that require oxygen for
respiration, suffocation through clogging of gill filaments
* Other effects potential starvation of filter feeding
animals, decreased visibility, interference with migration
patterns of fish

* Primary production smothering and scouring, physical
barrier to gas exchange
* Bottom animals scouring and blanketing with sediments
* Fish populations reduction of food supply, destruction
of habitat, elimination of spawning areas, smothering of
eggs and larvae


Topic











cleared areas and deposited in downstream areas. Borman et al. (1968) found

cation losses from 3 to 20 times greater from clearcut watersheds than from

undisturbed control watersheds. Riekerk et al. (1980) showed significant

increases in sediment and higher nutrient cation loading of runoff from a

clearcut, relatively low-gradient watershed after one year, but no significant

differences after the second year. In watersheds composed of wet savanna

forests of Florida's Lower Coastal Plain, Hollis et al. (1978) recorded

significant loss rates of dissolved minerals including ammonium-nitrogen as

well as phosphorus and suspended sediments.

Of less concern, unless a large-scale accident occurs, is the increase in

petroleum products that may pass from construction sites into downstream

wetlands and watercourses. Spills in maintenance yards and the general

operation of equipment in and near wetlands increases the likelihood of

increased contamination. In all, however, contamination from petroleum

products during the construction phase should be of minor concern if proper

care is taken.

Effects of Operation and Maintenance

Long-term water quality impacts associated with construction activities in

areas adjacent to wetlands and watercourses is a function of subsequent human

uses and management. Stormwaters running off developed lands carry both

organic and inorganic materials, both suspended and in solution. Many of the

organic are degraded through biological pathways or through chemical

oxidation. As degradation occurs, oxygen is consumed causing decreases in

available oxygen. Thus the breakdown of these compounds "demands" oxygen.

Their presence and potential for negative water quality impacts is measured by

tests for Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD).











The final land use of a developed area has a marked effect on the quality

of stormwater runoff. The Florida Department of Environmental Regulation

(FDER) (1978) summarized the work of Sartor and Boyd (1972) that compared the

total solids loading from residential, commercial, and industrial land uses.

Industrial areas were shown to have the highest loadings and commercial areas

to have the lowest. Another stormwater study of three sub-basins (a forested,

a suburban, and an urban basin) of Lake Jackson in northern Florida as reported

in Wanielista (1975) and summarized by the FDER (1978) compared mean

concentrations for various constituents in stream water under stormflow and

baseflow conditions. The findings showed that the export from the urban

watershed was greater for all constituents than from the forested or suburban

watersheds, and that mean concentrations of suspended solid loadings from the

urban basins and suburban basins were approximately 10 times and 5 times,

respectively, those of the forested watershed.

In most time-related studies of the quality of urban runoff, a common

finding is the difference in concentrations of constituents between the initial

"first flush" and later runoff. Typically, the initial rainfall flushes the

stormwater system, carrying with it large quantities of suspended solids and

materials in solution. Later discharges have significant, but much lower,

concentrations of pollutants.

Stormwater management rules generally recognize the potential for

downstream water quality impacts from urban and suburban areas, and while there

is some variation in regulation throughout the state, generally they address

the problem through retention of a prescribed amount of the initial rainfall

from a storm event. This treatment method assumes that through retention of

the first flush, a majority of the constituents that would enter surface waters

are retained. However, most stormwater systems, while retaining this first










flush, accumulate the remaining stormwater in the same retention basin,

diluting initial concentrations with the added waters. Under these conditions,

if the rainfall event is large enough, the diluted first flush is discharged

along with remaining stormwaters to receiving water bodies. The net result is

little if any retention of the pollutant carried by the storm runoff.

Recently, more stringent regulations have been put into effect in the Wekiva

River Basin that require off-line retention to avoid this problem.

The problems associated with degradation of water quality as a result of

the operation and maintenance of a stormwater management system once a

development is in place may be little affected by a buffer requirement. The

potential impacts on water quality from the combined effects of increased

runoff and increased concentrations of pollutants that result from urbanization

are not so much functions of how close the developed areas are to wetlands and

watercourses as they are of land use, size of the development, and stormwater

system design. However, potential impacts from systems designed to allow

portions of a development to discharge without treatment may be mitigated

through a buffer requirement. In many instances, where slopes prohibit

stonrwaters to be collected into a system, portions of the lowest areas in the

development (typically those closest to and abutting the wetland/watercourse

edge) may discharge directly. A buffer requirement in these situations would

allow for some treatment of stormwaters if they were allowed to sheetflow

through the buffer area.



II.A.4. Water Quantity Benefits of Buffer Zones

The construction and subsequent operation of urban land uses within areas

adjacent to wetlands and watercourses affect the quantity and timing of waters

that flow over the lands and often surficial groundwaters beneath the developed








24

lands. The effects are the result of both construction-related activities and

operation and management-related activities. During construction, the volume

of runoff increases, since removed vegetation and surface accumulations of

organic matter can no longer act to retard runoff, and transpiration is greatly

reduced,

Studies of water yield from watersheds having varying degrees of clearing

show strong relationships between the amount of disturbance and water yield.

One study in north central Florida by Riekerk et al. (1980) found water yield

increases of 165% from a clearcut, highly disturbed watershed and over 65% from

a minimally disturbed watershed. In a later study Riekerk (1985) found 2.5-

fold and 4.2-fold increases in runoff from minimally and maximally disturbed

watersheds, respectively. In most studies, the effects of disturbance on

runoff volumes decreases markedly from 2 to 3 years after treatment as

vegetation again plays a role in the site's hydrologic balance. The net

effects of clearing are reflected in higher soil moisture levels which may

contribute to higher stream baseflow and greater direct runoff during storm

events.

Once vegetation has been removed, it is quite common for groundwater table

elevations to increase as a result of decreased transpiration. In areas of

existing high water tables, soils can become saturated and extremely difficult

to work without extensive "drainage improvements." Stormwaters are often

routed through temporary swales and ditches into downstream areas to minimize

flooding while drainage and stormwater systems are being constructed. Such

practices can add significantly to construction-related water quality impacts

and alter quantity and timing of surface water discharge.

Typically, areas immediately adjacent to floodplain and seepage wetlands

are dominated by seasonally high water tables. This is a predominate aspect of










the lands adjacent to the floodplain wetlands throughout the Wekiva River

Basin. Lowering of water tables to accommodate construction-related activities

and as a permanent consequence of development can reduce groundwater elevations

and intercept groundwater flows to adjacent wetlands. Of all the impacts of

development, when the mitigating effects on surface water of properly designed

retention/detention systems are taken into account, the loss and interception

of groundwaters has the most profound consequences. Drainage in areas with

high water tables is a widely accepted practice that allows development of

lands that would otherwise be difficult to develop. Positive drainage

"dewaters" the upper portions of the soil, which lowers the surrounding

groundwater elevations. The effects spread radially from the drainage system

with the actual amount of decline in water table elevation dependent on the

elevation of the drainage system and soil properties and topography of the

surrounding lands. Wang (1978) and Wang and Overman (1981) found the effects

of a 10-foot lowering of the groundwater table to extend up to 1 mile from

drainage ditches in south Florida. While this is probably not typical

throughout Florida, it does indicate the magnitude of the problem.

The impact of lowered water tables on adjacent wetlands is a reduction in

hydrologic function. Where adjacent wetlands are depressional wetlands that

intercept the groundwater table, lower water table elevations reduce depths of

surface waters and shorten hydroperiods. Under extreme conditions the wetland

may remain dry throughout the year. In areas dominated by seepage wetlands,

lowered water table elevations result in a reduction or even a cessation of

groundwater seepage and subsequent drying of the wetland. The long-term, wide-

scale effects of general drainage practices throughout the state have been

discussed by Brown (1986) and are pervasive. While immediate ecological

changes resulting from drainage are subtle--to the untrained eye, no change is







26

observable--the long-term consequences are loss of hydrological functions,

gradual replacement of wetland vegetation with upland types, and consequent

loss of habitat values for aquatic and wetland-dependent wildlife species.

The maintenance of setbacks or buffers in areas immediately adjacent to

wetlands and watercourses can have significant impact in minimizing these

effects. A properly sized buffer between construction activities and

downstream wetlands can slow down and filter runoff and mitigate the drawdown

effects of drainage ditches on adjacent wetlands. It cannot be stated strongly

enough that the lowering of water tables to accommodate development is probably

the single most important impact affecting adjacent wetlands, and that a

properly sized buffer will go a long way toward minimizing these impacts.



II.A.5. Edge Effects on Wildlife

The question of how wide a buffer zone must be to maintain biological

integrity cannot be answered without considering the problem of edge effects.

Edge is defined as the place where plant communities meet or where

successional stages or vegetative conditions within plant communities come

together (Thomas et al. 1979). Edge effects have been investigated intensively

in wildlife management ever since 1933, when Aldo Leopold's classic text was

published. Evidence of a positive edge effect (i.e., an increase in species

richness or density of individuals near an edge in contrast to adjoining

habitat types) has been reported for birds (Lay 1938, Beecher 1942, Galli et

al. 1976, Laudenslaver and Balda 1976, McElveen 1977, Gates and Gysel 1978),

mammals (Bider 1968, Forsyth and Smith 1973), and several other groups of

organisms.

Most of the early studies of edge effects were concerned with documenting

an increase in wildlife abundance near edges. They implied that managing land










to increase edge will also increase wildlife. Edge habitat has high cover

density and food availability for many animals, and it is an index of carrying

capacity for species that require two or more habitat types for survival

(Johnson et al. 1979, Thomas et al. 1979). Hence, Leopold (1933) described

game (wildlife) as "a phenomenon of the edge" because wildlife "occurs where

the types of food and cover which it needs come together." Subsequently, edge

became a fundamental principle of wildlife management (e.g., Allen 1962,

Dasmann 1964), and some wildlife management texts went so far as to urge

managers to "develop as much edge as possible" (Yoakum and Dasmann 1971).

Ghiselin (1977) suggested that an edge index based on the amount of edge or

ecotone present is useful as an indicator of relative animal productivity

between similar habitats.

.Unfortunately, these wildlife management recommendations were naive about

the consequences of edge management on nongame animals, on plant communities,

and on regional diversity patterns (reviewed in Noss 1983). In a management

context, there are two types of edge: inherent edge and induced edge (Thomas

et al. 1979). Inherent edge is a natural phenomenon that represents the

juxtaposition of community types and a continuum of successional stages in the

landscape mosaic. This natural heterogeneity is in large part a product of the

natural disturbance regime of fire, flood, treefalls, windthrows, landslides,

and other events (White 1979, Sousa 1984, Pickett and White 1985). Moreover,

this natural heterogeneity may be the primary determinant of wildlife

composition and diversity in a region (reviewed in Noss 1987).

Induced edge, on the other hand, is a product of manipulation of habitat

by humans. It is closely tied to the process of habitat fragmentation that

produces sharp contrasts between vegetation types. Simple geometry shows that

small habitat islands have larger edge-to-interior ratios than do similar








28

shaped large habitat islands. As a natural landscape is fragmented into

disjunct pieces of habitat in a sea of developed land, the proportion of edge

habitat in the landscape increases. Thus, species that are restricted to

habitat interiors gradually are replaced by species characteristic of edge

habitats. The latter species are generally opportunistic or "weedy" and do not

need reserves for survival (Diamond 1976, Whitcomb et al. 1976, 1981, Noss

1983). Conservation biologists therefore recognize that interior species

dependent on large tracts of undisturbed habitat should receive priority

attention in conservation plans.

The recognition of negative edge effects associated with induced edge was

a major breakthrough in wildlife ecology. Until the mid-1970s, the attention

of most wildlife scientists was focused on relatively small tracts of land

(i.e., on local diversity) and on the small subset of animal species that could

be hunted. Under these circumstances, induced edge habitat can be seen as

favorable. Species such as white-tailed deer, bobwhite quail, cottontail

rabbit, and ring-necked pheasant often increase under such circumstances, as

does the species list of individual management units. But if one focuses on

regional and global diversity, and on entire ecosystems (including nongame

animals and endangered species of plants), the negative consequences of induced

edge are all too clear. The end result is often a landscape that has lost its

native character and is dominated by weeds that are either alien to the region

or were previously restricted to recently-disturbed patches (Faaborg 1980,

Samson 1980, Noss 1981, 1983, Samson and Knopf 1982, Harris 1984, Noss and

Harris 1986).

The negative effects of induced edge are easier to understand when one

considers that edge is more than a one-dimensional boundary between habitat

types. Effects of an open, disturbed habitat penetrate some distance into an








29

adjoining wooded natural area; hence, edge has a width of influence. Much of

this influence is ultimately climatic. Lovejoy et al. (1986), summarizing the

status of their research on forest fragmentation and induced edge effects in

Amazonia, recognize an abiotic class of edge-related changes that includes

temperature, relative humidity, penetration of light, and exposure to wind.

The type of habitat on the outside of a forest edge will determine the

nature of edge effects. A general principle is that the greater the contrast

between habitat types, the greater the edge effect (Harris 1984). When a

forest is fragmented, the matrix which surrounds it is usually some type of

early successional habitat. (Housing subdivisions would generally fall in this

category.) This secondary successional habitat is a constant source of weedy

plant and animal propagules that invade the forest fragment and alter species

composition and relative abundances (Janzen 1983). Opportunistic animals that

achieve artificially high densities in the early successional habitat often

invade pristine areas, exerting abnormally high levels of trampling, browsing,

and seed predation; this can destroy a natural area as surely as can a chainsaw

(Janzen 1983, 1986). Bratton and White (1980) reported that manipulation of

habitat to support a huntable deer herd can result in heavy browsing in

adjacent natural areas and further endanger a number of rare plant species.

The effects of habitat fragmentation and induced edge on animal

communities (especially birds) has been particularly well studied over the last

two decades. Application of island biogeography theory (MacArthur and Wilson

1967) to habitat islands have led to recommendations for the design of nature

reserves. Nature reserves and forest fragments have been portrayed as islands

because they are patches of natural habitat in a matrix or sea of culturally

modified land (Terborgh 1974, Diamond 1975, Sullivan and Shaffer 1975, Wilson

and Willis 1975, Diamond and May 1976, Forman et al. 1976, Galli et al. 1976,








30

and many others). Most early work on this problem was essentially a

confirmation of the familiar species-area relationship (Arrhenius 1921, Gleason

1922, Preston 1960, 1962): larger pieces of habitat support more species.

There are many potential explanations for the species-area relationship. Three

general explanations are (1) larger areas support more kinds of habitats (and

thus more habitat-specific species), (2) larger areas offer bigger "targets"

for organisms dispersing across the landscape, (3) larger areas maintain larger

populations that are less vulnerable to extinction due to random or

deterministic population fluctuations, and (4) larger areas support animals of

large territory and home range size that cannot be supported in small areas.

Any one of these explanations is powerful enough to support the general

recommendation that nature reserves should be as large as possible (e.g., Soule

and Wilcox 1980, Frankel and Soule 1981, Schonewald-Cox et al. 1983, Harris

1984, Soule 1986).

The process of habitat fragmentation is accompanied by insularization of

fragments, i.e., isolated pieces of habitat surrounded by dissimilar habitat

begin to resemble islands in many of their ecological dynamics. Eventually,

fewer native species will be found in a habitat islands than in sample areas of

equal size within extensive blocks of habitat (Miller and Harris 1977).

Alternately, species richness may not change much, or may even increase, with

habitat insularization, but species composition will shift towards edge species

at the expense of area-dependent interior species. These edge species are

generally common in the developed landscape and do not need reserves of any

kind for survival (reviewed in Noss 1983).

In New Jersey, Forman et al. (1976) found that forest islands contained

more bird species than did sample plots of equal size within extensive forests,

but the additional species were primarily birds of the forest edge. Forest










interior birds were limited to the larger forest islands. Since then, the

changes in avifauna that occur with forest fragmentation have been th.oougihly

documented (for the most extensive treatment, see Whitcomb et al. 1981). In

Florida hardwood hammocks, Harris and Wallace (1984) documented area-dependence

in a number of bird species. In the Wekiva River bottomland hardwood foresc,

breeding bird species that have been shown elsewhere to be area-dependent and

vulnerable to negative edge effects include the red-eyed vireo and the Acadian

flycatcher, both near the limits of their ranges in this area (H. Kale, Florida

Audubon Society, pers. comm.).

More generally, the species most vulnerable to extinction in fragmented

landscapes are large animals with large home ranges (i.e., top carnivores),

ecological specialists, and species with variable populations that depend on

patchy or unpredictable resources (Terborgh and Winter 1980, Karr 1982, Wright

and Hubbell 1983). The characteristically small populations of these species

are vulnerable to problems related to environmental stochasticity, demographic

stochasticity, social dysfunction, and genetic deterioration brought on by

inbreeding or genetic drift (Frankel and Soule 1981, Shaffer 1981, Schonewald-

Cox et al. 1983, Soule and Simberloff 1986).

Biotic aspects of edge effects have played a major role in the ecological

deterioration that accompanies fragmentation. Some effects of edge on

vegetation were discussed above. Because animal communities respond to

vegetation structure (e.g., MacArthur and MacArthur 1961, Roth 1976), any edge-

related changes in vegetation will cause corresponding changes in animal

communities for a certain distance into a habitat interior. But there are more

insidious processes at work. The opportunistic animals that are attracted to

edge (or to the early successional habitat outside) often prey on, out compete








32

or parasitize interior species, sometimes with disastrous consequences, to the

latter's populations.

Most of the research on faunal deterioration near edges has been done on

birds. Whitcomb et al. (1976) provided evidence that, in areas where forest

has been reduced to isolated fragments, avian brood parasites (brown-headed

cowbirds), nest predators (small mammals, grackles, jays, and crows), and non-

native nest-hole competitors (e.g., starlings) are usually abundant in the

urban-agricultural matrix and often invade small forest tracts and narrow

riparian strips. Gates and Gysel (1978) found that a field-forest edge

attracts a variety of open-nesting birds, but such an edge functions as an

"ecological trap." Birds nesting near the edge had smaller clutches and were

subject to higher rates of predation and cowbird parasitism than those nesting

in either adjoining habitat interior. Brown-headed cowbirds, which were not

found east of the Mississippi River before widespread forest fragmentation, are

a particularly noxious species. Half or more of the songbird nests within 200

m of the edge may be parasitized, reducing reproductive success for some

species below the level of population sustainability (Brittingham and Temple

1983). Brown-headed cowbirds have been increasing in number and are moving

south in Florida, and they will undoubtedly become more problematic as forests

continue to be fragmented; meanwhile, the ecologically similar shiny cowbird,

which has caused severe problems in parts of the Caribbean (Post and Wiley

1976, Post and Wiley 1977), has been moving north and was reported in Florida

in 1986.

Experimental studies of nest predation have documented significantly

higher predation rates in small forests compared to large forests, in forests

surrounded by suburbs compared to forests surrounded by agricultural land, and

at decreasing distances to forest edge (Wilcove 1985, Wilcove et al. 1986).










This abnormally high predation rate is related to the artificially high

densities of many opportunistic animals near forest edges and in disturbed

habitats (including suburbs; Wilcove et al. 1986). A primary reason why these

opportunistic animals (which in Florida include raccoons, opossums, gray

squirrels, armadillos, house cats, and blue jays) achieve such high densities

is that the large predators (e.g., panthers, wolves, and bears) that once

regulated their populations have been extirpated or greatly reduced (Matthiae

and Stearns 1981, Whitcomb et al. 1981, Wilcove et al. 1986). The deleterious

effects of increased nest predation may extend 300 to 600 m inside a forest

border (Wilcove et al. 1986). More generally, Janzen (1986) suggests that

managers can expect serious edge effects (including problems related to heavy

use by humans and domestic animals) anywhere within 5 km of a reserve boundary.

The studies discussed above suggest that any forest tract has a "core

area" that is relatively immune to deleterious edge effects and is always far

smaller than the total area of the forest (Temple 1986). Relatively round

forest tracts with small edge-to-interior ratios would thus be more secure,

whereas thin, elongated forests (such as those along riparian strips) may have

very little or no core area and would be highly vulnerable to negative edge

effects.



II.A.6. Regional Habitat Needs of Wildlife: Corridors

A great deal of recent literature in the fields of island biogeography and

conservation biology has discussed the effects of inbreeding and genetic drift

on wildlife due to genetic isolation and small population sizes (e.g., Miller

1979, Soule 1980, Senner 1980, Wilcox 1980, and Franklin 1980). Inbreeding has

the effect of decreasing population heterozygosity (genetic variation) by

increasing the probability that progeny will receive duplicate alleles from a








34

common ancestor. This loss of genetic variation can have both immediate and

future implications for a species' survival. Inbreeding can lower species

vigor and fecundity within a few generations (Soule 1980). The very reduced

population of Florida panthers may be suffering from the effects of inbreeding.

All five males examined have had greater than 93% abnormal sperm (Roelke 1986).

Over the long term, inbreeding can also limit the ability of a population to

evolve to meet changing environmental conditions (Soule 1980, Harris et al.

1984).

Other literature has questioned the effectiveness of fragmented parks and

preserves in maintaining viable populations of animals which require large home

ranges or activity areas (Pickett and Thompson 1978, Lovejoy and Oren 1981,

Harris and Noss 1985, Harris 1984, Noss and Harris 1986, Noss [in press]). In

Florida, bears may range over 15,000 ac and bobcats over 5,000 ac. An otter

may require several miles of linear river and riparian habitat (Harris 1985).

To maintain viable populations of these and other far-ranging animals, large

blocks of land are needed.

One proposed management alternative for providing for these wildlife needs

is the use of wildlife corridors (Diamond 1975, Butcher et al. 1981, Forman and

Godron 1981, Harris 1983, Noss 1983, Harris 1984, Harris and Noss 1985, Noss

and Harris 1986, Wilcove and May 1986, Noss [in press]). Wildlife corridors

can be defined as strips or parcels of land which allow safe passage of

wildlife between larger blocks of habitat. This contiguity effectively

increases the size of protected lands and their ability to maintain viable

wildlife populations. Genetic variation is maintained because genetic material

is carried freely back and forth across the corridor and among large habitat

blocks by dispersing wildlife. Dispersing animals can recolonize areas which

have suffered from local extinctions (Fahrig and 1Merriam 1985). Large









carnivores such as panthers, bears, bobcats, and otters which require large

home range sizes would be free to continue their natural movement between

habitat blocks which would otherwise be rendered inaccessible to them by

physical barriers. They gain the increased resource base needed to support

top-level carnivores. In addition to serving as travel routes, corridors also

serve as habitat for some species.

Evidence of wildlife use of travel corridors comes from a variety of

sources at several scales. In the extreme, land bridges between continents

have historically acted as wildlife corridors (Simpson 1940, Simpson 1965).

The Bearing Sea land bridge allowed the migration of many animals, including

man, into North America from Siberia. The Isthmus of Panama similarly allowed

the migration of wildlife between North and South America. Other

paleontological research has pointed to the development of a broad, flat

corridor which formed along the Gulf coast of Florida during the glacial

lowering of the sea level. Webb and Wilkins (1984) found that during these

periods Florida's wildlife was highly influenced by fauna which had migrated

into Florida from South America and southwestern North America. Riverine

gallery forests in Brazil apparently act as mesic corridors which have allowed

Amazonian forest species to invade and become components of the xeric cerrado

fauna (Redford and da Fonseca, 1986).

On a smaller scale, habitat corridors have also been shown to be important

for wildlife. Riverine forest corridors are known to be important habitats for

many species. The maintenance of streamside strips of vegetation is an

important management tool for maintaining gray squirrel populations within pine

plantations (McElfresh et al. 1980). Turkeys have been successfully managed in

a mosaic of poor habitat (short-rotation pine plantations) by maintaining

hardwood and mature pine trees in travel corridors. These corridors allowed








36

the turkeys to move widely among foraging and roosting areas (Gehrken 1975).

Several species of birds have been found to regularly use fencerows and

hedgerows as safe travel routes (Bull et al. 1976). MacClintock et al. (1977)

found that a small forest fragment connected by a corridor to an extensive

forest block was characterized by birds typical of the forest interior, while

similar but isolated forest fragments were not. Johnson and Adkisson (1985)

noted that blue jays used vegetated fencerows as travel routes apparently

because they afforded some escape cover from hawks. Wegner and Merriam (1977)

found that small mammals and many birds travel more frequently along fence

hedgerow corridors than across open fields. Wildlife populations in isolated

blocks of forest have been shown to have lower growth rates than populations in

forest blocks tied together by corridors (Fahrig and Merriam 1985).

The relevance of wildlife corridor management to the Wekiva River Basin

lies in the presence of a large number of parks and preserves in the area.

Many wildlife species in Rock Springs Run State Reserve, Wekiva Springs State

Park, Lower Wekiva River State Reserve, and Kelly Park will be adversely

affected if an adequate corridor is not preserved. While several types of

corridors have been defined (Forman and Godron 1981), two are perhaps most

important for a discussion of the Wekiva River Basin. "Line" corridors are

narrow and are entirely edge habitat, while "strip" corridors.are wide enough

to maintain interior conditions. This distinction between edge and interior

habitat is important (see previous discussion on edge effects) as some interior

species cannot live or even migrate through extensive edge habitats (Forman and

Godron 1981). Edge effects are a function of corridor width. Beyond the

deleterious effects of edge, width also has other effects on corridor function.

A wide corridor may provide actual habitat for an animal while a narrower one

may simply provide a travel route. A study of cypress domes showed that










certain species of birds were excluded from smaller cypress domes (McElveen

1978). Stauffer (1978) found that bird species richness increased

significantly with the width of wooded riparian habitat, where some species

were restricted to wider strips. Tassone (1981) reported similar results from

a study of hardwood leave strips. Interior forest species such as Acadian

flycatchers were only infrequently found in corridors less than 50 m. Hairy

and pileated woodpeckers required minimum strip widths of 50 to 60 m, while the

parula warbler required at least 80 m. He suggested that leave strips must be

a minimum of 100 m on larger streams to take advantage of their intrinsic

wildlife value. Corridors which provide habitat should be much more effective

in connecting larger habitat blocks than those which only provide paths for

travel. Forman (1983) has stated that width is the most important variable

affecting corridor function.

An upland buffer along the Wekiva River floodplain would maintain the

width of the corridor, allowing it to function more efficiently as a wildlife

corridor. This would be particularly true where the river floodplain is

narrow. Narrow sections may act as barriers through which some animals are

reluctant to pass. An upland buffer would allow continued movement and provide

a refuge for some terrestrial wetland species during periods of high water. It

would also encourage use of the corridor by upland species which do not make

regular use of wetland habitats (Forman 1983).

In addition to providing dispersal pathways for animal wildlife,

floodplain corridors are also important in plant dispersal. Flood waters

collect and disperse large numbers of seeds from both wetland and upland plants

(Wolfe 1987, Schneider and Sharitz [in press]). This dispersal of upland seeds

may be very important in maintaining the diversity of upland plant species on

topographic highs or islands within the floodplain (Schneider and Sharitz [in








38

press]). Wharton et al. (1982) noted that these upland areas within the

floodplain are very important for wildlife habitat. Upland seeds carried onto

the floodplain originate in the wetland-upland ecotone and from smaller

tributaries feeding the river. Protection of this ecotone, which may extend 10

to 35 m in Florida (Hart 1981), and the adjacent upland would ensure continued

input of seeds to the floodplain.

In summary, width is probably the most important variable affecting

corridor function (Forman 1983). Several forest interior species are known to

be excluded when corridor width falls below a critical level, which is a

function of edge effects and home range requirements. Increasing the width of

the Wekiva River corridor by maintaining an upland buffer can only increase its

effectiveness in providing both a travel route for dispersing wildlife and

high-quality habitat.



II.A.7. Between-habitat Needs of Wildlife

Between-habitat needs refer to wildlife utilization of more than one

habitat type to fulfill their requirements. Several authors have substantiated

the close association and interaction of wildlife in wetland and adjacent

upland communities. Fredrickson (1978) reported that various species more

commonly associated with either wetlands or uplands depend on seasonal or daily

shifts into different habitat types to escape flooding, to forage, to disperse,

or to hibernate. Examples that he cited are turkey, river otter, swamp rabbit,

deer, bobcat, and gray fox. Other species such as raccoon, gray squirrel, tree

frogs, and many woodland bird species occur with similar frequency in both

wetlands and uplands.

Bottomland hardwoods are integrally coupled to the surrounding uplands

(Wharton et al. 1982). Terrestrial lowland fauna may be coupled to the








39

uplands; for example, deer base their home range in floodplains and graze in

uplands. Conversely, upland forms such as the black racer, slimy salamander,

and pine vole may use the floodplain during drydowns. Although many species

breed in both habitat types, their densities may differ considerably between

adjacent areas. However, the lower-density populations may serve as important

recruitment sources. The greenbelts of bottomland hardwoods also provide

routes for migration and restocking.

Many semiaquatic Florida turtles, such as the mud turtle and snapping

turtle, loaf and feed in marshes but need sandy upland sites to lay eggs

(Weller 1978). The river cooter is an example of a turtle which is largely

confined to water but must trek to adjacent uplands to deposit eggs (Patrick et

al. 1981). Documented cases of Florida aquatic turtles laying eggs several

hundred yards from a river are not uncommon (P. Moler, Florida Game and Fresh

Water Fish Commission, pers. comm.). Weller (1978) also indicated a need for

more information relating to the wetland-upland interface. He wrote, "Upland

areas often serve as buffers, nesting areas, or food resources for wetlands

wildlife but their relative importance is undocumented."

The eastern indigo snake is classified as a wetland species but frequently

occurs in dry, sandy areas (Kockman 1978). Speake et al. (1978) found that

indigo snakes concentrated on the higher ridges of sandhill habitat during

winter and moved down into streambottom thickets in summer. Shelter provided

by gopher tortoise burrows is critical to the survival of this snake while it

is in upland areas.

Many wildlife species need both uplands and wetlands to satisfy their food

requirements. Peak mast production occurs at different times of the year in

uplands and lowlands (Harris et al. 1979). Winter and spring is the fruiting

season for most bottomland species, while upland plants bear fruit in the








40

summer and fall. Correspondingly, both upland and wetland nesting birds often

concentrate in wetland areas during the non-nesting season (Wharton et al.

1981). Landers et al. (1979) found that black bears also respond to seasonal

differences in mast production. In North Carolina, they shift their food

preferences from predominantly bottomland species in the winter and spring to

predominantly upland fruits and nuts in summer and fall. Florida bears

primarily inhabit swamps in the center of the state but are long distance

travellers utilizing both wetlands and uplands (Williams 1978). They eat

acorns, palmetto berries and the terminal bud ("swamp cabbage") of the cabbage

palm.

Wild turkeys may be found in a variety of wet and dry habitats and

normally depend on acorns as a staple food in Florida. But they also have been

known to eat crawfish occasionally. (Wild turkeys were recently reintroduced

into the Rock Springs Run State Reserve on the Wekiva River.) During the 'egg-

laying season, female wood ducks eat a large percentage of invertebrates

obtained from the wetland-upland transitional areas (Fredrickson 1979).

Pileated woodpeckers nest and roost primarily in wet hardwoods and cypress

habitats but forage in uplands (Hoyt 1957, Jackson 1978). Conner et al. (1975)

did not find any pileated woodpecker nest trees farther than 150 m from water

in southwestern Virginia.

Jennings (1951) observed that gray squirrels in the Gulf Hammock region of

Levy County, Florida, were dispersed through all habitats while food was

plentiful in the fall. When red maple and elm began to bud and produce seed in

mid-January, the squirrels began to concentrate in the hvdric hammocks and

swamps to utilize this food source. As upland foods became available in the

spring and the lowland areas flooded, the squirrels moved to higher elevations.











Kantola (1986) found higher fox squirrel densities in ecotone or

transitional areas than in upland areas on the Ordway Reserve in Putnam County,

Florida. But she also reported that home-range size and use within ecotones

and uplands may vary with seasonal food abundance, reproductive activity, and

climate.

Between-habitat needs may vary among sites because of differences in

habitat quality. More than 33% of the 30 small vertebrates species caught by

pit-fall traps in the floodplain of the Chattahoochee River in Georgia were

classified as upland species (Wharton et al. 1981). In contrast, only 14% of

21 small vertebrates sampled by the same method along the Alcovy River in

Georgia received the same classification. This dissimilarity was attributed to

vegetation structural differences in the floodplain.

Numerous researchers have been interested in the response of small mammals

to flooding. Most studies concluded that floodplains were marginal habitats

for these species. However, Batzli (1977) found that Illinois floodplain

populations of the white-footed mouse were remarkably similar in density, adult

survival, and age structure to those in the adjacent upland areas. The

exchange of individuals between these two communities consisted mainly of a few

floodplain mice occasionally moving into the uplands. He suggested that mature

trees with abundant holes and cavities may be necessary refuges for small

mammal survival during flooding.

In a blackwater creek bottom in South Carolina's inner Coastal Plain,

Gentry et al. (1968) found that the abundance of the cotton mouse, short-tailed

shrew, and southeastern shrew were 2, 3, and 10 times greater, respectively, in

the bottomland hardwood than in the adjacent uplands. Golden mouse specimens

were collected only from the hardwoods.










Because wetlands are often the last lands to be developed, some species

normally considered upland wildlife are sometimes forced to adapt to wetlands

that can supply their habitat needs (Schitoskey and Linder 1978). When

uplands required by animals are destroyed, animals may concentrate in the

nearby wetlands. Ozoga and Venre (1968) reported that deer mice, which are

usually abundant in uplands, were also found in wetlands. White-tailed deer,

an edge species, is known to adapt well to the swamps and lowland areas (Verme

1961, Verme 1965, Sparrowe and Springer 1970). Weller and Spatcher (1965)

found that upland bird species such as the meadowlark and mourning dove nested

in unflooded portions of wetlands.

High densities of prey species also attract adaptable upland predators

such as the skunk, raccoon, and red fox: Bailey (1971) found that striped

skunk densities were greater in narrow wetlands than in adjacent uplands where

cultivation and other development adversely affected upland feeding sites.

This situation is suspected to cause an abnormally high predation rate on

waterfowl eggs by skunks.

Bobcats in the Welaka Reserve showed a preference for bottomland hardwoods

(Progulske 1982). More than 20% of the 269 recorded locations of two radio-

collared bobcats from July 1980 to December 1981 were in this type of overstory

habitat. Although the other locations were spread among seven different upland

habitat types, their need for wetlands is obvious.

Melquist and Hornocker (1983) found that although Idaho otters generally

followed stream beds, they often took shortcuts across peninsulas formed by

stream meanders. Overland travel of up to about 3 km was recorded. Extensive

cross-country movements considerably reduced the distance an animal would

normally have had to travel to reach the same destination by water. However,

these movements also subjected the animals to highway hazards. Three of nine










known mortalities were road-kills. In Great Britain, Chanin and Jefferies

(1978) reported that in some areas dead otters were found repeatedly at the

same location on roads over a number of years.

In a report that synthesized extant literature for southeastern bottomland

hardwood swamp habitats, Wharton et al. (1982) stated that bottomland animals

do not occur in the same distinct zonal pattern as plants ranging from aquatic

to upland ecosystems. Wetland wildlife inhabitants move freely into

irregularly flooded or dry zones over the year. They also noted that some

overlap among zones occurs, especially in the transitional areas characterized

by periodic annual flooding and a duration of flooding during a portion of the

growing season. Their examples of overlapping species that might occur along

the Wekiva River are mole salamander, slimy salamander, narrowmouth toad,

spadefoot toad, cricket frogs, chorus frogs, box turtle, five-lined skink,

southeastern five-lined skink, brown snake, garter snake, ribbon snakes, rat

snakes, kingsnake, southern black racer, coachwhip snake, barred owl, downy and

red-bellied woodpeckers, cardinal, turkey, common yellowthroat, wood thrush,

eastern wood peewee, white-breasted nuthatch, Swainson's warbler, carolina

wren, yellow-throated vireo, cotton mouse, golden mouse, short-tailed shrew,

least shrew, southeastern shrew, woodrat, marsh rabbit, pine vole, and eastern

mole.

The use of various bottomland hardwood ecological zones by wildlife

differs by species, season and flooding regime (Larson 1981). Some are site

specific during the breeding period while at other times they may use a broad

range of ecological zones. Larson also referred to many of the species

examples used by Wharton et al. (1981).

Many studies have documented utilization of adjacent uplands by wetland

wildlife species. Removal or alteration of this important habitat type could








44

destroy critical requirements for many species and thus render the riverine

system in that area no longer habitable for them.



II.A.8. Within-habitat Needs of Wildlife

Within-habitat needs refer to requirements of wildlife species within the

habitat areas they occupy. Habitat alterations and land use changes can affect

adjacent resident wildlife populations by fragmenting habitat to nonfunctional

sizes and shapes and by introducing disturbance factors above the tolerance

levels of some species. Because of the paucity of Florida-specific data, we

authors have included information from research conducted in other states.

Although not actual descriptions of local species/habitat relationships, there

is no reason to believe that similar situations do not exist in Florida.

Temple (1986) found that 16 of 43 bird species encountered on 49 Wisconsin

study areas occurred less frequently, if at all, in smaller-sized forest

fragments. Fragment-sensitive birds did not occur regularly in fragments that

were large in total area but lacked a secure core area more than 100 m from

edges at which forest adjoined non-forested habitat. Large stretches of linear

habitats without sufficient core areas were not utilized by sensitive species

which included three (hairy woodpecker, pileated woodpecker, and acadian

flycatcher) that have been recorded in a partial listing of Wekiva wildlife

residents (Florida Dept. of Environmental Regulation, 1983). Of the 13 other

sensitive species, it is highly likely that six (tufted titmouse, blue-gray

gnatcatcher, wood thrush, yellow-throated vireo, American redstart, and hooded

warbler) nest along the Wekiva and the remaining seven (least flycatcher,

veery, chestnut-sided warbler, cerulean warbler, ovenbird, mourning warbler,

and scarlet tanager) overwinter along the Wekiva. Stauffer and Best (1980)








45

predicted that the scarlet tanager would be absent from riparian strips in Iowa

less than 200 m wide.

Galli et al. (1976) and Stauffer (1978) found the number of breeding bird

species increased significantly with the width of wooded habitats in New Jersey

and Iowa. Of the 46 species recorded in New Jersey, 18 were size-dependent

species, limited to a particular range of forest sizes from the largest down to

a specific minimum size. The minimum areas varied from 0.8 to 10.3 hectares

and are considered characteristic of each species. As the habitat size

increased, new species appeared when their minimum habitat size requirements

were fulfilled. An example of a size-dependent species that requires a large

wooded riparian habitat is the red-shouldered hawk. This species, which is a

common year-round resident in Florida, was not found in any of the New Jersey

sites less than 10.3 hectares (about 25 ac). Of the 32 species that occurred

in Iowa wooded riparian habitats, 16 restricted breeding to relatively wide

plots.

Bird species diversity is also strongly influenced by vegetation

composition and structural heterogeneity or diversity within a habitat type

(MacArthur et al. 1962, MacArthur 1964, Weller 1978). This type of

heterogeneity is a function of foliage height and cover diversity. The

vertical and horizontal stratification of plants within a forest habitat is

positively correlated with the number of bird species that reside there.

Therefore, land-use conversion of the most diverse portion of a wooded riparian

habitat would have significantly greater negative impacts on the overall avian

community than conversion of the least diverse portion. Transition or ecotone

areas containing both wetland and upland plant species are typically the most

diverse (Wharton et al. 1982).










Fragment-sensitive species or species that require large tracts of

undisturbed, closed-canopy forest are also referred to as interior species.

Tassone (1981) found that many forest interior bird species in Virginia were

most common in riparian buffer widths above a mean value of 62 m, and certain

species occurred very infrequently below different minima. Examples are the

northern parula (80 m), yellow-throated vireo (70 m), Louisiana waterthrush (60

m), hairy and pileated woodpeckers (50 to 60 m), and acadian flycatcher (50 m).

All of these species also breed in Florida's riparian areas. Tassone (1981)

concluded that several other species, observed too infrequently to estimate

width requirements, may also be sensitive to buffer width. He suggested:

Until more extensive research is done, strips should be left 60 or
more meters in width if it is desired to provide breeding habitat for
these species. They should also be situated as corridors between
other hardwood and pine-hardwood stands whenever possible. Strips
located on larger streams should be 100 or more meters in width to
make full use of the intrinsic wildlife values associated with the
riparian zone.

Small and Johnson (1985) recommended that riparian buffer strips be 75 m

wide to protect woodland bird communities in Maine. Johnson's (1986) study of

the tolerance levels of some woodland breeding species supported this

suggestion.

Fragmentation also affects squirrel populations. In an eastern Texas

study of clearcut effects conducted two to four years after tree harvest, gray

and fox squirrels were abundant in mature woody riparian zones wider than 55 m

but were rare in riparian zones narrower than 40 m (Hedrick 1973). The highest

squirrel density index was calculated for the widest stringer study plot (185

m),

The home-range size requirement for an individual gray squirrel is about

two acres (Burt and Grossenheider 1964). Larger Wekiva wildlife residents

require larger areas. For example, home-range sizes for individual gray foxes










and bobcats in Welaka, Florida, is about 625 and 4,580 ha, respectively

(Progulske 1982). Any actions that reduce suitable contiguous habitat below

these home-range sizes will prevent individual animals from occupying those

areas. Of course, viable self-sustaining wildlife populations require

considerably larger home ranges than do of individuals.

Aside from the fragmentation factor, various human activities may alter

behavior patterns or cause undue stress to some wildlife individuals in

adjacent habitats. This is a relatively new aspect of wildlife biology, and

very little research data are available regarding .the effects of specific human

activities on different wildlife species.

Noise associated with construction, operation, and maintenance of

developments can cause harmful impacts on wildlife. Animals that rely on their

hearing for courtship and mating behavior, prey location, predator detection,

homing, etc., will be more threatened by increased noise than will species that

utilize other sensory modalities. However, due to the complex

interrelationships that exist among all the organisms in an ecosystem, direct

interference with one species will indirectly affect many others.

Unfortunately, few data are available that demonstrate the effects of noise on

wildlife. Much of what is found in the literature lacks specific information

concerning noise intensity, spectrum, and duration of exposure.

A few laboratory studies have documented decreased nesting and aversion

reactions of small mammals in response to various sound frequencies (Sprock et

al. 1967, Greaves and Rowe 1969). Other research has focused on the use of

noise for damage or nuisance control. Diehl (1969), Crummett (1970), Hill

(1970), and Messersmith (1970) reported on the success of using sound to repel

rodents, bats, rabbits, deer, and birds.










The Environmental Protection Agency (1971), Ames (1978), and others have

reported on the physiological responses of laboratory and farm animals to

different noise stimuli. These data suggest that chronic sound may cause

stress on wild animals which in turn may affect reproduction.

Most people can easily relate to auditory interference, annoyance, hearing

damage, sleep interference, and stress-related effects of noise. And in

response to public demands, many noise-control ordinances have been enacted to

reduce these adverse impacts. However, it is doubtful that these laws

sufficiently protect wildlife species.

van der Zande et al. (1980) found that breeding densities of three open

grassland bird species were significantly reduced within 500 m of quiet rural

roads and 1,600 m of busy highways in The Netherlands. They suggested that

disturbance is also caused by farms, other buildings, and plantations.

Although Robertson and Flood (1980) found no significant differences in

several vegetation variables between developed and undeveloped sites along

Ontario shoreline areas, bird species diversity was negatively correlated with

disturbance. A greater number of species was found in the natural areas than

along shorelines where cottages were present and boat use was high. Several

species which also nest in Florida (yellow-billed cuckoo, yellow-throated

vireo, American redstart, and pileated woodpecker) were more abundant in, or

restricted to, the less disturbed transects.

The Florida Game and Fresh Water Fish Commission is in the process of

developing habitat protection guidelines for threatened and endangered species

to provide land-use decisionmakers with recommendations and management

practices that would integrate protection for these habitats in the context of

large-scale developments. Many of these recommendations will address within-

habitat needs such as those identified in The Recovery Plan for the Bald Eagle








49

in Florida (Murphy et al. 1984). This U.S. Fish and Wildlife Service document

states that no human activity should occur within 750 ft (250 m) of active

eagle nests and that the building of housing developments should be restricted

within 750 to 1,500 ft (500 m) of active nests. Potential bald eagle nesting

sites are currently abundant along the Wekiva.

Predation and harassment of wildlife by cats and dogs are other

detrimental effects of development adjacent to wildlife habitat areas.

Although relationships between domestic animals and wildlife are not fully

understood, there is enough information in the literature to justify a

legitimate concern. Several authors have documented the occurrence of wildlife

prey in the diets of free-ranging cats and dogs and the effects of their

predatory behavior on individual wildlife animals and populations (Errington

1936, McMurry and Sperry 1941, Bradt 1949, Hubbs 1951, Parmalee 1953, Eberhard

1954, Korschgen 1957, Smith 1966, Corbett et al. 1971, Gilbert 1971, Jackson

1971, Gavitt 1973, George 1974, Gill 1975, van Aarde 1980).

Cats can be especially devastating on local wildlife populations. Hunting

is a feline instinct, and predation rates are not related to hunger (Davis

1957, Holling 1966, Holling and Buckingham 1976). Bradt (1949) reported that a

single cat, who regularly consumed domestic food, killed over 1,600 mammals and

60 birds in Michigan during an 18-month period.

van Aarde (1980) found that free-ranging cats associated with households

utilized open fields, edges, and timber areas. Home range sizes for females

and males were 30 to 40 ha (about 100 ac) and four to eight square km (about

four sections), respectively. In an Illinois study, the average home range for

females and males was 112 and 228 ha, respectively (Warner 1985). These free-

ranging rural cats spent about 40% of their time on farmsteads. Approximately








50

73% of the radiolocations of these cats occurred in edge areas such as

roadsides, field interfaces, farmstead perimeters, and waterways.

Beck (1973) reported that the average home range for free-ranging dogs in

Baltimore was about four acres. Schaefer (1978) reported that dogs in rural

Iowa traveled up to two miles to kill pastured sheep.

Alteration of natural vegetation or other components of wildlife habitat

may make modified areas unsuitable for some species. As these unsuitable areas

encroach upon natural areas, core habitat fragments become smaller and the

number of supported species is reduced. Various forms of disturbance can also

adversely affect adjacent wildlife populations. An upland buffer would reduce

or eliminate negative disturbance impacts associated with development.



II.B. Review of Buffer Zone Regulations

In this section methods and models for determining requirements and

physical dimensions of buffer zones are presented. Buffer zones are normally

considered to protect quality and wetland-dependent wildlife and to reduce the

potential for negative impacts on a wetland resulting from adjacent upland

development.

The determination of buffer requirements (i.e., widths in relation to land

use, soils, topography, etc.) for the most part are not quantitative, but rely

on what is felt to be qualitative evidence for the necessity of buffering

development impacts. Never-the-less, there are numerous rules and regulations

that have been promulgated throughout the country that require buffers around

wetland areas.









The Pinelands Area

One of the most noteworthy buffer zones is that developed by the New

Jersey Pinelands Commission. The Pinelands Area (also known as the Pine

Barrens) is an area of about 445,000 ha of an interrelated complex of uplands,

wetlands, and aquatic communities in southeast New Jersey. It is a largely

undeveloped region within the Northeast Urban Corridor and was designated as

the country's first National Preserve in 1978. In the next year the State of

New Jersey passed the New Jersey Pinelands Protection Act that in essence

called for the preservation, protection, and enhancement of the significant

values of Pinelands land, water, and cultural resources.

In response to both federal and state legislative mandates, the Pinelands

Commission developed a Comprehensive Management Plan to preserve and protect

the unique and essential character of the Pinelands ecosystem. In the plan,

wetlands protection is fostered through a regional land allocation program, a

land acquisition program, and a wetland management program. The management

program prohibits most development within wetlands and also requires an upland

buffer around wetlands. The required "transition or buffer area" established

between proposed development and adjacent wetlands measures 300 ft wide, and

except for those regulated uses which have been described, no development may

occur within the area.

Rationale for the width of the Pinelands buffer is derived from areal

nutrient dilution models (Harlukowicz and Ahlert, 1978; Trela and Douglas, 1979

and Browne 1980) that were used to predict the travel distance necessary for

groundwaters laden with nutrients (from septic tank leachate) to be diluted to

background levels. Depending on the values used for input variables to the

model, it predicted distances to attain background concentrations of 2 mg/1

NO3-nitrogen of between 325 ft and 600 ft.










Since the implementation of the Pinelands Comprehensive Management Plan,

327 development applications that involved wetland issues have been reviewed by

the Pinelands Commission. More than one third of these were considered

inconsistent with the plan because they proposed development within wetlands or

within 300 ft of wetlands (Zampella and Roman, 1983).

Figures compiled by Zampella and Roman (1983) show that more than over

half of the development applications that involved wetland issues were

consistent with the wetland management provisions of the plan. However, among

the conditions imposed on these projects was the need to establish and maintain

a buffer adjacent to wetlands. Approximately one third of these applications

were required to maintain the maximum buffer of 300 ft, while the remainder

were required to maintain variously sized buffers which averaged about 135 ft

in width.

The Pinelands scheme of determining wetland buffers uses a Wetlands Buffer

Delineation Model that evaluates relative wetland quality, and relative impacts

of development. Prior to evaluating wetland quality a determination of the

presence of threatened or endangered species is made, and if the wetland is

known to support resident and/or breeding populations and if the wetland area

is critical to their survival, the wetland is ranked having the maximum

relative wetland value index and is, assigned a buffer of 300 ft. The

following qualities, values, and functions are evaluated as part of the

wetlands evaluation scheme and are evaluated after determination of presence of

threatened and/or endangered species is made:

Vegetation quality,
Surface water quality,
Potential for water quality maintenance,
Wildlife habitat, and
Socio-cultural value.











Each of the five general factors listed above has a score from I to 3,

where 3 is high value. A wetland is scored for each factor, and scores are

summed and divided by 5 to obtain a Relative Wetland Value Index.

Next, Potential for Impacts is evaluated by ranking the following factors:

Potential for site-specific wetland impacts,
Potential for cumulative impacts on a regional basis, and
Significance of watershed-wide impacts.

Once ranked, the scores for each of the potential impact factors are summed and

divided by 3 to obtain an average score for the Relative Potential for Impacts

Index.

To assign buffer areas, the final step is to average the Relative Wetland

Value Index and the Relative Potential for Impacts Index to obtain a Buffer

Delineation Index. Thiqsfinal index is used to determine the buffer distance

in three different Land Capability Areas using a table of assigned values.

The strengths of the methodology are: (1) Wetland attributes and the

potential for on- and off-site impacts are evaluated for each individual

wetland and each development proposal on a case-by-case basis. Depending on

the type of wetland, existing terrain, existing land use designations, and type

of development, the buffer varies from a minimum of 50 ft to a maximum of 300

ft. (2) The method is quantitative and repeatable thus insuring some degree of

consistency. (3) It does not require detailed scientific information about a

wetland.



State of New Jersey

The House of the State of New Jersey has passed a bill whose short title

is "Freshwater Wetlands Proctction Act." As of this writing the State Senate

has not acted upon the bill the ace would establish

...a transition area adjacent to all wetlands having the following
purposes:











(1) Ecological transition zone from uplands to wetlands which is an
integral portion of the wetlands ecosystem providing temporary refuge
for wetlands fauna during high water episodes, critical habitat for
animals dependent upon but not resident in wetlands, and slight
variations of wetland boundaries over time due to hydrologic or
climatic effects:

(2) Sediment and stormwater control zone to reduce the impacts of
development upon wetlands and wetland species.

The bill would also establish the width of the transitional area as no greater

than 150 ft and no less than 75 ft for freshwater wetlands of exceptional

resource value, no greater than 50 ft and no less than 25 ft for freshwater

wetlands of intermediate resource value, and no transitional area for wetlands

of ordinary resource value. The act prohibits the following activities in

transition areas:

Removal, excavation or disturbance of the soil;
Dumping or filling with any material;
Erection of structures;
Placement of pavements; and
Destruction of plant life which would alter the existing pattern
of vegetation.



New York State Wetlands Protection Act

The recent adoption of the Freshwater Wetlands Act (6 NYCCR) protects

wetlands 12.4 ac or greater in size. The Act recognizes ten specific functions

and benefits which freshwater wetlands provide for the public and for the

environment. To achieve the goals of the Act to protect, preserve, and

conserve New York's freshwater wetlands, the statute makes provisions for

mapping, classification, regulation and local government protection. The act

provides for the regulation, of a 100-foot buffer adjacent to wetland

boundaries. Provisions exist in the law to extend the 100-foot adjacent area

if necessary to protect the wetland.










California Coastal Act of 1976

The California Coastal Act (Public Resources Code, Division 20)

established the California Coastal Commission which in turn prolmugated the

Statewide Interpretive Guidelines (SIG) to assist in the application of various

Coastal Act policies to permit decisions. The SIG has set standards for siting

development adjacent to environmentally sensitive habitat areas (ESHA).

Wetlands are considered environmentally sensitive habitat areas, as are

estuaries, streams, riparian habitats, lakes, and portions of open coastal

waters. "Adjacent to" is defined as situated near or next to, adjoining,

abutting, or juxtaposed to an ESHA. This usually means that any proposed

development in an undeveloped area within of up to 500 ft of an ESHA will be

considered to be adjacent and subject to critical review.

Criteria for establishing buffer areas around ESHA's are designed to

provide essential open space between the development and the ESHA. Development

allowed in a buffer area is limited to access paths, fences necessary to

protect the habitat area, and similar uses which have either beneficial effects

or at least no significant adverse effects. The buffer is not itself part of

the ESHA, but it is a "screen" that protects the habitat area from adverse

environmental impacts caused by development. Widths of buffer areas are

variable depending upon site analysis. It is usually a minimum of 100 ft;

however, it may reduce for small projects (defined as single family home or one

commercial office building). Additionally, provisions are suggested that the

100 ft may be reduced if the applicant can demonstrate that it is not necessary

to protect the resource. Standards for determining the appropriate width of

the buffer area:

I. Biological significance of adjacent lands,
2. Sensitivity of species to disturbance,
3. Susceptibility of parcel to erosion,
4. Use of natural topographic features to locate development,










5. Use of existing cultural features to locate development,
6. Lot configuration and location of existing development, and
7. Type and scale of development proposed.



Humboldt County, California

Humboldt County's Southcoast Plan defines riparian corridors and limits

development within them. It defines riparian corridors to include the uplands

on both sides of streams as follows:

Riparian corridors on all perennial and intermittent streams shall
be, at a minimum, the larger of the following: (i) 100 ft, measured
as the horizontal distance from the stream transition line on both
sides; (ii) 50 ft plus four times the average percent of slope,
measured as a slope distance from the stream transition line on both
sides; (iii) where necessary, the width of riparian corridors may be
expanded to include significant areas of riparian vegetation adjacent
to the corridor, slides, and areas with visible evidence of slope
instability, not to exceed 200 ft. (Humboldt County Planning
Department 1981, as cited by Ray et al. 1984)

Uses in the riparian corridor have been limited to minor facilities,

minimal timber harvest, maintenance of existing facilities, residential wells,

road and bridge replacement, and tree removal for disease control. There must

be, at a minimum, replanting of vegetation for any approved disturbance, and

any trees that have visible evidence of current use as nesting sites by hawks,

owls, eagles, osprey, herons, or egrets must be retained.



Massachusetts Wetlands and Floodplain Protection Act

The Massachusetts Wetlands and Floodplain Protection Act recognizes three

types of wetlands: 1) land areas bordering water bodies; 2) land under water

bodies; and 3) land subject to tidal action, coastal storm flowage, or

flooding. These wetlands must border on a listed water body with 50% or more

wetland vegetation or within the 100-year floodplain. Permits are required for

virtually any development activity in, near, or affecting jurisdictional areas.

Work within a 100-foot buffer zone around wetlands may require a permit since








57

the Act defines "bordering" as a distance of 100 ft. The regulation provides

that the extent of protection is to be 100 ft landward from wetland resources

or 100 ft landward from the water elevation of the 100-year flood, whichever is

greater.



Rhode Island Coastal Resources Management Program

The General Laws of the State of Rhode Island, Title 46, Chapter 23,

establishes the Coastal Resources Management Council (CRMC). The CRMC has

developed the Coastal Resources Management Program. The Program establishes

setbacks ranging from 50 to 180 ft from the inland boundary of coastal features

such as beaches, wetlands, cliffs, banks, rocky shores, and existing manmade

shorelines and apply to the following activities:

Filling, removal, grading;
Residential buildings;
Sewage disposal systems;
Industrial, commercial, recreational structures; and
Transportation facilities.

The setback minimum in areas not designated as Critical Erosion Areas is 50 ft,

and within Critical Erosion Areas it is 30 times the calculated average annual

erosion rate, which has been determined to vary between 75 and 180 ft.

In addition to setback requirements, the program establishes Buffer Zones

defined as land areas on or contiguous to a shoreline feature that is retained

in its natural and undisturbed condition by the applicant. Buffer zones must

be tailored to on-site conditions and the specific alterations and activities

that are taking place. Further, the determination of the boundaries of a

buffer zone need to balance the property owners' rights to enjoy their property

with the Council's responsibility to preserve and, where possible, to restore

ecological systems. There are four benefits of buffer zones as follows:

1. Erosion control,
2. Preventi.-n of water body pollution,










3. Preservation and enhancement of scenic qualities, and
4. Protection of flora and fauna.

The buffer zones are established according to values and sensitivities of the

site as assessed by the Council's staff engineer and biologist, and the area

may be wider than the setback distance. The buffer must be maintained by the

applicant as an undisturbed area and in its natural condition.



Marion County, Florida

The Board of County Commissioners of Marion County, Florida adopted an

emergency ordinance (Marion County Ordinance No. 73-4) in June of 1973

"...prohibiting dredging, filling, earth moving, and
landclearing, and underbrushing except mowing, pruning, and
care of existing lawns and planted trees and shrubs for a
distance of 500 ft from the water's edge upon either side
of Rainbow River or Blue Run in Marion County, Florida,
between Rainbow Springs and the northern city limits of the
city of Dunnellon...."



Cross Creek Buffer Requirement

In an amendment to its Comprehensive Plan, the Alachua County Commission

adopted a 300-foot setback line from lakeshores for most development in a

designated area in the southeast part of the county known as Cross Creek. The

only construction allowed within the setback zone are structures such as docks

built for access to the lake. The setback line is measured upland from the

jurisdictional line set by the Department of Environmental Regulation or the

St. Johns River Wacer Management District, or, where the lakeshore has been

cleared, from the 100-year floodplain line. The setback width of 300 ft was

determined qualitatively. The plan amendment is currently being rewritten. A

new version expected to be completed by the second week of October 1987, may

require a variable setback line based on such factors as soils, slope, habitat,










and groundwater, with a minimum setback of 75 ft. (John Hendricks, Alachua

County Department of Environmental Services, pers. comm.)



Hillsborough County Wetland Buffer Requirement

A 30-foot buffer around "conservation areas" and a 50-foot buffer around

"preservation areas" are required by Hillsborough County. The former category

includes most freshwater wetlands and Class III waters; the latter includes

saltwater wetlands, Class I waters, and critical habitats. These categories

originated in the Conservation Element of the county's Comprehensive Plan

adopted in the mid-1970s. That document set a policy to require "appropriate

buffers" around those areas, but no width or formula to calculate width was set

forth. However, in the definition of "natural shoreline"--another category of

conservation area--a 30-foot width was mentioned as one way to delimit natural

shorelines, and that number was applied by county zoning staff in rezoning

applications involving freshwater wetlands. The larger buffer was required

around preservation areas because they are considered to be more sensitive than

conservation areas, but no formula was used to establish that width.

Both buffers were adopted by the Hillsborough County Commission in a 1985

ordinance (revised in 1987) and as part of its zoning code. A variety of uses

are permitted within the buffer zone, such as detention ponds, stilted

structures, and boardwalks, but impervious surfaces are prohibited. Removal of

natural vegetation is discouraged but not prohibited. (Charner Benz,

Hillsborough County Planning and Growth Management Group, pers. comm.)



II.C. Summary: Resource Buffer Zones

Effects of activities in the upland areas immediately adjacent to

floodplain wetlands may be separated into three time-related categories:










1. Direct and immediate impacts which occur during the
construction phase,

2. Impacts which occur immediately following the construction
phases during the period of stabilization, and

3. Long-term impacts that are permanent as a result of
the alterations themselves or subsequent use and/or
management of the altered areas.

These development impacts affect three broad sets of parameters normally

considered of particular importance from a regulatory perspective. They

include:

1. Water quality,
2. Water quantity, and
3. Aquatic and wetland dependent wildlife.

Thus each of these attributes may be affected during construction, immediately

following construction, or in the long term through human uses and management.

Water Quality. The need for a buffer to insure that water quality is not

degraded as the result of upland development in areas immediately adjacent to

floodplain wetlands of the Wekiva River Basin is related to two potential

sources of degraded waters. The first is sediments carried by surface waters

from developed lands into down-gradient wetlands and waters. The second is

dissolved pollutants and suspended particulate matter that degrade water

quality through what might be termed chemical pathways. These include

nutrients, pesticides, and particulate organic matter which increase nutrient

loading, may be harmful to aquatic plant and animal life, or increase BOD.

Both sources of degraded water may come from the result of runoff during

construction, during the period immediately following construction as the

landscape stabilizes, or as a result of urban stormwater runoff long after the

period of initial urbanization.

Loss of valuable wetland functions as a result of sedimentation may be the

most serious impact during construction activities. Sedimentation causes loss








61

of soil properties and vegetation that are characteristic of wetlands and loss

of wildlife habitat. In addition, sediments may carry significant amounts of

pollutants and nutrients. Siltation and sedimentation of the wetland edge

result from increased water velocities acting on soils susceptible to erosion,

removal of ground cover in adjacent areas, or increased volumes of stormwaters

entering the wetland that carry increased amounts of sediments.

Where the waterward lots of a development are not incorporated into the

stormwater management system, the potential for long-term decreased water

quality after the construction phase is related to surface runoff from

driveways and lawns and groundwaters carrying increased levels of nutrients and

pesticides/herbicides from lawn care practices. While the rule criteria of the

District requires specific stormwater management practices to mitigate water

quality impacts from stormwaters, the rules allow 10% of the developed area to

be "unconnected," that is, to receive no treatment.

Water Quantity. The water flowing into the waters and wetlands of the

Wekiva River Basin is derived from three general sources. The first is

groundwater (or surficial groundwater) that becomes surface seepage where

ground surface elevations intersect the zone of saturation. This usually

occurs on inclines near the base of sandy slopes and is characterized by

surface soils that are saturated, shallow ponding of seepage waters, and small

seeps that coalesce into undefined flowing surface streams. The second source

is surface runoff as sheet flow from adjacent higher ground during and

immediately following rainfall events, and the third source from artesia flow

of deep groundwaters.

Development in the zone immediately upland from the floodplain wetland

edge may have dramatic impacts on the quantity of water from surface and

surficial groundwater sources. Seepage is usually derived from rains that have








62

recharged groundwaters in higher sandy soils and are moving downslope over a

broad front thus, seepage areas tend to extend over the toe of the slope in a

perpendicular line across the slope where the ground surface intersects the

groundwater elevation. The site of seepage is usually dominated by floodplain

vegetation. Alteration of the ground surface elevation through excavation in

areas immediately upslope from the site of seepage may intersect the

groundwater plain, and if positive drainage is maintained, can lower

groundwater levels and essentially cut off further downslope seepage. If no

positive outfall is maintained, the effects of excavations immediately upslope

from seepage sites may have only minor impacts, since waters may be intercepted

and discharged on the upslope side of the excavation, but may become

groundwaters through recharge on the downslope side.

In most areas where seepage is present, groundwater elevations immediately

upslope are quite near the soil surface and are not conducive to many land

uses. General engineering practices in areas with high water tables is to

lower water table elevations by drainage or raise ground elevations by filling

to make such areas more suitable for development. While filling may have

little impact on subsurface water flows, drainage has the overall effect of

short-circuiting groundwater flows, cutting off potential groundwater seepage

downslope, and increasing surface discharge elsewhere.

The effects of development on surface water flows in areas immediately

upslope of the wetland edge are more easily seen and more direct. Impervious

surfaces and sod increase runoff coefficients significantly over coefficients

characteristic of natural lands. If these waters are not intercepted by a

stormwater management system, they enter the wetlands and eventually the waters

of the river. The increased volumes and velocities may cause significant

degradation of downslope communities. However, under most development










conditions, these waters are required to be routed through a stormwater

management system, thus lessening the burden of the downslope communities. Yet

these very requirements may in effect decrease sheetflow from rainfall events,

since intercepted surface waters are routed elsewhere. The obvious

implications of altered surface runoff and water quality have already been

discussed.

The temporal differences of impacts on ground and surface water quantity

before, during, and after construction may be significantly different.

Construction practices may dictate that surface waters and groundwaters be

routed differently than will be the case after construction, or that

groundwaters be temporarily drained to facilitate construction activities.

Once construction is completed and the stormwater system is under operating,

the impacts on surface and groundwater quantity may vary little over time.

Generally, stormwater discharge requirements within the Wekiva River Hydrologic

Basin are designed to minimize negative impacts to surface waters through

detention/retention, off-line treatment, and additional criteria. However,

these requirements, and the fact that typically all lands within a project are

engineered as part of the stormwater system, have the effect of isolating

developed land. Contributions of overland flow runoff to downslope communities

are minimized under such circumstances, since normal engineering practices are

to discharge collected stormwaters at one or several point sources.

Aquatic and Wetland-Dependent Wildlife. Construction, operation, and

maintenance of developed areas immediately adjacent to Wekiva Ri-.r wetlands

will result in both direct and indirect impacts on aquatic and wetland

dependent wildlife. Noise during construction will interfere with

vocalizations necessary for courtship, mating, prey location, and predator

detection. Although this hindrance will be only temporary, there is no way to








64

predict long-term consequences. After individuals disperse to less noisy

territories, they may or may. not return. Chronic and acute noises of occupied

residential communities will cause less severe impacts. However, auditory

interference and stress-related effects will still occur in close proximity to

these developed areas. A vegetated buffer will help to attenuate harmful

sounds.

Domestic animal harassment and predation on wildlife will also increase

when pets are brought into adjacent developments. Development covenants and

local laws usually require owners'to leash their pets. However, the

probability of a few free-ranging dogs and many free-ranging cats is quite

high. Because cats tend to spend most of their prey-searching time in edge

areas, an upland buffer will help to alleviate cat predation on wetland

wildlife species.

Indirect impacts on wildlife will be related to habitat alteration

resulting from construction. The removal of natural uplands vegetation

adjacent to the wetlands will cause the originally mesic community along the

outer edge of the wetlands to become more xeric. Drier community species will

invade and eventually dominate this area. The ultimate result will be a

reduction in the wetlands and a corresponding decline in those species that are

wetland-dependent. In some areas, the width of the wetlands may become too

small, and the species composition will change because those with larger

spatial requirements will no longer be present. Increased predation and

parasitism associated with sharp induced edges will also encroach farther into

the forest.

Wetland-dependent species that require uplands to fulfill at least some of

their life functions will extirpated from the Wekiva River Basin if there is no








65

access to these uplands. An upland buffer adjacent to the wetlands will be

needed to protect this necessary habitat element.















III. LANDSCAPE ECOLOGY OF THE WEKIVA RIVER BASIN


III.A. Landscape Perspective


III.A.I. Physical Description

Topography. The landscape of the Wekiva River Basin is a complex mosaic of

wetland and upland habitats distributed over approximately 130 sq mi in north

central Orange County, southeastern Lake County, and western Seminole County.

The basin contains the physiogeographic province known as the Wekiva River

Plain. Its topography is flat to gently rolling. Elevation declines towards

the northeast, where the Wekiva Plain merges into the valley of the St. Johns

River.

On the western side of the upper Wekiva River, the land slopes gently

upward to the sandhills, from whence it rises abruptly to elevations of 120 to

195 ft above sea level. Sandhills and sloping terraces separate large tracts

of swampy lowlands and determine the circuitous route by which the waters of

Rock Springs Run State Reserve flow southeastward. These waters turn north

below the confluence of Wekiva Springs Run and the Little Wekiva River. North

of this confluence, the floodplain narrows and turns to the northeast above

State Road 46. The floodplain broadens out again where the Wekiva River joins

Blackwater Creek and the St. Johns River in the Lower Wekiva River State

Reserve (DNR, 1985, 1987).

Along the west bank of the Wekiva River upstream (south) of its confluence

with the Little Wekiva, elevation rises gradually towards the northwest from 15

ft above sea level along the river to approximately 35 ft above sea level.

67








68

Beyond the 35-foot contour, the land surface rises abruptly into upland

sandhill tracts in the north central section of Rock Springs Run State Reserve.

Downstream (north) of the Wekiva/Little Wekiva confluence, the floodplain

narrows abruptly, and the flow gradient increases rapidly to 1.6 ft/mi. The

flow gradient in this stretch of the central Wekiva River is one of the

steepest in east-central Florida, and the elevation along this section of the

Wekiva rises much more steeply above the narrowed floodplain than it does in

the flat swamps of the upper and lower sections. The width of the

Wekiva/Little Wekiva floodplain narrows to about 1,000 ft along the central

portion of the river, decreasing rapidly from its maximum dimensions of about 5

mi east/west by 3 mi north/south in the Wekiva Swamp. The floodplain broadens

out once again in the Lower Wekiva River State Reserve (near the confluence

with Blackwater Creek) to a width of 1 mi at the Wekiva's confluence with the

St. Johns River (DNR, 1985, 1987).

Blackwater Creek is a major tributary of the Wekiva which drains the

watershed lying just north of the Wekiva Basin. Its watershed covers

approximately 125 sq mi, nearly all of which is in southern Lake County.

Blackwater Creek's headwaters are in Lake Dorr, and its floodplain varies in

width from 800 ft at State Road 44A to over a mile along its upper and lower

reaches. Another major tributary, Seminole Creek, joins Blackwater Creek at

the eastern edge of Seminole Swamp. Seminole Swamp extends north and west from

the confluence of Blackwater and Seminole creeks, covering an area of about 3

mi east/west and 1.5 to 2 mi north/south. This swamp lies between State Road

46A and State Road 44 in southern Lake County. Blackwater Creek flows into the

lower Wekiva near the confluence of the Wekiva and the St. Johns. The waters

of the Wekiva River Basin merge with those of the St. Johns and flow northward

to enter the Atlantic Ocean at Jacksonville, Florida (DNR, 1985, 1987).










The wetlands of the Wekiva Swamp's northern end connect with the lower

reaches of Seminole Swamp through a narrow wetland corridor (not shown on all

maps) which bisects the lands lying above the west bank of the Wekiva River and

the northern borders of Wekiva Swamp. This wetland strip is an extremely

important feature of the basin. It provides a wildlife corridor through which

animals can move between these otherwise disjunct wetland communities (see Noss

and Harris, 1986).

The basin's diverse topography engenders a wide range of habitats, ranging

from submerged aquatic plant associations to upland sandhill communities.

Local soil characteristics and elevational effects combined with past and

present disturbances influence the development of the various plant communities

found within the Wekiva Basin.

Geology and Hydrology. The Wekiva Plain was formed by Pleistocene terrace

sands deposited during times of elevated sea level which occurred during

interglacial periods of the Pleistocene. The most recent extended saltwater

incursion probably occurred during the Sanamonian interglacial about 100,000

to 200,000 years ago, when sea levels were about 20 ft above those of the

present time (Bloom, 1983). Dunes were built up during the dry and windy

periods of earlier and later glacial periods (Watts and Hansen, in press).

These sands overlie the older marine limestones, clays, and marls of the

Hawthorne Formation, which rest upon the deeper, porous Paleocene limestones

and dolomites ccnt3ining the Floridan Aquifer (Heath and Conover, 1981). The

non-sedimentary bedrock of the Florida peninsula upon which these marine

deposits have accumulated lies at least 4,100 ft below the present ground

surface and ties in with the crustal rock of the continental plate.

Soils in the Wekiva Basin can be grouped in five associations. The

Freshwater Swamp Association occurs in the Wekiva River floodplain and the








70

bottomlands around the upper part of Rock Springs Run State Reserve. These

soils are usually saturated with water and are flooded much of the time. They

are adjoined by the Manatee-Delray Association, which grades uphill into the

P.omp-no-Delray Association. The two latter groups include soils which are

sandy, nearly level, poorly drained, and subject to periodic flooding. The

Myakka-Placid Association soils of the north-central and northeastern portions

of the Rock Springs Run State Reserve are sandy, nearly level, poorly drained,

and not normally subject to flooding. The St. Lucie-Pomello Association soils

of the uplands are sandy, moderately to excessively well-drained, and not

subject to flooding. They are restricted to the upland sandhill areas of the

Wekiva Basin (DNR, 1985; see also USDA, 1960, 1966).

Organic matter content of soils in the Wekiva Basin is high only in

wetland soils. Silt deposition and decayed plant materials have formed the

rich organic soils of river alluvium, swamp muds, and peat bogs in the basin.

The general absence of well-developed topsoil horizons in sandy upland

soils of the region encourage the rapid infiltration of rainwater. However,

the lack of organic matter, clays, and silts in the surface soils restricts

nutrient availability and limits the water-holding capacity of upland soils.

Although highly permeable for the most part, the upper horizons of upland sandy

surface soils quickly reach saturation during heavy rains, and sheetflow

movement of rainwater can result. Problems associated with surface runoff and

erosion may develop in conjunction with the heavy rains accompanying major

storm fronts, especially in areas where the protective vegetation cover has

been disturbed or removed. Ecosystem disturbances of historical importance to

the disruption of the vegetative cover of Wekiva Basin soils include logging,

livestock grazing, high-intensity recreational use, construction and

development, and wildfire. Wildfire is by far the least destructive of these










disturbances to the natural vegetation and wildlife. Indeed, fire is an

essential ecological component of several endemic plant communities native to

the region.

Lakes and sinkholes are scattered throughout the basin as the result of

the formation and subsequent collapse of solution cavities within the upper

layer of the underlying Hawthorne Formation limestone bedrock. Sudden surface

collapses due to sinkhole formation have in recent years swallowed buildings,

automobiles, and sections of roads in the suburbs of nearby Orlando. The

prevalence of sinkhole formations in the regions bordering the southern edge of

the Wekiva Basin dictate caution in siting industrial and residential

development.

The same forces which create sinkholes also created the many artesian

springs for which the Wekiva Basin is renowned. The water in these springs

comes from the Florida aquifer in deep Paleocene limestones and dolomites via

faults in the overlying Hawthorne Formation. Crevices and solution channels

have penetrated the otherwise impervious clay and marl layers of the Hawthorne

Formation and dissolved the underlying limestone. These provide the means for

developing surface outlets for artesian springwaters.

The major springwater sources of the upper Wekiva River are Wekiva Springs

(48 million gallons per day [MGDI), Rock Springs (42 MGD), Sanlando Springs (14

MGD), and Sheppard Springs (11 MGD). More than two-thirds of the Little Wekiva

River's flow is provided by a combined discharge of 14 MCD from Seminnle, Palm,

and Starbuck Springs. Springflows from the Floridan Aquifer comprise most of

the Wekiva River's water volume, which averages 186 MGD at State Road 46 (DUR,

1986, 1987). Reductions in flow of several major springs during the past two

decades have been attributed to water withdrawals from numerous deep








72

groundwater wells in the region which supply water for residential, industrial,

and agricultural uses (FWR, 1985; see also Heath and Conover, 1981).

Two man-made springwells at Wekiva Falls with a combined flow of 40 MGD

enter the Wekiva just south of State Road 46. Withdrawals from these deepwater

wells may be partly responsible for the recent decrease in springflow volume

from various natural springs in the Wekiva Basin. However, cutting off

upstream springflows from Wekiva Falls may not have particularly adverse

effects on lower Wekiva River wetlands. The proximity of this source to the

confluence of Blackwater Creek and the St. Johns River and the steep flow

gradient in this section of the Wekiva River tend to reduce the importance of

this water source to the ecology of the Lower Wekiva Aquatic Preserve region.

The natural channelling of the river into a relatively restricted wetland zone

caused by the increase in flow gradient tends to mitigate the negative, impacts

on wetlands of the lower Wekiva River from reduced flows caused by the Wekiva

Falls wells.

Further drawdowns in the regional water table due to over-exploitation of

water resources from the Floridan Aquifer will have major impacts on the

wetland habitats of the Wekiva Basin. Since about 70% of the Wekiva River's

water comes from springs, any reduction in springflow volumes will adversely

affect the size, distribution, character, and quality of state-domain wetlands,

waterways, and aquatic habitats in the Wekiva Basin (DNR, 1987).

Climate. The Wekiva Basin lies in the southernmost latitudes of the humid

subtropical climate zone of the southeastern United States. About two-thirds

of the precipitation in the basin falls between June and September. On

average, 10 to 15% of the annual rainfall occurs from December to February.

Annual rainfall averages 52 inches, with most rain deposited during brief,

heavy showers and thunderstorms (Heath and Conover, 1981). Tropical storms,









73

including hurricanes, contribute on average about 15% of the precipitation from

June to November. Rainfall events greater than 30 inches within a single 24-

hour period have been recorded during hurricanes at some Florida locations, and

such events are possible in the basin if a severe hurricane moves through

central Florida (Yoho and Pirkle, 1985). Tornadoes are not uncommon in central

Florida, and torrential rains and high winds typically accompany the storm

fronts which spawn these dangerous and sometimes highly destructive storms.

The average temperature for the central Florida region is 72 degrees F.;

ambient temperatures of 85 degrees F. or higher can occur during all months of

the year. Arctic air masses sometimes penetrate into the region during winter

months, bringing usually brief but occasionally intense episodes of sub-

freezing temperatures (Yoho and Pirkle, 1985; Heath and Conover, 1981). Record

freezes occurring during the past few years have devastated the citrus industry

in Lake County and most of north central Florida. Tens of thousands of acres

of orange groves were severely damaged or killed outright during sometimes

week-long periods of sub-freezing temperatures. Whether these recent spates of

unusually cold winter weather in central Florida represent a long-term trend

toward harsher winter climates is unknown.

The effects of these hard freezes do not seem to be as severe on native

wildlife and plants as they are on agricultural crops, with one major

exception. Populations of manatees (Trichechus manatus) in northern and

central peninsular Florida suffer high mortality rates from cold stress and

related causes during extended periods of freezing weather (T.J. O'Shea, USFWS,

pers. comm.; see O'Shea et al., 1985). Although the artesian springheads of

the St. Johns River valley create warm water refuges (72 degrees F.) for

manatees, the animals must leave areas of warmer water to feed. As food plants

become increasingly scarce near warm-water refuges, manatees are forced to








74

travel farther and farther in search of food, increasing their exposure to

colder water temperatures and the risk of collisions with boats (see Hartman,

1979). Radio-tagged manatees from Blue Spring on the St. Johns River have been

sighted in the Wekiva River, and residents have reported seeing manatees in the

Wekiva (Beeler and O'Shea, 1978).

Solar insolation is generally high in central Florida. Clear skies

predominate throughout much of the year, but morning ground fogs and rain

clouds often reduce direct sunlight penetration for brief periods. The

relatively high insolation and temperature regimes characteristic of Florida

combine to produce high evapotranspiration rates. In peninsular Florida,

surface water and groundwater losses to evaporation and transpiration may

approach or exceed the amount of water gained from precipitation (Heath and

Conover, 1981). The potential for such a water deficit demonstrates the

importance of springflows from the Floridan Aquifer to the maintenance of

surface-water levels in the Wekiva Basin. The preservation of existing wetland

ecosystems in the central and upper Wekiva River Basin is absolutely dependent

on continued supply of springflow waters at present levels (DNR, 1987).



III.A.2. Biological Description

Ecological Communities. The Wekiva Basin is a unique natural ecosystem.

It lies in the zone where tropical and temperate floras overlap. Tropical

plant species at the northern limits of their range grow side by side with

temperate-zone plants (DER, 1983). The distribution of plant species in

various plant communities varies according to specific site characteristics,

and species typical of one community may frequently occur in another (see Hart,

1984). Some species have fairly rigid microhabitat requirements, while others

occur in wide ranges of soil, shade, and moisture conditions. The soil










characteristics and disturbance history of a given area may result in the

anomalous presence or absence of species or species groups. A knowledge of

prior disturbance history (fires, logging, farming, ranching, etc.) is

important in determining the extent to which present vegetation conditions

reflect native vegetation patterns or the presence of human-altered plant

communities (Noss, 1985). For example, selective logging has greatly reduced

the abundance of cypress trees in the mixed hardwood swamp community of Rock

Springs Run State Reserve (DNR, 1985).

Rigid separations among plant communities do not typically occur within

most natural biotas. The distinct edges (abrupt ecotones) associated with

fire-maintained communities and human-altered landscapes are exceptions. For

the most part, categories for community types are general constructs devised

for analysis and identification of gross habitat characteristics. Despite the

overlap between community types, these recognized associations reflect

important biological differences among various communities and special

interactions or interdependencies among the constituent species of each

community.

The flows of numerous artesian springs from the Floridan Aquifer, together

with groundwater drainage from the surrounding watershed, have created the vast

network of stream channels and associated floodplains, lakes, and sinkholes

which support extensive areas of hydric and mesic habitats in the Wekiva River

Basin. The basin's landscape is dominated by wetland and lowland plant

communities but is interdigitated by relatively limited and patchily

distributed areas of transitional and upland habitats.

Deep-water and shallow-water herbaceous marsh communities inhabit the

stream channels and flooded regions, grading into the hardwood swamp vegetation

which also occurs on permanently flooded sites. Bottomland hardwood







76

communities (swamps and bayheads) grade into hydric hammocks where groundwater

seeps riverward from upland communities and into mesic hammocks and flatwoods

in areas of higher elevation. Drier upland communities in the region include

pine sandhill, xeric hammock, and sand pine/oak scrub. Sinks and ponded areas

support cypress domes and patches of wet prairie and mesic hammock (DNR, 1985,

1987; Brown and Starnes, 1983).

Wildlife. Many of the Wekiva Basin's wildlife species are locally

ubiquitous mammals which are common throughout the region or not restricted to

one specific plant community or habitat type. These include black bear (Ursus

americanus), white-tailed deer (Odocoileus virginiana), feral hog (Sus scrofa),

bobcat (Felis rufus), river otter (Lutra canadensis), striped skunk (Mephitis

mephitis), opossum (Didelphis marsupialis), raccoon (Procyon lotor), two

shrews, several bats, cotton mouse (Peromyscus gossypinus), wood rat (Neotoma

floridiana), and two cottontail rabbits. Most of the ubiquitous species of the

Wekiva Basin frequent swamps, and other species--including wood duck (Aix

sponsa), pileated woodpecker (Dryocopus pileatus), and many songbirds--require

forested wetlands for nesting and/or foraging habitats.

Many of these species require large expanses of diversified habitat

mosaics. For example, black bears, sandhill cranes (Grus canadensis), and wild

turkey (Meliagris gallipavo) need between-habitat diversity (presence of a

patchwork of different habitats) within their home ranges to support the

extensive daily or seasonal shifts in activity among various plant communities.

Species such as bats, pileated woodpeckers, and water turtles, which typically

forage and live within one habitat, may utilize quite different habitats for

dispersal, reproduction, or hibernation. Other species, such as river otters,

have large home ranges and travel widely among various habitat patches, even










though most of their activities are conducted in one habitat type (in this

case, aquatic wetlands).

In describing the faunal communities of the Wekiva Basin, the focus'will

be upon typical species associations within given habitat types. As noted in

reference to plant communities, these associations are, for the most part,

flexible. Overlaps and omissions in the presence of species within community

types may occur. However, the upland communities of the Wekiva Basin are

exceptional in having several characteristic and interdependent commensall)

species which are entirely restricted to specific upland habitats. The wetland

faunal communities include many species of restricted distribution (such as

fishes or the endemic snail and crayfish species), as well as a large

complement of more freely ranging forms which utilize several wetland habitat

types.

Aquatic wildlife communities are comprised of species which are largely or

entirely dependent upon aquatic ecosystems (rivers, lakes, springs, ponds:

places where standing or flowing water is present to some degree at any given

time) for at least part of their life cycle. These communities include animals

such as toads and tree frogs which spend their adult lives in terrestrial

habitats but which require aquatic habitats for breeding and the development of

young (larvae or tadpoles). Aquatic communities in the Wekiva Basin region

support a great diversity of wildlife, ranging from microscopic protozoans and

invertebrates to the massive American alligator. Literally hundreds of species

of snails, mussels, crayfish, insects, fishes, birds, amphibians, reptiles, and

mammals share aquatic habitats with a broad spectrum of aquatic plant life.

The aquatic plant community provides critical resources such as food, shelter,

and oxygen for animals in aquatic environments and is the base of the aquatic

food chain.










The aquatic plant communities in the rivers, springs, and floodplains of

the Wekiva Basin support populations of numerous fishes, including various

types of bass, sunfish, mullet, catfish, pickerel, shad, crappie, perch,

shiner, topminnow, killifish, molly, and bowfin (see appendix for scientific

names of species not detailed in this discussion).

The wetland herpetofauna of the region is exceptionally diverse and

contains many aquatic forms. Amphibians which are largely or entirely

dependent upon aquatic habitats include sirens, amphiumas, newts, bullfrogs,

pigfrogs, and leopard frogs. The largely aquatic reptiles of wetland habitats

in the region include American alligators, softshell turtles, cooters, mud

turtles, alligator snapping turtles, stinkpots, water moccasins, and several

non-poisonous water snakes. .In contrast to amphibians--which typically lay

their eggs in water--reptiles need terrestrial or semi-terrestrial sites in

which to incubate their eggs. Some reptile species (especially turtles) must

travel some distance from the water into adjacent upland habitats to find

patches of sunlit, sandy soil necessary for successful nesting.

Some of the invertebrates of the Wekiva Basin (including three endemic

snails of the genus Cincinnatia and the threatened Wekiva Springs Aphaostracon

snail) are restricted to springhead habitats. The threatened Orlando Cave

crayfish is an endemic form restricted to habitats in the Little Wekiva River

system. Other important invertebrates of the basin are apple snails and

burrowing crayfish. The apple snail is the primary food of the limpkin, a

large snipe-like bird found in wetland habitats that support populations of

this golf-ball-size snail. Burrowing crayfish spend part of the year in

vertical burrows which are dug in muddy soils in non-flooded wetland and

transitional zones. Excavated soil from the burrow is formed into a nearly

cylindrical cone rising as much as 6 inches above ground level. Crayfish










emerge from these burrows periodically to forage and breed. Crayfish are an

important food source for many larger vertebrates, including various fish,

bird, and mammal species.

Many species of birds found within the Wekiva Basin are dependent upon

aquatic and wetland habitats for foraging and/or nesting habitats. Osprey,

anhinga, wood stork, egrets, herons, ibises, bitterns, ducks, snipe,

gallinules, coot, limpkin, and grebes are characteristic of the open wetland

and aquatic habitats of the region. Bald eagles (USFWS: Endangered; FGFWFC:

Threatened) are expected to occur as transients in the aquatic communities of

the area even if no resident individuals are known at the present time. The

resident wood stork (Mycteria americana) has been classified as an endangered

species by both state and federal agencies (FGFWFC, 1987). Sandhill cranes

(threatened) utilize marsh, wetland, and upland sites in the Wekiva Basin.

Other resident species such as the little blue heron (Florida caerulea),

tricolored heron (Egretta tricolor), snowy egret (Egretta thula), and limpkin

(Aramus guarauna) have been designated as Species of Special Concern (SSC) by

the Florida Game and Fresh Water Fish Commission (FGFWFC, 1987). The wetlands

bird community of the Wekiva region is exceptionally diverse. Encroachment

upon wetland habitats will directly and indirectly affect these attractive and

often highly visible components of the Wekiva Basin wildlife community.

Typical mammals of the aquatic marsh communities in this region include

river otter, round-tailed muskrat (Neofiber alleni), raccoon, rice rat

(Oryzomys palustris), and marsh rabbit (Silvilagus palustris). Otters and

raccoons range widely among other habitats, while round-tailed muskrat, marsh

rabbit, and rice rat are usually associated with marsh, swamp, or wet prairie

communities.










The bottomland hardwood associations (hardwood swamp and bayhead

communities) typically occur as closed-canopy woodlands which are distributed

either as extensive wetland forests in flooded basins or as gallery forests

along stream and lake margins. These communities represent a transitional

gradient between strictly aquatic and terrestrial environments and retain

characteristics of both. Consequently, the wildlife associated with swamp and

bayhead communities includes species of both aquatic and terrestrial

affinities. The Wekiva Basin swamps and bottomland hardwoods support not only

numerous aquatic forms, but also many typically terrestrial animals, including

black bear, white-tailed deer, turkey, opossum, gray squirrel (Sciurus

carolinensis), cotton mouse, wood rat, gray fox (Urocyon cinereoargentus), and

striped skunk. The Wekiva Basin and the nearby southern portion of the Ocala

National Forest constitute perhaps the best remaining areas of suitable bear

habitat in central Florida (DER, 1983). The Florida black bear (Ursus

americanus floridanus) is unique among North America's extant black bear

populations in that its large size is commensurate with that of the ancestral

black bears of Ice Age times (Kurten and Anderson, 1980). Management

strategies keyed to protection of black bear populations and habitat

requirements should benefit virtually all other wildlife in the Wekiva Basin.

The largely terrestrial habitats of the uplands include pine flatwoods,

pine sandhills, and sand pine/oak scrubs. Flatwoods are used by bear, deer,

spotted skunk (Spilogale putorius), cotton rat (Sigmodon hispidus), cotton

mouse, diamondback rattlesnake (Crotalis adamanteus), and various other

ubiquitous species. Flatwoods provide good cover and shelter for animals that

forage in adjacent habitats, move between habitats, and seek refuge from high

floodwaters during storms. The truly upland habitats of the region are the

pine sandhill and sand pine/oak scrubs of the dry dune-ridges. Typical








81

wildlife species of these upland habitats include the gopher tortoise (Gopherus

polyphemus, SSC) and its many associated commensal (interdependent) species,

including the gopher frog (Rana sphenocephala, SSC), the Florida mouse

(Peromyscus floridanus, SSC), and the eastern diamondback rattlesnake. Pocket

gophers (Geomys pinetis; also known as salamander or sandy-mounder) occur in

more open habitats of deep, well-drained, sandy soils on high ridges in the

Wekiva Basin. Longleaf pine sandhills are the preferred habitat of the

Sherman's fox squirrel (Sciurus niger shermani, SSC). This species has been

decimated over the past century by logging of mature pines in the sandhill

communities. Reduced populations survive in remnant turkey oak forests, and

the species may occur around cypress domes in flatwoods and in a few other

upland ecotone situations (DER, 1983). The logging of mature longleaf pines

and conversion of sandhill communities into citrus and slash pine plantations

have severely affected the structure, composition, and distribution of sandhill

ecosystems. The preponderance of listed species among the typical wildlife of

the once widespread sandhill community is an indication of the extent to which

this habitat has been disrupted by development.

The sand pine/oak scrub community contains several highly specialized

endemic species such as scrub lizard (Sceloporus woodi), sand skink (Neoseps

reynoldsi, threatened), and Florida scrub jay (Aphelecoma coerulescens

coerulescens, threatened). Many sandhill wildlife species also utilize scrub

habitats and range freely between adjacent scrub and sandhill habitats. The

acorns of various oak species common in these habitats are an important

seasonal food for black bear, deer, turkey, and feral hog populations of the

Wekiva Basin.







82

III.B. Wetland Communities

Wetlands habitats of the Wekiva Basin can be subdivided loosely into three

major community types. These are the aquatic herbaceous marsh community of

stream channels and springheads, the mixed hardwood swamp community of the

river floodplains, and the hydric hammock community of groundwater and surface

runoff seepage wetlands. Marshes and swamps are characterized by saturated or

flooded soils which are subject to regular and extended periods of inundation

by standing or flowing water. Hydric hammock soils are saturated but only

occasionally inundated.

Marsh vegetation consists of submerged, emergent, and floating herbaceous

plants. Swamp vegetation consists of water-tolerant trees and shrubs. Gradual

shifts in plant species composition occur according to the regularity and depth

of immersion for ground-level vegetation in floodplain habitats. The presence

of surface water will greatly affect the types of wildlife species which are

present at any given time.



III.B.I. Aquatic/Marsh Communities

The freshwater marshes of Florida are critically endangered. Freshwater

marshes are vulnerable to changes in water levels, water quality, hydroperiod,

and fire regimes. Drainage of marshes for development and agriculture has

eliminated much of Florida's freshwater marsh habitat. Heavy recreational use,

particularly when associated with off-road vehicle and boat traffic, can

drastically alter the structure and composition of vegetation within marshes

and inhibit the vital ecosystem functions of these communities.

The freshwater marsh is a critical resource for many species of birds,

fishes, reptiles, mammals, and amphibians in the Wekiva Basin. Undisturbed

areas of freshwater marsh provide excellent cover and travel routes for many








83

wildlife species. The vegetation of freshwater marshes filters surface runoff

that feeds rivers and lakes. Soil particles are trapped within the vegetation

matrix, and plant roots stabilize the soil surface both above and below the

water level. Dense rafts and mats of marsh plants protect the stream banks

from strong current flows and help prevent erosion during periods of high water

and storm floods. Marsh plants fix and store nutrients and soil particles

filtering in from the surrounding landscape, thus helping to prevent

eutrophication.

The deepwater marsh communities (Water Hyacinch/Coontail/ Watergrass:

Eichhornia/Ceratophyllum/Echinochloa) are dominated by rooted or free-floating

aquatic herbaceous plants, and they typically occur on permanently flooded

sites with water depths of 3 to 6 ft (Brown and Starnes, 1983). This community

is found in the main channels and deeper sections of spring runs in the Wekiva

Basin, with maximum development in sites not shaded by streamside tree canopy.

These high-gradient, fast-moving streams tend to flush out the organic debris

and compounds which stain the waters of blackwater swamp systems. High flow

rates and steep gradients also create clearwater stream conditions within large

tracts of hardwood swamps.

The large springflows of the upper Wekiva River system generate clearwater

alkaline streams with high flow rates and clean, sandy bottoms. These

calcareous springflows are rich in phosphorous and other nutrients and support

luxuriant aquatic plant growth. Other representative plants of this habitat

include water lily (Nymphaea odorata), hydrilla (Hydrilla verticullata),

water-lettuce (Pistia stratioides), and duckweed (Lemna spp.). The common

water hyacinth (Eichhornia crassipes) is a weedy exotic which has invaded

aquatic habitats throughout Florida. This species has become the dominant

aquatic plant in many localities within the region, severely encroaching upon








84

important native species such as eelgrass and coontail. Elimination of water

hyacinth is a desirable but presently unachievable management goal.

Shallow-water marsh communities (Cutgrass/Maidencane/Cattail/ Arrowhead:

Leersia/Panicum/Typha/Sagittaria) typically occur in sites which may be flooded

only seasonally but which have water depths of 6 inches or more during the

growing season (Brown and Starnes, 1983). Other representative species include

sawgrass (Cladium jamaicense), sedges (Carex spp.), and rushes (Juncus spp.,

Elocharis spp., and Rynchospora spp.) These shallow-water herbaceous plant

associations typically occur in the shallower sections of stream channels and

along stream margins within the Wekiva Basin.

Wet prairie communities are similar to shallow marsh communities in terms

of both their constituent species and flooding regimes. Water depths range

from 0.5 to 2 ft in the growing season. Sometimes called grassy ponds,

sloughs, or prairie lakes (DNR, 1985), the wet prairie is a grass/herb plant

community associated with seasonally and permanently flooded areas of upland

habitats (see below for a more detailed discussion of this community).



III.B.2. Mixed Hardwood Swamp Community

The shallower waters in floodplains and along the margins of lakes and

streams in the Wekiva Basin support large tracts of swamp and bottomland

hardwood vegetation. This community is comprised of cypress species and a

variety of deciduous hardwood trees that grow on saturated and flooded soils.

Nutrient availability is generally low, but wildlife habitat value is high.

Swamps assimilate organic and inorganic wastes and pollutants, store water, and

impede the movement of floodwaters. By slowing down the rate of water flow,

swamps help to minimize erosion, promote infiltration, and facilitate the

settling out of debris, silt, and nutrients carried by floodwaters. These










functions improve water quality, stabilize water flows in streams and rivers,

and help to maintain high groundwater levels in the region. Swamps provide

habitat for many wildlife species and are used as travel corridors by wildlife

in developed areas.

The mixed hardwood swamp (cypress/tupelo/water ash: Taxodium/

Nyssa/Fraxinus) and bayhead (red bay/loblolly bay/pond cypress:

Persea/Gordonia/Taxodium) community occurs on poorly drained sites which are

regularly or permanently flooded (Brown and Starnes, 1983). Tannins and humic

acids from plant debris color and acidify the waters in swamps and in their

drainage streams. These blackwater systems tend to occur in the low-gradient

streams and basins of cypress and hardwood swamps where organic debris

accumulates on stream bottoms and in backwaters. Blackwater Creek is a typical

example of this distinctive stream type.

Pure stands of cypress stands and old cypress trees are no longer common

in the swamps of the Wekiva Basin. Old-growth cypress has been selectively

logged from swamps throughout Florida during the past century (see DNR, 1985;

Monk, 1968). Fluctuations in water level are required for cypress

regeneration: cypress seeds must be soaked before they will germinate, but

they will not germinate if they are underwater. Other important species of the

mixed hardwood swamp are red maple (Acer rubrum), American elm (Ulmus

americana), water hickory (Carva aquatica), buttonbush (Cephalanthus

occidentalis), and bluestem palmetto (Sabal minor) (Brown and Starnes, 1983).

The American elm was formerly common and widespread throughout eastern and

central North America, but in the past century the introduction of Dutch Elm

disease, an exotic pathogen, has nearly exterminated this species throughout

much of its range (see Davis, 1981). However, this species still survives as a

common element in the floodplain forests of the Wekiva Basin.












III.B.3. Hydric Hammock Community

In some areas between the mixed bottomland hardwoods and the upland

communities along the Wekiva River, seepage of groundwater from uplands is the

dominant source of water. The topography of these areas is flat, and the soils

are poorly drained and almost constantly saturated with seepage water.

Although subject to occasional flooding, the hydroperiod in hydric hammocks is

shorter than in the adjacent swamps.

Hydric hammock communities support more plant species than any other

wetland type in the Wekiva Basin. Among the species are popash (Fraxinus

caroliniana), live oak, laurel oak (Quercus laurifolia), red maple, southern

magnolia (Magnolia virginiana), red cedar (Juniperus siliciola), cabbage palm,

saw palmetto (Serenoa repens), tulip poplar (Liriodendron tulipfera), pond pine

(Pinus serotina), slash pine (Pinus elliotii), sweet gum (Liquidambar

styraciflua) wax myrtle (Myrica cerifera), and several vines and ferns (Brown

and Starnes, 1983). The hydric hammock is excellent wildlife habitat and is

used by ubiquitous mammals and birds as well as by numerous reptiles and

amphibians.

This community is very sensitive and vulnerable to changes in groundwater

hydrology in upland areas. Drawdowns caused by nearby wells and diversion of

groundwater via retention ponds and ditches in uplands can interrupt the supply

of seepage water to hydric hammocks, causing the soil to dry out and,

eventually, species composition to shift toward more mesic and fewer wetland

species. Lowering the water table also makes hydric hammock more vulnerable to

fire, a disturbance to which these ecosystems are not adapted.










III.C. Transitional Communities: Mesic Hammock and Scrubby Flatwoods

In the Wekiva Basin, the transitional communities between the wetlands and

the uplands are largely ecotonal in character, occurring as edges or borders

around the larger areas of swamp. Distinct separations between the swamp,

bayhead, and lowland hammock communities occupying floodplain habitats of the

Wekiva Basin are typically absent. Transitional species of the wetland/upland

ecotone include hydric and mesic hammock forms such as cabbage palm, saw

palmetto, tulip poplar, pond pine, slash pine, and sweet gum (Brown and

Starnes, 1983).

Scrubby flatwoods associations form ecotones between the mesic flatwoods

and the xeric sandhill and scrub communities. Scrubby flatwoods occupy sites

which are sufficiently well-drained so that there is no standing water present

even under extremely wet conditions. Pines (slash, sand, and longleaf) are

typically present but scattered within a matrix of shrubby oaks and palmettos.

Scrub oak (Q. inopina), Chapman's oak (Q. chapmanii), and sand live oak

intermix with saw palmetto and scrub palmetto (Sabal etonia) to form a

generally thick shrub layer 1 to 2 m high. Herbaceous cover tends to be

sparse. Lichens (Cladonia spp.) and spike moss (Selaginella arenicola) provide

considerable ground cover except on recently burned sites. Fire is important

in determining the structure and composition of scrubby flatwoods vegetation,

which is intermediate in character between flatwoods and sandhill/scrub

communities.



III.D. Upland Communities

The drier, sandy soils of the uplands support scrubby flatwoods on their

lower edges and longleaf pine sandhill and sand pine scrub on better-drained

and slightly higher sites. Longleaf pine-turkey oak sandhills and sand








88

pine-oak scrub are distinct in structure and composition from flatwoods

communities. These communities occur as savanna or scrub formations on the

well-drained upland soils of the Wekiva Basin and are subject to frequent

burning. Differences in past burning regimes and. local soil characteristics

strongly affect the particular vegetation characteristics of these communities

(see Kalisz and Stone, 1984). These habitats are home to a number of important

endemic species and are particularly sensitive to changes in natural

disturbance regimes (see Monk, 1968).

Upland habitats have been severely disturbed by past and present

management practices, and major ecological components cannot become

reestablished following certain types of human-caused disturbances (Means and

Grow, 1985). In many respects, these specialized uplands communities are at

the greatest risk from development at present (see Means and Grow, 1985). They

occupy substrates and soils which are often preferred over those of wetland

sites for agriculture, silviculture, industry, and residential development. As

a consequence, few large tracts of native upland vegetation and wildlife

survive at the present time. Those upland communities which remain have been

subjected to major changes in vegetation regimes and wildlife species diversity

as the direct result of human disturbance. Such human-caused changes in the

ecology of upland terrestrial communities can greatly alter the movement of

water, soil, and nutrients into adjacent wetlands and regional watersheds (see

Odum, 1971, 1983).



III.D.1. Pine Flatwoods Communities

Flatwoods are fire-adapted communities which occur on moderately to poorly

drained soils of terraced lands above the floodplain in areas subject to

periodic burning. Wildfires tend to kill off most typical hardwood hammock










tree species while leaving the fire-tolerant forms, especially pines and

palmetto, as local dominants. Exclusion of fire will result in succession to

bottomland hardwoods or mesic hammock on most flatwoods sites (Monk, 1968).

The dominant species in the basin's mesic pine flatwoods community are

pines, scattered oaks, and saw palmetto (Pinus spp./quercus spp./Serenoa

repens). A dense shrub layer carpets the understory level. Pines of flatwoods

habitats include longleaf pine, slash pine, and pond pine. Live oak and dwarf

live oak (_. minima) are often present. Saw palmetto is usually the dominant

shrub species, with dwarf live oak, fetterbush (Lyonia lucida), staggerbush

(Lyonia fruticosa), dwarf huckleberry (Gaylussacia dumosa), and wax myrtle as

secondary components. Saw palmetto, threeawn grass (Aristida patula),

greenbriar (S~ilax spp.), and gallberry (Ilex glabra) are typical understory

species.

Flatwoods often contain patchily distributed areas of cypress dome,

bayhead, mesic hammock, wet prairie, sandhill, and scrub vegetation due to

variations in topography, soils, and soil moisture regimes. Standing water may

be present in flatwoods during periods of high precipitation and elevated

groundwater levels.

Longleaf pine was formerly dominant on drier sites, while slash pine and

pond pine tend to be dominant on more mesic soils. Repeated selective

harvesting of longleaf pines, changes in fire regimes, and conversion of

flatwoods and sandhills to agriculture during the past century have greatly

affected the distribution and abundance of native longleaf pine communities

(Monk, 1965, 1968; Means and Grow, 1985). Slash pine is now the dominant tree

on many former longleaf sites. Pond pine becomes dominant in acidic, poorly

drained flatwoods where soil pH is less than 4.5, while slash pine occurs

primarily on more neutral soils (Monk, 1968).












III.D.2. Wet Prairie Communities

Wet prairies typically occur in sinks and depressions within areas of low

topographic relief which receive water through runoff from adjacent higher

ground. Patches.of wet prairie vegetation are commonly found scattered

throughout the flatwoods and sandhills of the region. Shrubs and small trees,

such as primrose willow (Ludwigia spp.) and elderberry (Sambucus simpsonii),

are sometimes present in wet prairies. Characteristic herbaceous plants

include panicum grasses (Panicum tenerum, P. dichotomum, etc.), sloughgrass

(Scleria spp.), swamp lily (Crinum americanum), and sundew (Drosera spp.). The

wet prairie is fire-adapted, and frequent burning will maintain wet prairies on

sites which would otherwise succeed to hydric or mesic woodland. These grassy

patches increase habitat diversity in flatwoods landscapes and provide

accessory foraging habitats for important wetland wildlife species. Because

wet prairies are dependent on surface water runoff to supply water (Brown and

Starnes, 1983), drawdowns of water tables in flatwoods by ditching can

eliminate wet prairies and reduce habitat diversity in upland regions.



III.D.3. Pine Sandhill Communities

The pine sandhill community is a savanna-type formation of scattered trees

and open woodlands having a well-developed ground cover of grasses, forbs, and

scattered shrubs. Characteristic species are longleaf pine, turkey oak, and

wirtgrass (Pinus palustris/Quercus laevis/Aristida stricta). Fire is an

important ecological component of sandhill environments and maintains the

characteristic open pine woodland and sparse understory vegetation. Burns

occur naturally in sandhill communities at about 3- to 5-year intervals,

usually started by lightning strikes (Means and Grow, 1985). These frequent








91

fires preserve the dominance of longleaf pine and inhibit succession to xeric

hammock vegetation (Kalisz and Stone, 1984). Sand pine may also invade

sandhill communities when fire is suppressed (Kalisz and Stone, 1984).

The upland dune formations of the Wekiva Basin are dominated by pine

sandhill communities containing patchily distributed areas of sand pine/oak

scrub (Pinus clausa/Quercus spp.) and xeric hammock. Pines and turkey oaks are

typically the principal overstory components. The relative dominance of turkey

oaks and pine species other than longleaf and the absence of old-growth

longleaf in the region's sandhill communities are due to selective logging in

these communities.

Sandhills have a more or less continuous herbaceous ground cover dominated

by wiregrass. Shrubs and hardwoods other than oaks are typically present at

low densities (Laessle, 1958). Other common plants of sandhill habitats are

bluestem grasses (Andropogon stolonifera, A. tenarius), persimmon (Diospyros

virginiana), prickly pear (Opuntia ammophila), blueberries (Vaccinium spp.),

gopher apple (Chrysobalnus oblongifolius), and spike moss. Shrub rosemary

(Ceratiola ericoides) is often common in sandhill communities but does not

usually occur in dense stands. Individual rosemary bushes are usually ringed

by narrow perimeters of bare soil. This phenomenon is caused by the release of

an allelopathic chemical from the rosemary which inhibits the growth of other

plants within its immediate vicinity.

The high primary productivity of sandhill habitats provides a rich food

base for a wide variety of wildlife. Turkey oak acorns are important to

mast-feeders such as deer, turkey, and feral hog. Sandhill communities support

a characteristic fauna which includes Sherman's fox squirrel and gopher

tortoise with its host of commensal wildlife species.










Sand pine scrub and oak scrub occur on various upland sites within the

Wekiva Basin (DNR 1985, 1987). Sand pine and oak scrub are characterized by a

mixed scrub oak understory dominated by scrub live oak, myrtle oak (Q.

myrtifolia), and Chapman's oak (Q. chapmanii). Sand pine is variably present

in the scrub habitats of the Wekiva Basin. Differences in burning and

disturbance regimes probably account for the absence of sand pine in some scrub

communities of the Rock Springs Run State Preserve (DNR, 1985). Shrubs such as

staggerbush, rosemary, and wild olive (Osmanthus americana) may also be

present. Scrub hickory (Carya floridana), a Florida endemic, is present in the

scrub habitats of the Wekiva Basin. Common herbaceous plants of scrub habitats

in the region include blueberries, gopher apple (Chrysobalnus oblongifolius),

prickly pear (Opuntia compressa), spike moss, and wiregrass. Lichens (Cladonia

spp., Usnea spp., and others) grow on patches of bare soil or as epiphytes on

the bark of woody plants.

Patches of xeric hammock (live oak/sand live oak/red oak/American

holly/deer moss: Quercus virginiana/Q. geminata/Q. falcata/Ilex opaca/Cladonia

spp.) occur within the upland sandhill habitats. Pine sandhill and sand pine

scrub communities will be succeeded by xeric hammock vegetation if the absence

of fire is prolonged (Monk, 1968). Exclusion of fire allows regeneration of

hardwoods and prevents the continued recruitment of pines. The leaf litter of

xeric hammock plants is fire-resistant, so that patches of hammocks within

large sandhill tracts typically remain unburned even though ground fires have

spread throughout the surrounding pine-dominated landscape. The prevalence of

natural and human-caused wildfires in the Wekiva Basin over the past centuries

has limited the significance of this community type in the region.










Sand pine scrub and oak scrub occur on various upland sites within the

Wekiva Basin (DNR 1985, 1987). Sand pine and oak scrub are characterized by a

mixed scrub oak understory dominated by scrub live oak, myrtle oak (q.

myrtifolia), and Chapman's oak (Q. chapmanii). Sand pine is variably present

in the scrub habitats of the Wekiva Basin. Differences in burning and

disturbance regimes probably account for the absence of sand pine in some scrub

communities of the Rock Springs Run State Preserve (DNR, 1985). Shrubs such as

staggerbush, rosemary, and wild olive (Osmanthus americana) may also be

present. Scrub hickory (Carya floridana), a Florida endemic, is present in the

scrub habitats of the Wekiva Basin. Common herbaceous plants of scrub habitats

in the region include blueberries, gopher apple (Chrysobalnus oblongifolius),

prickly pear (Opuntia compressa), spike moss, and wiregrass. Lichens (Cladonia

spp., Usnea spp., and others) grow on patches of bare soil or as epiphytes on

the bark of woody plants.

Patches of xeric hammock (live oak/sand live oak/red oak/American

holly/deer moss: Quercus virginiana/g.. geminata/Q. falcata/Ilex opaca/Cladonia

spp.) occur within the upland sandhill habitats. Pine sandhill and sand pine

scrub communities will be succeeded by xeric hammock vegetation if the absence

of fire is prolonged (Monk, 1968). Exclusion of fire allows regeneration of

hardwoods and prevents the continued recruitment of pines (see Williamson and

Black, 1981). The leaf litter of xeric hammock plants is fire-resistant, so

that patches of hammocks within large sandhill tracts typically remain unburned

even though ground fires have spread throughout the surrounding pine-dominated

landscape. The prevalence of natural and human-caused wildfires in the Wekiva

Basin over the past centuries has limited the significance of this community

type in the region.
















IV. STATUTORY & DISTRICT CRITERIA RELATED TO BUFFER ZONES


Questions have been raised concerning the authority of the District to

enact requirements which restrict or preclude the construction and operation of

systems within the Wekiva River Basin. The rulemaking related to the Wekiva

Basin has been the subject of serious concern, and much debate has resulted.

An earlier draft of the Wekiva Basin Rule had requirements that buffered the

river from impacts, but was withdrawn following considerable controversy, and

staff was directed to revisit the issue. Following several drafts of proposed

language for buffer requirements, a Petition for Administrative Determination

of Invalidity of Proposed Rule was filed that alleged the proposed rule

constitutes an invalid exercise of delegated legislative authority or is

otherwise invalid.

The statutory authority granted the Governing Board of the District

related to the enactment of requirements that restrict or preclude the

construction, operation, or maintenance of systems is clearly stated, but

somewhat general. Broad rulemaking authority has been granted by the

Legislature (Chapter 373, FS). The Board may adopt reasonable rules that are

consistent with the law and reasonably necessary to efftecuate its powers,

duties, and functions. Rules adopted by the Board must be reasonably related

to the purposes of Chapter 373. The Board cannot act in an arbitrary and

capricious manner and should have before it competent and substantial evidence

to support a proposed rule.










Two questions related to the statutory authority given in Chapter 373 (FS)

have occurred to us. First, in Sections 373.413 and 373.416 the Legislature

enacted two statutory provisions related to water management systems; the

former addressing construction of systems and the later addressing operation

and maintenance of systems. As a result, an arbitrary distinction is made

between construction and operation and maintenance. Second, the statute does

not provide a definition for the term "water resources."



IV.A. Statutory Criteria, Sections 373.413 & 373.416, FS

Sections 373.413 and 373.416 draw a distinction between permits

required for construction or alteration of dams, impoundments, reservoirs, or

works (373.413, FS) and permits required for maintenance and operation of same

(373.416, FS). In the former, the District may require permits to assure that

construction or alteration of any system will not be harmful to the water

resources of the District. In the latter, the District may require permits to

assure that the operation or maintenance of a system will not be harmful to the

water resources of the District and will not be inconsistent with the overall

objectives of the District. The distinction between the harm that may result

from construction activities and harm that may arise from operation and

maintenance is a confusing one in light of the review a permit application may

receive. Can the District evaluate an application for construction based only

on harm to water resources, or can the application also be evaluated relative

to the overall objectives of the District?

Conceptually it may be relatively easy to separate impacts on water

resources that result from development activities into those that occur during

construction and those that may result from the operation and maintenance of

that which has been constructed. From a resource management perspective,




Full Text

PAGE 1

Final Report AN EVALUATION OF THE APPLICABILITY OF UPLAND BUFFERS FOR THE WETLANDS OF THE WEKIVA BASIN Mark T. Brown and Joseph M. Schaefer, Principal Investigators with K. H. Brandt, S. J. Doherty, C. D. Dove, J. P. Dudley, D. A. Eifler, L. D. Harris, R. F. Noss, and R. W. Wolfe October, 1987 Center for Wetlands University of Florida Gainesville, Florida 32611 ( 904) 392 -2424

PAGE 2

Acknowledgements The authors wish to express their appreciation to the staff of the Center For Wetlands, for their dedication and service way beyond the call of duty. Their attitude made completion of this report so much easier. Specifically, Jenny Carter, Staff Assistant, coordinated personnel and somehow managed to get the report finalized under difficult odds. Linda J. Crowder processed all the words over and over again as we edited and polished. Carol Cox proofread each draft. Stephen Roguski, our expert draftsperson, drafted the figures. Karla Brandt not only helped with research and writing, but did a fantastic job of final editing. Steven Tennenbaum devoted two days to derivations of the Theis Equation. We thank you for your energy. Ms. Sidney Brinson, spent a day in the field with the authors explaining the Districts methodology for wetlands determination. Staff from the Florida Department of Natural Resources, especially Ms. Deborah Shelly, provided support and transportation, Glenn Lowe, Chief Environmental Specialist a the St. Johns River Water Management District was project manager for the District and was extremely patient and effective in his support. ii

PAGE 3

Preface This document is the product of a contract between the St. Johns River Water Management District and the Center for Wetlands, University of Florida to evaluate the applicability of upland buffers to the wetlands of the Wekiva River Basin. The purpose of this report is to develop critical insight concerning the need for, potential applicability of, and criteria for delineating upland buffers in the Wekiva Basin. In this report, we have reviewed the literature related to buffers, wetlands, wildlife habitat, transition zones, water quality and quantity, and other models and criteria for determining buffer zones. We have reviewed this information as a means of evaluating the need for an upland buffer to protect the water resources of the Wekiva River System. Whether an upland/wetland buffer zone is desirable and/or necessary for the Wekiva River System is not a question in the minds of the authors. Our review of the literature; our understanding of the unique character of the Wekiva River System; our knowledge of the limitations of the criteria for issuing of permits for construction, operation, and maintenance of stormwater systems; the limits of jurisdiction under current wetlands regulation; and the expressed policies of the Governing Board of the St. Johns River Water Management District suggest that an upland buffer is desirable and necessary if the wetlands, waters, and wildlife of the Wekiva River Basin are to be preserved. Two issues have surfaced during our study which need clarification as a prelude to the report. Both are related to the language in Chapter 373, iii

PAGE 4

Florida Statutes. In 373.413 and 373.416 a distinction is drawn between permits for construction and permits for operation and maintenance of water management systems. Both kinds of permits require that such systems cannot be harmful to the water resources of the District. Operation and maintenance permits are subject to an additional criterion: such activities cannot be inconsistent with the overall objectives of the District. Using one standard for construction and two for operation and maintenance is confusing. Operation and maintenance cannot be separated from construction, since once constructed, a system normally will be operated. Or to put it another way, if constructed, it seems backwards to then evaluate a permit for operation and find a system inconsistent with District objectives. Such a finding should be made prior to construction so that the project may be altered or redesigned to conform to District objectives. Thus, in our view, the review process for construction permit applications must also include operation and maintenance concerns. The District needs to review whether the constructed system will be harmful to the water resources and whether it will be consistent with the District's overall objectives during the construction permit review process. The second issue is related to the definition of "water resources." We believe that one cannot separate the waters of the District from the overall aquatic system when determining harm to the resource. The water resource must include not only the abio:ic substance (H20), but also the other abiotic substances and the biotic organisms that are carried and sustained by it. The water resource cannot be artificially dissected into parts which are regulated separat1y (although it is attempted quite often, much to the detriment of the resource); for as the water goes, so the organisms, and vice-versa." iv

PAGE 5

TABLE OF CONTENTS Acknowledgements . . . ii Preface iii I. INTRODUCTION .1 A. The Concept of Buffer Zones. .1 B. Buffers for Wetlands, Wildlife, and Water Quality. .2 C. Intent and Scope of the Report .5 II. REVIEW OF THE LITERATURE. .7 A. Significance of Buffer Zones 1. Ecological Significance of Transition Zones 2. Physical and Ecological Significance of Wetland 3. Water Quality Benefits of Buffer Zones. 4. Water Quantity Benefits of Buffer Zones .... 5. Edge Effects on Wildlife ... 6. Regional Habitat Needs of Wildlife: Corridors. 7. Between-Habitat Needs of Wildlife 8. Within-Habitat Needs of Wildlife. B. Review of Buffer Zone Regulations. C. Summary: Resource Buffer Zones III. LANDSCAPE ECOLOGY OF THE WEKIVA RIVER BASIN A. Landscape Perspective .. 1. Physical Description 2. Biological Description .7 7 Forest Edges. 11 14 23 26 33 38 44 50 59 67 67 67 74 B. Wetland Communities ................. 82 1. Aquatic/Marsh Communities ............... 82 2. Mixed Hardwood Swamp Community .84 3. Hydric Hammock Community. ......... 86 C. Transitional Communities: Mesic Hammock and Scrubby Flatwoods. 87 D. Upland Communities 87 1. Pine Flatwoods Communities. 88 2. Wet Prairie Communities. 90 v

PAGE 6

3. Pine Sandhill Communities. 4. Sand Pine Scrub Communities IV. STATUTORY & DISTRICT CRITERIA RELATED TO BUFFER ZONES A. Statutory Criteria, Sections 373.413 & 373.416, FS B. Rule Criteria, 40C-4, 40C-41 and 40C-42, FAC V. DETERMINATION OF BUFFER ZONE REQUIREMENTS 90 92 95 96 98 .111 A. Overview of the Methodology for Determination of Buffer Zones. .111 B. Determining Buffer Zone Requirements .118 C. Illustration of Buffer Zone Determinations .128 LITERATURE CITED .145 APPENDIX A. WILDLIFE ASSOCIATED WITH WEKIVA RIVER BASIN .169 vi

PAGE 7

I. INTRODUCTION I.A. The Concept of Buffer Zones The landscape is a mosaic of uplands and wetlands, developed lands and natural lands, and forests and fields. Somehow, without complete knowledge about how these pieces fit together, society must make decisions concerning how best to assemble the puzzle. Some decisions are easier than others, especially when there are no conflicting elements. Unlike a puzzle, however, the ease of adding a new land use to the landscape is inversely related to the number of pieces already on the board. As more and more land uses are added to the landscape, the decisions concerning placement require more and more thought. The more pieces there are on the board, the more conflicts there will be between pieces. Most often, it is at the borders between pieces where conflicts arise. Decisions are easier to make when adjoining uses are not significantly different, i.e., when the existing land uses abutting the boundaries of a decision piece are similar to the proposed use of the piece in question. However, when adjoining uses significantly different, consideration must be given to the interrelationships that are being created and to how one piece might affect surrounding pieces. When uses are significantly different, or where the potential for conflict is serious, it is common practice to create a buffer between them. Thus we have buffers around airports, nuclear power plants, and bombing ranges. Demilitarized zones (DMZ's) between warring nations are often used to maintain peace. Zoning in urban areas uses successively lower-density districts to make 1

PAGE 8

2 transitions between high-density land uses and low-density residential districts. Buffer zones can be relatively narrow, like the grassed shoulders of highways which separate high-energy roads from forested landscapes, or quite wide, like the DMZ between North and South Korea. Generally, as the density of activity or the potential for conflict increases, the width of the buffer necessary to contain the negative effects increases proportionally. In addition, as the difference in activity level between bordering land uses increases, the width of the border must increase, since it is not the absolute magnitude of activity but rather the relative magnitudes of activity between neighboring uses that require buffering. I.B. Buffers for Wetlands, Wildlife, and Water Quality The differences between developed lands and wild lands are significant; the more intensely developed, the more the differences. Frequently, on developed lands the native vegetation is removed and replaced with exotics, drainage is improved, soil is compacted or covered with impervious materials, wildlife habitat is replaced with human habitat, and activity levels increase 10 to 100 times those found in the wild. The gradient in the intensity of nOise, wastes, temperature, light, structure, and activity from undeveloped to developed lands is remarkable. It is this gradient that affects the edge between developed and wild lands, creating a new environment unlike the original and not at all similar to the developed land. The edge between wild lands and developed lands is characterized by overflows of materials and energy that "flow" from high density to low. Water runs off developed land, carrying sediments and nutrients. Noise from developed land intrudes into the edge, disrupts natural activity, and interferes with the less intense communications of wildlife that are cues for

PAGE 9

3 territorial protection and breeding. Increased temperatures caused by removing tree canopy and paving the ground surface have marked effects on the forest microclimate. Edges are common in the landscape, with or without development. In the wild landscape, however, sharp edges are hard to find. The lake edge is not a clean line; as the water level rises and falls throughout the year, it creates a littoral zone that is neither open water nor dry land, but somewhere in between. The sea edge is buffered by estuaries and coastal wetlands, which are neither open ocean nor dry land. The forest edge is a transition from the mature canopy with moist soils and minimal understory through a zone of more open canopy, with drier soils and dense understory, to the prairie with its xeric soils and lack of woody vegetation. As the landscape is developed, the wild lands that surround cities retreat. If the world was a homogeneous flat plain and development happened as a simple outward progression from the central city, the edge would constantly be moving and little need would be generated for buffer zones between developed lands and undeveloped lands. However, the world is not homogeneous, but heterogeneous, having many differences, many patches, and many obstructions to development. The development process becomes patchy, areas are skipped, wetlands left, and parks created. Areas are set aside as wildlife habitat, or protected for water quality purposes, or left undeveloped as remnants to remind us of what the landscape was once like. The patches that are created in this manner undergo constant change as they "evolve" or succeed toward ecological communities that are islands in the developed landscape. In Florida, under continuing growth pressure, the wild landscape has been mostly developed, leaving behind large and small islands of managed national, state, and local parks, along with many wetlands. Wetlands were first left

PAGE 10

4 behind because their development required a relatively greater commitment of funds and time than they were worth. Where the demand was high, in coastal areas for instance, wetlands were converted into dry lands and developed. Development skirted the swamps and marshes of inland areas not as a result of comprehensive planning, but because of piecemeal decisions made on a projectby-project basis. As land became more valuable and wetlands were threatened, state and local governments responded to increased pressure by enacting laws to protect the special values of wetlands recognized by society. Of primary concern was their function for maintaining clean, productive surface water and their value as very productive wildlife habitat. In the minds of many, wetlands are now "protected." The Warren S. Henderson Wetlands Protection Act of 1983 established state permitting authority over activities in wetlands by virtue of the fact that they were defined as waters of the state. A methodology for determining state waters, developed as a rule (Ch. 17-4 FAC) by the Florida Department of Environmental Regulation, was required by the Henderson Act. The rule uses vegetation as a means of determining landward extent of state waters. Plant species normally found in wetlands are sorted into three broad categories: submerged species, transitional species, and "invisible" species. All plants not found on these plant lists are considered upland species. The rule then uses simple formulas that relate dominance of these species to determine the upland edge of "state waters. II It is import-ant to note that at no time does the rule or the original legislation (except in the name of the Act) delineate "wetlands". It only refers to a selective list of plant species. The intent of the rule and legislation is to protect state waters, which include areas that are dominated by certain plant species that indicate regular and periodic inundation. Wetlands can, and do, extend landward of this jurisdictional line.

PAGE 11

5 The area immediately adjacent to and upland of the jurisdictional line is often a transition zone between wetlands and uplands. It is a zone that is wetland at times and upland at times, exhibiting characteristics of each and vegetated by species that are found in each. It is important to both the wetland and the upland as a seed reservoir, as habitat for aquatic and wetlanddependent wildlife species, as a refuge to wildlife species during high-water events, and as a buffer to the extreme environmental conditions of sharp vegetated edges. To protect the values and functions of areas that are waterward of the jurisdictional line, attention must be given to the area immediately upland of the line. Wholesale alteration of this edge has immediate and potentially large-scale permanent impacts on the waterward area. Wetland-dependent wildlife species that are frequent users of this area are excluded, silt laden surface waters are no longer filtered, the microclimate is greatly affected and groundwaters may be diverted or drained. In the natural state the transition zone is a buffer zone both for the adjacent wetland and state waters and for the wildlife species that inhabit them. It should be recognized as such, and afforded some degree of development control. I.C. Intent and Scope of the Report This report is intended to provide a detailed review of the existing scientific understanding of upland buffer zones, their importance to the adjacent wetlands and waters, and the effects of alterations of these transitional areas on downstream water quality and quantity, and wetland wildlife habitat values. As we researched the topic, we found a dearth of information directly addressing buffer zones. However, there has been much recent interest in the literature concerning the impacts of edges on wildlife

PAGE 12

6 habitat values, and some recent investigations of the extent and species composition of transitional zones between wetlands and uplands. The habitat values of transitional areas are related to between and within habitat needs of wildlife, the water quality values of buffer zones are related to protection of surface and groundwater, and their value related to water quantity issues is in their ability to mitigate adverse drainage impacts. The report is organized in five parts with an appendix that gives lists of aquatic and wetland-dependent wildlife species that are characteristic of the Wekiva Basin. After the Introduction, the second section reviews the literature and summarizes and relates it to the concept of a resource buffer zone. The third section gives a brief physical and ecological description of the Wekiva Basin. The fourth section reviews the Water Management District's statutory criteria (Chapter 373 FS) and permit criteria in 40C-4, 40C-41, and 40C-42 FAC and relates them to protection of the water resources of the Basin. The fifth section develops a methodology for determining buffer zone requirements.

PAGE 13

II. REVIEW OF THE LITERATURE II.A. Significance of Buffer Zones II.A.l. Ecological Significance of Transition Zones The zone that lies between what are unconditionally identified as uplands and wetlands is a zone of transition (sometimes called an ecotone). In this zone, environmental conditions resemble neither the true wetland nor upland, but fluctuate and may resemble each during different times of the year or from one year to the next. Plant species that characterize transition zones may be an assemblage of both wetland species and upland species and may contain species that are not found in either of the two adjacent zones. It has long been held that highest species diversity occurs in areas of habitat overlap (MacArther and Pianka 1966, Allen 1962, Ranney 1977). The Florida Department of Environmental Regulation (FDER), in its rules concerning the delineation and definition of landward extent of waters of the state, recognizes three main catagories of plants: submerged, transitional, and "invisible" species (Ch. 17-4.022 FAG). In an area dominated by transitional species, a preponderance of evidence that indicates it is regularly inundated is necessary before the area is considered a state water. In other words, without regular inundation, an area dominated by transitional species is not considered state waters, and by inference, therefore not a wetland. Under 17-4.022 FAG, Florida does not recognize purely transitional areas as state waters, and as a result does not recognize them as important or necessary for protection under the Warren S. Henderson Wetlands Protection Act 7

PAGE 14

8 (Chapter 430 Florida Statutes). However, their ecological significance as wildlife habitat and seedbanks, as well as their role in maintaining the integrity of the adjacent wetland community, is unrelated to their classification under 17-4.022 FAC. The FDER has chosen a cut-off based on dominance of "submerged" species to delineate state waters. The line so determined in most cases classifies all vegetation to the landward side as uplands. Most transition zones are to the landward side of the FDER jurisdictional line. The role of transition zones as wildlife habitat for wetland-dependent species will be reviewed in subsequent sections, as well as their role as seedbanks. Generally, their ecological value stems from (1) direct use by wildlife and (2) seed sources for plant species that are more upland in growth reqUirements, yet are found within wetlands and are an important component of the community. Transition zones occupy the key upland fringe and as a result are the main source for seed material that contributes to the spatial heterogeneity of wetlands. Wetland communities are not homogeneous. They are heterogeneous communities whose spatial variation in species composition is probably controlled by topography and ultimately by periods of inundation. Higher areas sometimes referred to as hummocks range in size from a few meters to several hectares. Hummocks have fewer periods of inundation and water depths are shallower, resulting in conditions that favor more "mesic" species. Lower areas are favored by those species that are to] ,.:, ant of flooding. This heterogeneity of the wetland landscape is (,r.,e of tte key fc:ctcrs that gives it its diversity and wildlife value. Wildlife values are greatly enhanced as a result of the increased diversity of vegetation and undulating topography.

PAGE 15

9 Studies of the Florida landscape indicate that the plant species diversity in transition zones is higher than the diversity of either the adjacent wetland or upland. Clewell (1982) found five community types on the Alafia River in central Florida along a gradient from wet to dry of which the "Moist Mesic Forest" seems to occupy that area that is transitional. The number of plant species found in this community exceeded all others by 25%. In Gross's (1987) study of 12 small-stream floodplain ecosystems in north and central Florida, 12 vegetation types were distinguished, using cluster analysis of which the three most diverse appeared to occur most often in the transitional areas. Studying methods for determining transition zones, Hart (1984) documented species composition of the wetland to upland continuum of eight wetland community types of north central Florida. She found that the transition zones were more diverse than either the wetland or upland and were different physiognomically from adjacent wetlands, yet were ... aligned more closely with wetlands than with uplands and were composed of species that tended to alternate between wetland and transition zones." The width of transition zones varied from a minimum of 10 m to a maximum of 30 m depending on the method used to delineate the zone and the type of wetland. Wildlife species richness shows direct spatial relationships to the increased of transition zones. Studies of forest edges (see Edge Effects on Wildlife) have documented increases in species richness and density of individuals within ecotones between habitats. Vickers et a1. (I 985) found that species richness and abundance of herpetofauna were greater along the edges of six wetlands in north central Florida than in either the wetland or upland habitat. Harris and Vickers (1984) found that virtually all mammals, because of their cursorial mode of locomotion and frequently herbivorous food habits, reside in "peripheral" areas, i.e., the transition zones. When water

PAGE 16

10 levels were increased, the movement of wildlife to the peripheral areas was also increased, suggesting the important role that transition zones play in providing refuge from wet-season increases in water levels in wetlands. The ecotone seems to play an even more important role when surrounded by clearcuts. Harris and McKlveen (1982) found a greater abundance and diversity of breeding birds in the ecotone between cypress wetlands and clearcut areas than in the ecotone between cypress and pinelands. Classifying the bottomland hardwood ecosystem into five classes, Wharton et al. (1981) represented the transition to upland communities as the fifth class. They listed the importance of environmental factors to fauna in each zone. Of the five classes, the transitional zone ranked highest in importance overall and highest in 18 of 27 factors, among which are: 1. Retardation of "side flooding," 2. Detritus source, 3. Diversity of oaks, 4. Availability of large variety of flora and fauna, S. Diversity of forest strata, 6. Refuge from high water, and 7. Forage and cover for upland species. The importance of the highest zones (transitional zones) of bottomland hardwoods to detrital food chains of downstream systems has been documented (Livingston et al. 1976, White et al. 1979). These studies showed that the infrequent pulses of organic matter and detritus form the higher zones in the floodplain after extreme flood and rainfall events correspond to peaks in fish production. Topography plays an important role in controlling the width of transition zones. The transition zone between wetland and upland may be only a few meters in width or may extend for several hundred meters. In areas of very low relief, where the landscape has little or no slope, the transition zone may be extensive and ill-defined; yet, in landscapes where slopes are more prominent,

PAGE 17

11 the transition from upland to wetland may be far more abrupt. In studies of the central Florida landscape (Brown et al. 1984, 1985, and 1986), transition zones as wide as 30 m were delineated using species composition as the controlling variable. Gross (1987) found community types using cluster analysis that were dominated by transition zone vegetation on central Florida streams as wide as 80 m, but 40-m zones were more common. II.A.2. Physical and Ecological Significance of Wetland Forest Edges When forest is cleared and some forested remnants are left, as when the landscape is developed for agriculture or urban uses or clearcut during silviculture operations, the remaining forested patches contain induced edge where there once was a forest continuum. These forested tracts develop characteristic edge habitats that differ from habitat of interior forests. Ranney (1977), in a review of the literature on forest island edges, suggested that edge habitat differed from interior forests in at least six ways: 1. Tree species composition, 2. Primary production, 3. Structure, 4. Development, 5. Animal activity, and 6. Propagule dispersal capabilities. The importance of edge is in its effects on the forested habitat and eventually on the suitability of the habitat for indigenous fauna. The conditions created when the forest continuum is cleared have detrimental long term consequences on the remaining forest system. Using current jurisdictional lines (Gh. 17-4.022 FAG) to determine the landward extent of state waters and given current development practices, the forest edge created between wetland and developed upland will coincide with the jurisdictionally determined line of regularly inundated wetland. In most instances this does not include transitional zones to the landward side of the jurisdictional line. The

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12 creation of an edge at this wetland/"upland" boundary opens the wetland to the many changes associated with edge conditions. When a forested edge is created through clearing and/or partial removal of the forest canopy, steep gradients of solar radiation, temperature, wind speed, and moisture are incurred between the relative extremes of the open land and the forest interior (Wales 1967, 1972). Studies of characteristics of newly created edges (Gysel 1951, Swift and Knoeerr 1973, Trimble and Tryson 1966, Wales 1972, 1976) suggest that solar radiation is probably the most important physical parameter influencing conditions at the forest edge. The forest edge environment is characterized by increased solar radiation which in turn increases temperatures and decreases moisture content of soils and relative humidity when combines with effects of increased wind flows. Physical and structural manifestations of these changes include increase of shadeintolerant, xeric tree and shrub species and an increase of species associated with early stages of succession (Gysel 1951, Trimble and Tryson 1966, Wales 1972) Of particular importance is the effect of increased wind speed on the newly created forest edge; especially when the edge is created at the wetland/upland interface. A major consequence of clearcutting is the loss of buffering of destructive wind speeds by the adjacent tree canopy. Tree windthrows are common along newly created edges since edge trees not exposed to wind velocities of the open landscape are not structurally prepared for them. Wetland trees do not have deep-rooted growth habits, but instead rely on a root mat very near the soil surface to provide structural support in the relatively low bearing-capacity soils of most swamps. Wind throws are relatively more common in the deep organic soils of wetland ecosystems than in forested upland

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communities because of soil instability and difficulty of trees to anchor sufficiently. 13 The spatial effects of forest edge conditions are variable and are highly dependent on the way the edge is maintained. Ranney (1977) summarizes the spatial influences of newly created edges as between 5 and 20 m deep from the forest edge toward the interior. In a study of microclimate on Ft. George Island near Jacksonville, Florida, Hart (1985) determined that most of the microclimatic change between cleared areas and a forest interior in north and south directions occurred within 10 m of the edge, although on western facing edges, 25 m was often required for equivalent microclimatic change. Hart notes that the eventual closure of newly created edges by shrubs and vines will ameliorate negative microclimatic conditions and suggests the planting of fastgrowing shrub species in some instances to speed up edge closure. Harris (1984) discusses the "three-tree-height" rule of thumb for the distance over which climatic effects of a surrounding clearcut will penetrate into an oldgrowth stand. Related to average tree heights of Florida wetland ecosystems, the three-tree-heights rule would suggest the penetration of influences as deep as 70 m. Conceptually, to maintain the integrity of the wetland community and to insure faunal habitat for wetland-dependent species, buffers from 5 to 70 m ,n depth are necessary. Clearing at the wetland edge opens the wetland to significant changes. However, with a buffer that encompasses the transitional zone on the landward side of the wetland, negative impacts can be avoided. Changes in abiotic parameters (due especially to increased solar radiation and wind) towards more xeric conditions along edges lead to corresponding changes in plant and animal communities (see Table 9 in Lovejoy et al. 1986) and in system properties such as nutrient cycling (Ranney 1977). Studies by

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14 Levenson (1981) and Ranney et al. (1981) in Wisconsin have documented major edge effects on the vegetation of forest islands. They found that climatic structural edge influences extend at least 10 to 15 m into a forest on the east, north, and south sides and 30 m on the west side. Once established, characteristic edge associations composed of xeric-adapted and shade-intolerant species act as sources of propagules that invade the forest interior; forest islands below a certain size (about 5 ha in Wisconsin) may be entirely edge habitat in terms of their flora and vegetation structure (Ranney et al. 1981). Such changes may be essentially permanent. In Ohio, Whitney and Runkle (1981) found that small but persistent environmental differences associated with forest edges have greater long-term effects on tree species composition and structure than did severe but relatively brief disturbances associated with logging. II.A.3. Water Quality Benefits of Buffer Zones The water quality benefits of buffer zones are related to the ability of the zone to abate destructive water velocities and quantities of pollutants carried by surface runoff from uplands that may have a negative impact on downstream water quality, flora, and fauna. Soils of transitional areas are generally characterized by a low accumulation of organic matter (Gross 1987, Clewell 1982) but have accumulations of organic debris on the order of 1 to 5 tons per ha, depending on vegetative cover (Hewlett 1982). This organic debris can absorb about 98% of rainfall energy, minimizing erosion potential. Known as litter detention storage, it disperses the energy of water that would otherwise break bonds of soil materials and produces a slurry of mud and eroded soil. The kinetic energy of sediment transport increases rapidly as the second power of water velocity (Hewlett 1982) suggesting that as a slope increases or

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15 loses obstructions (such as vegetation) to uninterrupted flow, erosion potential increases dramatically. occupying topographic lows in the landscape, wetlands are particularly susceptible to erosional deposition from higher grounds and to erosional scouring as a result of increased water velocities from mismanaged upland surface waters. Maintaining undisturbed vegetation in transition zones can help to minimize these destructive forces. The Florida Division of Forestry's Silviculture Best Management Practices (BMP) Manual 1979) recommends a Discretionary Zone (DZ) for land occurring within 300 ft of a watercourse. This 300-foot-wide strip of land is considered the zone most influential to surface water quality. Recommendations are given for varying site sensitivities regarding the intensity level of activities such as construction of roads, site preparation, and harvesting practices. Within the DZ, two Streamside Management Zones (8MZ) are further delineated: a fixed primary and a variable secondary zone, each of which has been assigned special management criteria. The primary zone is 10 m from the edge of the watercourse ,1 while the secondary zone is from 10 to about 50 m from the water's edge. The width of the secondary zone is determined by the soil and topographic characteristics of the site. Within each of the 8MZ's, recommendations for site preparation and harvesting are given relative to slope and soil erodibility. Since the main objective of Silviculture BMP's is to minimize negative impacts on water quality, and since silviculture, by definition, is the l80metimes the border of the 8MZ's are referred to as ..... the edge of the watercourse or lake ..... (Florida Division of Forestry 1979); other times the 8MZ is "adjacent to perennially open waters" (Riekerk and Winter 1982); still others as a II strip of forest land surrounding all perennial streams and lakes 10 acres or larger" or as "a vegetated strip adjacent to a watercourse ... or as occurring ... along all perennial and intermi ttent streams ..... (Florida Division of Forestry 1979). A strict definition of the watercourse's edge as related to 17-4 FAC may be important to help determine from what point the 8MZ should be applied.

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16 management of forests for their wood fiber, the BMP's are designed to maximize the forest area that can be harvested. If the goal was to minimize negative impacts on state water resources,2 the primary and secondary zones would begin at the wetland edge and extend upland. In this manner the zones would occupy the area that is commonly termed the transition zone between upland and wetland and would insure minimum impacts to state waters. It is generally agreed that the more sensitive a site is to sediment production, the wider the undisturbed vegetative buffer should be. Since sediment production can result in the deposition of materials in locations where they may have negative impacts, and since sediments provide a major vehicle by which pollutants are transported, every effort should be made to encourage the use of vegetative buffers to minimize sediment deposition in wetlands and water courses. The width and efficiency are variable. Karr and Schlosser (1977), relying on the work of Trimble and Sartz (1957), suggest a minimum width of buffers for conditions encountered in IImunicipal conditions" as 15 to 20 m for lowest (0 to 3%) slopes and as high as 80 m for slopes of 60%. There has been much research on the effects of logging in close proximity to streams, especially in the northwest United States. Erman et a1. (1977), in of logged landscapes with and without streamside buffers, found that buffers were very important in minimizing negative impacts as a result of erosion from logged lands, and that streams with narrow (less than 30 m) buffers showed effects comparable to streams with no buffers. Generally, their 2Waters of the state are those lands that are regularly and periodically inundated as defined by 17-4.022 FAC which includes areas dominated by "submerged" wetland vegetation. Thus to protect state waters and achieve Best Management Practices as they relate to these waters, the discretionary zone, primary zone, and secondary zone should be measured as distance from the edge of the wetland instead of the edge of the watercourse.

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17 research on 62 northern California streams showed a strong correlation between buffer width and stream community diversity index. Streams with highest diversity indices had buffers greater than 50 m in width. Streamside buffers in the high-relief landscapes that characterize most of the continental United States are generally measured from the channel bank. Where landscape relief is high, channel slopes are high, and associated floodplain ecosystems are narrow; and as a consequence, streamside buffers measured in this way probably adequately protect the resource. However, where landscape relief is low, as in the Southern Coastal Plain, terrain is flatter, stream channel slopes are lower, and associated riparian ecosystems are wider. The measurement of streamside buffers in low relief landscapes needs to reflect these important differences and begin at the upland edge of the riparian ecosystem. Effects of Construction Activities Darnell et al. (1976) summarized the effects of construction activities on riparian ecosystems and grouped them into three time related catagories: 1. Direct and immediate results which take place during the construction process; 2. Effects which occur during the period of stabilization following completion of the construction; and 3. Long-term effects of more or less permanent changes brought about by the construction itself or by subsequent human use and environmental management occasioned by the constructed facilities. The water quality effects of construction activities within upland boundaries of riparian ecosystems can be grouped into the same time-related catagories, although for the sake of simplicity, the first two may be combined. The overall impacts of any construction activity vary depending on environmental features (e.g., physical characteristics such as slope, soils,

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18 and vegetative cover), timing, type of' construction activity, and the care taken during the active construction phases. Long-term impacts associated with subsequent uses vary depending on environmental features, intensity of uses, and management practices. During and immediately following construction the major impacts on water quality can be grouped into three broad classes: 1. Impacts associated with erosion of loose soils and their subsequent deposition in downslope wetlands; 2. Suspended sediment increases in surface waters, resulting in increased turbidity; and 3. Introduction of unusual levels of chemical compounds that may have negative effects on resident fish and wildlife populations. The most obvious results of the deposition of eroded sediments in wetlands are the impacts associated with filling. When wetland soils are covered with additional depths of fill material, the most serious impact is loss of oxygen penetration to the root zone and resulting stress on vegetation. If the accu-mulation of sediment is deep enough, or if the sediment is fine enough to plug up soil pores so as to effectively starve roots of oxygen, death of vegetation results. Secondary impacts are experienced by wildlife as a result of the loss of habitat. The authors have on numerous occasions witnessed the results of inad-vertent filling along wetland edges throughout Florida. In most cases these results were caused by erosion of unstable soils during clearing and con-struction activities. The deposition of eroded material resembles a wedge of sediments where the bigger particles drop out of the sediment stream first and successively finer materials drop out farther into the wetland system. Depths of sediment are greatest along the periphery and taper off to shallower and shallower accumulations as the sediment stream penetrates into the wetland. In

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19 most instances the effects are immediate and dramatic. Where sediment depths are greatest, both understory and canopy plants are killed, and as the sediment wedge tapers off, tree kills are less noticeable, but the many varieties of understory vegetation with their shallower root systems are killed. Finally, at the farthest extreme of the sediment wedge, only the herbaceous vegetation is affected. The net result of the deposition of eroded sediments within the limits of wetland communities is to shift the conditions of the transitional edge farther into the wetland. Dead and dying vegetation is replaced over time by early successional upland vegetation. The impacts are less a loss of water storage capacity (since the volume of sediments may be small compared to the overall volume of water stored in the wetland) as they are a loss of valuable wetland function and wildlife habitat. If the disturbed area is close enough to surface waters, or if the configuration of the wetland is such that stormwater runoff from the upland edge can collect and form an intermittent stream, sediments eroded during construction phases may directly affect aquatic environments. In their review of impacts of construction activities in wetlands, Darnell et al. (1976) grouped the biological impacts of suspended and sedimented solids Under the topics of turbidity, suspended solids, and sedimentation. Within each group they review the biological effects that have been documented in the literature. Their review is summarized in Table II.A.l. The final water quality effect during the construction phase is related to the release of chemicals, the levels of which may be harmful to downstream fish aand wildlife or negatively affect ecosystem function. When areas are cleared, runoff increases, carrying with it increased volumes of soil and sediment. Large quantities of dissolved cations and other minerals are lost from the

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20 Table II.A.I Biological Effects of Sediments and Suspended Solids on Aquatic Environments (after Darnell et al. 1976) Topic Biological Effect Turbidity Suspended Solids Sedimentation Reduction of photosynthesis -eliminates phytoplankton, attached algae, and rooted vegetation, thus eliminating base of aquatic food chain Decreased visibility -interferes with normal behavior patterns of higher aquatic organisms Temperature effects -water absorbs more radiant energy, inhibiting vertical mixing in calm waters or uniformly heating moving waters modifying oxygen content Oxygen reduction -through inhibition of photosynthesis, heating, or increased COD and BOD Reduction of primary production -inhibits light penetration, absorption of critical nutrients, removal of algae and zooplankton from suspension through adherence to particles Effects on respiration -oxygen reduction can selectively eliminate aquatic animals that require oxygen for respiration, suffocation through clogging of gill filaments Other effects -potential starvation of filter feeding animals, decreased visibility, interference with migration patterns of fish Primary production -smothering and scour,ng, physical barrier to gas exchange Bottom animals -scouring and blanketing with sediments Fish populations -reduction of food supply, destruction of habitat, elimination of spawning areas, smothering of eggs and larvae

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21 cleared areas and deposited in downstream areas. Borman et al. (1968) found cation losses from 3 to 20 times greater from clearcut watersheds than from undisturbed control watersheds. Riekerk et al. (1980) showed significant increases in sediment and higher nutrient cation loading of runoff from a clearcut; relatively low-gradient watershed after one year, but no significant differences after the second year. In watersheds composed of wet savanna forests of Florida's Lower Coastal Plain, Hollis et al. (1978) recorded significant loss rates of dissolved minerals including ammonium-nitrogen as well as phosphorus and suspended sediments. Of less concern, unless a large-scale accident occurs, is the increase in petroleum products that may pass from construction sites into downstream wetlands and watercourses. Spills in maintenance yards and the general operation of equipment in and near wetlands increases the likelihood of increased contamination. In all, however, contamination from petroleum products during the construction phase should be of minor concern if proper care is taken. Effects of Operation and Maintenance Long-term water quality impacts associated with construction activities in areas adjacent to wetlands and watercourses is a function of subsequent human uses and management. Stormwaters running off developed lands carry both organic and inorganic materials, both suspended and in solution. Many of the organics are degraded through biological pathways or through chemical oxidation. As degradation occurs, oxygen is consumed causing decreases in available oxygen. Thus the breakdown of these compounds "demands" oxygen. Their presence and potential for negative water quality impacts is measured by tests for Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD).

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22 The final land use of a developed area has a marked effect on the quality of stormwater runoff. The Florida Department of Environmental Regulation (FDER) (1978) summarized the work of Sartor and Boyd (1972) that compared the total solids loading from residential, commercial, and industrial land uses. Industrial areas were shown to have the highest loadings and commercial areas to have the lowest. Another stormwater study of three sub-basins (a forested, a and an urban basin) of Lake Jackson in northern Florida as reported in Wanielista (1975) and summarized by the FDER (1978) compared mean concentrations for various constituents in stream water under stormflow and baseflow conditions. The findings showed that the export from the urban watershed was greater for all constituents than from the forested or suburban watersheds, and that mean concentrations of suspended solid loadings from the urban basins and suburban basins were approximately 10 times and 5 times, respectively, those of the forested watershed. In most time-related studies of the quality of urban runoff, a common finding is the difference in concentrations of constituents between the initial "first flush" and later runoff. Typically, the initial rainfall flushes the stormwater system, carrying with it large quantities of suspended solids and materials in solution. Later discharges have significant, but much lower, concentrations of pollutants. Stormwater management rules generally recognize the potential for downstream water quality impacts from urban and suburban areas, and while there is some variation in regulation throughout the state, generally they address the problem through retention of a prescribed amount of the initial rainfall from a storm event. This treatment method assumes that through retention of the first flush, a majority of the constituents that would enter surface waters are retained. However, most stormwater systems, while retaining this first

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23 flush, accumulate the remaining stormwater in the same retention basin, diluting initial concentrations with the added waters. Under these conditions, if the rainfall event is large enough, the diluted first flush is discharged along with remaining stormwaters to receiving water bodies. The net result is little if any retention of the pollutant carried by the storm runoff. Recently, more stringent regulations have been put into effect in the Wekiva River Basin that require off-line retention to avoid this problem. The problems associated with degradation of water quality as a result of the operation and maintenance of a stormwater management system once a development is in place may be little affected by a buffer requirement. The potential impacts on water quality from the combined effects of increased runoff and increased concentrations of pollutants that result from urbanization are not so much functions of how close the developed areas are to wetlands and watercourses as they are of land use, size of the development, and stormwater system design. However, potential impacts from systems designed to allow portions of a development to discharge without treatment may be mitigated through a buffer requirement. In many instances, where slopes prohibit stormwaters to be collected into a system, portions of the lowest areas in the development (typically those closest to and abutting the wetland/watercourse edge) may discharge directly. A buffer requirement in these situations would allow for some treatment of stormwaters if they were allowed to sheet flow through the buffer area. II.A.4. Water Quantity Benefits of Buffer Zones The construction and subsequent operation of urban land uses within areas adjacent to wetlands and watercourses affect the quantity and timing of waters that flow over the lands and often surficial groundwaters beneath the developed

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24 lands. The effects are the result of both construction-related activities and operation and management-related activities. During construction, the volume of runoff increases, since removed vegetation and surface accumulations of organic matter can no longer act to retard runoff, and transpiration is greatly reduced. Studies of water yield from watersheds having varying degrees of clearing show strong relationships between the amount of disturbance and water yield. One study in north central Florida by Riekerk et al. (1980) found water yield increases of 165% from a clearcut, highly disturbed watershed and over 65% from a minimally disturbed watershed. In a later study Riekerk (1985) found 2.5-fold and 4.2-fold increases in runoff from minimally and maximally disturbed watersheds, respectively. In most studies, the effects of disturbance on runoff volumes decreases markedly from 2 to 3 years after treatment as vegetation again plays a role in the site's hydrologic balance. The net effects of clearing are reflected in higher soil moisture levels which may contribute to higher stream base flow and greater direct runoff during storm events. Once vegetation has been removed, it is quite common for groundwater table elevations to increase as a result of decreased transpiration. In areas of existing high water tables, soils can become saturated and extremely difficult to work without extensive "drainage improvements.1I Stormwaters are often routed through temporary swales and ditches into downstream areas to minimize flooding while drainage and stormwater systems are being constructed. Such practices can add significantly to construction-related water quality impacts and alter quantity and timing of surface water discharge. Typically, areas immediately adjacent to floodplain and seepage wetlands are dominated by seasonally high water tables. This is a predominate aspect of

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25 the lands adjacent to the floodplain wetlands throughout the Wekiva River Basin. Lowering of water tables to accommodate construction-related activities and as a permanent consequence of development can reduce groundwater elevations and intercept groundwater flows to adjacent wetlands. Of all the impacts of development, when the mitigating effects on surface water of properly designed retention/detention systems are taken into account, the loss and interception of groundwaters has the most profound consequences. Drainage in areas with high water tables is a widely accepted practice that allows development of lands that would otherwise be difficult to develop. Positive drainage "dewaters" the upper portions of the soil, which lowers the surrounding groundwater elevations. The effects spread radially from the drainage system with the actual amount of decline in water table elevation dependent on the elevation of the drainage system and soil properties and topography of the surrounding lands. Wang (1978) and Wang and Overman (1981) found the effects of a lO-foot lowering of the groundwater table to extend up to 1 mile from drainage ditches in south Florida. While this is probably not typical throughout Florida, it does indicate the magnitude of the problem. The impact of lowered water tables on adjacent wetlands is a reduction in hydrologic function. Where adjacent wetlands are depressional wetlands that intercept the groundwater table, lower water table elevations reduce depths of surface waters and shorten hydroperiods. Under extreme conditions the wetland may remain dry throughout the year. In areas dominated by seepage wetlands, lowered water table elevations result in a reduction or even a cessation of groundwater seepage and subsequent drying of the wetland. The long-term, widescale effects of general drainage practices throughout the state have been discussed by Brown (1986) and are pervasive. While immediate ecological changes resulting from drainage are subt1e--to the untrained eye, no change is

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26 observable--the long-term consequences are loss of hydrological functions, gradual replacement of wetland vegetation with upland types, and consequent loss of habitat values for aquatic and wetland-dependent wildlife species. The maintenance of setbacks or buffers in areas immediately adjacent to wetlands and watercourses can have significant impact in minimizing these effects. A properly sized buffer between construction activities and downstream wetlands can slow down and filter runoff and mitigate the drawdown effects of drainage ditches on adjacent wetlands. It cannot be stated strongly enough that the lowering of water tables to accommodate development is probably the single most important impact affecting adjacent wetlands, and that a properly sized buffer will go a long way toward minimizing these impacts. II.A.S. Edge Effects on Wildlife The question of how wide a buffer zone must be to maintain biological integrity cannot be answered without considering the problem of edge effects. Edge is defined as the place where plant communities meet or where successional stages or vegetative conditions within plant communities come together (Thomas et al. 1979). Edge effects have been investigated intensively in wildlife management ever since 1933, when Aldo Leopold's classic text was published. Evidence of a positive edge effect (i.e., an increase in species richness or density of individuals near an edge in contrast to adjoining habitat types) has been reported for birds (Lay 1938, Beecher 1942, Galli et al. 1976, Laudenslayer and Balda 1976, McElveen 1977, Gates and Gysel 1978), mammals (Bider 1968, Forsyth and Smith 1973), and several other groups of organisms. Most of the early studies of edge effects were concerned with documenting an increase in wildlife abundance near edges. They implied that managing land

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27 to increase edge will also increase wildlife. Edge habitat has high cover density and food availability for many animals, and it is an index of carrying capacity for species that require two or more habitat types for survival (Johnson et al. 1979, Thomas et al. 1979). Hence, Leopold (1933) described game (wildlife) as "a phenomenon of the edge" because wildlife "occurs where the types of food and cover which it needs come together." Subsequently, edge became a fundamental principle of wildlife management (e.g., Allen 1962, Dasmann 1964), and some wildlife management texts went so far as to urge managers to "develop as much edge as possible" (Yoakum and Dasmann 1971). Ghiselin (1977) suggested that an edge index based on the amount of edge or ecotone present is useful as an indicator of relative animal productivity between similar habitats Unfortunately, these wildlife management recommendations were naive about the consequences of edge management on nongame animals, on plant communities, and on regional diversity patterns (reviewed in Noss 1983). In a management context, there are two types of edge: inherent edge and induced edge (Thomas et al. 1979). Inherent edge is a natural phenomenon that represents the juxtaposition of community types and a continuum of successional stages in the landscape mosaic. This natural heterogeneity is in large part a product of the natural disturbance regime of fire, flood, treefalls, wind throws landslides, and other events (White 1979, Sousa 1984, Pickett and White 1985). Moreover, this natural heterogeneity may be the primary determinant of wildlife composition and diversity in a region (reviewed in Noss 1987). Induced edge, on the other hand, 1S a product of manipulation of habitat by humans. It is closely tied to the process of habitat fragmentation that produces sharp contrasts between vegetation types. Simple geometry shows that small habitat islands have larger edge-to-interior ratios than do similar

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28 shaped large habitat islands. As a natural landscape is fragmented into disjunct pieces of habitat in a sea of developed land, the proportion of edge habitat in the landscape increases. Thus, species that are restricted to habitat interiors gradually are replaced by species characteristic of edge habitats. The latter species are generally opportunistic or "weedy" and do not need reserves for survival (Diamond 1976, Whitcomb et al. 1976, 1981, Noss 1983). Conservation biologists therefore recognize that interior species dependent on large tracts of undisturbed habitat should receive priority attention in conservation plans. The recognition of negative edge effects associated with induced edge was a major breakthrough in wildlife ecology. Until the mid-1970s, the attention of most wildlife scientists was focused on relatively small tracts of land (i.e., on local diversity) and on the small subset of animal species that could be hunted. Under these circumstances, induced edge habitat can be seen as favorable. Species such as white-tailed deer, bobwhite quail, cottontail rabbit, and ring-necked pheasant often increase under such circumstances, as does the species list of individual management units. But if one focuses on regional and global diversity, and on entire ecosystems (including nongame animals and endangered species of plants), the negative consequences of induced edge are all too clear. The end result is often a landscape that has lost its native character and is dominated by weeds that are either alien to the region or were previously restricted to recently-disturbed patches (Faaborg 1980, Samson 1980, Noss 1981, 1983, Samson and Knopf 1982, Harris 1984, Noss and Harris 1986). The negative effects of induced edge are easier to understand when one considers that edge is more than a one-dimensional boundary between habitat types. Effects of an open, disturbed habitat penetrate some distance into an

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29 adjoining wooded natural area; hence, edge has a width of influence. Much of this influence is ultimately climatic. Lovejoy et al. (1986), summarizing the status of their research on forest fragmentation and induced edge effects in Amazonia, recognize an abiotic class of edge-related changes that includes temperature, relative humidity, penetration of light, and exposure to wind. The type of habitat on the outside of a forest edge will determine the nature of edge effects. A general principle is that the greater the contrast between habitat types, the greater the edge effect (Harris 1984). When a forest is fragmented, the matrix which surrounds it is usually some type of early successional habitat. (Housing subdivisions would generally fall in this category.) This secondary successional habitat is a constant source of weedy plant and animal propagules that invade the forest fragment and alter species composition and relative abundances (Janzen 1983). Opportunistic animals that achieve artificially high densities in the early successional habitat often invade pristine areas, exerting abnormally high levels of trampling, browsing, and seed predation; this can destroy a natural area as surely as can a chainsaw (Janzen 1983, 1986). Bratton and White (1980) reported that manipulation of habitat to support a huntable deer herd can result in heavy browsing in adjacent natural areas and further endanger a number of rare plant species. The effects of habitat fragmentation and induced edge on animal communities (especially birds) has been particularly well studied over the last two decades. Application of island biogeography theory (MacArthur and Wilson 1967) to habitat islands have led to recommendations for the design of nature reserves. Nature reserves and forest fragments have been portrayed as islands because they are patches of natural habitat in a matrix or sea of culturally modified land (Terborgh 1974, Diamond 1975, Sullivan and Shaffer 1975, Wilson and willis 1975, Diamond and May 1976, Forman et al. 1976, Galli et al. 1976,

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30 and many others). Most early work on this problem was essentially a confirmation of the familiar species-area relationship (Arrhenius 1921, Gleason 1922, Preston 1960, 1962): larger pieces of habitat support more species. There are many potential explanations for the species-area relationship. Three general explanations are (1) larger areas support more kinds of habitats (and thus more habitat-specific species), (2) larger areas offer bigger "targets" for organisms dispersing across the landscape, (3) larger areas maintain larger populations that are less vulnerable to extinction due to random or deterministic population fluctuations, and (4) larger areas support animals of large territory and home range size that cannot be supported in small areas. Anyone of these explanations is powerful enough to support the general recommendation that nature reserves should be as large as possible (e.g., Soule and Wilcox 1980, Frankel and Soule 1981, Schonewald-Cox et al. 1983, Harris 1984, Soule 1986). The process of habitat fragmentation is accompanied by insularization of fragments, i.e., isolated pieces of habitat surrounded by dissimilar habitat begin to resemble islands in many of their ecological dynamics. Eventually, fewer native species will be found in a habitat islands than in sample areas of equal size within extensive blocks of habitat (Miller and Harris 1977). Alternately, species richness may not change much, or may even increase, with habitat insularization, but species composition will shift towards edge species at the expense of area-dependent interior species. These edge species are generally common in the developed landscape and do not need reserves of any kind for survival (reviewed in Noss 1983). In New Jersey, Forman et al. (1976) found that forest islands contained more bird species than did sample plots of equal size within extensive forests, but the additional species were primarily birds of the forest edge. Forest

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31 interior birds were limited to the larger forest islands. Since then, the changes in avifauna that occur with forest fragmentation have been thoroughly documented (for the most extensive treatment, see Whitcomb et al. 1981). In Florida hardwood hammocks, Harris and Wallace (1984) documented area-dependence in a number of bird species. In the Wekiva River bottomland hardwood forest, breeding bird species that have been shown elsewhere to be area-dependent and vulnerable to negative edge effects include the red-eyed vireo and the Acadian flycatcher, both near the limits of their ranges in this area (H. Kale, Florida Audubon Society, pers. comm.). More generally, the species most vulnerable to extinction in fragmented landscapes are large animals with large home ranges (i.e., top carnivores), ecological specialists, and species with variable populations that depend on patchy or unpredictable resources (Terborgh and Winter 1980, Karr 1982, Wright and Hubbell 1983). The characteristically small populations of these species are vulnerable to problems related to environmental stochasticity, demographic stochasticity, social dysfunction, and genetic deterioration brought on by inbreeding or genetic drift (Frankel and Soule 1981, Shaffer 1981, SchonewaldCox et al. 1983, Soule and Simberloff 1986). Biotic aspects of edge effects have played a major role in the ecological deterioration that accompanies fragmentation. Some effects of edge on vegetation were discussed above. Because animal communities respond to vegetation structure (e.g., MacArthur and MacArthur 1961, Roth 1976), any edgerelated changes in vegetation will cause corresponding changes in animal communities for a certain distance into a habitat interior. But there are more insidious processes at work. The opportunistic animals that are attracted to edge (or to the early successional habitat outside) often prey on, out compete

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32 or parasitize interior species, sometimes with disastrous consequences, to the latter's populations. Most of the research on faunal deterioration near edges has been done on birds. Whitcomb et al. (1976) provided evidence that, in areas where forest has been reduced to isolated fragments, avian brood parasites (brown-headed cowbirds), nest predators (small mammals, grackles, jays, and crows), and nonnative nest-hole competitors (e.g., starlings) are usually abundant in the urban-agricultural mafrix and often invade small forest tracts and narrow riparian strips. Gates and Gysel (1978) found that a field-forest edge attracts a variety of open-nesting birds, but such an edge functions as an "ecological trap." Birds nesting near the edge had smaller clutches and were subject to higher rates of predation and cowbird parasitism than those nesting in either adjoining habitat interior. Brown-headed cowbirds, which were not found east of the Mississippi River before widespread forest fragmentation, are a particularly noxious species. Half or more of the songbird nests within 200 m of the edge may be parasitized, reducing reproductive success for some species below the level of population sustainability (Brittingham and Temple 1983). Brown-headed cowbirds have been increasing in number and are moving south in Florida, and they will undoubtedly become more problematic as forests continue to be fragmented; meanwhile, the ecologically similar shiny cowbird, which has caused severe problems in parts of the Caribbean (Post and Wiley 1976, Post and Wiley 1977), has been moving north and was reported in Florida in 1986. Experimental studies of nest predation have documented significantly higher predation rates in small forests compared to large forests, in forests surrounded by suburbs compared to forests surrounded by agricultural land, and at decreasing distances to forest edge (Wilcove 1985, Wilcove et al. 1986).

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33 This abnormally high predation rate is related to the artificially high densities of many opportunistic animals near forest edges and in disturbed habitats (including suburbs; Wilcove et al. 1986). A primary reason why these opportunistic animals (which in Florida include raccoons, opossums, gray squirrels, armadillos,house cats, and blue jays) achieve such high densities is that the large predators (e.g., panthers, wolves, and bears) that once regulated their populations have been extirpated or greatly reduced (Matthiae and Stearns 1981, Whitcomb et al. 1981, Wilcove et al. 1986). The deleterious effects of increased nest predation may extend 300 to 600 m inside a forest border (Wilcove et al. 1986). More generally, Janzen (1986) suggests that managers can expect serious edge effects (including problems related to heavy use by humans and domestic animals) anywhere within 5 km of a reserve boundary. The studies discussed above suggest that any forest tract has a "core area" that is relatively immune to deleterious edge effects and is always far smaller than the total area of the forest (Temple 1986). Relatively round forest tracts with small edge-to-interior ratios would thus be more secure, whereas thin, elongated forests (such as those along riparian strips) may have very little or no core area and would be highly vulnerable to negative edge effects. II.A.6. Regional Habitat Needs of Wildlife: Corridors A great deal of recent literature in the fields of island biogeography and conservation biology has discussed the effects of inbreeding and genetic drift on wildlife due to genetic isolation and small population sizes (e.g., Miller 1979, Soule 1980, Senner 1980, wilcox 1980, and Franklin 1980). Inbreeding has the effect of decreasing population heterozygosity (genetic variation) by increasing the probability that progeny will receive duplicate alleles from a

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34 common ancestor. This loss of genetic variation can have both immediate and future implications for a species' survival. Inbreeding can lower species vigor and fecundity within a few generations (Soule 1980). The very reduced population of Florida panthers may be suffering from the effects of inbreeding. All five males examined have had greater than 93% abnormal sperm (Roelke 1986). Over the long term, inbreeding can also limit the ability of a population to evolve to meet changing environmental conditions (Soule 1980, Harris et al. 1984). Other literature has questioned the effectiveness of fragmented parks and preserves in maintaining viable populations of animals which require large home ranges or activity areas (Pickett and Thompson 1978, Lovejoy and Oren 1981, Harris and Noss 1985, Harris 1984, Noss and Harris 1986, Noss [in press]). In Florida, bears may range over 15,000 ac and bobcats over 5,000 ac. An otter may require several miles of linear river and riparian habitat (Harris 1985). To maintain viable populations of these and other far-ranging animals, large blocks of land are needed. One proposed management alternative for providing for these wildlife needs is the use of wildlife corridors (Diamond 1975, Butcher et al. 1981, Forman and Godron 1981, Harris 1983, Noss 1983, Harris 1984, Harris and Noss 1985, Noss and Harris 1986, Wilcove and May 1986, Noss [in press]). Wildlife corridors can be defined as strips or parcels of land which allow safe passage of wildlife between larger blocks of habitat. This contiguity effectively increases the size of protected lands and their ability to maintain viable wildlife populations. Genetic variation is maintained because genetic material is carried freely back and forth across the corridor and among large habitat blocks by dispersing wildlife. Dispersing animals can recolonize areas which have suffered from local extinctions (Fahrig and Merriam 1985). Large

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35 carnivores such as panthers, bears, bobcats, and otters which require large home range sizes would be free to continue their natural movement between habitat blocks which would otherwise be rendered inaccessible to them by physical barriers. They gain the increased resource base needed to support top-level carnivores. In addition to serving as travel routes, corridors also serve as habitat for some species. EVidence of wildlife use of travel corridors comes from a variety of sources at several scales. In the extreme, land bridges between continents have historically acted as wildlife corridors (Simpson 1940, Simpson 1965). The Bearing Sea land bridge allowed the migration of many animals, including man, into North America from Siberia. The Isthmus of Panama similarly allowed the migration of wildlife between North and South America. Other paleontological research has pointed to the development of a broad, flat corridor which formed along the Gulf coast of Florida during the glacial lowering of the sea level. Webb and Wilkins (1984) found that during these periods Florida's wildlife was highly influenced by fauna which had migrated into Florida from South America and southwestern North America. Riverine gallery forests in Brazil apparently act as mesic corridors which have allowed Amazonian forest species to invade and become components of the xeric cerrado fauna (Redford and da Fonseca, 1986). On a smaller scale, habitat corridors have also been shown to be important for wildlife. Riverine forest corridors are known to be important habitats for many species. The maintenance of streamside strips of vegetation is an important management tool for maintaining gray squirrel populations within pine plantations (McElfresh et a1. 1980). Turkeys have been successfully managed in a mosaic of poor habitat (short-rotation pine plantations) by maintaining hardwood and mature pine trees in travel corridors. These corridors allowed

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36 the turkeys to move widely among foraging and roosting areas (Gehrken 1975). Several species of birds have been found to regularly use fencerows and hedgerows as safe travel routes (Bull et al. 1976). MacClintock et a1. (1977) found that a small forest fragment connected by a corridor to an extensive forest block was characterized by birds typical of the forest interior, while similar but isolated forest fragments were not. Johnson and Adkisson (1985) noted that blue jays used vegetated fencerows as travel routes apparently because they afforded some escape cover from hawks. Wegner and Merriam (1977) found that small mammals and many birds travel more frequently along fence hedgerow corridors than across open fields. Wildlife populations in isolated blocks of forest have been shown to have lower growth rates than populations in forest blocks tied together by corridors (Fahrig and Merriam 1985). The relevance of wildlife corridor management to the Wekiva River Basin lies in the presence of a large number of parks and preserves in the area. Many wildlife species in Rock Springs Run State Reserve, Wekiva Springs State Park, Lower Wekiva River State Reserve, and Kelly Park will be adversely affected if an adequate corridor is not preserved. While several types of corridors have been defined (Forman and Godron 1981), two are perhaps most important for a discussion of the Wekiva River Basin. "Line" corridors are narrow and are entirely edge habitat, while "stripll corridors .. are wide enough to maintain interior conditions. This distinction between edge and interior habitat is important (see previous discussion on edge effects) as some interior species cannot live or even migrate through extensive edge habitats (Forman and Godron 1981). Edge effects are a function of corridor width. Beyond the deleterious effects of edge, width also has other effects on corridor function. A wide corridor may provide actual habitat for an animal while a narrower one may simply provide a travel route. A study of cypress domes showed that

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37 certain species of birds were excluded from smaller cypress domes (McElveen 1978). Stauffer (1978) found that bird species richness increased significantly with the width of wooded riparian habitat, where some species were restricted to wider strips. Tassone (1981) reported similar results from a study of hardwood leave strips. Interior forest species such as Acadian flycatchers were only infrequently found in corridors less than 50 m. Hairy and pileated woodpeckers required minimum strip widths of 50 to 60 m, while the parula warbler required at least 80 m. He suggested that leave strips must be a minimum of 100 m on larger streams to take advantage of their intrinsic wildlife value. Corridors which provide habitat should be much more 'effective in connecting larger habitat blocks than those which only provide paths for travel. Forman (1983) has stated that width is the most important variable affecting corridor function. An upland buffer along the Wekiva River floodplain would maintain the width of the corridor, allowing it to function more efficiently as a wildlife corridor. This would be particularly true where the r1ver floodplain is narrow. Narrow sections may act as barriers through which some animals are reluctant to pass. An upland buffer would allow continued movement and provide a refuge for some terrestrial wetland species during periods of high water. It would also encourage use of the corridor by upland species which do not make regular use of wetland habitats (Forman 1983). In addition to providing dispersal pathways for animal wildlife, floodplain corridors are also important in plant dispersal. Flood waters collect and disperse large numbers of seeds from both wetland and upland plants (Wolfe 1987, Schneider and Sharitz [in press]). This dispersal of upland seeds may be very important in maintaining the diversity of upland plant species on topographic highs or islands within the floodplain (Schneider and Sharitz [in

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38 press]). Wharton et al. (1982) noted that these upland areas within the floodplain are very important for wildlife habitat. Upland seeds carried onto the floodplain originate in the wetland-upland ecotone and from smaller tributaries feeding the river. Protection of this ecotone, which may extend 10 to 35 m in Florida (Hart 1981), and the adjacent upland would ensure continued input of seeds to the floodplain. In summary, width is probably the most important variable affecting corridor function (Forman 1983). Several forest interior species are known to be excluded when corridor width falls below a critical level, which is a function of edge effects and home range requirements. Increasing the width of the Wekiva River corridor by maintaining an upland buffer can only increase its effectiveness in providing both a travel route for dispersing wildlife and high-quality habitat. II.A.7. Between-habitat Needs of Wildlife Between-habitat needs refer to wildlife utilization of more than one habitat type to fulfill their requirements. Several authors have substantiated the close association and interaction of wildlife in wetland and adjacent upland communities. Fredrickson (1978) reported that various species more commonly associated with either wetlands or uplands depend on seasonal or daily shifts into different habitat types to escape flooding, to forage, to disperse, or to hibernate. Examples that he cited are turkey, river otter, swamp rabbit, deer, bobcat, and gray fox. Other species such as raccoon, gray squirrel, tree frogs, and many woodland bird species occur with similar frequency in both wetlands and uplands. Bottomland hardwoods are integrally coupled to the surrounding uplands (Wharton et al. 1982). Terrestrial lowland fauna may be coupled to the

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39 uplands; for example, deer base their home range in floodplains and graze in uplands. Conversely, upland forms such as the black racer, slimy salamander, and pine vole may use the floodplain during drydowns. Although many species breed in both habitat types, their densities may differ considerably between adjacent areas. However, the lower-density populations may serve as important recruitment sources. The greenbelts of bottomland hardwoods also provide routes for migration and restocking. Many semiaquatic Florida turtles, such as the mud turtle and snapping turtle, loaf and feed in marshes but need sandy upland sites to lay eggs (Weller 1978). The river cooter is an example of a turtle which is largely confined to water but must trek to adjacent' uplands to deposit eggs (Patrick et al. 1981). Documented cases of Florida aquatic turtles laying eggs several hundred yards from a river are not uncommon (P. Moler, Florida Game and Fresh Water Fish Commission, pers. comm.). Weller (1978) also indicated a need for more information relating to the wetland-upland interface. He wrote, "Upland areas often serve as buffers, nesting areas, or food resources for wetlands wildlife but their relative importance is undocumented." The eastern indigo snake is classified as a wetland species but frequently occurs in dry, sandy areas (Kockman 1978). Speake et al. (1978) found that indigo snakes concentrated on the higher ridges of sandhill habitat during winter and moved down into streambottom thickets in summer. Shelter provided by gopher tortoise burrows is critical to the survival of this snake while it in upland areas. Many wildlife species need both uplands and wetlands to satisfy their food requirements. Peak mast production occurs at different times of the year in uplands and lowlands (Harris et al. 1979). Winter and spring is the fruiting season for most bottomland species, while upland plants bear fruit in the

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40 summer and fall. Correspondingly, both upland and wetland nesting birds often concentrate in wetland areas during the non-nesting season (Wharton et al. 1981). Landers et a1. (1979) found that black bears also respond to seasonal differences in mast production. In North Carolina, they shift their food preferences from predominantly bottomland species in the winter and spring to predominantly upland fruits and nuts in summer and fall. Florida bears primarily inhabit swamps in the center of the state but are long distance travellers utilizing both wetlands and uplands (Williams 1978). They eat acorns, palmetto berries and the terminal bud (" swamp cabbage") of the cabbage palm. wild turkeys may be found in a variety of wet and dry habitats and normally depend on acorns as a staple food in Florida. But they also have been known to eat crawfish occasionally. (Wild turkeys were recently reintroduced into the Rock Springs Run State Reserve on the Wekiva River.) During the "egglaying season, female wood ducks eat a large percentage of invertebrates obtained from the wetland-upland transitional areas (Fredrickson 1979). Pileated woodpeckers nest and roost primarily in wet hardwoods and cypress habitats but forage in uplands (Hoyt 1957, Jackson 1978). Conner et al. (1975) did not find any pileated woodpecker nest trees farther than 150 m from water in southwestern Virginia. Jennings (1951) observed that gray squirrels in the Gulf Hammock region of Levy County, Florida, were dispersed through all habitats while food was plentiful in the fall. When red maple and elm began to bud and produce seed in mid-January, the squirrels began to concentrate in the hydric hammocks and swamps to utilize this food source. As upland foods became available in the spring and the lowland areas flooded, the squirrels moved to higher elevations.

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41 Kantola (1986) found higher fox squirrel densities in ecotone or transitional areas than in upland areas on the Ordway Reserve in Putnam County, Florida. But she also reported that home-range size and use within ecotones and uplands may vary with seasonal food abundance, reproductive activity, and climate. Between-habitat needs may vary among sites because of differences in habitat quality. More than 33% of the 30 small vertebrates species caught by pit-fall traps in the floodplain of the Chattahoochee River in Georgia were classified as upland species (Wharton et al. 1981). In contrast, only 14% of 21 small vertebrates sampled by the same method along the Alcovy River 1n Georgia received the same classification. This dissimilarity was attributed to vegetation structural differences in the floodplain. Numerous researchers have been interested in the response of small mammals to flooding. Most studies concluded that floodplains were marginal habitats for these species. However, Batzli (1977) found that Illinois floodplain populations of the white-footed mouse were remarkably similar in density, adult survival, and age structure to those in the adjacent upland areas. The exchange of individuals between these two communitie,s consisted mainly of a few floodplain mice occasionally moving into the uplands. He suggested that mature trees with abundant holes and cavities may be necessary refuges for small mammal survival during flooding. In a blackwater creek bottom in South Carolina's inner Coastal Plain, Gentry et al. (1968) found that the abundance of the cotton mouse, short-tailed shrew, and southeastern shrew were 2, 3, and 10 times greater, respectively, in the bottomland hardwood than in the adjacent uplands. Golden mouse specimens were collected only from the hardwoods.

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42 Because wetlands are often the last lands to be developed, some species normally considered upland wildlife are sometimes forced to adapt to wetlands that can supply their habitat needs (Schitoskey and Linder 1978). When uplands required by animals are destroyed, animals may concentrate in the nearby wetlands. Ozoga and Verme (1968) reported that deer mice, which are usually abundant in uplands, were also found in wetlands. White-tailed deer, an edge species, is known to adapt well to the swamps and lowland ar.eas (Verme 1961, Verme 1965, Sparrowe and Springer 1970). Weller and Spatcher (1965) found that upland bird species such as the meadowlark and mourning dove nested >n unflooded portions of wetlands. High densities of prey species also attract adaptable upland predators such as the skunk, raccoon, and red Bailey (1971) found that striped skunk densities were greater in narrow wetlands than in adjacent uplands where cultivation and other development adversely affected upland feeding sites. This situation is suspected to cause an abnormally high predation rate on waterfowl eggs by skunks. Bobcats in the Welaka Reserve showed a preference for bottomland hardwoods (Progulske 1982). More than 20% of the 269 recorded locations of two radiocollared bobcats from July 1980 to December 1981 were in this type of overs tory habitat. Although the other locations were spread among seven different upland habitat types, their need for wetlands is obvious. Melquist and Hornocker (1983) found that although Idaho otters generally followed stream beds, they often took shortcuts across peninsulas formed by stream meanders. Overland travel of up to about 3 km was recorded. Extensive cross-country movements considerably reduced the distance an animal would normally have had to travel to reach the same destination by water. However, these movements also subjected the animals to highway hazards. Three of nine

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known mortalities were road-kills. In Great Britain, Chanin and Jefferies (1978) reported that in some areas dead otters were found repeatedly at the same location on roads over a number of years. 43 In a report that synthesized extant literature for southeastern bottomland hardwood swamp habitats, Wharton et al. (1982) stated that bottomland animals do not occur in the same distinct zonal pattern as plants ranging from aquatic to upland ecosystems. Wetland wildlife inhabitants move freely into irregularly flooded or dry zones over the year. They also noted that some overlap among zones occurs, especially in the transitional areas characterized by periodic annual flooding and a duration of flooding during a portion of the growing season. Their examples of overlapping species that might occur along the Wekiva River are mole salamander, slimy salamander, narrowmouth toad, spadefoot toad, cricket frogs, chorus frogs, box turtle, five-lined skink, southeastern five-lined skink, brown snake, garter snake, ribbon snakes, rat snakes, kingsnake, southern black racer, coachwhip snake, barred owl, downy and red-bellied woodpeckers, cardinal, turkey, common yellowthroat, wood thrush, eastern wood peewee, white-breasted nuthatch, Swainson's warbler, carolina wren, yellow-throated vireo, cotton mouse, golden mouse, short-tailed shrew, least shrew, southeastern shrew, woodrat, marsh rabbit, pine vole, and eastern mole. The use of various bottomland hardwood ecological zones by wildlife differs by species, season and flooding regime (Larson 1981). Some are site specific during the breeding period while at other times they may use a broad range of ecological zones. Larson also referred to many of the species examples used by Wharton et al. (1981). Many studies have documented utilization of adjacent uplands by wetland wildlife species. Removal or alteration of this important habitat type could

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44 destroy critical requirements for many species and thus render the riverine system in that area no longer habitable for them. II.A.8. Within-habitat Needs of Wildlife Within-habitat needs refer to requirements of wildlife species within the habitat areas they occupy. Habitat alterations and land use changes can affect adjacent resident wildlife populations by fragmenting habitat to nonfunctional sizes and shapes and by introducing disturbance factors above the tolerance levels of some species. Because of the paucity of Florida-specific data, we authors have included information from research conducted in other states. Although not actual descriptions of local species/habitat relationships, there is no reason to believe that similar situations do not exist in Florida. Temple (1986) found that 16 of 43 bird species encountered on 49 Wisconsin study areas occurred less frequently, if at all, in smaller-sized forest fragments. Fragment-sensitive birds did not occur regularly in fragments that were large in total area but lacked a secure core area more than 100 m from edges at which forest adjoined non-forested habitat. Large stretches of linear habitats without sufficient core areas were not utilized by sensitive species which included three (hairy woodpecker, pileated woodpecker, and acadian flycatcher) that have been recorded in a partial listing of Wekiva wildlife residents (Florida Dept. of Environmental Regulation, 1983). Of the 13 other sensitive species, it is highly likely that six (tufted titmouse, blue-gray gnatcatcher, wood thrush, yellow-throated vireo, American redstart, and hooded 'warbler) nest along the Wekiva and the remaining seven (least flycatcher, veery, chestnut-sided warbler, cerulean warbler, ovenbird, mourning warbler, and scarlet tanager) overwinter along the Wekiva. Stauffer and Best (1980)

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45 predicted that the scarlet tanager would be absent from riparian strips Iowa less than 200 m wide. Galli et al. (1976) and Stauffer (1978) found the number of breeding bird species increased significantly with the width of wooded habitats in N.ew Jersey and Iowa. Of the 46 species recorded in New Jersey, 18 were size-dependent species, limited to a particular range of forest sizes from the largest down to a specific minimum size. The minimum areas varied from 0.8 to 10.3 hectares and are considered characteristic of each species. As the habitat size increased, new species appeared when their minimum habitat size requirements were fulfilled. An example of a size-dependent species that requires a large wooded riparian habitat is the red-shouldered hawk. This species, which is a common year-round resident in Florida, was not found in any of the New Jersey sites less than 10.3 hectares (about 25 ac). Of the 32 species that occurred in Iowa wooded riparian habitats, 16 restricted breeding to relatively wide plots. Bird diversity is also strongly influenced by vegetation composition and structural heterogeneity or diversity within a habitat type (MacArthur et al. 1962, MacArthur 1964, Weller 1978). This type of heterogeneity is a function of foliage height and cover diversity. The vertical and horizontal stratification of plants within a forest habitat is positively correlated with the number of bird species that reside there. Therefore, land-use conversion of the most diverse portion of a wooded riparian habitat would have significantly greater negative impacts on the overall avian community than conversion of the least diverse portion. Transition or ecotone areas containing both wetland and upland plant species are typically the most diverse (Wharton et al. 1982).

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46 Fragment-sensitive species or species that require large tracts of undisturbed, closed-canopy forest are also referred to as interior species. Tassone (1981) found that many forest interior bird species in Virginia were most common in riparian buffer widths above a mean value of 62 m, and certain species occurred very infrequently below different minima. Examples are the northern parula (80 m), yellow-throated vireo (70 m), Louisiana water thrush (60 m), hairy and pileated woodpeckers (50 to 60 m), and acadian flycatcher (50 m). All of these species also breed in Florida's riparian areas. Tassone (1981) concluded that several other species, observed too infrequently to estimate width requirements, may also be sensitive to buffer width. He suggested: Until more extensive research is done, strips should be left 60 or more meters in width if it is desired to provide breeding habitat for these species. They should also be situated as corridors between other hardwood and pine-hardwood stands whenever possible. Strips located on larger streams should be 100 or more meters in width to make full use of the intrinsic wildlife values associated with the riparian zone. Small and Johnson (1985) recommended that riparian buffer strips be 75 m wide to protect woodland bird communities in Maine. Johnson's (1986) study of the tolerance levels of some woodland breeding species supported this suggestion. Fragmentation also affects squirrel populations. In an eastern Texas study of clearcut effects conducted two to four years after tree harvest, gray and fox squirrels were abundant in mature woody riparian zones wider than 55 m but were rare in riparian zones narrower than 40 m (Hedrick 1973). The highest squirrel density index was calculated for the widest stringer study plot (185 m). The home-range Slze requirement for an individual gray squirrel is about two acres (Burt and Grossenheider 1964). Larger Wekiva wildlife residents require larger areas. For example, home-range sizes for individual gray foxes

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and bobcats in Welaka, Florida, is about 625 and 4,580 ha, respectively (Progulske 1982). Any actions that reduce suitable contiguous habitat below these home-range sizes will prevent individual animals from occupying those areas. Of course, viable self-sustaining wildlife populations require considerably larger home ranges than do of individuals. 47 Aside from the fragmentation factor, various human activities may alter behavior patterns or cause undue stress to some wildlife individuals in adjacent habitats. This is a relatively new aspect of wildlife biology, and very little research data are available regarding .the effects of specific human activities on different wildlife species. Noise associated with construction, operation, and maintenance of developments can cause harmful impacts on wildlife. Animals that rely on their hearing for courtship and mating behavior, prey location, predator detection, homing, etc., will be more threatened by increased noise than will species that utilize other sensory modalities. However, due to the complex that exist among all the organisms in an ecosystem, direct interference with one species will indirectly affect many others. Unfortunately, few data are available that demonstrate the effects of noise on wildlife. Much of what is found in the literature lacks specific information concerning noise intensity, spectrum, and duration of exposure. A few laboratory studies have documented decreased nesting and aversion reactions of small mammals in response to various sound frequencies (Sprock et al. 1967, Greaves and Rowe 1969). Other research has focused on the use of noise for damage or nuisance control. Diehl (1969), Crummett (1970), Hill (1970), and Messersmith (1970) reported on the success of using sound to repel rodents, bats, rabbits, deer, and birds.

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48 The Environmental Protection Agency (1971), Ames (1978), and others have reported on the physiological responses of laboratory and farm animals to different noise stimuli. These data suggest that chronic sound may cause stress on wild animals which in turn may affect reproduction. Most people can easily relate to auditory interference, annoyance, hearing damage, sleep interference, and stress-related effects of noise. And in response to public demands, many noise-control ordinances have been enacted to reduce these adverse impacts. However, it is doubtful that these laws sufficiently protect wildlife species. van der Zande et al. (1980) found that breeding densities of three open grassland bird species were significantly reduced within 500 m of quiet rural roads and 1,600 m of busy highways in The Netherlands. They suggested that disturbance is also caused by farms, other buildings, and plantations. Although Robertson and Flood (1980) found no significant differences 1n several vegetation variables between developed and undeveloped sites along Ontario shoreline areas, bird species diversity was negatively correlated with disturbance. A greater number of species was found in the natural areas than along shorelines where cottages were present and boat use was high. Several species which also nest in Florida (yellow-billed cuckoo, yellow-throated vireo, American redstart, and pileated woodpecker) were more abundant in, or restricted to, the less disturbed transects. The Florida Game and Fresh Water Fish Commission is in the process of developing habitat protection guidelines for threatened and endangered species to provide land-use decisionmakers with recommendations and management practices that would integrate protection for these habitats in the context of large-scale developments. Many of these recommendations will address withinhabitat needs such as those identified in The Recovery Plan for the Bald Eagle

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49 in Florida (Murphy et al. 1984). This U.S. Fish and wildlife Service document states that no human activity should occur within 750 ft (250 m) of active eagle nests and that the building of housing developments should be restricted within 750 to 1,500 ft (500 m) of active nests. Potential bald eagle nesting sites are currently abundant along the Wekiva. Predation and harassment of wildlife by cats and dogs are other detrimental effects of development adjacent to wildlife habitat areas. Although relationships between domestic animals and wildlife are not fully understood, there is enough information in the literature to justify a legitimate concern. Several authors have documented the occurrence of wildlife prey in the diets of free-ranging cats and dogs and the effects of their predatory behavior on individual wildlife animals and populations (Errington 1936, McMurry and Sperry 1941, Bradt 1949, Hubbs 1951, Parmalee 1953, Eberhard 1954, Korschgen 1957, Smith 1966, Corbett et al. 1971, Gilbert 1971, Jackson 1971, Gavitt 1973, George 1974, Gill 1975, van Aarde 1980). Cats can be especially devastating on local wildlife populations. Hunting is a feline instinct, and predation rates are not related to hunger (Davis 1957, Holling 1966, Holling and Buckingham 1976). Bradt (1949) reported that a single cat, who regularly consumed domestic food, killed over 1,600 mammals and 60 birds in Michigan during an l8-month period. van Aarde (1980) found that free-ranging cats associated with households utilized open fields, edges, and timber areas. Home range sizes for females and males were 30 to 40 ha (about 100 ac) and four to eight square km (about four sections), respectively. In an Illinois study, the average home range for females and males was 112 and 228 ha, respectively (Warner 1985). These freeranging rural cats spent about 40% of their time on farmsteads. Approximately

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50 73% of the radiolocations of these cats occurred in edge areas such as roadsides, field interfaces, farmstead perimeters, and waterways. Beck (1973) reported that the average home range for free-ranging dogs in Baltimore was about four acres. Schaefer (1978) reported that dogs in rural Iowa traveled up to two miles to kill pastured sheep. Alteration of natural vegetation or other components of wildlife habitat may make modified areas unsuitable for some species. As these unsuitable areas encroach upon natural areas, core habitat fragments become smaller and the number of supported species is reduced. Various forms of disturbance can also adversely affect adjacent wildlife populations. An upland buffer would reduce or eliminate negative disturbance impacts associated with development. II.B. Review of Buffer Zone Regulations In this section methods and models for determining requirements and physical dimensions of buffer zones are presented. Buffer zones are normally considered to protect quality and wetland-dependent wildlife and to reduce the potential for negative impacts on a wetland resulting from adjacent upland development. The determination of buffer requirements (i.e., widths in relation to land use, soils, topography, etc.) for the most part are not quantitative, but rely on what is felt to be qualitative evidence for the necessity of buffering development impacts. Never-the-less, there are numerous rules and regulations that have been promulgated throughout the country that require buffers around wetland areas.

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51 The Pinelands Area One of the most noteworthy buffer zones is that developed by the New Jersey Pinelands Commission. The Pinelands Area (also known as the Pine Barrens) is an area of about 445,000 ha of an interrelated complex of uplands, wetlands, and aquatic communities in southeast New Jersey. It is a largely undeveloped region within the Northeast Urban Corridor and was designated as the country's first National Preserve in 1978. In the next year the State of New Jersey passed the New Jersey Pinelands Protection Act that in essence called for the preservation, protection, and enhancement of the significant values of Pine1ands land, water, and cultural resources. In response to both federal and state legislative mandates, the Pinelands Commission developed a Comprehensive Management Plan to preserve and protect the unique and essential character of the Pine1ands ecosystem. In the plan, wetlands protection is fostered through a regional land allocation program, a land acquisition program, and a wetland management program. The management program prohibits most development within wetlands and also requires an upland buffer around wetlands. The required "transition or buffer area" established between proposed development and adjacent wetlands measures 300 ft wide, and except for those regulated uses which have been described, no development may occur within the area. Rationale for the width of the Pinelands buffer is derived from areal nutrient dilution models (Harlukowicz and Ahlert, 1978; Trela and Douglas, 1979 and Browne 1980) that were used to predict the travel distance necessary for groundwaters laden with nutrients (from septic tank leachate) to be diluted to background levels. Depending on the values used for input variables to the model, it predicted distances to attain background concentrations of 2 mg/l N03 -nitrogen of between 325 ft and 600 ft.

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52 Since the implementation of the Pinelands Comprehensive Management Plan, 327 development applications that involved wetland issues have been reviewed by the Pinelands Commission. More than one third of these were considered inconsistent with the plan because they proposed development within wetlands or within 300 ft of wetlands (Zampella and Roman, 1983). Figures compiled by Zampella and Roman (1983) show that more than over half of the development applications that involved wetland issues were consistent with the wetland management provisions of the plan. However, among the conditions imposed on these projects was the need to establish and maintain a buffer adjacent to wetlands. Approximately one third of these applications were required to maintain the maximum buffer of 300 ft, while the remainder were required to maintain variously sized buffers which averaged about 135 ft 1n width. The Pinelands scheme of determining wetland buffers uses a Wetlands Buffer Delineation Model that evaluates relative wetland quality, and relative impacts of development. Prior to evaluating wetland quality a determination of the presence of threatened or endangered species is made, and if the wetland is known to support resident and/or breeding populations and if the wetland area is critical to their survival, the wetland is ranked having the maximum relative wetland value index and is, assigned a buffer of 300 ft. The following qualities, values, and functions are evaluated as part of the wetlands evaluation scheme and are evaluated after determination of presence of threatened and/or endangered species is made: Vegetation quality, Surface water quality, Potential for water quality maintenance, Wildlife habitat, and Socia-cultural value.

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53 Each of the five general factors listed above has a score from 1 to 3, where 3 is high value. A wetland is scored for each factor, and scores are summed and divided by 5 to obtain a Relative Wetland Value Index. Next, Potential for Impacts is evaluated by ranking the following factors: Potential for site-specific wetland impacts, Potential for cumulative impacts on a regional basis, and Significance of watershed-wide impacts. Once ranked, the scores for each of the potential impact factors are summed and divided by 3 to obtain an average score for the Relative Potential for Impacts Index. To assign buffer areas, the final step is to average the Relative Wetland Value Index and the Relative Potential for Impacts Index to obtain a Buffer Delineation Index. index is used to determine the buffer distance in three different Land Capability Areas using a table of assigned values. The strengths of the methodology are: (1) Wetland attributes and the potential for on-and off-site impacts are evaluated for each individual wetland and each development proposal on a case-by-case basis. Depending on the type of wetland, existing terrain, existing land use designations, and type of development, the buffer varies from a minimum of 50 ft to a maximum of 300 ft. (2) The method is quantitative and repeatable thus insuring some degree of consistency. (3) It does not require detailed scientific information about a wetland. State of New Jersey The House of the State of New Jersey has passed a bill whose short title is "Freshwater Wetlands Protection Act." As of this writing the State Senate has not acted upon the bill the ace would establish ... a transition area adjacent to all wetlands having the following purposes:

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54 (1) Ecological trans1t10n zone from uplands to wetlands which is an integral portion of the .wetlands ecosystem providing temporary refuge for wetlands fauna during high water episodes, critical habitat for animals dependent upon but not resident in wetlands, and slight variations of wetland boundaries over time due to hydrologic or climatic effects: (2) Sediment and stormwater control zone to reduce the impacts of development upon wetlands and wetland species. The bill would also establish the width of the transitional area as no greater than 150 ft and no less than 75 ft for freshwater wetlands of exceptional resource value, no greater than 50 ft and no less than 25 ft for freshwater wetlands of intermediate resource value, and no transitional area for wetlands of ordinary resource value. The act prohibits the following activities in transition areas: Removal, excavation or disturbance of the soil; Dumping or filling with any material; Erection of structures; Placement of pavements; and Destruction of plant life which would alter the existing pattern of vegetation. New York State Wetlands Protection Act The recent adoption of the Freshwater Wetlands Act (6 NYCCR) protects wetlands 12.4 ac or greater in size. The Act recognizes ten specific functions and benefits which freshwater wetlanfts provide for the public and for the environment. To achieve the goals of the Act to protect, preserve, and conserve New York's freshwater wetlands, the statute makes provisions for mapping, classification, regulation and local government protection. The act provides for the regulation, of a 100-foot buffer adjacent to wetland boundaries. Provisions exist in the law to extend the 100-foot adjacent area if necessary to protect the wetland.

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55 California Coastal Act of 1976 The California Coastal Act (Public Resources Code, Division 20) established the California Coastal Commission which in turn prolmugated the Statewide Interpretive Guidelines (SIG) to assist in the application of various Coastal Act policies to permit decisions. The SIG has set standards for siting development adjacent to environmentally sensitive habitat areas (ESHA). Wetlands are considered environmentally sensitive habitat areas, as are estuaries, streams, riparian habitats, and portions of open coastal waters. "Adjacent to" is defined as situated near or next to, adjoining, abutting, or juxtaposed to an ESHA. This usually means that any proposed development in an undeveloped area within of up to 500 ft of an ESHA will be considered to be adjacent and subject to critical review. Criteria for establishing buffer areas around ESHA's are designed to provide essential open space between the development and the ESHA. Development allowed in a buffer area is limited to access paths, fences necessary to protect the habitat area, and similar uses which have either beneficial effects or at least no significant adverse effects. The buffer is not itself part of the ESHA, but it is a "screen" that protects the habitat area from adverse environmental impacts caused by development. Widths of buffer areas are variable depending upon site analysis. It is usually a minimum of 100 ft; however, it may reduce for small projects (defined as single family home or one commercial office building). Additionally, provisions are suggested that the 100 ft may be reduced if the applicant can demonstrate that it is not necessary to protect the resource. Standards for determining the appropriate width of the buffer area: 1. Biological significance of adjacent lands, 2. Sensitivity of species to disturbance, 3. Susceptibility of parcel to erosion, 4. Use of natural topographic features to locate development,

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56 5. Use of existing cultural features to locate development, 6. Lot configuration and location of existing development, and 7. Type and scale of development proposed. Humboldt County, California Humboldt County's Southcoast Plan defines riparian corridors and limits development within them. It defines riparian corridors to include the uplands on both sides of streams as follows: Riparian corridors on all perennial and intermittent streams shall be, at a m1n1mum, the larger of the following: (i) 100 ft, measured as the horizontal distance from the stream transition line on both sides; (ii) 50 ft plus four times the average percent of slope, measured as a slope distance from the stream transition line on both sides; (iii) where necessary, the width of riparian corridors may be expanded to include significant areas of riparian vegetation adjacent to the corridor, slides, and areas with visible evidence of slope instability, not to exceed 200 ft. (Humboldt County Planning Department 1981, as cited by Ray et al. 1984) Uses in the riparian corridor have been limited to minor facilities, minimal timber harvest, maintenance of existing facilities, residential wells, road and bridge replacement, and tree removal for disease control. There must be, at a minimum, replanting of vegetation for any approved disturbance, and any trees that have visible evidence of current use as nesting sites by hawks, owls, eagles, osprey, herons, or egrets must be retained. Massachusetts Wetlands and Floodplain Protection Act The Massachusetts Wetlands and Floodplain Protection Act recognizes three types of wetlands: 1) land areas bordering water bodies; 2) land under water bodies; and 3) land subject to tidal action, coastal storm flowage, or flooding. These wetlands must border on a listed water body with 50% or more wetland vegetation or within the 100-year floodplain. Permits are required for virtually any development activity in, near, or affecting jurisdictional areas. Work within a 100-foot buffer zone around wetlands may require a permit since

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57 the Act defines "bordering" as a distance of 100 ft. The regulation provides that the extent of protection is to be 100 ft landward from wetland resources or 100 ft landward from the water elevation of the 100-year flood, whichever is Rhode Island Coastal Resources Management Program The General Laws of the State of Rhode Island, Title 46, Chapter 23, establishes the Coastal Resources Management Council (CRMC). The CRMC has developed the Coastal Resources Management Program. The Program establishes setbacks ranging from 50 to 180 ft from the inland boundary of coastal features such as beaches, wetlands, cliffs, banks, rocky shores, and existing manmade shorelines and apply to the following activities: Filling, removal, grading; Residential buildings; Sewage disposal systems; Industrial, commercial, recreational structures; and Transportation facilities. The setback minimum in areas not designated as Critical Erosion Areas is 50 ft, and within Critical Erosion Areas it is 30 times the calculated average annual erosion rate, which has been determined to vary between 75 and 180 ft. In addition to setback requirements, the program establishes Buffer Zones defined as land areas on or contiguous to a shoreline feature that is retained in its natural and undisturbed condition by the applicant. Buffer zones must be tailored to on-site conditions and the specific alterations and activities that are taking place. Further, the determination of the boundaries of a buffer zone need to balance the property owners' rights to enjoy their property with the Council I s responsibility to preserve and, .where possible, to restore ecological systems. There are four benefits of buffer zones as follows: 1. Erosion control, 2. Prevention of water body pollution,

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58 3. Preservation and enhancement of sceniC qualities, and 4. Protection of flora and fauna. The buffer zones are established according to values and sensitivities of the site as assessed by the Council's staff engineer and biologist, and the area may be wider than the setback distance. The buffer must be maintained by the applicant as an undisturbed area and in its natural condition. Marion County, Florida The Board of County Commissioners of Marion County, Florida adopted an emergency ordinance (Marion County Ordinance No. 73-4) in June of 1973 .. prohibiting dredging, filling, earth moving, and landclearing, and underbrushing except mowing, pruning, and care of existing lawns and planted trees and shrubs for a distance of 500 ft from the water's edge upon either side of Rainbow River or Blue Run in Marion County, Florida, between Rainbow Springs and the northern city limits of the city of Dunnellon ... Cross Creek Buffer Requirement In an amendment to its Comprehensive Plan", the Alachua County Commission adopted a 300-foot setback line from lakeshores for most development in a designated area in the southeast part of the county known as Cross Creek. The only construction allowed within the setback zone are structures such as docks built for access to the lake. The setback line is measured upland from the jurisdictional line set by the Department of Environmental Regulation or the St. Johns River Water Management District, or, where the lakeshore has been cleared, from the 100-year floodplain line. The setback width of 300 ft was determined qualitatively. The plan amendment is currently being rewritten. A new version expected to be completed by the second week of October 1987, may require a variable setback line based on such factors as soils, slope, habitat,

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and groundwater, with a minimum setback of 75 ft. (John Hendricks, Alachua County Department of Environmental Services, pers. comm.) Hillsborough County Wetland Buffer Requirement 59 A 3D-foot buffer around "conservation areas" and a 50-foot buffer around "preservation areas" are required by Hillsborough County. The former category includes most freshwater wetlands and Class III waters; the latter includes saltwater wetlands, Class I waters, and critical habitats. These categories originated in the Conservation Element of the county's Comprehensive plan adopted in the mid-l 970s That document set a policy to require "appropriate buffers" around those areas, but no width or formula to calculate width was set forth. However, in the definition of "natural shoreline"--another category of conservation area--a 3D-foot width was mentioned as one way to delimit natural shorelines, and that number was applied by county zoning staff in rezoning applications involving freshwater wetlands. The larger buffer was required around areas because they are considered to be more sensitive than conservation areas, but no formula was used to establish that width. Both buffers were adopted by the Hillsborough County Commission in a 1985 ordinance (revised in 1987) and as part of its zoning code. A variety of uses are permitted within the buffer zone, such as detention ponds, stilted structures, and boardwalks, but impervious surfaces are prohibited. Removal of natural vegetation is discouraged but not prohibited. (Charner Benz, Hillsborough County Planning and Growth Management Group, pers. comm.) II.C. Summary: Resource Buffer Zones Effects of activities in the upland areas immediately adjacent to floodplain wetlands may be separated into three time-related catagories:

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60 1. Direct and immediate impacts which occur during the construction phase, 2. Impacts which occur immediately following the construction phases during the period of stabilization, and 3. Long-term impacts that are permanent as a result of the alterations themselves or subsequent use and/or management of the altered areas. These development impacts affect three broad sets of parameters normally considered of particular importance from a regulatory perspective. They include: 1. Water quality, 2. Water quantity, and 3. Aquatic and wetland dependent wildlife. Thus each of these attributes may be affected during construction, immediately following or in the long term through human uses and management. Water Quality. The need for a buffer to insure that water quality is not degraded as the result of upland development in areas immediately adjacent to floodplain wetlands of the Wekiva River Basin is related to two potential sources of degraded waters. The first is sediments carried by surface waters from developed lands into down-gradient wetlands and waters. The second is dissolved pollutants and suspended particulate matter that degrade water quality through what might be termed chemical pathways. These include nutrie.nts, pesticides, and particulate organic matter which increase nutrient loading, may be harmful to aquatic plant and animal life, or increase BOD. Both sources of degraded water may come from the result of runoff during construction, during the period immediately following construction as the landscape stabilizes, or as a result of urban stormwater runoff long after the period of initial urbanization. Loss of valuable wetland functions as a result of sedimentation may be the most serious impact during construction activities. Sedimentation causes loss

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61 of soil properties and vegetation that are characteristic of wetlands and loss of wildlife habitat. In addition, sediments may carry significant amounts of pollutants and nutrients. Siltation and sedimentation of the wetland edge result from increased water velocities acting on soils susceptible to erosion, removal of ground cover in adjacent areas, or increased volumes of stormwaters entering the wetland that carry increased amounts of sediments. Where the waterward lots of a development are not incorporated into the stormwater management system, the potential for long-term decreased water quality after the construction phase is related to surface runoff from driveways and lawns and groundwaters carrying increased levels of nutrients and pesticides/herbicides from lawn care practices. While the rule criteria of the District requires specific stormwater management practices to mitigate water quality impacts from stormwaters, the rules allow 10% of the developed area to be "unconnected," that is, to receive no treatment. Water quantity. The water flowing into the waters and wetlands of the Wekiva River Basin is derived from three general sources. The first is groundwater (or surficial groundwater) that becomes surface seepage where ground surface elevations intersect the zone of saturation. This usually occurs on inclines near the base of sandy slopes and is characterized by surface soils that are saturated, shallow ponding of seepage waters, and small seeps that coalesce into undefined flowing surface streams. The second source is surface runoff as sheet flow from adjacent higher ground during and immediately following rainfall events, and the third source from artesia flow of deep groundwaters. Development in the zone immediately upland from the floodplain wetland edge may have dramatic impacts on the quantity of water from surface and surficial groundwater sources. Seepage is usually derived from rains that have

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62 recharged groundwaters in higher sandy soils and are moving downslope over a broad front thus, seepage areas tend to extend over the toe of the slope in a perpendicular line across the slope where the ground surface intersects the groundwater elevation. The site of seepage is usually dominated by floodplain vegetation. Alteration of the ground surface elevation through excavation in areas immediately upslope from the site of seepage may intersect the groundwater plain, and if positive drainage is maintained, can lower groundwater levels and essentially cut off further downslope seepage. If no positive outfall is maintained, the effects of excavations immediately upslope from seepage sites may have only minor impacts, since waters may be intercepted and discharged on the upslope side of the excavation, but may become groundwaters through recharge on the downslope side. In most areas where seepage is present, groundwater elevations immediately upslope are quite near the soil surface and are not conducive to many land uses. General engineering practices in areas with high water tables is to lower water table elevations by drainage or raise ground elevations by filling to make such areas more suitable for development. While filling may have little impact on subsurface water flows, drainage has the overall effect of short-circuiting groundwater flows, cutting off potential groundwater seepage downslope, and increasing surface discharge elsewhere. The effects of development on surface water flows in areas immediately upslope of the wetland edge are more easily seen and more direct. Impervious surfaces and sod increase runoff coefficients significantly over coefficients characteristic of natural lands. If these waters are not intercepted by a stormwater management system, they enter the wetlands and eventually the waters of the river. The increased volumes and velocities may cause significant degradation of downslope communities. However, under most development

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63 conditions, these waters are required to be routed through a stormwater management system, thus lessening the burden of the downslope communities. Yet these very requirements may in effect decrease sheet flow from rainfall events, since intercepted surface waters are routed elsewhere. The obvious implications of altered surface runoff and water quality have already been discussed. The temporal differences of impacts on ground and surface water quantity before, during, and after construction may be significantly different. Construction practices may dictate that surface waters and ground waters be routed differently than will be the case after construction, or that groundwaters be temporarily drained to facilitate construction activities. Once construction is completed and the stormwater system is under operating, the impacts on surface and groundwater quantity may vary little over time. Generally, stormwater discharge requirements within the Wekiva River Hydrologic Basin are designed to minimize negative impacts to surface waters through detention/retention, off-line treatment, and additional criteria. However, these requirements, and the fact that typically all lands within a project are engineered as part of the stormwater system, have the effect of isolating developed land. Contributions of overland flow runoff to downslope communities are minimized under such circumstances, since normal engineering practices are to discharge collected stormwaters at one or several point sources. Aquatic and Wetland-Dependent wildlife. Construction, operation, and maintenance of developed areas immediately adjacent to Wekiva River wetlands will result 1n both direct and indirect impacts on aquatic and wetland dependent wildlife. Noise during construction will interfere with vocalizations necessary for courtship, mating, prey location, and predator detection. Although this hindrance will be only temporary, there is no way to

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64 predict long-term consequences. After individuals disperse to less noisy territories, they mayor may not return. Chronic and acute noises of occupied residential communities will cause less severe impacts. However, auditory interference and stress-related effects will still occur in close proximity to these developed areas. A vegetated buffer will help to attenuate harmful sounds. Domestic animal harassment and predation on wildlife will also increase when pets are brought into adjacent developments. Development covenants and local laws usually require owners' to leash their pets. However, the probability of a few free-ranging dogs and many free-ranging cats is quite high. Because cats tend to spend most of their prey-searching time in edge areas, an upland buffer will help to alleviate cat predation on wetland wildlife species. Indirect impacts on wildlife will be related to habitat alteration resulting from construction. The removal of natural uplands vegetation adjacent to the wetlands will cause the originally mesic community along the outer edge of the wetlands to become more xeric. Drier community species will invade and eventually dominate this area. The ultimate result will be a reduction in the wetlands and a corresponding decline in those spec1es that are wetland-dependent. In some areas, the width of the wetlands may become too small, and the species composition will change because those with larger spatial requirements will no longer be present. Increased predation and parasitism associated with sharp induced edges will also encroach farther into the forest. Wetland-dependent species that require uplands to fulfill at least some of their life functions will extirpated from the Wekiva River Basin if there is no

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access to these uplands. An upland buffer adjacent to the wetlands will be needed to protect this necessary habitat element. 65

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III. LANDSCAPE ECOLOGY OF THE WEKIVA RIVER BASIN III.A. Landscape Perspective III.A.I. Physical Description Topography. The landscape of the Wekiva River Basin is a complex mosaic of wetland and upland habitats distributed over approximately 130 sq mi in north central Orange County, southeastern Lake County, and western Seminole County. The basin contains the physiogeographic province known as the Wekiva River Plain. Its topography is flat to gently rolling. Elevation declines towards the northeast, where the Wekiva Plain merges into the valley of the St. Johns River. On the western side of the upper Wekiva River, the land slopes gently upward to the sandhills, from whence it rises abruptly to elevations of 120 to 195 ft above sea level. Sandhills and sloping terraces separate large tracts of swampy lowlands and determine the circuitous route by which the waters of Rock Springs Run State Reserve flow southeastward. These waters turn north below the confluence of Wekiva Springs Run and the Little Wekiva River. North of this confluence, the floodplain narrows and turns to the northeast above State Road 46. The floodplain broadens out again where the Wekiva River joins Blackwater Creek and the St. Johns River in the Lower Wekiva River State Reserve (DNR, 1985, 1987). Along the west bank of the Wekiva River upstream (south) of its confluence with the Little Wekiva, elevation rises gradually towards the northwest from 15 ft above sea level along the river to approximately 35 ft above sea level. 67

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68 Beyond the 35-foot contour, the land surface rises abruptly into upland sandhill tracts in the north central section of Rock Springs Run State Reserve. Downstream (north) of the Wekiva/Little Wekiva confluence, the floodplain narrows abruptly, and the flow gradient increases rapidly to 1.6 ft/mi. The flow gradient in this stretch of the central Wekiva River is one of the steepest in east-central Florida, and the elevation along this section of the Wekiva rises much more steeply above the narrowed floodplain than it does in the flat swamps of the upper and lower sections. The width of the Wekiva/Little Wekiva floodplain narrows to about 1,000 ft along the central portion of the river, decreasing rapidly from its maximum dimensions of about 5 mi east/west by 3 mi north/south in the Wekiva Swamp. The floodplain broadens out once again in the Lower Wekiva River State Reserve (near the confluence with Blackwater Creek) to a width of 1 mi at the Wekiva's confluence with the St. Johns River (DNR, 1985, 1987). Blackwater Creek is a major tributary of the Wekiva which drains the watershed lying just north of the Wekiva Basin. rts watershed covers approximately 125 sq mi, nearly all of which is in southern Lake County. Blackwater Creek's headwaters are in Lake Dorr, and its floodplain varies in width from 800 ft at State Road 44A to over a mile along its upper and lower reaches. Another major tributary, Seminole Creek, joins Blackwater Creek at the eastern edge of Seminole Swamp. Seminole Swamp extends north and west from the confluence of Blackwater and Seminole creeks, covering an area of about 3 mi east/west and 1.5 to 2 mi north/south. This swamp lies between State Road 46A and State Road 44 in southern Lake County. Blackwater Creek flows into the lower Wekiva near the confluence of the Wekiva and the St. Johns. The waters of the Wekiva River Basin merge with those of the St. Johns and flow northward to enter the Atlantic Ocean at Jacksonville, Florida (DNR, 1985, 1987).

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69 The wetlands of the Wekiva Swamp's northern end connect with the lower reaches of Seminole Swamp through a narrow wetland corridor (not shown on all maps) which bisects the lands lying above the west bank of the Wekiva River and the northern borders of Wekiva Swamp. This wetland strip is an extremely important feature of the basin. It provides a wildlife corridor through which animals can move between these otherwise disjunct wetland communities (see Noss and Harris, 1986). The basin's diverse topography engenders a wide range of habitats, ranging from submerged aquatic plant associations to upland sandhill communities. Local soil characteristics and elevational effects combined with past and present disturbances influence the development of the various plant communities found within the Wekiva Basin. Geology and Hydrology. The Wekiva Plain was formed by Pleistocene terrace sands deposited during times of elevated sea level which occurred during interglacial periods of the Pleistocene. The most recent extended saltwater .incursion probably occurred during the Sangamonian interglacial about 100,000 to 200,000 years ago, when sea levels were about 20 ft above those of the present time (Bloom, 1983). Dunes were built up during the dry and windy periods of earlier and later glacial periods (Watts and Hansen, in press). These sands overlie the older marine limestones, clays, and marls of the Hawthorne Formation, which rest upon the deeper, porous Paleocene limestones and dolomites containing the Floridan Aquifer (Heath and Conover, 1981). The non-sedimentary bedrock of the Florida peninsula upon which these marine deposits have accumulated lies at least 4,100 ft below the present ground surface and ties in with the crustal rock of the continental plate. Soils in the Wekiva Basin can be grouped in five associations. The Freshwater Swamp Association occurs in the Wekiva River floodplain and the

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70 bottomlands around the upper part of Rock Springs Run State Reserve. These soils are usually saturated with water and are flooded much of the time. They are adjoined by the Manatee-Delray Association, which grades uphill into the Pompano-Delray Association. The two latter groups include soils which are sandy, nearly level, poorly drained, and subject to periodic flooding. The Myakka-Placid Association soils of the north-central and northeastern portions of the Rock Springs Run State Reserve are sandy, nearly level, poorly drained, and not normally subject to flooding. The St. Lucie-Pomello Association soils of the uplands are sandy, moderately to excessively well-drained, and not subject to flooding. They are restricted to the upland sandhill areas of the Wekiva Basin (DNR, 1985; see also USDA, 1960, 1966). Organic matter content of soils in the Wekiva Basin is high only in wetland soils. Silt deposition and decayed plant materials have formed the rich organic soils of river alluvium, swamp muds, and peat bogs in the basin. The general absence of well-developed topsoil horizons in sandy upland soils of the region encourage the rapid infiltration of rainwater. However, the lack of organic matter, clays, and silts in the surface soils restricts nutrient availability and limits the water-holding capacity of upland soils. Although highly permeable for the most part, the upper horizons of upland sandy surface soils quickly reach saturation during heavy rains, and sheetflow movement of rainwater can result. Problems associated with surface runoff and erosion may develop in conjunction with the heavy rains accompanying major storm fronts, especially in areas where the protective vegetation cover has been disturbed or removed. Ecosystem disturbnnces of historical importance to the disruption of the vegetative cover of Wekiva Basin soils include logging, livestock grazing, high-intensity recreationa; use, construction and development, and wildfire. Wildfire is by fa,the least destructive of these

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71 disturbances to the natural vegetation and wildlife. Indeed, fire is an essential ecological component of several endemic plant communities native to the region. Lakes and sinkholes are scattered throughout the basin as the result of the formation and subsequent collapse of solution cavities within the upper layer of the underlying Hawthorne Formation limestone bedrock. Sudden surface collapses due to sinkhole formation have in recent years swallowed buildings, automobiles, and sections of roads in the suburbs of nearby Orlando. The prevalence of sinkhole formations in the regions bordering the southern edge of the Wekiva Basin dictate caution in siting industrial and residential development. The same forces which create sinkhqles also created the many artesian springs for which the Wekiva Basin is renowned. The water in these springs comes from the Florida aquifer in deep Paleocene limestones and dolomites via faults in the overlying Hawthorne Formation. Crevices and solution channels have penetrated the otherwise impervious clay and marl layers of the Hawthorne Formation and dissolved the underlying limestone. These provide the means for developing surface outlets for artesian springwaters. The major springwater sources of the upper Wekiva River are Wekiva Springs (48 million gallons per day [MGD)), Rock Springs (42 MGD), Sanlando Springs (14 MGD), and Sheppard Springs (11 MGD). More than two-thirds of the Little Wekiva River's flow is provided by a combined discharge of 14 MGD from Seminole, Palm, and Starbuck Springs. Spring flows from the Floridan Aquifer comprise most of the Wekiva River's water volume, which averages 186 MGD at State Road 46 (DNR, 1986, 1987). Reductions in flow of several major springs during the past two decades have been attributed to water withdrawals from numerous deep

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72 groundwater wells in the region which supply water for residential, industrial, and agricultural uses (FWR, 1985; see also Heath and Conover, 1981). Two man-made springwel1s at Wekiva Falls with a combined flow of 40 MGD enter the Wekiva just south of State Road 46. Withdrawals from these deepwater wells may be partly responsible for the recent decrease in spring flow volume from various natural springs in the Wekiva Basin. However, cutting off upstream springflows from Wekiva Falls may not have particularly adverse effects on lower Wekiva River wetlands. The proximity of this source to the confluence of Blackwater Creek and the St. Johns River and the steep flow gradient in this section of the Wekiva River tend to reduce the importance of this water source to the ecology of the Lower Wekiva Aquatic Preserve region. The natural channelling of the river into a relatively restricted wetland zone caused by the increase in flow gradient tends to mitigate the negative. impacts on wetlands of the lower Wekiva River from reduced flows caused by the Wekiva Falls wells. Further in the regional water table due to over-exploitation of water resources from the Floridan Aquifer will have major impacts on the wetland habitats of the Wekiva Basin. Since about 70% of the Wekiva River's water comes from springs, any reduction in springflow volumes will adversely affect the size, distribution, character, and of state-domain wetlands, waterways, and aquatic habitats in the Wekiva Basin (DNR, 1987). Climate. The Wekiva Basin lies in the southernmost latitudes of the humid subtropical climate zone of the southeastern United States. About two-thirds of the precipitation in the basin falls between June and September. On average, 10 to 15% of the annual rainfall occurs from December to February. Annual rainfall averages 52 inches, with most rain deposited during brief, heavy showers and thunderstorms (Heath and Conover, 1981). Tropical storms,

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73 including hurricanes, contribute on average about 15% of the precipitation from June to November. Rainfall events greater than 30 inches within a single 24-hour period have been recorded during hurricanes at some Florida locations, and such events are possible in the basin if a severe hurricane moves through central Florida (Yoho and Pirkle, 1985). Tornadoes are not uncommon in central Florida, and torrential rains and high winds typically accompany the storm fronts which spawn these dangerous and sometimes highly destructive storms. The average temperature for the central Florida region is 72 degrees F.; ambient temperatures of 85 degrees F. or higher can occur during all months of the year. Arctic air masses sometimes penetrate into the region during winter months, bringing usually brief but occasionally intense episodes of subfreezing temperatures (Yoho and pirkle, 1985; Heath and Conover, 1981). Record freezes occurring during the past few years have devastated the citrus industry in Lake County and most of north central Florida. Tens of thousands of acres of orange groves were severely damaged or killed outright during sometimes week-long periods of sub-freezing temperatures. Whether these recent spates of unusually cold winter weather in central Florida represent a long-term trend toward harsher winter climates is unknown. The effects of these hard freezes do not seem to be as severe on native wildlife and plants as they are on agricultural crops, with one major exception. Populations of manatees (Trichechus manatus) in northern and central peninsular Florida suffer high mortality rates from cold stress and related causes during extended periods of freezing weather (T.J. O'Shea, USFWS, pers. comm.; see O'Shea et al., 1985). Although the artesian springheads of the St. Johns River valley create warm water refuges (72 degrees F.) for manatees, the animals must leave areas of warmer water to feed. As food plants become increasingly scarce near warm-water refuges, manatees are forced to

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74 travel farther and farther in search of food, increasing their exposure to colder water temperatures and the risk of collisions with boats (see Hartman, 1979). Radio-tagged manatees from Blue Spring on the St. Johns River have been sighted in the Wekiva River, and residents have reported seeing manatees in the Wekiva (Beeler and O'Shea, 1978). Solar insolation is generally high in central Florida. Clear skies predominate throughout much of the year, but morning ground fogs and rain clouds often reduce direct sunlight penetration for brief periods. The relatively high insolation and temperature regimes characteristic of Florida combine to produce high evapotranspiration rates. In peninsular Florida, surface water and groundwater losses to evaporation and transpiration may approach or exceed the amount of water gained from precipitation (Heath and Conover, 1981). The potential for such a water deficit demonstrates the importance of spring flows from the Floridan Aquifer to the maintenance of surface-water levels in the Wekiva Basin. The preservation of existing wetland ecosystems in the central and upper Wekiva River Basin is absolutely dependent on continued supply of springflow waters at present levels (DNR, 1987). III.A.2. Biological Description Ecological Communities. The Wekiva Basin is a unique natural ecosystem. It lies in the zone where tropical and temperate floras overlap. Tropical plant species at the northern limits of their range grow side by side with temperate-zone plants (DER, 1983). The distribution of plant species in var10US plant communities varies according to specific site characteristics, and species typical of one community may frequently occur in another (see Hart, 1984). Some species have fairly rigid microhabitat requirements, while others occur in wide ranges of soil, shade, and moisture conditions. The soil

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75 characteristics and disturbance history of a given area may result in the anomalous presence or absence of species or species groups. A knowledge of prior disturbance history (fires, logging, farming, ranching, etc.) is important in determining the extent to which present vegetation conditions reflect native vegetation patterns or the presence of human-altered plant communities (Noss, 1985). For example, selective logging has greatly reduced the abundance of cypress trees in the mixed hardwood swamp community of Rock Springs Run State Reserve (DNR, 1985). Rigid separations among plant communities do not typically occur within most natural biotas. The distinct edges (abrupt ecotones) associated with fire-maintained communities and human-altered landscapes are exceptions. For the most part, categories for community types are general constructs devised for analysis and identification of gross habitat characteristics. Despite the overlap between community types, these recognized associations reflect important biological differences among various communities and special interactions or among the constituent species of each community. The flows of numerous artesian springs from the Floridan Aquifer, together with groundwater drainage from the surrounding watershed, have created the vast network of stream channels and associated floodplains, lakes, and sinkholes which support extensive areas of hydric and mesic habitats in the Wekiva River Basin. The basin's landscape 1S dominated by wetland and lowland plant communities but is interdigitated by relatively limited and patchily distributed areas of transitional and upland habitats. Deep-water and shallow-water herbaceous marsh communities inhabit the stream channels and flooded regions, grading into the hardwood swamp vegetation which also occurs on permanently flooded sites. Bottomland hardwood

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76 communities (swamps and bayheads) grade into hydric hammocks where groundwater seeps riverward from upland communities and into mesic hammocks and flatwoods in areas of higher elevation. Drier upland communities in the region include pine sandhill, xeric hammock, and sand pine/oak scrub. Sinks and ponded areas support cypress domes and patches of wet prairie and mesic hammock (DNR, 1985, 1987; Brown and Starnes, 1983). wildlife. Many of the Wekiva Basin's wildlife species are locally ubiquitous mammals which are common throughout the region or not restricted to one specific plant community or habitat type. These include black bear (Ursus americanus), white-tailed deer (Odocoileus virginiana), feral hog (Sus scrofa), bobcat (Felis rufus), river otter (Lutra canadensis), striped skunk (Mephitis mephitis), opossum (Didelphis marsupial is) raccoon (Procyon lotor), two shrews, several bats, cotton mouse (Peromyscus gossypinus), wood rat (Neotoma floridiana), and two cottontail rabbits. Most of the ubiquitous species of the Wekiva Basin frequent swamps, and other species--including wood duck (Aix sponsa), pileated woodpecker (Dryocopus pileatus), and many songbirds--require forested wetlands for nesting and/or foraging habitats. Many of these species require large expanses of diversified habitat mosaics. For example, black bears, sandhill cranes and wild turkey (Meliagris gallipavo) need between-habitat diversity (presence of a patchwork of different habitats) within their home ranges to support the extensive daily or seasonal shifts in activity among various plant communities. Species such as bats, pileated woodpeckers, and water turtles, which typically forage and live within one habitat, may utilize quite different habitats for dispersal, reproduction, or hibernation. Other species, such as river otters, have large home ranges and travel widely among various habitat patches, even

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though most of their activities are conducted 1n one habitat type (in this case, aquatic wetlands). 77 In describing the faunal communities of the Wekiva Basin, the focus 'will be upon typical species associations within given habitat types. As noted in reference to plant communities, these associations are, for the most part, flexible. Overlaps and omissions in the presence of species within community types may occur. However, the upland communities of the Wekiva Basin are exceptional in having several characteristic and interdependent (commensal) species which are entirely restricted to specific upland habitats. The wetland faunal communities include many species of restricted distribution (such as fishes or the endemic snail and crayfish species), as well as a large complement of more freely ranging forms which utilize several wetland habitat types. Aquatic wildlife communities are comprised of species which are largely or entirely dependent upon aquatic ecosystems (rivers, lakes, springs, ponds: places where standing or flowing water is present to some degree at any given time) for at least part of their life cycle. These communities include animals such as toads and tree frogs which spend their adult lives in terrestrial habitats but which require aquatic habitats for breeding and the development of young (larvae or tadpoles). Aquatic communities in the Wekiva Basin region support a great diversity of wildlife, ranging from microscopic protozoans and invertebrates to the massive American alligator. Literally hundreds of species of snails, mussels, crayfish, insects, fishes, birds, amphibians, reptiles, and mammals share aquatic habitats with a broad spectrum of aquatic plant life. The aquatic plant community provides critical resources such as food, shelter, and oxygen for animals in aquatic environments and is the base of the aquatic food chain.

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78 The aquatic plant communities in the rivers, springs, and floodplains of the Wekiva Basin support populations of numerous fishes, including various types of bass, sunfish, mullet, catfish, pickerel, shad, crappie, perch, shiner, topminnow, killifish, molly, and bowfin (see appendix for scientific names of species not detailed in this discussion). The wetland herpetofauna of the region is exceptionally diverse and contains many aquatic forms. Amphibians which are largely or entirely dependent upon aquatic habitats include sirens, amphiumas, newts, bullfrogs, pigfrogs, and leopard frogs. The largely aquatic reptiles of wetland habitats in the region include American alligators, softshell turtles, cooters, mud turtles, alligator snapping turtles, stinkpots, water moccasins, and several non-poisonous water snakes .. In contrast to amphibians--which typically lay their eggs in water--reptiles need terrestrial or semi-terrestrial sites in which to incubate their eggs. Some reptile species (especially turtles) must travel some distance from the water into adjacent upland habitats to find patches of sunlit, sandy soil necessary for successful nesting. Some of the invertebrates of the Wekiva Basin (including three endemic snails of the genus Cincinnatia and the threatened Wekiva Springs Aphaostracon snail) are restricted to springhead habitats. The threatened Orlando Cave crayfish is an endemic form restricted to habitats in the Little Wekiva River system. Other important invertebrates of the basin are apple snails and burrowing crayfish. The apple snail is the primary food of the limpkin, a large snipe-like bird found in wetland habitats that support populations of this golf-balI-size snail. Burrowing crayfish spend part of the year in vertical burrows which are dug in muddy soils in non-flooded wetland and transitional zones. Excavated soil from the burrow is formed into a nearly cylindrical cone rising as much as 6 inches above ground level. Crayfish

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emerge from these burrows periodically to forage and breed. Crayfish are an important food source for many larger vertebrates, including various fish, bird, and mammal species. Many species of birds found within the Wekiva Basin are dependent upon aquatic and wetland habitats for foraging and/or nesting habitats. Osprey, anhinga, wood stork, egrets, herons, ibises, bitterns, ducks, snipe, gallinules, coot, limpkin, and grebes are characteristic of the open wetland and aquatic habitats of the region. Bald eagles (USFWS: Endangered; FGFWFC: 79 Threatened) are expected to occur as transients in the aquatic communities of the area even if no resident individuals are known at the present time. The resident wood stork (Mycteria americana) has been classified as an endangered species by both state and federal agencies (FGFWFC, 1987). Sandhill cranes (threatened) utilize marsh, wetland, and upland sites in the Wekiva Basin. Other resident species such as the little blue heron (Florida caerulea), tricolored heron (Egretta tricolor), snowy egret (Egretta thula) and limpkin (Aramus guarauna) have been designated as Species of Special Concern (SSC) by the Florida Game and Fresh Water Fish Commission (FGFWFC, 1987). The wetlands bird community of the Wekiva region is exceptionally diverse. Encroachment upon wetland habitats will directly and indirectly affect these attractive and often highly visible components of the Wekiva Basin wildlife community. Typical mammals of the aquatic marsh communities in this region include river otter, round-tailed muskrat CNeofiber alIeni), raccoon, rice rat (Oryzomys palustris), and marsh rabbit (Silvilagus palustris). Otters and raccoons range widely among other habitats, while round-tailed muskrat, marsh rabbit, and rice rat are usually associated with marsh, swamp, or wet prairie communities.

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80 The bottomland hardwood associations (hardwood swamp and bayhead communities) typically occur as closed-canopy woodlands which are distributed either as extensive wetland forests in flooded basins or as gallery forests along stream and lake margins. These communities represent a transitional gradient between strictly aquatic and terrestrial environments and retain characteristics of both. Consequently, the wildlife associated with swamp and bayhead communities includes species of both aquatic and terrestrial affinities. The Wekiva Basin swamps and bottomland hardwoods support not only numerous aquatic forms, but also many typically terrestrial animals, including black bear, white-tailed deer, turkey, opossum, gray squirrel (Sciurus carolinensis), cotton mouse, wood rat, gray fox (Urocyon cinereoargentus), and striped skunk. The Wekiva Basin and the nearby southern portion of the Ocala National Forest constitute perhaps the best remaining areas of suitable bear habitat in central Florida (DER, 1983). The Florida black bear (Ursus americanus floridanus) is unique among North America I s extant black bear populations in that its large size is commensurate with that of the ancestral black bears of Ice Age times (Kurten and Anderson, 1980). Management strategies keyed to protection of black bear populations and habitat requirements should benefit virtually all other wildlife in the Wekiva Basin. The largely terrestrial habitats of the uplands include pine flatwoods, pine sandhills, and sand pine/oak scrubs. Flatwoods are used by bear, deer, spotted skunk (Spilogale putorius), cotton rat (Sigmodon hispidus), cotton mouse, diamondback rattlesnake (Crotalis adamanteus), and various other ubiquitous species. Flatwoods provide good cover and shelter for animals that forage in adjacent habitats, move between habitats, and seek refuge from high floodwaters during storms. The truly upland habitats of the region are the pine sandhill and sand pine/oak scrubs of the dry dune-ridges. Typical

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81 wildlife species of these upland habitats include the gopher tortoise (Gopherus polyphemus, SSe) and its many associated commensal (interdependent) species, including the gopher frog (Rana sphenocephala, SSe), the Florida moUSe (Peromyscus floridanus, SSe), and the eastern diamondback rattlesnake. Pocket gophers (Geomys pinetis; also known as salamander or sandy-mounder) occur in more open habitats of deep, well-drained, sandy soils on high ridges in the Wekiva Basin. Longleaf pine sandhills are the preferred habitat of the Sherman's fox squirrel (Sciurus niger shermani, sse). This species has been decimated over the past century by logging of mature pines in the sandhill communities. Reduced populations survive in remnant turkey oak forests, and the species may occur around cypress domes in flatwoods and in a few other upland ecotone situations (OER, 1983). The logging of mature longleaf pines and conversion of sandhill communities into citrus and slash pine plantations have severely affected the structure, composition, and distribution of sandhill ecosystems. The preponderance of listed species among the typical wildlife of the once widespread sandhill community is an indication of the extent to which this habitat has been disrupted by development. The sand pine/oak scrub community contains several highly specialized endemic species such as scrub lizard (Sceloporus woodi) sand skink (Neoseps reynoldsi, threatened), and Florida scrub jay (Aphelecoma coerulescens coerulescens, threatened). Many sandhill wildlife species also utilize scrub habitats and range freely between adjacent scrub and sandhill habitats. The acorns of various oak species common in these habitats are an important seasonal food for black bear, deer, turkey, and feral hog populations of the Wekiva Basin.

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82 III.B. Wetland Communities Wetlands habitats of the Wekiva Basin can be subdivided loosely into three major community types. These are the aquatic herbaceous marsh community of stream channels and springheads, the mixed hardwood swamp community of the river floodplains, and the hydric hammock community of groundwater and surface runoff seepage wetlands. Marshes and swamps are characterized by saturated or flooded soils which are subject to regular and extended periods of inundation by standing or flowing water. Hydric hammock soils are saturated but only occasionally inundated. Marsh vegetation consists of submerged, emergent, and floating herbaceous plants. Swamp vegetation consists of water-tolerant trees and shrubs. Gradual shifts in plant species composition occur according to the regularity and depth of immersion for ground-level vegetation in floodplain habitats. The presence of surface water will greatly affect the types of wildlife species which are present at any given time. III.B.I. Aquatic/Marsh Communities The freshwater marshes of Florida are critically endangered. Freshwater marshes are vulnerable to changes in water levels, water quality, hydroperiod, and fire regimes. Drainage of marshes for development and agriculture has eliminated much of Florida's freshwater marsh habitat. Heavy recreational use, particularly when associated with off-road vehicle and boat traffic, can drastically alter the structure and composition of vegetation within marshes and inhibit the vital ecosystem functions of these communities. The freshwater marsh is a critical resource for many species of birds, fishes, reptiles, mammals, and amphibians in the Wekiva Basin. Undisturbed areas of freshwater marsh provide excellent cover and travel routes for many

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83 wildlife species. The vegetation of freshwater marshes filters surface runoff that feeds rivers and lakes. Soil particles are trapped within the vegetation matrix, and plant roots stabilize the soil surface both above and below the water level. Dense rafts and mats of marsh plants protect the stream banks from strong current flows and help prevent erosion during periods of high water and storm floods. Marsh plants fix and store nutrients and soil particles filtering in from the surrounding landscape, thus helping to prevent eutrophication. The deepwater marsh communities (Water Hyacinth/Coontail/ Watergrass: Eichhornia/Ceratophyllum/Echinochloa) are dominated by rooted or free-floating aquatic herbaceous plants, and they typically occur on permanently flooded sites with water depths of 3 to 6 ft (Brown and Starnes, 1983). This community is found in the main channels and deeper sections of spring runs in the Wekiva Basin, with maximum development in sites not shaded by streamside tree canopy. These high-gradient, fast-moving streams tend to flush out the organic debris and compounds which stain the waters of blackwater swamp systems. High flow rates and steep gradients also create clearwater stream conditions within large tracts of hardwood swamps. The large spring flows of the upper Wekiva River system generate clearwater alkaline streams with high flow and clean, sandy bottoms. These calcareous spring flows are rich in phosphorous and other nutrients and support luxuriant aquatic plant growth. Other representative plants of this habitat include water lily (Nymphaea odorata), hydrilla (Hydrilla verticullata), water-lettuce (Pistia stratioides), and duckweed (Lemna spp.). The common water hyacinth (Eichhornia crassipes) is a weedy exotic which has invaded aquatic habitats throughout Florida. This species has become the dominant aquatic plant in many localities within the region, severely encroaching upon

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84 important native species such as eelgrass and coontail. of water hyacinth is a desirable but presently unachievable management goal. Shallow-water marsh communities (Cutgrass/Maidencane/Cattail/ Arrowhead: Leersia/Panicum/Typha/Sagittaria) typically occur in sites which may be flooded only seasonally but which have water depths of 6 inches or more during the growing season (Brown and Starnes, 1983). Other representative species include sawgrass (Cladium jamaicense), sedges and rushes (Juncus spp., Elocharis spp., and Rynchospora spp.) These shallow-water herbaceous plant associations typically occur in the shallower sections of stream channels and along stream margins within the Wekiva Basin. Wet prairie communities are similar to shallow marsh communities in terms of both their constituent species and flooding regimes. Water depths range from 0.5 to 2 ft in the growing season. Sometimes called grassy ponds, sloughs, or prairie lakes (DNR, 1985), the wet prairie is a grass/herb plant community associated with seasonally and permanently flooded areas of upland habitats (see below for a more detailed discussion of this community). III.B.2. Mixed Hardwood Swamp Community The shallower waters in floodplains and along the margins of lakes and streams in the Wekiva Basin support large tracts of swamp and bottomland hardwood vegetation. This community is comprised of cypress species and a variety of deciduous hardwood trees that grow on saturated and flooded soils. Nutrient availability is generally low, but wildlife habitat value is high. Swamps assimilate organic and inorganic wastes and pollutants, store water, and impede the movement of floodwaters. By slowing down the rate of water flow, swamps help to minimize erosion, promote infiltration, and facilitate the settling out of debris, silt, and nutrients carried by floodwaters. These

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85 functions improve water quality, stabilize water flows in streams and rivers, and help to maintain high groundwater levels in the region. Swamps provide habitat for many wildlife species and are used as travel corridors by wildlife in developed areas. The mixed hardwood swamp (cypress/tupelo/water ash: Taxodium/ Nyssa/Fraxinus) and bayhead (red bay/loblolly bay/pond cypress: Persea/Gordonia/Taxodium) community occurs on poorly drained sites which are regularly or permanently flooded (Brown and Starnes, 1983). Tannins and humic acids from plant debris color and acidify the waters in swamps and in their drainage streams. These blackwater systems tend to occur in the low-gradient streams and basins of cypress and hardwood swamps where organic debris accumulates on stream bottoms and in backwaters. Blackwater Creek is a typical example of this distinctive stream type. Pure stands of cypress stands and old cypress trees are no longer common in the swamps of the Wekiva Basin. Old-growth cypress has been selectively logged from swamps throughout Florida during the past century (see DNR, 1985; Monk,1968). Fluctuations in water level are required for cypress regeneration: cypress seeds must be soaked before they will germinate, but they will not germinate if they are underwater. Other important species of the mixed hardwood swamp are red maple (Acer rubrum), American elm (Ulmus americana), water hickory (Carya aquatica), buttonbush (Cephalanthus occidentalis), and bluestem palmetto (Sabal minor) (Brown and Starnes, 1983). The American elm was formerly common and widespread throughout eastern and central North America, but in the past century the introduction of Dutch Elm disease, an exotic pathogen, has nearly exterminated this species throughout much of its range (see Davis, 1981). However, this species still survives as a common element in the floodplain forests of the Wekiva Basin.

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86 III.B.3. Hydric Hammock Community In some areas between the mixed bottomland hardwoods and the upland communities along the Wekiva River, seepage of groundwater from uplands is the dominant source of water. The topography of these areas is flat, and the soils are poorly drained and almost constantly saturated with seepage water. Although subject to occasional flooding, the hydroperiod in hydric hammocks is shorter than in the adjacent swamps. Hydric hammock communities support more plant species than any other wetland type in the Wekiva Basin. Among the species are popash (Fraxinus caroliniana), live oak, laurel oak (Quercus laurifolia), red maple, southern magnolia (Magnolia virginiana), red cedar (Juniperus siliciola), cabbage palm, saw palmetto (Serenoa repens), tulip poplar (Liriodendron tulipfera), pond pine (Pinus serotina), slash pine (Pinus elliotii), sweet gum (Liquidambar styraciflua) wax myrtle (Myrica cerifera), and several vines and ferns (Brown and Starnes, 1983). The hydric hammock is excellent wildlife habitat and is used by ubiquitous mammals and birds as well as by numerous reptiles and amphibians. This community is very sensitive and vulnerable to changes in groundwater hydrology in upland areas. Drawdowns caused by nearby wells and diversion of groundwater via retention ponds and ditches in uplands can interrupt the supply of seepage water to hydric hammocks, causing the soil to dry out and, eventually, species composition to shift toward more mesic and fewer wetland species. Lowering the water table also makes hydric hammock more vulnerable to fire, a disturbance to which these ecosystems are not adapted.

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87 III.C. Transitional Communities: Mesic Hammock and Scrubby Flatwoods In the Wekiva Basin, the transitional communities between the wetlands and the uplands are largely ecotonal in character, occurring as edges or borders around the larger areas of swamp. Distinct separations between the swamp, bayhead, and lowland hammock communities occupying floodplain habitats of the Wekiva Basin are typically absent. Transitional species of the wetland/upland ecotone include hydric and mesic hammock forms such as cabbage palm, saw palmetto, tulip poplar, pond pine, slash pine, and sweet gum (Brown and Starnes, 1983). Scrubby flatwoods associations form ecotones between the mesic flatwoods and the xeric sandhill and scrub communities. Scrubby flatwoods occupy sites which are sufficiently well-drained so that there is no standing water present even under extremely wet conditions. Pines (slash, sand, and longleaf) are typically present but scattered within a matrix of shrubby oaks and palmettos. Scrub oak inopina), Chapman's oak chapmanii), and sand live oak intermix with saw palmetto and scrub palmetto (Sabal etonia) to form a generally thick shrub layer 1 to 2 m high. Herbaceous cover tends to be sparse. Lichens (Cladonia spp.) and spike moss (Selaginella arenicola) provide considerable ground cover except on recently burned sites. Fire is important in determining the structure and composition of scrubby flatwoods vegetation, which is intermediate in character between flatwoods and sandhill/scrub communities. III.D. Upland Communities The drier, sandy soils of the uplands support scrubby flatwoods on their lower edges and longleaf pine sandhill and sand pine scrub on better-drained and slightly higher sites. Longleaf pine-turkey oak sandhills and sand

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88 pine-oak scrub are distinct in structure and composition from flatwoods communities. These communities occur as savanna or scrub formations on the well-drained upland soils of the Wekiva Basin and are subject to frequent burning. Differences in past burning regimes and. local soil characteristics strongly affect the particular vegetation characteristics of these communities (see Kalisz and Stone, 1984). These habitats are home to a number of important endemic species and are particularly sensitive to changes in natural disturbance regimes (see Monk, 1968). Upland habitats have been severely disturbed by past and present management practices, and major ecological components cannot become reestablished following certain types of human-caused disturbances (Means and Grow, 1985). In many respects, these specialized uplands communities are at the greatest risk from development at present (see Means and Grow, 1985). They occupy substrates and soils which are often preferred over those of wetland sites for agriculture, silviculture, industry, and residential development. As a consequence, few large tracts of native upland vegetation and wildlife survive at the present time. Those upland communities which remain have been subjected to major changes in vegetation regimes and wildlife species diversity as the direct result of human disturbance. Such human-caused changes in the ecology of upland terrestrial communities can greatly alter the movement of water, soil, and nutrients into adjacent wetlands and regional watersheds (see Qdum, 1971, 1983). III.D.l. Pine Flatwoods Communities Flatwoods are fire-adapted communities which occur on moderately to poorly drained soils of terraced lands above the floodplain in areas subject to periodic burning. Wildfires tend to kill off most typical hardwood hammock

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89 tree species while leaving the fire-tolerant forms, especially pines and palmetto, as local dominants. Exclusion of fire will result in succession to bottomland hardwoods or mesic hammock on most flatwoods sites (Monk, 1968). The dominant species in the basin's mesic pine flatwoods community are pines, scattered oaks, and saw palmetto (Pinus spp./Quercus spp./Serenoa repens). A dense shrub layer carpets the understory level. Pines of flatwoods habitats include longleaf pine, slash pine, and pond pine. Live oak and dwarf live oak minima) are often present. Saw palmetto is usually the dominant shrub species, with dwarf live oak, fetterbush (Lyonia lucida) staggerbush (Lyonia fruticosa), dwarf huckleberry (Gaylussacia dumosa), and wax myrtle as secondary components. Saw palmetto, threeawn grass (Aristida patula), greenbriar (smilax spp.), and gallberry (Ilex glabra) are typical understory species. Flatwoods often contain patchily distributed areas of cypress dome, bayhead, mesic hammock, wet prairie, sandhill, and scrub vegetation due to variations in topography, soils, and soil moisture regimes. Standing water may be present in flatwoods during periods of high precipitation and elevated groundwater levels. Longleaf pine was formerly dominant on drier sites, while slash pine and pond pine tend to be dominant on more mesic soils. Repeated selective harvesting of longleaf pines, changes in fire regimes, and conversion of flatwoods and sandhills to agriculture during the past century have greatly affected the distribution and abundance of native longleaf pine communities (Monk, 1965, 1968; Means and Grow, 1985). Slash pine is now the dominant tree on many former longleaf sites. Pond pine becomes dominant in acidic, poorly drained flatwoods where soil pH is less than 4.5, while slash pine occurs primarily on more neutral soils (Monk, 1968).

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90 IILD.Z. Wet Prairie .Communities Wet prairies typically occur in sinks and depressions within areas of low topographic relief which receive water through runoff from adjacent higher ground. Patches of wet prairie vegetation are commonly found scattered throughout the flatwoods and sandhills of the region. Shrubs and small trees, such as primrose willow (Ludwigia spp.) and elderberry (Sambucus simpsonii), are sometimes present in wet prairies. Characteristic herbaceous plants include panicum grasses (Panicum tenerum, dichotomum, etc.), sloughgrass (Scleria spp.), swamp lily (Crinum americanum), and sundew (Drosera spp.). The wet prairie is fire-adapted, and frequent burning will maintain wet prairies on sites which would otherwise succeed to hydric or mesic woodland. These grassy patches increase habitat diversity in flatw90ds landscapes and provide accessory foraging habitats for important wetland wildlife species. Because wet prairies are dependent on surface water runoff to supply water (Brown and Starnes, 1983), drawdowns of water tables in flatwoods by ditching can eliminate wet prairies and reduce habitat diversity in upland regions. III.D.3. Pine Sandhill Communities The pine sandhill is a savanna-type formation of scattered trees and open woodlands having a well-developed ground cover of grasses, forbs, and scattered shrubs. Characteristic species are longleaf pine, turkey oak, and wiregrass (Pinus palustris/Quercus laevis/Aristida stricta). Fire is an important ecological component of sandhill environments and maintains the characteristic open pine woodland and sparse understory vegetation. Burns occur naturally in sandhill communities at about 3-to 5-year intervals, usually started by lightning strikes (Means and Grow, 1985). These frequent

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91 fires preserve the dominance of longleaf pine and inhibit succession to xeric hammock vegetation (Kalisz and Stone, 1984). Sand pine may also invade sandhill communities when fire is suppressed (Kalisz and Stone, 1984). The upland dune formations of the Wekiva Basin are dominated by pine sandhill communities containing patchily distributed areas of sand pine/oak scrub (Pinus clausa/Quercus spp.) and xeric hammock. Pines and turkey oaks are typically the principal overs tory components. The relative dominance of turkey oaks and pine species other than longleaf and the absence of old-growth longleaf in the region's sandhill communities are due to selective logging in these communities. Sandhills have a more or less continuous herbaceous ground cover dominated by wiregrass. Shrubs and hardwoods other than oaks are typically present at low densities (Laessle, 1958). Other common plants of sandhill habitats are bluestem grasses (Andropogon stolonifera, A. tenarius), persimmon (Diospyros virginiana), prickly pear (Opuntia ammophila), blueberries (Vaccinium spp.), gopher apple (Chrysobalnus oblongifolius), and spike moss. Shrub rosemary (Ceratiola ericoides) is often common in sandhill communities but does not usually occur in dense stands. Individual rosemary bushes are usually ringed by narrow perimeters of bare soil. This phenomenon is caused by the release of an allelopathic chemical from the rosemary which inhibits the growth of other plants within its imnediate vicinity. The high primary productivity of sandhill habitats provides a rich food base for a wide variety of wildlife. Turkey oak acorns are important to mast-feeders such as deer, turkey, and feral hpg. Sandhill communit ies support a characteristic fauna which includes Sherman's fox squirrel and gopher tortoise with its host of commensal wildlife species.

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92 Sand pine scrub and oak scrub occur on various upland sites within the Wekiva Basin (DNR 1985, 1987). Sand pine and oak scrub are characterized by a mixed scrub oak understory dominated by scrub live oak, myrtle oak myrtifolia), and Chapman's oak chapmanii). Sand pine is variably present in the scrub habitats of the Wekiva Basin. Differences in burning and disturbance regimes probably account for the absence of sand pine in some scrub communities of the Rock Springs Run State Preserve (DNR, 1985). Shrubs such as staggerbush, rosemary, and wild olive (Osmanthus americana) may also be present. Scrub hickory (Carya floridana), a Florida endemiC, is present in the scrub habitats of the Wekiva Basin. Common herbaceous plants of scrub habitats in the region include blueberries, gopher apple (Chrysobalnus oblongifolius), prickly pear (Opuntia compressa), spike moss, and wiregrass. Lichens (Cladonia spp., Usnea spp., and others) grow on patches of bare soil or as epiphytes on the bark of woody plants. Patches of xeric hammock (live oak/sand live oak/red oak/American holly/deer moss: Quercus virginiana/Q. falcata/Ilex opaca/Cladonia spp.) occur within the upland sandhill habitats. Pine sandhill and sand pine scrub communities will be succeeded by xeric hammock vegetation if the absence of fire is prolonged (Monk, 1968). Exclusion of fire allows regeneration of hardwoods and prevents the continued recruitment of pines. The leaf litter of xeric hammock plants is fire-resistant, so that patches of hammocks within large sandhill tracts typically remain unburned even though ground fires have spread throughout the surrounding pine-dominated landscape. The prevalence of natural and human-caused wildfires in the Wekiva Basin over the past centuries has limited the significance of this community type in the region.

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93 Sand pine scrub and oak scrub occur on various upland sites within the Wekiva Basin (DNR 1985, 1987). Sand pine and oak scrub are characterized by a mixed scrub oak understory dominated by scrub live oak, myrtle oak myrtifolia), and Chapman's oak chapmanii). Sand pine is variably present in the scrub habitats of the Wekiva Basin. Differences in burning and disturbance regimes probably account for the absence of sand pine in some scrub communities of the Rock Springs Run State Preserve (DNR, 1985). Shrubs such as staggerbush, rosemary, and wild olive (Osmanthus americana) may a1sobe present. Scrub hickory (Carya f10ridana), a Florida endemic, is present in the scrub habitats of the Wekiva Basin. Common herbaceous plants of scrub habitats in the region include blueberries, gopher apple (Chrysobalnus ob10ngifolius), prickly pear (Opuntia compressa), spike moss, and wiregrass. Lichens (Cladonia spp., spp., and others) grow on patches of bare soil or as epiphytes on the bark of woody plants. Patches of xeric hammock (live oak/sand live oak/red oak/American holly/deer moss: Quercus .. geminata/Q. falcata/Ilex opaca/Cladonia spp.) occur within the upland sandhill habitats. Pine sandhill and sand pine scrub communities will be succeeded by xeric hammock vegetation if the absence of fire is prolonged (Monk, 1968). Exclusion of fire allows regeneration of hardwoods and prevents the continued recruitment of pines (see Williamson and Black, 1981). The leaf litter of xeric hammock plants is fire-resistant, so that patches of hammocks within large sandhill tracts typically remain unburned even though ground fires have spread throughout the surrounding pine-dominated landscape. The prevalence of natural and human-caused wildfires in the Wekiva Basin over the past centuries has limited the significance of this community type in the region.

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IV. STATUTORY & DISTRICT CRITERIA RELATED TO BUFFER ZONES Questions have been raised concerning the authority of the District to enact requirements which restrict or preclude the construction and operation of systems within the Wekiva River Basin. The rulemaking related to the Wekiva Basin has been the subject of serious concern, and much debate has resulted. An earlier draft of the Wekiva Basin Rule had requirements that buffered the river from impacts, but was withdrawn following considerable controversy, and staff was directed to revisit the issue. Following several drafts of proposed language for buffer requirements, a Petition for Administrative Determination of Invalidity of Proposed Rule was filed that alleged the proposed rule constitutes an invalid exercise of delegated legislative authority or is otherwise invalid. The statutory authority granted the Governing Board of the District related to the enactment of requirements that restrict or preclude the construction, operation, or maintenance of systems is clearly stated, but somewhat general. Broad rulemaking authority has been granted by the Legislature (Chapter 373, FS). The Board may adopt reasonable rules that are consistent with the law and reasonably necessary to effectuate its powers, duties, and functions. Rules adopted by the Board must be reasonably related to the purposes of Chapter 373. The Board cannot act in an arbitrary and capricious manner and should have before it competent and substantial evidence to support a proposed rule. 95

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96 Two questions related to the statutory authority given in Chapter 373 (FS) have occurred to us. First, in Sections 373.413 and 373.416 the Legislature enacted two statutory provisions related to water management systems; the former addressing construction of systems and the later addressing operation and maintenance of systems. As a result, an arbitrary distinction is made between construction and operation and maintenance. Second, the statute does not provide a definition for the term "water resources.1t IV.A. Statutory Criteria, Sections 373.413 & 373.416, FS Sections 373.413 and 373.416 draw a distinction between permits required for construction or alteration of dams, impoundments, reservoirs, or works (373.413, FS) and permits required for maintenance and operation of same (373.416, FS). In the former, the District may require permits to assure that construction or alteration of any system will not be harmful to the water resources of the District. In the latter, the District may require permits to assure that the operation or maintenance of a system will not be harmful to the water resources of the District and will not be inconsistent with the overall objectives of the District. The distinction between the harm that may result from construction activities and harm that may arise from operation and maintenance is a confusing one in light of the review a permit application may receive. Can the District evaluate an application for construction based only on harm to water resources, or can the application also be evaluated relative to the overall objectives of the District? Conceptually it may be relatively easy to separate impacts on water resources that result from development activities into those that occur during construction and those that may result from the operation and maintenance of that which has been constructed. From a resource management perspective,

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97 however, it is not an easy distinction to make. Determining the harm to water resources during construction and following construction is not too difficult, but what is difficult is separating the consideration of these potential impacts when determining if a permit for construction should be issued. To issue a permit for construction of a system or work and evaluate only the potential impacts to water resources without evaluating its impact on the overall objectives of the District once the system is in place is like basing the decision to operate on a patient only upon his/her chances of living through the operation, with no regard as to whether the organ removed is essential for survival after the operation. The distinction is an artificial one at best. If the overall objective is to manage the water resources of the District and insure that the construction, operation, and maintenance of works are not harmful to them, the District must evaluate potential harm resulting from operation and maintenance concurrently with potential harmful impacts resulting from construction. Foregoing sections of this report have established that while impacts caused by construction and those resulting from operation and maintenance can be separated for discussion purposes, they are intimately interconnected, and they must both be considered if the potential impacts are to be evaluated, understood, and resolved. To manage the water resources of the District effectively, all relevant information and potential consequences of any decision must be evaluated during application review. To do otherwise cannot possibly result in effective resource management. In this light, when the District reviews a construction permit, not only should potential harm to water resources be evaluated (Chapter 373.413 FS), but District staff should also determine if it is consistent with the overall objectives of the District (Chapter 373.416 FS).

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98 The second question is also important in permit evaluation. In evaluating a permit for construction and/or operation and maintenance, the District strives to assure that the system or work will not be harmful to the water resources of the District. In a narrow sense, water resources can be thought of as the water only. Then harm would constitute affecting the quality or quantity of water (the abiotic substance). In a broader sense, however, water resources must be thought of as not only the water (the H20) but as the combined biotic and abiotic components--the ecological system of plant and animal life and abiotic elements that are the whole resource. It is not easily dissected or decomposed into two distinct parts for the purposes of management, since the quality of the resource is a complex functional interrelationship of abiotic substances and living organisms. The management of one aspect without regard for the other may at times run counter to sound management of the whole. A working definition of water resources should include the entire resource, and may be something like the following: Water Resource The combined abiotic substances and biotic organisms that constitute the aquatic systems of ground and surface waters. IV.B. Rule Criteria, 40C-4, 40C-4l and 40C-42, FAC Chapter 40C-4, FAC, implements the permitting program in a manner that is consistent with the Objectives and policies of the St. Johns River Water Management District and the declared water policy of the State of Florida. In essence it declares that surface water management permits will be required prior to the construction, alteration, operation, maintenance, removal, Or abandonment of any dam, impoundment, reservoir, appurtenant work, or works. To obtain a permit, each applicant must give reasonable assurance that such activity will not adversely affect navigability, recreational development, or

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99 public lands; endanger life, health, or property; adversely affect the availability of water; be incapable of being effectively operated; adversely affect existing agricultural, commercial, industrial, or residential developments; cause adverse u.pacts to the quality of receiving waters; adversely affect natural resources, fish, and wildlife; increase the potential for damage to off-site property or the public; increase the potential for flood damage; or otherwise be inconsistent with the objectives of the District, among others (emphasis added). The chapter also establishes size thresholds for which permits are required. In addition to the above, the District's Applicants Handbook states that State Water Policy (Chapter 17-40, FAC) is used as guidance to determine harm to water resource and that consideration should be given to the impacts of facilities on recreation; navigation; water quality; fish and wildlife; wetlands, floodplains, and other environmentally sensitive areas;.saltwater or pollution intrusion; reasonable beneficial uses of water; minu.um flow levels; and other factors related to the public health, safety, and welfare; among others (emphasis added). Further, the Handbook states that the District recognizes that ... wetlands are important components of the water resource because they serve as spawning, nursery and feeding habitats for many species of fish and wildlife, and because they provide important flood storage and water quality benefits. Review criteria are provided to determine whether a system will meet District objectives regarding hydrologically related environmental functions. Except when threatened or endangered species are involved, the District will only consider off-site impacts on aquatic and wetland-dependent species relative to the functions currently being provided by the wetland to these types of fish and wildlife. An applicant must provide assurance that a proposed system will not cause changes in the habitat of off-site aquatic and wetland-dependent

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100 species; the abundance and diversity of off-site aquatic and wetland-dependent species; and the food sources of off-site aquatic and wetland-dependent species. Chapter 40C-41, FAC establishes basin-specific surface water management permitting criteria for the Wekiva River Basin that are in addition to the District-wide criteria specified in Chapters 40C-4 and 40C-40, FAC. The Wekiva River Basin Rule was adopted in March 1987, establishing permitting standards as follows: 1. RECHARGE -Three inches of runoff from all directly connected impervious areas must be retained within the project area for projects or portions of projects in Most Effective Recharge Areas. As an alternative, applicants may demonstrate that the post development recharge capacity is equal to or greater than the predevelopment recharge capacity. 2. STORAGE -A system may not cause a net reduction in flood storage within the 100 year floodplain of a stream or other watercourse which has a drainage area upstream of more than one square mile and which has a direct hydrologic connection to the Wekiva or Little Wekiva Rivers or Black Water Creek. Definitions of Most Effective Recharge Areas and directly connected impervious areas are given in 40C-41, as follows: .. Most Effective Recharge Areas have been defined by the U.S. Geological Survey as areas which have 10-20 inches of recharge per year ... Most Effective Recharge Areas can be more accurately defined by soil types. The Soil Conservation Service has categorized soils according to hydrologic characteristics. Those soils determined by SCS to be Type "A" Hydrologic Soil Group shall be considered to be Most Effective Recharge Areas Directly connected impervious areas are those impervious areas which are connected to the surface water management system by a drainage improvement such as a stormwater, paved channel, or other man-made conveyance. Stormwater that is retained must be infiltrated into the soil or evaporated such that the storage volume is recovered within 14 days following a storm event.

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In addition, when stormwater management systems discharge to Class I, Class II, or outstanding Florida Waters, Chapter 40C-42, FAC provides for further treatment of stormwaters as follows: (10) Stormwater discharge facilities which directly discharge to Class I, Class II, and outstanding Florida Waters shall include an additional level of treatment equal to fifty percent of the treatment criteria specified in Section 40C-42.03S(1) (b) or Section 40C-42.04l(S) and shall provide off-line retention or off-line detention with filtration of the first one-half inch of run-off of the total amount required to be treated. 101 In all, the criteria in 40C-4l, and 40C-42 recognize the special values of the water resources of the Wekiva River Basin and were designed to afford additional protection. Rule criteria are generally designed to protect water resources (both quality and quantity of surface water and quantity of recharged groundwater) as a result of the construction, operation, and maintenance of a work or system. In most instances, however, specific construction techniques and specific engineering of a project' s stormwater management system are not adequately addressed by criteria simply because these are outside the purview of the review criteria. Language may be inserted in conditions for permits that require particular attention be paid to minimizing impacts during construction from eros loon and siltation, for example, but lIaccidents do happen." In other words, there are two s igni ficant potential gaps in the rule criteria related to water quality that an appropriately designed buffer rule will overcome. The potential gaps are as follows: 1. Water quality impacts resulting from construction activities in the areas immediately adjacent to wetland; and 2. Water quality impacts resulting from portions of projects constructed adjacent to wetlands, but not directly connected to the stormwater management system.

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102 While the existing rule criteria recognize the importance of recharge in the Wekiva River Basin to maintain both the quality and quantity of groundwaters, the "discharge" of groundwaters that are of particular importance to maintenance of ecologically significant hydric hammocks and floodplain wetlands of the Basin is not addressed in the present rules. These wetland systems are particulary sensitive to the lowering of the groundwater table. The District's policy regarding the lowering of groundwater tables found in Section 10.6.3 of the Applicants handbook states: It is presumed that an adverse impact will result if the system causes the groundwater table to be lowered; a) more than an average three feet lower over the project area than the average dry season low water table; or b) at any location, more than five feet lower than the average dry season low water table; or c) to a level that would drain adjacent surface water bodies below a minimum level established by the Governing Board pursuant to Section 373.042, FS. In most instances, in areas adjacent to the floodplain wetlands of the Wekiva Basin a lowering of the water table from 3 to 5 ft would severely impact hydrologic functions, draining groundwater, disrupting seepage regimes, and diverting surface waters. The net result would be the disruption of ecological functions and loss of wildlife habitat. Thus a third potential gap in the protection of the water resources of the Wekiva River Basin and the importance of the groundwater table to seepage and floodplain wetlands that an appropriately designed buffer may overcome is as follows: 3. Water quantity impacts resulting from excavations and general lowering of the groundwater table in areas adjacent to seepage wetlands. Finally, while it is the policy of the District to evaluate permit applications uSlng reVlew criteria that expressly states consideration should be given to impacts on fish and wildlife, wetlands, floodplains, and other environmentally sensitive areas, present rule criteria in 40C-4l or 40C-42 do

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103 not address these factors. Recognizing the special significance of the wetland and wildlife resources of the Wekiva River Basin, a fourth potential gap in protection of the resources may be overcome with an appropriate buffer as follows: 4. Impacts to flora and fauna resulting from loss of habitat and disturbance as a consequence of construction, operation, and maintenance of systems in areas adjacent to wetlands. Further discussion related to water quality and water quantity issues is given next to better explain the rationale for recommending a buffer to minimize negative impacts of development in areas immediately adjacent to the wetlands and watercourses of the basin. Water Quality Issues. The potential for significant degradation of water quality during construction is directly related to the proximity to the resource and the type of construction activity. Given in Figure IV.l is a plan view of an area along a section of river typical of the Wekiva River. The figure illustrates a typical wetland/upland interface and two typical residential development patterns. In the first type of development, lots and housing units are built up to the wetland line, and some clearing of canopy and understory is required. In the second type of development, because the wetland/upland edge is generally the lowest elevation of the project site, retention/detention basins are constructed along the edge, requiring complete removal of vegetation and excavation. Both development patterns could be constructed under current permit criteria. Where lots and house construction occur adjacent to the wetland edge, typically, the downslope areas are wholly or partially excluded from the stormwater management system. This results from the fact that the edge of the floodplain generally is the lowest elevation, and either the back of lots must be filled to elevations so that surface waters flow toward the front of the

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104 lot, or the back portions of lots are excluded from the management system. The size of lots on the floodplain edge dictate to a large degree how much land is excluded from the management system and allowed to sheet flow stormwaters downslope to the wetland edge. While this development pattern may minimize disturbances along the edge from clearing and digging, surface waters running downslope from these areas are not subject to treatment by the stormwater system and can cause significant water quality problems both in the short term during construction and in the long term during use and management. If the area upslope from the wetland edge is to be excavated for detention or retention ponds, initial c1earcutting, additional heavy equipment for digging, and placement of spoils contribute additional potential water quality problems. The c1earcutting required exposes soils to even greater erosion potential since all vegetation must be removed and the ground surface is scraped clean in preparation for digging equipment. The heavy equipment associated with excavations and earthwork necessary to contour basin side slopes and surrounding lands contribute to significant potential constructionrelated "accidental infringement" into the downslope wetlands/water resources. Finally, spoil placement in adjacent areas and filling along the wetland line expose the downslope wetland/water resource to potential sedimentation from newly excavated non-stabilized soils. Figure IV.2 is a cross section of a floodplain swamp, transition zone, and uplands typical of portions of the Wekiva River Basin. In the top drawing the undisturbed condition is shown. In the bottom drawing the effects of clearing and construction activities in areas immediately adjacent to the wetland line are summarized. Under these conditions, protective ground cover and litter are scraped off the soils, leaving them bare and easily washed downslope during construction. The resulting erosion and deposition will significantly affect

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lOS Figure IV.l. Drawing of two development patterns typical of the Wekiva River Basin. The development pattern in the upper portion of the drawing has housing down to the line and stormwater retention/detention ponds in the upland portions of the development. The development in the lower portion of the drawing has stormwater retention/detention basins constructed immediately adjacent to the wetlands line. The former development scheme minimizes water quantity impacts, but may cause water quality impacts. The latter scheme will impact water quantity, but storm water system may minimize water quality impacts.

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106 those wetlands/water resources that are waterward of the construction line. While precautions might be taken, such as installation of barriers to impede and/or filter silt laden runoff, there is no assurance that the precautions will be effective or that they will remain in place long enough for the area to stabilize. Degradation of water quality as a result of construction and long-term runoff from developed lands may be easily avoided by providing a construction setback or buffer that can act as a sediment trap, dissipate destructive velocities, and minimize water quality problems through filtration of surface runoff. Water Quantity Issues. Criteria in 40C-4, 40C-41, and 40C-42 related to water quantity are generally concerned with recharge of groundwaters in areas of significant recharge potential and with surface runoff patterns. Not protected and of special significance in river systems like the Wekiva are seepage at the base of sandy slopes that maintain saturated soils and standing and flowing surface waters at seepage locations. Shown in Figure IV.3 are the groundwater relationships of the sandy, welldrained ridges along the upland fringes of the Wekiva floodplain and the seepage areas at their bases. It is at these seeps that groundwaters become surface waters and contribute base flow to the Wekiva. In the natural condition waters exiting at the seepage edge are typically low in nutrient content, having recharged through the sparse scrub vegetation of the sandhills and filtered through several hundred (or thousand) feet of well-washed sand. Upon exit from the soil, the newly emerged surface waters support a unique assemblage of vegetation (often referred to as a hydric hammock) adapted to constant saturation and periodic inundation with oligotrophic waters. The wetland line typically coincides or is just landward of these areas.

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Figure IV.2. Cross section drawing of the floodplain and adjacent uplands showing the natural condition in the upper drawing, and the consequences of clearing and development in the bottom drawing. 107

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108 The bottom drawing in Figure IV.3 summarizes the effects of excavations 1n the area immediately landward of the wetland line on the quantity of seepage water exiting in downslope locations. Where excavations are deep and interrupt groundwater flows, seepage areas are "robbed" of sustaining groundwaters, as they are routed through the stormwater management system and discharged at outfall points, or are exposed to surface evaporation in water retention/detention systems. The net effect on total quantity of water that may leave a project site when the effects of increased impervious surfaces and the stormwater management systems are factored in is not easily determined. However, it is quite apparent that the loss of seepage waters will significantly alter species composition in seepage wetlands and have potential consequences on dry season base flows of the Wekiva. Potential consequences of lowered water tables and intercepted groundwater flow to downstream hydric hammocks and floodplain forests can be mitigated through implementation of a buffer zone requirement in the Wekiva Basin. While its function will be to insure high groundwater elevations in close proximity to seepage wetlands, it may also serve a role in insuring maintenance of high water quality.

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Figure IV.3. Cross section drawing of the floodplain and adjacent uplands showing the natural condition in the upper drawing, and the effects of construction of drainage ditches or retention/detention structures in close proximity to the wetlands edge on groundwater table. 109

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V. DETERMINATION OF BUFFER ZONE REQUIREMENTS Given in this section is a description and rationale for the methodology for determining buffer zone requirements. The need for a buffer zone to effectively protect the special values of the water resources of the Wekiva Basin is based on three potential impacts of the construction, maintenance, and operation of works. They are related to impacts on water quality that result from construction and long-term use, impacts that may result from alterations of groundwater tables, and impacts on aquatic and wetland-dependent wildlife habitat. This section is organized into three parts. First an overview of the methodology is presented that discusses the parameters that control the determination of a buffer zone width. Second, methods for the determination of buffer zones are given, with formulae where appropriate. Finally, sample sections of the Wekiva River and Black Water Creek are used to describe each of the controlling parameters and to display the resulting buffer widths. V.A. Overview of the Methodology for Determination of Buffer Zones Four factors are used to determine the width of buffer zones to protect the water resources of the Wekiva River System. The four factors are (1) the Water Management District wetland line (40C-4 FAC) (2) the erodibility of soils in the zone immediately upland of the wetland line, (3) the depth of the groundwater table below the soil surface in the zone immediately upland of the wetland line, and (4) the habitat requirements of aquatic and wetlanddependent wildlife species. 111

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112 Because of the detailed nature of the data required to determine the need for and extent of upland buffers, determinations must be made on a case-by-case basis. However, in the final part of this section we have included maps and figures of the relevant data for a typical sections of the river system to illustrate the methodology's application. Controlling Parameters The parameters that control the width of the required buffer are related to the need to protect water quality and quantity and aquatic and wetlanddependent wildlife, both during and following construction of any development project in areas immediately adjacent to the floodplains of the Wekiva River System. It is important that construction and operation are considered simultaneously, since a project cannot be operated unless it is built, nor is it realistic to aSSume that it will not be operated should it be built. The descriptions and rationale for the following parameters reflect this important integration. Some parameters result from the need for protective measures during construction, others from the need for measures after construction, and still others result from both. (1) 40C-4 Wetland line. The wetland line is the landward extent of wetlands using the methodology outlined in 40C-4 (FAC) and Chapter 16 of the Applicant's Handbook. The determination is made by District staff using dominant vegetation, soils, and other indicators of wetland conditions. The line so determined in most cases is the same as the jurisdictional line set by the Florida Department of Environmental Regulation (17-4 FAC) for demarcation of the landward extent of state waters. The wetland line defines the waterward boundary of the area for which buffer zone requirements are to be determined.

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113 (2) Soil Erodibility. Soil erodibility is a function of slope and soil type. Used in combination, both factors determine the potential for soil erosion and subsequent sedimentation in downslope areas. (a) Slope. Ground surface slope is expressed as percent slope and is determined by measuring the change in elevation over a distance of 300 ft landward of the wetland line. The slope is an indicator of the erosion potential of soils during and immediately following construction activities and/or site preparation. The steeper the slope, the greater the potential for soils to be eroded by surface runoff during rainevents. (b) Soil Type. The soil type may be determined by consulting the USDA SCS Soil Survey for the county in which the development project is located, or it may be determined in the field by a qualified soil scientist. Highly erodible soils in combination with steep slopes dictate severe limitations on removal of vegetative cover; gentle slopes with highly erodible soils or steep slopes with minimally erodible soils dictate moderate limitations; and gentle slopes with minimally erodible soils dictate slight limitations. A formula is used to calculate the exact buffer requirement (see Section V .B). (3) Depth to Water Table. The depth to the groundwater table in areas immediately upland of the wetland line is an important indicator of groundwater interaction with downslope wetlands. Where the water table is near the surface and slopes toward the wetland, the area is dominated by discharging groundwaters, and a buffer to avoid drainage of the wetlands is warranted. The depth to the groundwater table may be determined by field measurements (although it should be understood that one measurement at one point in time does not give a true picture of average year-to-year, season-to-season

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114 conditions) or through field determination of soil type and interpretation of county soil survey data. Excavations in areas where the water table is near the surface in the zone immediately upslope from seepage wetlands (i.e., where the hydraulic gradient is toward the wetland area) intercept groundwater flows and have the potential to drain wetlands on the downslope side of the excavations. Where these are present, a setback is warranted to insure that proposed development activities do not diminish the quantity of water entering the downslope wetlands. (4) Wildlife Habitat Requirements. The old adage that an ounce of prevention is worth a pound of cure is particularly appropriate to wildlife conservation. Loss of habitat is the greatest threat to many of Florida's wildlife species. One approach to alleviating this threat would be to monitor each species and to take protective action if it is determined that any given species is declining. This approach is risky in that such a determination may be made too late to reverse the decline. Another approach would be to prevent any change in the amount of habitat available to each species, but this is neither practical nor possible. It is better to formulate a general method to accommodate the wildlife of a given region as a whole. The practical solution, then, is to determine the amount of harm that is acceptable and to prevent it from increasing. By far, the most common cause of wildlife population reduction is landscape alteration through agriculture, silviculture, or construction activities. Altering or changing natural conditions to which species are adapted often harms native wildlife communities by destroying key conditions that make a given site suitable habitat. An obvious example is the removal of snags (dead trees) that are essential nesting structures, food sources, and

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115 perches for many birds, mammals, reptiles, and amphibians. A common misconception is that no harm is done because there are plenty of other undeveloped areas containing the same requirements. On the contrary, other areas that have the necessary elements for a particular species are probably already occupied at a saturation level, leaving no rOom for individuals that are ousted by development occurring elsewhere. Therefore, the most effective method of protecting wildlife resources in the Wekiva River Basin would be to preserve areas in their most natural conditions and in large enough parcels so that self-sustaining populations can be maintained. Buffer requirements to protect aquatic and wetland-dependent wildlife species are related to four factors: habitat suitability; spatial requirements; access to upland and/or transitional habitat; and noise impacts on feeding, breeding, and other life functions. Wetland-dependent species are those which depend on wetland communities for at least some of their essential requirements. (a) Habitat Suitability. Food, cover, and water are life-sustaining elements for all species. If every requirement for an animal is available in a particular area, the area is considered to be suitable habitat for that species; if one or more of a species' requirements is not available, the area is unsuitable. Some species are extremely specialized. For example, the Everglades or snail kite has an exclusive diet of only one snail species, Pomus depressus. Others, such as the raccoon, are generalists and can readily substitute many items to fulfill their needs. Several methods have been developed recently to determine if sites are suitable for a given species. These methods are based on availability of food, cover and water requirements, and various parameter measurements have been

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116 shown to be associated with these requirements. Examples of the parameters used for this report are tree canopy closure and tree height. (b) Spatial Requirement. Every animal requires a certain amount of space to carry out life functions such as feeding, courtship, and nesting. Spatial needs are highly variable, even within species. Differences are associated with many factors, including sex and age of the animal, time of year, availability and distribution of food and cover, and social structures. In general, larger species tend to have greater spatial requirements. Obvious comparisons are the black bear versus the cotton mouse and the red-shouldered hawk versus the mockingbird. Also, species with more unpredictable and unevenly distributed food sources require more space to satisfy their nutritional needs. For example, marsh rabbits have small spa.tial requirements relative to their size because they eat grasses and forbs which are plentiful within small areas. Conversely, gray squirrels need relatively larger territories to find mast, which is unevenly distributed. It should be realized that the .Wekiva River acts as a border to many species living in the river basin. Even those that can swim or fly across the river are affected by the impacts of increased predation and disturbance factors associated with the edge ecotone created at the water/forest interface. Because many forest-dwelling, wetland wildlife species utilize more than one habitat type, their spatial requirements can often be satisfied even if a portion of the forested area does not fit the definition of a wetland community but does fulfill other habitat suitability criteria. In most cases, areas immediately landward of the wetland line that are cleared for agriculture or silviculture or which are planted in monocultural pine plantations will not be suitable habitat for wetland-dependent species. Where these situations occur, buffer zone requirements are not as sensitive to wildlife considerations as

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117 they might be if the area had a continuous, relatively natural, forest canopy. For this reason, it is essential that serious consideration be given to whether or not agriculture and silviculture should be exempt from buffer zone requirements where the protection of aquatic and wetland-dependent wildlife species is of particular importance. Although it is difficult to rationalize the use of wildlife considerations when the canopy has been removed, mitigation of previous adverse impacts on wildlife could be addressed by replanting the would-be buffer zone (determined by the application of the other factors) with native tree species to reestablish wildlife values. (c) Access to Upland or Transitional Habitat. Several wetland-dependent wildlife species must have access to upland or transitional habitat regardless of the landward extent of the wetlands. For example, many semiaquatic turtles need sandy and relatively warm upland sites to lay eggs. Elimination of such habitats could extirpate numerous wetland-dependent species from the Wekiva River Basin. (d) Noise Impacts. Noise can interfere with signals and directly affect wildlife behavior. Many species rely on vocalizations for warnings, mate recognition, detection of separated young, and to establish territorial boundaries. Background noise can interfere with these vocalizations and cause direct reductions in populations or dispersal to less noisy areas. Sudden loud noises can disturb or harass some individuals and cause harmful stress which affects reproduction and other life functions. To protect aquatic and wetland-dependent species from noise interference, buffer zones between the point of noise generation and the habitat are warranted. The distance of buffer necessary for protection from noise is related to both the level of noise and the space through which the noise

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118 passes. Dense vegetation diminishes the level of noise more quickly than open ground; pavement tends to propagate noise better than vegetated grasslands. The required buffer depends upon the characteristics of the intervening area. V.B. Determining Buffer Zone Requirements The order in which each of the four parameters is calculated or measured is important. The 40C-4 wetland line must be determined first, since all determinations are based on the 'establishment of this line as the waterward boundary of the buffer zone. Once the wetland line is established, the order in which the remaining parameters are determined is of little consequence. Since the requirements for a buffer zone depend on a dynamic landscape where the relationships between the controlling variables are not constant, each of the parameters must be calculated. The spatial frequency at which the calculations are made (i.e., how often the buffer zone lines need to be determined along the waterward edge of a proposed development) depends on the variation in the measured parameters. If there is no reason to believe the parameters and their relationships to each other are different along the entire length of the water-ward edge of the proposed development, each parameter needs to be determined only once. However, if the parameters appear to change significantly, more determinations are necessary. The exact number of determinations is a function of the relative changes in slope, soil type, water table elevation, and forest canopy and vegetative structure. In most cases, estimates of the relative changes in parameters can be made using topographic and soils maps and aerial photographs. Final buffer zone widths are set by determining the controlling parameter, i.e., the parameter that results in the widest buffer zone. The following

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119 paragraphs detail methods for determining buffer widths based on each of three parameters (water quality, water quantity, and wildlife habitat suitability). (1) 40C-4 Wetland line. The wetland line is determined using the methodology outlined in Part III, Section 16 of the Applicants Handbook. (2) Water Quality Maintenance. The requirement for a buffer zone for maintenance of water quality is related to the filtering capacity and roughness of natural undisturbed vegetation to minimize inputs of sediments and destructive velocity of waters. The potential for erosion and subsequent sedimentation is a function of the erodibility of soil and slope. The velocity of water varies as the square root of slope (Manning's formula), and the potential for a particle of soil to be moved is a function of erodibility and velocity of water over the surface. Thus a simple relationship of slope and e,odibility may be used to determine buffer widths as follows: where: Bw = Sl/2 E Bw = the width of the buffer in ft; S = average slope of the land in ft per 100 ft; and (1) E = erodibility factor; use 4 for soils with SCS erosion factors (k) of 0.1, use 3 for soils with k = 0.15, use 2 for soils with k = 0.17, and 1 for soils with k> 0.17. using Equation I, the required buffer for an average slope of 3% and soils with low erodibility factor (E = 4) would be 43 ft. The buffer required for soils with the same slope and erodibility factors of 3 and 2 are 57 ft and 87 ft, respectively. Table V.l lists pertinent soil properties for many soil types found in and adjacent to wetlands in the Wekiva River System. It highlights some of the important constraints likely to be encountered within the Basin. The second column lists k factors (erosion factors) that can be used in determining the erodibility factor.

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120 Table V. 1. Soil properties and interpretation. K Depth t0 2 Limitations 2 Soil type Erosion 1 W. Table Group S.Tank Bldg. Excav. Albany sand, 0-5%1 .10 15-40" C M M M Anclote fine sand .10 0-10" 0 S S S Anclote & Myakka .10 0-10" 0 S S S Astatula sand, dark, 0-5% .10 >120" A Sl Sl M Blanton fine sand, high, 0_5%3 .17-.28 18-30" A Sl Sl S Blanton fine sand, low, 0_5%3 .17-.28 1B-30" A M M S Cassia sand .10 10-40" C S S S Delray fine sand3 .15 +12-0" AID S S S Delray fine sand, NA 0 NA VP IN Delray fine sand, high .15 0-12" AID S S S Emeralda fine .10 0 0 S S S relda fine sand 3 .17-.28 0-12" BID S S S Immokalee fine sand .17-.20 0-12" AID S S S Iberia & .10-.28 0 0 S S S Immokalee sand .17-.20 0-12" AID S S S Leon fine sand3 .17-.20 0-12" AID S S S Leon fine sand, 0_2%3 .17-.20 0-12" AID S S S Myakka sand .10 0-10" 0 S S S Myakka & Placid sands, 2-8% .10 0-10" 0 S S S Ocilla sand .10 40-60" C M M M Paola sand, 0-5% .10 >80" A Sl Sl Sl Plummer fine .17-.28 0-12" AID S S S Pomello fine sand .17-.20 12-30" A M Sl S Pomello fine sand, 0_5%3 .17-.20 12-30" A M Sl S Pomello sand .10 30-40" C M M M Pompano fine sand3 .15 0-12" AIO S S S Pompano fine sand, shallow phase .10 0 0 VP IN Placid sand .10 0 0 S S S Pompano fine sand3 3 .15 0-12" AIO S S S Sandy alluvial land S S S Swamp .10 +24"-0 0 +S +S +S Tavares sand .10 40-60" C Sl Sl M Tavares sand, white subsurf. .10 40-60" C Sl M M Wabasso sand .10 0-10" 0 S S S Wauchula sand .10 0-10" 0 S S S

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Table V. 1. Continued. (footnotes) 1K Erosion is a measure of the rate at which a soil will erode. Values are expressed as tons of soil loss per acre per unit of R (rainfall factor) from continuous fallow on a 9% slope 73 feet long. Hydrologic Group is a relative index of runoff rate. A = low runoff potential, B = moderately low runoff potential, C = moderately high runoff potential, and 0 = high runoff potential. When two letters are given, the first applies to the drained condition while the second applies to the natural condition. Source for K factors and hydrologic groups, unless otherwise noted: U.S. Soil Conservation Service Soil Interpretation Sheets (provided by SCS office in Gainesville, Florida, September 1987) for lake, Orange, and Seminole counties. 2 Oepth to water table = depth to seasonally high water table. The range reflects yearto-year variation. Standing water above the soil surface is indicated by a "-". limitations apply to septic tank drainage fields, dwellings without basements or foundations for low buildings, and shallow excavations (ponds or below-ground basements). Sources for depth to water table and limitations are the Soil Survey of Orange County, Florida (1960), Soil Survey of Seminole County, Florida (1966), or Soil Survey of lake County Area, Florida (1975) except where otherwise noted. 51 = slight, M = moderate, 5 = severe, and _5 = very severe. The Orange County Soil Survey does not include a rating for building suitability. Ratings for septic tank drainage fields range from very poor (VP) to poor (P) to fair (F) to good (G). It does not rate soils for excavated ponds, but only describes the elevation [high (H) or medium (ME)], shallow water table (SH), or inundated (IN). 3 Source: Soil Survey Supplement, Seminole County, Florida (1975). 121

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122 The above formula is included as a means of providing a framework from which hydrologists, soil scientists, and engineers working in conjunction might develop nomographs or equations better suited for the conditions encountered in the Wekiva River Basin. A derivation of the Universal Soil Loss Equation, while requiring very specific information, may be a better means of determining buffer zone widths for protection of water quality if an allowable field soil loss can be established, although any soil erosion has the potential to cause disruption of downstream waters and wetlands. Without the detailed analysis required by the more sophisticated methodologies, the above equation is given as an example for determining the buffer requirements for protection of water quality. (3) Water Quantity Maintenance. The buffer width required for protecting water quantity is related to the drainage impacts of lowered water tables on adjacent wetlands. The lowering of groundwater tables is accomplished through drainage structures that cause transient groundwater flows toward the structure in the upper portions of the shallow aquifer (water table aquifer). The effect of water table drawdown diminishes with distance from the structure. Current regulations of the District allow an average drawdown of 3 ft throughout a development project, with no one area having a drawdown greater than 5 ft. The width of the buffer depends on the drawdown anticipated as a result of the drainage structures and the hydraulic conductivity of the soil. Using a design drawdown (depth to which groundwaters are to be lowered) in the vicinity of a structure, the buffer required to minimize drawdown effects on adjacent wetlands can be calculated using a derivation of the Theis equation as follows: ho -h = (2.3 Q/4 p. K D)(log [2.25 T t/r2 nl) (2) and substituting: Q = K sOL (3)

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and t = 4 D n/pi K s2 (4) where: ho -h = Q = D = L = K = s = T = t = S = r = acceptable drawdown at wetlands edge taken as 0.25 ft. discharge depth of ditch or basin length of ditch or basin hydraulic conductivity, taken as 10 ft/day slope of water table surface K x depth of ditch time in days coefficient of storage, taken as 0.2 distance radially from ditch or basin n = porosity. 123 Equation 2 may be simplified and rearranged to solve for the distance, r, where the drawdown will be equal to 0.25 ft in terms of the length, L, of ditch or basin. Substituting the buffer width, B w for the distance, r, the equation then stated as follows: Bw = (1.69D/S)(10-[1.3/SL]) (5) The solution of Equation 5 is trivial for very small ditch lengths. The assumption is made that a drawdown of 0.25 ft at the wetland edge is acceptable. The buffer distances for drawdowns of 1, 2, 3, and 5 ft with a ditch length of 300 ft are 78, 156, 235, and 392 ft, respectively. Determining drawdowns in unconfined water table aquifers where conditions vary from one site to the next is a very complex task, and the methodology presented here is likely to be controversial. Be that as it may, the above formula may be used to determine a buffer width based on gross assumptions concerning such factors as hydraulic conductivity and coefficient of storage, among others. It is a much simplified version of much more complex relationships. Without a detailed analysis of the conditions and soils characteristic of the Wekiva Basin--which are beyond the scope of this report--the simplified relationships expressed in Equation 2 may be used as guides to

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124 determine effective setbacks to minimize drawdown effects. The authors suggest that groundwater hydrologists, engineers and ecologists be consulted to better define parameters more precisely and to formulate an acceptable methodology for determining drawdown effects. (4) Maintaining Habitat Suitability Specific quantitative data are not currently available for all of the wildlife species in the Wekiva River Basin. However, we were able to obtain information on several of the more sensitive forest-dwelling wetland-dependent species which would be adversely affected by landscape alterations (Table V.2). Areas that are suitable for these species would, of course, also be suitable for less sensitive species. The following are minimum standards that are required for an area to be considered suitable for a full spectrum of wildlife along the Wekiva River. 1. Tree canopy height greater than 50 ft; 2. Tree canopy greater than 70%; 3. Average tree. crown diameter greater than 15 ft; 4. More than 3 trees of at least 20 inches dbh/ac; 5. More than 0.1 snags greater than 20 inches dbh/ac; 6. Average shrub height greater than 2 ft but less than 15 ft; and 7. Shrub canopy closure greater than 70%. (a) Calculating Spatial Requirements. The amount of suitable contiguous habitat required to support at least one individual of most species living in the Wekiva River Basin is a circular area of 5.17 ac (diameter = 536 ft). This was derived by combining information from several references (see Table V.2). First of all, many forest interior songbirds do not live in plots smaller than 1 ac (diameter = 236 ft). Other data suggest that individuals found in some of the smallest plots were probably living in stressful and unhealthy environments. Negative edge effects have been shown to affect species within 300 ft of forest boundaries. Ideally then, the minimum diameter

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Table V.2. Minimum habitat suitability and spatial requirements of some of the most sensitive wetland dependent wildlife species in the Wekiva River Basin. Species Florida cooter and other 1 aquatic turtles 2 wood stork Pileated 3 4 woodpecker hawk Song birds4,5,8,9 10 Indlgo snake Habitat Types aquatic, all wetlands, sandy uplands cypress swamps, shallow fresh water all forested wetlands all forested wetlands Minimum Habitat Suitability uplands for nesting, water for food large cypress trees for nesting, water for food -tree canopy closure > 25% -> 3 trees of at least 20 in. dbh/acre -> 0.1 snags (>20 in. dbh)/acre -tree canopy height > 17.7 m -tree canopy closure > 70% -avg. tree crown diam. > 8 m -shrub canopy closure > 20% -avg. shrub ht. > 0.5 m but < 5.0 m wetlands for most of the year but gopher tortoise burrows in winter Minimum Spatial Requirements in Suitable Habitat Areas Distance Upland from Total Width River Edge of Timber Including River (50 ft of uplands) 197 ft 795 ft 236 ft 300 ft from large cypress trees 4,221 ft 2,606 ft (300 ft of uplands) ,... N '"

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Table V.2 (page 2 of 2) lWeller, M.W. 1978. Management of Freshwater Marshes for Wildlife. Pages 276-84 in R.E. Good, D.F. Whigham, and R.L. Simpson (eds.), Freshwater Wetlands: Ecological Processes and Management Potential. New York, NY: Academy Press. 2palmer, R.S. Flamingos. 1962. Handbook of North American Birds: Volume 1, Loons through Yale University Press, New Haven. 567 pp. 3Schroeder, R.L. 1983. Habitat suitability index models: U.S. Dept. Int., Fish. wildl. Servo FWS/OBS-82/10.39. Pileated woodpecker. 15 pp. 4Tassone, J.F. 1981. Utility of Hardwood Leave Strips for Breeding Birds in Virginia's Central piedmont. MS Thesis. Blacksburg, VA: Virginia Polytechnic Institute and State College, 83 pp. 5Galli, A.E., C.F. Leck, and R.T.T. Forman. 1976. Avian distribution patterns in forest islands of different sizes in central New Jersey. Auk 93:356-64. 6Bryant, A.A. 1986. Influence of selective logging on red-shouldered hawks, Buteo lineatus, in Waterloo Region, Ontario, 1953-1978. Canadian Field 100(4):520-25. 7Bednarz, J.C. and J.J. Dinsmore. 1982. Nest-sites and habitat of redshouldered and red-tailed hawks in Iowa. Wilson Bull. 94(1):31-45. 8Sousa, P.J. 1982. Habitat suitability index models: Veery. U.S. Dept. Int., Fish. Wildl. Servo FWS/OBS-82/10.22. 12 pp. 9remple, S.A. 1986. predicting impacts of habitat fragmentation on forest birds: A comparison of two models. Pages 301-04 in J. Verner, M.L. Morrison and C.J. Ralph (eds.), Wildlife 2000: Modeling Habitat Relationships of Terrestrial Vertebrates. Madison, WI: The University of Wisconsin Press. 10Speake, D.W., J.A. McGlincy, and T.R. Colvin. 1978. Ecology and management of the eastern indigo snake in Georgia: A progress report. Pages 64-73 in R.R. Odum and L. Landers (eds.), Proceedings of the Rare and Endangered Wildlife Symposium, Aug. 3-4, 1978. Georgia Dept. Nat. Res. Tech. Bull. WL 4. ,... N a-

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127 of a stress-free suitable habitat area should be 836 ft (300 ft + 236 ft + 300 ft). However, it is assumed that edge effects along the river are not as severe as those along the uplands, and the average of 236 flnd 836 (536 ft) is recommended as the minimum width necessary to prevent harmful effects of development on individual wetland-dependent animals. Self-sustaining populations require suitable areas many times larger. Their spatial needs can be easily satisfied by protecting a minimum width of 536 ft of suitable habitat landward from the edge of the forest along both sides of the river. In some situations, the wetland area will be sufficient and no upland buffer is needed to fulfill this requirement. Where wetlands are relatively narrow but forest canopy continues into the uplands, an upland buffer will be needed. Although some large species such as the hawk need correspondingly wider areas, it is our opinion that the requirements of these low-density nesting birds are satisfied by the large wetland areas within the existing designated wetlands along the Wekiva River. The 536-foot width is believed to be sufficient contiguous habitat to satisfy corridor requirements of large mammals such as black bear, river otter, and bobcat. (b) Calculating Necessary Access to Uplands or Transitional Habitat. Enough upland or transitional habitat must be preserved adjacent to the wetlands so that semiaquatic turtles can find suitable safe areas to lay their eggs. Although a narrow upland strip of sandy soil would provide the necessary substrate, nests constructed in this type of environment would be subjected to high predation rates associated with edges. A minimum 50-foot upland buffer along the entire length of the river is recommended for turtles. Areas where gopher tortoises are present within 300 ft of the adjacent wetlands should be protected so indigo snakes in the wetlands can continue

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128 their seasonal movements into upland gopher tortoise burrows. In these situations, the buffer should include the entire gopher tortoise area. (c) Calculating Buffers for Noise Impacts. The effects of noise on wildlife breeding, feeding, and territorial protection is not completely understood, although data suggest that noise more than human presence that drives wildlife from areas surrounding developed land. A simple method proposed by Brown (1981) for determining buffer sizes necessary to attenuate highway noise to acceptable levels was to utilizes forested areas to reduce noise levels to background levels. Using the following equation,3 noise level at the source can be related to vegetation of the buffer zone to determine buffer width necessary to reduce noise levels to background (40 dBA). where: Bw = In (40/Ni)/-Ac (6) Bw = Ac = N' 1 = buffer width in ft attenuation coefficient. Use .002 for paved buffer, .0037 for nonforested buffer, and .0053 for heavily forested buffer noise level of source. Use 50 dBA for residential areas, 60 dBA for nonarterial general traffic, 70 dBA arterial traffic, and 70 dBA for commercial areas The required buffers to reduce average residential noise levels (50 dBA) to background (40 dBA) is 60 ft when the buffer is cleared or 42 ft when the buffer is forested. V.C. Illustration of Buffer Zone Determinations Given in this section are several maps of portions of the Wekiva River Basin and Black Water Creek Basin depicting relevant information and highlighting examples of buffer width determinations for controlling 3 The equation is derived from data presented in several studies (Eyring 1946, Weiner and Keast 1959, Embleton 1963, and a summary by Robinette 1972).

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129 parameters. The information shown on each of the maps has been derived from aerial photographs, USDA SCS soil surveys, and USGS topographic maps. The scale of the original information determines the resolution at which buffer widths can be graphically depicted. As a result, the resolution of these maps is not sufficient to locate buffer requirements accurately at a scale that is suitable for actual determinations. Instead, maps and data should be compiled at a scale of about I" = 100 ft, or possibly 1" = 200 ft, to render the zone in which buffer determinations are to be made in sufficient detail. The areas chosen for these illustrations were selected because of the variety of conditions that are illustrated within relatively small geographic locales. Whether these areas can ultimately be developed was not taken into consideration, so to the astute observer, it may be obvious that portions of the areas are in state ownership. No attempt has been made to single out these areas for any purpose other than for their illustrative value. Tables V.3, V.4, and V.5 list ranges of buffer widths generated using the above equations and a given set of parameter values. It is important to note that there is an infinite range of buffer widths and that the values shown are only representative possibilities. The variables. in the equations are to be determined in the field on a site-by-site basis. (1) 40C-4 Wetland Line. Given in Maps V.1 and V.6 are simplified vegetation maps to show the forest canopy and wetland line. The wetland line was drawn from interpretation of aerial photographs and is an estimate of the line that would be determined using field verification of the dominance of wetland vegetation (2) Wildlife Habitat Suitability. Also shown on Maps V.1 and V.6 are the three habitat buffer zones. When forest canopy is absent, the buffer zone resulting from spatial requirements of wildlife is not determined and is only

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130 shown when the wetland line is waterward of the necessary 536 ft. The transitional habitat buffer is shown as a SO-foot zone landward of the wetland line, and the noise attenuation buffer is drawn based on the vegetative characteristics of the intervening area between the habitat line and the area reserved for development. The most landward line is then drawn as the wildlife buffer. (3) Water Quality Buffer. Shown on Maps V.2, V.3, V.7, and V.8 are slope and generalized soil characteristics derived from SCS soil surveys that are used in calculating buffer zone requirements to minimize erosion and sedimentation. The indicated buffer zone requirement is a function of the erodibility of the soil and slope of the ground surface in the area immediately landward of the wetland line. Where two or more soil types occur along the 300-foot survey swath, either the dominant type was used or an average value was taken if the soils were evenly distributed. (4) Water Quantity Buffer. Shown on Maps V.4 and V.9 are generalized water table characteristics that are used to determine the buffer zone required to minimize adverse impacts from water table drawdown. A design drawdown of 3 ft was used to calculate buffer zone requirements. The assumption was made that if water table elevations were between 0" and 12", then a full drawdown of 3 ft was necessary. In like manner, if the water table elevation was between 12" and 24" or between 24" and 36", the drawdown was taken as 2 ftand 1 foot, respectively. (5) Composite Buffer. Given in Maps V.5 and V.lO are the composites derived by taking the most landward buffer boundary determined by each of the four controlling parameters.

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Table V.3. Sample buffer widths (ft) determined by water quality criteria (refer to Equation 1, Section V.B.2) Erodibility* Slope % ** 1 2 3 4 3.9 198 99 66 49 6.9 263 131 88 67 7.9 281 140 94 70 10.0 316 158 105 79 Erodibility factors are interpreted as follows: 131 1) Most erodible soils (K > 0.17) or no. 2 soils with no vegetative cover. 2) Soils with (K = 0.17) conditions or medium soils (3) with no vegetation. 3) Medium erodibility (K = 0.15) or good soils (4) with no vegetative cover. 4) Good soils (K = 0.10) with vegetative cover. ** Numbers shown represent upper limits of slope categories.

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132 Table V.4. Sample buffer widths (ft) determined by water quantity criteria (refer to Equation 5, Section V.B.3) Drawdown (ft) Slope % '* 1 2 3 5 3.9 56 112 168 280 6.9 28 57 85 142 7.9 24 49 73 121 10.0 19 37 56 93 Numbers shown represent upper limits of slope categories. The slope of the groundwater table was assumed to equal that of the ground surface in the area immediately adjacent to the wetland line.

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Table V.5. Sample buffer widths (ft) determined by noise attenuation criteria (refer to Equation 6, Section V.B.4) Noise Level (dBA) Buffer Type 50 60 70 Canopy 42 76 105 No Canopy 60 110 151 Paved 112 203 280 133

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LITERATURE CITED Allen, D.L. 1962. Our Wildlife Legacy. New York, NY: Funk and Wagnalls. Ames, D.R. 1978. Physiological responses to auditory stimuli. J.L. Fletcher and R.G. Busnell (eds.), Effects of noise on wildlife. New York: Academic Press. Arrhenius, o. 1921. Species and Area. J. Ecol. 9: 95-99. Bailey, T.N. Marsh. 1971. Biology of Striped Skunks on a Southwestern Lake Erie J. Wildl. Manage. 85: 196-207. Batzli, G.O. 1977. Population Dynamics of the White-Footed Mouse in Floodplain and Upland Forests. Amer. MidI. Natl. 97(1): 18-32. Beck, A.A. 1973. The Ecology of Stray Dogs: a Study of Free-Ranging Urban Animals. Baltimore, MD: York Press, 98 pp. Beecher, W.J. 1942. Nesting Birds and Vegetative Substrate. Chicago, IL: Chicago Ornithol. Soc. Beeler, I.E., and T.J. O'Shea. 1987. Distribution and Mortality of the West Indian Manatee (Trichechus manatus) in the Southeastern United States: A Compilation and Review of Recent Information. Vol. 1: The Atlantic Coast. U.S. Fish and Wildlife Service Contract Report, Contract /114-16-0009-861815. Prepared for the U.S. Army Corps of Engineers, Jacksonville District. 328 pp. Bider, J.R. 1968. Animal Activity in Uncontrolled Terrestrial Communities as Determined by a Sand Transect Technique. Ecol. Monogr. 38: 269-308. Bloom, A.L. 1983. Sea Level and Coastal Morphology of the United States Through the Late Wisconsin Glacial Maximum. Pages 215-219 in Late Quaternary Environments of the United States, Vol I: The Pleistocene (S.C. Porter, ed.). University of Minnesota Press, Minneapolis. Borman, F.H., G.E. Likens, D. W. Fisher, and R.S. Pierce. 1968. Nutrient Loss Science 159: 882-884. Acceleration by Clearcutting of a Forest Ecosystem. Bradt, G.W. 1949. Farm Cat as Predator. Michigan Conserv. 18: 23-25. Bratton, S.P., and P.S. White. 1980. Rare Plant Management--After Preservation What? Rhodora 82: 49-75. Brittingham, M.C., and S.A. Temple. 1983. Have Cowbirds Caused Forest Songbirds to Decline? BioScience 33: 31-35. Brown, M.T. 1981. The Use of Planted Pines for Highway Noise Reduction. Working Paper. Gainesville, FL: Center for Wetlands, Univ of FL. 145

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146 Brown, M.T. 1986. Cumulative Impacts in Landscapes Dominated by Humanity. Pages 33-50 in E.D. Estevez, J. Miller, J. Morris, and R. Hamman (eds.), Managing Cumulative Effects in Florida Wetlands: Conference Proceedings. New College Environmental Studies Program Publication No. 37 (Sarasota, FL). Madison, WI: Ominipress. (CFW-86-09.) Brown, M.T., G.R. Best, B. Coggins, C. Diamond, B. Dunn, F. Gross, J. Sendzimir, P. Straub, M. Sullivan, R. Tighe, and P. Wallace. 1984. Development of Techniques and Guidelines for Reclamation of Phosphate Mined Lands as Diverse Landscapes and Complete Hydrologic Units. First Annual Report to Florida Institute of Phosphate Research, Bartow, FL. Gainesville, FL: Center for Wetlands, Univ of FL, pp. 51. (CFW-84-07.) Brown, M.T., G.R. Best, M. Davis, F. Gross, R. Hassoun, H. Riekerk, P. Straub, M. Sullivan, and W.T.S. Swank. 1985. Development of Techniques and Guidelines for Reclamation of Phosphate Mined Lands as Diverse Landscapes and Complete Hydrologic Units. Second Annual Report to Florida Institute of Phosphate Research, Bartow, FL. Gainesville, FL: Center for Wetlands, Univ of FL, pp. 184. (CFW-85-04.) Brown, M.T., G.R. Best, H. Riekerk, M. Davis, F. Gross, M. Sullivan, R. Tighe, and S. Roguski. 1986. Development of Techniques and Guidelines for Reclamatiori of Phosphate Mined Lands as Diverse Landscapes and Complete Hydrologic Units. Preliminary Third Annual Report to Florida Institute of Phosphate Research, Bartow, FL. Gainesville, FL: Center for Wetlands, Univ of FL, pp. 92. (CFW-86-08.) Brown, M.T., and E.M. Starnes (with C. Diamond, B. Dunn, P. McKay, M. Noonan, S. Schreiber, J. Sendzimer, S. Thompson, and B. Tighe). 1983. A Wetlands Study of Seminole County. Center for Wetlands and Department of Urban and Regional Planning, University of Florida, Gainesville. Technical Report 41. iv + 284 pp. Browne, K.W., and Associates. 1980 An Assessment of the Impact of Septic Leach Fields, Home Fertifications, and Agricultural Activities on Groundwater Quality. Final Report to the New Jersey Pinelands Commission. Bull, A.L., C.J. Meade, and K. Williamson. in Relation to Agricultural Changes. 1976. Bird-Life on a Norfolk Farm Bird Study 23: 163-82. Burt, W.H. and R.P. Grossenheider. 1964. A Field Guide to the Mammals. Boston, MA: Houghton Mifflin Co., 284 pp. Butcher, G.S., W.A. Niering, W.J. Barry, and R.H. Goodwin. 1981. Equilibrium Biogeography and the Size of Nature Preserves: An Avian Case Study. Oecologia 49: 29-37. Chanin, P.R.F., and D.J. Jefferies. 1978. The Decline of the Otter (Lutra lutra L.) in Britain: An Analysis of Hunting Records and Discussions of Causes. BioI. J. Linn. Soc. 10: 305-28. Clewell, A.F., J.A. Goolsby, and A.G. Shuey. South Prong Alafia River System, Florida. 1982. Riverine Forests of the Wetlands 2: 21-72.

PAGE 139

147 Conner, R.N., R.G. Hooper, H.S. Crawford, and H.S. Mosby. 1975. Woodpecker Nesting Habitat in Cut and Uncut Woodlands in Virginia. J. Wildl. Manage. 39(1): 144-50. Corbett, R.L., R.L. Marchinton, and C.E. Hill. 1971. Preliminary Study of the Effects of Dogs on Radio-Equipped Deer in Mountainous Habitat. Proc. Ann. Conf. of S.E. Assoc. Game and Fish Comm. 25: 69-77. Crummett, J.G. 1970. Acoustic information denial as a means for vertebrate pest control. Paper presented at the 80th meeting of the Acoustical Society of America, Houston, November, 1970. Darnell, R.M., W.E. Pequegnot, B.M. James, F.J. Benson, and R.A. Defenbaugh. 1976. Impacts of Construction Activities in Wetlands of the United States. U.S. EPA, Office of Resesrch and Development, Corvallis ERL. Corvallis, OR. Dasmann, R.F. 1964. Wildlife Biology. New York, NY: John Wiley and Sons. Davis, D.E. Mammal. 1957. The Use of Food as a Buffer in a Predatory-Prey System. 38: 466-72. J. Davis, M.B. 1981. Pages 132-153 H.H. Shugart, Quaternary history and the stability of forest communities. in Forest Succession: Concepts and Application (D.C. West, and D.B. Botkin, (eds.) Springer-Verlag, New York. DER (Department of Environmental Regulation, State of Florida). 1983. Report to the Environmental Regulation Commission on Extending the Boundaries of the Outstanding Florida Water Designation Within the Wekiva River System. Victoria J. Tschinke1, Secretary. DER, Tallahassee. Diamond, J.M. 1975. Studies for the 129-46. The Island Dilemma: Lessons of Modern Biogeographic Design of Natural Preserves. Biological Conservation 7: Diamond, J.M. 1976. Island Biogeography and Conservation: Strategy and Limitations. Science 193: 1027-29. Diamond, J.M., and R.M. May. 1976. Island Biogeography and the Design of Natural Reserves. Pages 163-86 in R.M. May (ed.), Theoretical Ecology: Principles and Applications. Philadelphia, PA. Diehl, F.P. 1969. Sound as a rodent deterrent. Pest control. 37: 36-34. DNR (Department of Natural Resources, State of Florida). 1985. Rock Springs Run State Reserve Unit Plan. Bureau of Land and Aquatic Resource Management, Division of Recreation and Parks. Tallahassee. DNR (Department of Natural Resources, State of Florida). 1987. Wekiva River Aquatic Preserve Management Plan, June 1987 (DRAFT) Bureau of Land and Aquatic Resource Management, Division of Recreation and Parks. Tallahassee.

PAGE 140

148 Eberhard, T. 1954. Food Habits of Pennsylvania House Cats. J,.Wildl. Manage. 18: 284-86. Environmental Protection Agency. 1971. Effects of noise on wildlife and other animals. NTID 300.5. 74 pp. Erman, D.C" J.D. Newbold, and K.B. Roby. 1977. Evaluation of Streamside Bufferstrips for Protecting Aquatic Organisms. Davis, CA: California Water Resources Center, Univ of CA. Errington, P.L. 1936. Notes of Food Habits of Southern Wisconsin House Cats. J. Mammal. 17: 64-65. Eyring, C.F. 1946. Jungle Acoustics. Journal of the Acoustical SOCiety of America, October 1946: 731. Faaborg, J, 1980. Potential Uses and Abuses of Diversity Concepts in Wildlife Management. Trans. Missouri Acad. Sci. 14: 41-49. Fahrig, L., and G. Merriam. 1985. Habitat Patch Connectivity and Population Survival. Ecology 66: 1762-68. Florida Department of Environmental Regulation. 1983. Extending the Boundaries of the Outstanding Florida Water Designation within the Wekiva River System. Report to the Environmental Regulation Commission. Tallahassee, FL: State of Florida Department of Environmental Regulation, 44 pp. Florida Division of Forestry. 1979. Silviculture Best Management Practices Manual. Tallahassee, FL: Florida Department of Agriculture and Consumer Services, Division of Forestry, Collins Bldg. FGFWFC (Florida Game And Fresh Water Fish Commission). 1987. Official lists of endangered and potentially endangered fauna and flora in Florida. GFC #86{7-050, Tallahassee. Florida Department of Environmental Regulation. 1978. Non-point Source Management: A Manual of Reference Management Practices for Urban Activities. Bureau of Water Analysis FDER. Tallahassee, FL. 96 p. Forman, R.T. 1983. Corridors in a Landscape: Their Ecological Structure and Function. Ecology (CSSR) 2(3): 375-87. Forman, R.T.T, A.E. Galli, and C.F. Leck. Diversity in New Jersey Woodlots with Oecologia 26: 1-8. 1976. Forest Size and Avian Some Land Use Implications. Forman, R.T.T., and M. Godron. 1981. Patches and Structural Components for a Landscape Ecology. BioScience 31: 733-40. Forman, R.T.T., and M. Gordon. 1986. Landscape Ecology. New York, NY: John Wiley & Sons, 619 pp.

PAGE 141

149 Forsyth, D.J., and D.A. Smith. 1973. Temporal Variability in Home Ranges of Eastern Chipmunks (Tamias straitus) in a Southeastern Ontario Woodlot. Am. MidI. Natl. 90: 107-17. Frankel, O.H., and M.E. Soule. 1981. Conservation and Evolution. Cambridge, England: Cambridge University Press. Franklin, I.R. 1980. Evolutionary Change in M.E. Soule and B.A. Wilcox (eds.), Evolutionary-Ecological Perspective. Inc., 395 pp. in Small Populations. Pages 209-24 Conservation Biology: An Sunderland, MA: Sinauer Associates, Fredrickson, L.H. 1979. Floral and Faunal Changes in Lowland Hardwood Forests in Missouri Resulting from Channelization, Drainage, and Impoundment. U.S. Fish and Wildl. Servo FWS/OBS-78/91. 130 pp. Fredrickson, L.H. 1978. Lowland Hardwood Wetlands: Current Status and Habitat Values for Wildlife. Pages 296-306 in P.E. Greeson, J.R. Clark and J.E. Clark (eds.), Wetland Functions The State of Our Understanding. Proceedings of the National Symposium on Wetlands, Nov. 710, 1978. Minneapolis, MN: American Water Resources Association. FWR (Technical Committee of THE FRIENDS OF THE WEKIVA RIVER, INC.). 1985. The Wekiva River Basin: A Resource Endangered. Friends of the Wekiva River, Inc. 36 pp. text + appendices. Galli, A.E., C.F. Leck, and R.T.T. Forman. 1976. Avian Distribution Patterns in Forest Islands of Different Sizes in Central New Jersey. Auk. 93: 356-64. Game, M., and G.F. Peterken. 1984. Nature Reserve Selection Strategies in the Woodlands of Central Lincolnshire, England. BioI. Conserv. 29: 157-81. Gates, J.E., and L.W. Gysel. 1978. Avian Nest Dispersion and Fledgling Success in Field-Forest Ecotones. Ecology 59: 871-83. Gavitt, J.D. 1973. Disturbance Effects of Free-Running Dogs on Deer Reproduction. MS Thesis. Blacksburg, VA: VPI and State University. Gehrken, G.A. 1975. Travel Corridor Technique of Wild Turkey Management. Pages 113-17 in L.K. Halls (ed.), Proceedings of the National Wild Turkey Symposium. Austin, TX: Wildlife Society, Texas Chapter. Gentry, J.B., F.B. Golley, and M.H. Smith. 1968. An Evaluation of the Proposed International Biological Program Census Method for Estimating Small Mammal Populations. Acta Theriologica 13(18): 313-27. George, W.G. 1974. of Raptor Prey. Domestic Cats as Predators and Factors in Winter Shortages Wilson Bull. 86: 384-96. Ghiselin, J. 1977. Analyzing Ecotones to Predict Biotic Productivity. Environ. Manage. 1: 235-38.

PAGE 142

150 Gilbert, F.F. 1971. Analysis of Deer Mortality Other Than Legal Kill. Maine No W-67-R2: Job No. 1-3. Maine Dept. Inland Fisheries and pp. Fed. Aid Proj. Game. Memo. 12 Giles, R.H. (ed.). 1971. Wildlife Management Techniques. Washington, D.C.: The Wildlife Society. Gill, D. 1975. The Feral House Cat as a Predator of Varying Hares. Can. Field-Nat. 89: 78-79. Gleason, H.A. 1922. On the Relationship Between Species and Area. Ecology 3: 158-62. Gottfried, B.M. 1979. Small Mammal Populations in Woodlot Islands. Amer. MidI. Nat. 102: 105-12. Greaves, J.H. and F.P. Rowe. 1969. Responses of confined rodent populations to an ultrasound generator. J. Wildl. Manage. 33: 409-17. Gross, F.E.H. 1987. Characteristics of Small Stream Floodplain Ecosystems in North and Central Florida. MS Thesis (CFW-87-01). Gainesville, FL: Univ of FL, pp. 167. Gysel, L.W. 1951. Borders and Openings of Beech-Maple Woodlands in Southern Michigan. Journal of Forestry 49: 13-19. Harlukowicz, T.J., and R.C. Ahlert. 1978. Effects of Septic Effluent on Groundwater Quality in the New Jersey Pine Barrens. Final Report to The Rockefeller Foundation. New Brunswick, NJ: College of Engineering, Bureau of Engineering Research, Rutgers. Harris, L.D. 1983. An Island Archipelago Model for Maintaining Biotic Diversity in Old-Growth Forests. Pages 378-82 in New Forests for a Changing World, Proceedings of the 1983 SAF National Convention. Harris, L.D. 1984. Preservation of Press, 211 pp. The Fragmented Forest: Island Biogeography Theory and the Biotic Diversity. Chicago, IL: University of Chicago Harris, L.D. 1985. Conservation Corridors: A Highway System for Wildlife. Winter Park, FL: Environmental Information Center of the Florida Conservation Foundation, Inc., ENFO report 85-5, 10 pp. Harris, L.D., D.H. Hirth, and W.R. Marion. Silvicultural Systems for Wildlife. Louisiana State University. 1979. The Development of The 28th Annual Forestry Symposium. Harris, L.D., and J.D. McElveen. 1982. Effects of Edge Type on North Florida Breeding Birds. Gainesville, FL: School of Forest Resources and Conservation, Univ of FL (unpublished manuscript). Harris, L.D., M.E. McGlothlen, and M.N. Manlove. 1984. Genetic Resources and Biotic Diversity. Pages 94-107 in L.D. Harris (ed.), The Fragmented

PAGE 143

Forest: Island Biogeography Theory and the Preservation of Biotic Diversity. Chicago, IL: University of Chicago Press, 211 pp. Harris, L.D., and R.F. Noss. 1985. Problems in Categorizing the Status of Species: Endangerment with Best of Intentions. l 16th IUCN Technical Meeting, Madrid, Spain. November 1984. 151 Harris, L.D., and C.R. Vickers. 1984. Some Faunal Community Characteristics of Cypress Ponds and the Changes Induced by Perturbations. Pages 171-85 in K.C. Ewel and H.T. Odum (eds.), Cypress Swamps. Gainesville, FL: University Presses of FL. (CFW-84-36.) Harris, L.D., and R. Wallace. 1984. Breeding Bird Species in Florida Forest Fragments. Proc. Ann. Conf. S.E. Assoc. Fish Wildl. Agencies 38: 87-96. Hart, R. 1981. Regulatory Definitions of Wetlands: Do They Maximize Wetland Function? Pages 273-83 in P. McCaffrey, T. Breemer, and S. Gatewood (eds.), Progress in Wetlands Utilization and Management. Proceedings of a Symposium, June 9-22, 1981. Coordinating Council on the Restoration of the Kissimmee River Valley and Taylor Creek--Nubbin Slough Basin. Hart, R.L. 1984. Evaluation of Methods for Sampling Vegetation and Delineating Wetlands Transition Zones in Coastal West-Central Florida, January 1979-May 1981. Technical Report Y-84-2 U.S. Army Engineer Waterways Experiment Station. Washington, DC: NTIS. Hart, R.L. 1985. Microclimate Studies, Volume 3: Terrestrial Ecology Appendix 3B. Fairfield, FT. George Island Master Resource Management Plan, ESE #83-612-0610-0120. Gainesville, FL: Environmental Sciences and Engineering Inc. Hartman, D.S. 1979. Ecology and behavior of the manatee (Trichechus manatus) in Florida. Amer. Soc. Mammal. Spec. Publ. 5: 1-153. Lawrence, Kansas. Heath, R.C. and C.S. Conover. 1981. Hydrologic Almanac of Florida. United States Department of Interior Geological Survey, Open-File Report 81-1107. USGS, Tallahassee. Hedrick, L.D. 1973. Silvicultural Practices and Tree Squirrels. MS Thesis. Texas A&M University. 97 pp. Hewlett, J.D. 1982. PrinCiples of Forest Hydrology. Athens, GA: Univ of Georgia Press. Hill, E.P. 1970. Bat control with high frequency sound. Pest Control. 38: 18. Holling, C.S. 1966. The Functional Response of Invertebrate Predators to Prey Density. Mem. Entomol. Soc. Can. 48, 88 pp. Hollis, C.A., R.F. Fisher, and W.L. Pritchett. 1978. Effects of Some Silvicultural Practices on Soil Site Properties in the Lower Coastal Plains. In Youngberg, C.T., (ed.), Forest Soils and Land Use. Forest and Wood SCiences, Colorado State University, Fort Collins, CO., pp. 585-607.

PAGE 144

152 Hoyt, S.F. 1957. The Ecology of the Pi1eated Woodpecker. Ecology 38(2): 246-56. Hubbs, E.L. 1951. Food Habits of Feral House Cats in the Sacramento Valley. Calif. Fish and Game 37: 177-89. Hunt, R. 1984. Evaluation of Methods for Sampling Vegetation and Delineating Wetlands Transition Zones in Coastal West-Central Florida, January 1979-May 1981. U.S. Army Engineer Waterways Experiment Station. Springfield, VA: NTIS, Technical Report Y-84-2. Jackson, J.A. 1978. Competition for Cavities and Red-Cockaded Woodpecker Management. Pages 103-12 S.A. Temple (ed.), Endangered Birds. Madison, WI: University of Wisconsin Press. Jackson, L.W. 1971. Annual Deer Mortality in Malone. Fed. Aid Proj. No. W89-R-15: Job No. XI-4. New York, NY: New York State Dept. Env. Cons. Delmar. 9. Janzen, D.H. 1983. No Park is an Island: Increase in Interference from Outside as Park Size Increases. Oikos 41: 402-10. Janzen, D.H. 1986. The Eternal External Threat. Pages 286-303 in M.E. Soule (ed.), Conservation Biology: The Science of Scarcity and Diversity. Sunderland, MA: Sinauer Associates. Jennings, W.L. 1951. Squirrel (Scirus Gainesville, FL: A Study of the Life History and Ecology c. carolinensis Gmelin) in Gulf Hammock. Univ of FL, 151 pp. of the Gray MS Thesis. Johnson, W.C., R.K. Schreiber, and R.L. Burgess. 1979. Diversity of Small Mammals in a Powerline Right-of-Way and Adjacent Forest in East Tennessee. Am. MidI. Nat. 101: 231-35. Johnson, W.C., and C.S. Adkisson. 1985. Dispersal of Beech Nuts by Blue Jays in Fragmented Landscapes. American Midland Naturalist 113: 319-24. Johnson, W.N., Jr. 1986. Avian Use of a Lakeshore Buffer Strip in Eastern Maine. MS thesis. Orono, ME: University of Maine, 63 pp. Johnston, V.R. Illinois. 1947. Breeding Birds of the Forest Edge in East-Central Condor 49(2): 45-53. Kalisz, P.J. and E.L. Stone. 1984. Longleaf pine islands of the Ocala Ecology 65(6): 1743-1754. National Forest: a soil study. Kantola, A.T. 1986. Fox Squirrel Home Range and Mast Crops in Florida. Thesis. Gainesville, FL: Univ of FL, 68 pp. MS Karr, J.R. 1982. Population Variability and Extinction in the Avifauna of a Tropical Land Bridge Island. Ecology 63: 1975-78.

PAGE 145

153 Karr, J.R., and I.J. Schlosser. 1977. Stream Morphology on Water Quality Environmental Resource Lab, Office Impact of Nearstream Vegetation and and Stream Biota. Athens, GA: U.S. of Resources and Development. Kockman, H.I. 1978. Eastern Indigo Snake. Pages 68-9 in R.W. McDiarmid (ed.), Rare and Endangered Biota of Florida: Amphibians and Reptiles. Gainesville, FL: University Presses of Florida. Korschgen, L.J. Missouri. 1957. Food Habits: Coyotes, Foxes, House Cats, Bobcats in Mo. Conserv. Comm. Bull. 15, 64 pp. B., and E. Anderson. 1980. Pleistocene mammals of North America. Columbia Univ. Press, New York. 442 pp. Laessle, A. M. 1958. The origin and successional relationships of sandhill vegetation and sand pine scrub. Ecol. Monog. 28: 361-387. EPA Landers, J.L., R.J. Hamilton, A.S. Johnson, and R.L. Marchington. 1979. Foods and Habitat of Black Bears in North Carolina. J. Wildl. Manage. 43: 143-53. Larson, J.S. 1981. Transition from Wetlands to Uplands in Southeastern Bottomland Hardwood Forests. Pages 225-74 in (eds.), J.R. Clark and J. Benforado, Wetland Bottomland Hardwood Forests. Proceedings of a Workshop on Bottomland Hardwood Forest Wetlands of the Southeastern United States. Amsterdam: Elsevier Scientific Publishing Company. Lavdenslayer, W.F., and R.P. Balda. Juniper-Ponderosa Pine Ecotone. 1976. Breeding Bird Use of a PinyonAuk 93: 571-86. Lay, D.W. 1938. How Valuable are Woodland Clearings to Birdlife? Wilson Bull. 45: 254-56. Leopold, A. 1933. Game Management. New York, NY: Charles Scribners Sons. Levenson, J.B. 1981. Woodlots as Biogeographic Islands is Southeastern Wisconsin. Pages 12-39 in R. L. Burgess and D. M. Sharpe (eds.), Forest Island Dynamics in Man-Dominated Landscapes. New York, NY: Springer Verlag. Livingston, R.J., R.L. Iverson, and D.C. White. 1976. Energy Relationships and Productivity of Apalachicola Bay. Final Research Report to Florida Sea Grant College. Tallahassee, FL: Florida State Univ. Lovejoy, T.E., and D.C. Oren. 1981. The Minimum Critical Size of Ecosystems. Pages 7-12 in R.L. Burgess and D.M. Sharpe, (eds.), Forest Island Dynamics in Man-Dominated Landscapes. New York, NY: Springer-Verlag. Lovejoy, T.E., R.O. Bierregaard, A.B. Rylands, J.R. Malcolm, C.E. QUintela, L.H. Harper, K.S. Brown, A.H. Powell, G.V.N. Powell, H.O.R. Schubart, and M.B. Hays. 1986. Edge and Other Effects of Isolation on Amazon Forest Fragments. Pages in M.E. Soule (ed.), Conservation Biology: The Science of Scarcity and Diversity. Sunderland, MA: Sinauer Associates.

PAGE 146

154 Lyle, Jr., E.S. 1987. Surface Mine Reclamation Manual. New York, NY: Elsevier. Lynch, J.F., and D.F. Whigham. 1984. Effects of Forest Fragmentation on Breeding Bird Communities in Maryland, USA. BioI. Conserv. 28: 287-324. MacArthur, R.H. 1964. Environmental Factors Affecting Bird Species Diversity. Ecology 42: 594-98. MacArthur, R.H., and J.W. MacArthur. 1961. On Bird Species Diversity. Ecology 42: 594-98. MacArthur, R.H., J.W. MacArthur, and J. Preer. 1962. On Bird Species Diversity. Amer. Naturalist 66: 167-74. MacArthur, R.H., and E.R. Pianka. 1966. On Optimal Use of a Patchy Environment. Am. Nat. IOU(916): 603-09. MacArthur, R.H., and E.O. Wilson. 1967. The Theory of Island Biogeography. Princeton, NJ: Princeton Press. MacClintock, L., R.F. Whitcomb, and B.L. Whitcomb. 1977. Evidence for the Value of Corridors and Minimization of Isolation in Preservation of Biotic Diversity. American Birds 31: 6-16. Matthiae, P.E., and F. Stearns. 1981. Mammals in Forest Islands in Southeastern Wisconsin. Pages 55-66 in R.L. Burgess and D.M. Sharpe (eds.), Forest Island Dynamics in Man-Dominated Landscapes. New York, NY: Springer-Verlag. McElfresh, R., J. Inglis, and B.A. Brown. Hardwood Ravines in Pine Plantations. Symp. 29: 79-89. 1980. Gray Squirrel Usage of Louisiana State Univ. Forestry McElveen, J.D. Florida. 1977. The Edge Effect on a Forest Bird Community in North Proc. S.E. Assoc. Fish Wildl. Agencies 31: 212-15. McElveen, J.D. 1978. The Effects of Different Types of Edge Types and Habitat Sizes on the Distribution of Breeding Birds in North Florida. MS Thesis. Gainesville, FL: Univ of FL, pp. 47. McMurry, F.B., and C.C. Sperry. 1941. Food of Feral House Cats in Oklahoma, a Progress Report. J. Mammal. 22: 184-90. Means, D.B. and G. Grow. 1985. The endangered longleaf pine community, ENFO 85(4): 1-12. Florida Conservation Foundation, Winter Park. Melquist, W.E. and M.G. Hornocker. 1983. Ecology of River Otters in West Central Idaho. Wildl. Monogr. 83: 1-60. Messersmith, D.H. 1970. Control of bird depredation. Agric. Dept. Coop. State Research. Serv., Maryland.

PAGE 147

155 Miller, R.I. 1979. Conserving the Genetic Integrity of Faunal Populations and Communities. Environmental Conservation 5: 191-95. Miller, R.I., and L.D. Harris. 1977. Isolation and Extirpations in Wildlife Reserves. Bid. Conserv. 12: 311-15. Mitsch, W.J., M.D. Hutchison, and G.A. Paulson. 1979. The Momence Wetlands of the Kankakee River in Illinois: An Assessment of Their Value. Chicago, IL: Illinois Institute of Natural Resources Doc 79/17; 55 pp. Monk, C.D. 1965. Southern mixed hardwood forest of north central Florida. Ecol. Monog. 35(4): 335-354. Monk, C.D. 1968. Successional and environmental relationships of the forest vegetation of north central Florida. Amer. MidI. Nat. 79(2): 441-457. Moore, N.W., and M.D. Hooper. 1975. On the Number of Bird Species in British Woods. BioI. Conserv. 8: 239-50. Murphy, T.M., F.M. Bagley, W. Dubuc, D. Mager, S.A. Nesbitt, W.B. Robertson, and B. Sanders. 1984. Southeastern States Bald Eagle Recovery Plan. Atlanta, GA: U.S. Fish and Wildlife Service. Noss, R.F. 1981. The Birds of Sugarcreek, an Ohio Nature Reserve. Ohio J. Sci. 81: 29-40. Noss, R.F. 1983. A Regional Landscape Approach to Maintain Diversity. BioScience 33(11): 700-06. Noss, R.F. 1985. Characterizing pre-settlement vegetation: how and why. Natural Areas Journal 5(1): 5-19. Noss, R.F. 1987. Corridors in Real Landscapes: A Reply to Simberloff and Cox. Conservation Biology Journal. (in press.) Noss, R.F. 1987. From Plant Communities to Landscapes in Conservation Inventories: press.) A Look at the Nature Conservancy (USA). BioI. Conserv. (in Noss, R.F. and L.D. Harris. 1986. Nodes, networks, and MUM's: preserving diversity at all scales. Environmental Management 10:299-309. Noss, R.F., and L.D. Harris. Diversity at All Scales. 1986. Nodes, Networks, and Mums: Preserving Environmental Management 10(3): 299-309. Odum, E.P. 1971. Fundamentals of Ecology, Third Edition. W.B. Saunders, Inc., Philadelphia. Odum, E.P. 1978. Ecological Importance of the Riparian Zone. Proc. of Symposium: Strategies for Protection and Management of Floodplain Wetlands and other Riparian Ecosystems. USDA For. Servo Gen. Tech. Rep. WO-12, 410 pp. Odum, E.P. 1983. Basic Ecology. W.B. Saunders, Inc., Philadelphia.

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156 O'Shea, T.J., C.A. Beck, R.K. Bonde, H.I. Kochman, and D.K. Odell. 1985. An analysis of manatee mortality patterns in Florida, 1976-1981. Journal of Wildlife Management 49(1): 1-11. Ozoga, J.J., and L.J. Verme. 1968. Small Mammals of Conifer Swamp Deeryards in Northern Michigan. Michigan Academy Sci., Arts, and Letters 53: 37-49. Parmalee, P.W. 1953. Food Habits of the Feral House Cat in East-Central Texas. J. Wildl. Manage. 17: 375-76. Patrick, W.H., Jr., G. Dissmeyer, D.D. Hook, V.W. Lambou, H.M. Leitman, and C.H. Wharton. 1981. Characteristics of Wetlands Ecosystems of Southeastern Bottomland Hardwood Forests. Pages 276-300 in J.R. Clark and J. Benforado (eds.), Wetland Bottomland Hardwood Forests.--Proceedings of a Workshop on Bottomland Hardwood Forest Wetlands of the Southeastern United States. Amsterdam: Elsevier Scientific Publishing. Pickett, S.T., and J.N. Thompson. 1978. Patch Dynamics and the Size of Nature Reserves. Biological Conservation 13: 27-37. Pickett, S.T.A., and P.S. White. 1985. The Ecology of Natural Disturbance and Patch Dynamics. Orlando, FL: Academic Press. Post, W., and J.W. Wiley 1976. The Yellow-Shouldered Blackbird: Present and Future. American Birds 30(1): 13-20. Post, W., and J.W. Wiley. 1977. The Shiny Cowbird in the West Indies. The Condor 79(1): 119-21. Post, W., and J.W. Wiley. 1977. Reproductive Interactions of the Shiny Cowbird and the Yellow-Shouldered Blackbird. The Condor 79(2): 176-84. Preston, F.W. 1960. Time and Space and the Variation in Species. Ecology 41: 611-27. Preston, F.W. 1962. The Canonical Distribution of Commonness and Rarity. Ecology 43: 185-215, 410-32. Progulske, D.R., Jr. Eastern Florida. 1982. Spatial Distribution of Bobcats and Gray Faxes in MS Thesis. Gainesville, FL: Univ of FL, 63 pp. Ranney, J.W. 1977. Forest Island Edges: Their Structure, Development and Importance to Regional Forest Ecosystem Dynamics. Oak Ridge, TN: Oak Ridge National Laboratory, Env. Sciences Div., Pub. No. 1069. Ranney, J.W., M.C. Bruner, and J.B. Levenson. 1981. The Importance of the Structure and Dynamics of Forest Islands. Pages 67-95 in R.L. and D.M. Sharpe (eds.), Forest Island Dynamics in Man-Dominated Landscapes. New York, NY: Springer-Verlag. Edge in Burgess Ray, D., W. Woodroof, and R.C. Roberts. 1984. Management of Riparian Vegetation in the Northcoast Region of California's Coastal Zone. Pages 660-685 in R.E. Warner and K.M. Hendrix (eds.), California Riparian

PAGE 149

157 Systems: Ecology, Conservation, and Productive Management. Berkeley, CA: University of California Press. Redford, K.H., and G.A.B. da Fonesca. 1986. The Role of Gallery Forests in the Zoogeography of the Cerrado's Non-Volant Mammalian Fauna. Biotropica 18(2): 126-35. Riekerk, H. 1985. Water Quality Effects of Pine Flatwoods Silviculture. Journal of Soil and Water Conservation. Vol 40(3): 306-09. Riekerk, H., B.F. Swindel, and J. A. Replogle. 1980. Effects of Forestry Practices in Florida Watersheds. Proceedings of the Symposium on Watershed Management. ASCE. pp. 706-20. Riekerk, H., and D.K. Winter. 1982. Forest Water Management Principles in Florida. Proceedings Specialty Conference on Environmentally Sound Water and Soil Management. Orlando, FL: ASCE. Robbins, C.S. 1980. Effect of Forest Fragmentation on Bird Populations. Pages 198-212 in R.M. DeGraaf and K.E. Evans, Compilers. Management of North Central and Northeastern Forests for Nongame Birds. U.S. Dept. Agric., Forest Service General Technical Report NC-51. Robertson, R.J., and N.J. Flood. 1980. Effects of Recreational Use of Shorelines on Breeding Bird Populations. Can. Field. Nat. 94(2): 131-38. Robinette, F.O. 1972. Plants, People, and Environmental Quality. Washington, DC: Department of the Interior, National Park Service, p 41. Roelke, M.E. 1986. Medical Management, Biological Findings, and Research Techniques for the Florida Panther. Pages 7-14 in W.V. Branan (ed.), Survival of the Florida Panther: A Discussion and Accomplishments. Tallahassee, FL: Florida Defenders of the Environment. Roth, R.R. 1976. Spatial Heterogeneity and Bird Species Diversity. Ecology 57: 733-82. Rusterholz, K.A., and R.W. Howe. 1979. Small Islands in a Minnesota Lake. Species-Area Relations of Birds on Evolution 33: 468-77. Samson, F.B. 1980. Island Biogeography and the Conservation of Nongame Birds. Trans. N. Am. Wildl. and Nat. Res. Conf. 45: 245-51. Samson, F.B., and F.L. Knopf. 1982. In Search of a Diversity Ethic for Wildlife Management. Trans. N. Am. Wi1dl. and Nat. Res. Conf. 47: 421-31. Sartor, J.D. and G.B. Boyd. 1972. Water Pollution Aspects of Street Surface Contaminants. U.S. EPA-R2-72-081. Washington, D.C. Schaefer, J.M. 1978. Coyote and Dog Depredation on Sheep in Southern Iowa. MS Thesis. Iowa State University, 140 pp. Schitoskey, Jr., F., and R.L. Linder. 1978. Use of Wetlands by Upland Wildlife. Pages 307-11 in P.E. Greeson, J.R. Clark and J.E. Clark (eds.),

PAGE 150

158 Wetland Functions and Values: the State of Our Understanding. Proceedings of the National Symposium on Wetlands, Nov. 7-10, 1978. Minneapolis, MN: American Water Resources Association. Schneider, R.L., and R.R. Sharitz. In press. Hydrochory and Swamp Forest Regeneration. Ecology. Schonewald-Cox, C.M., S.M. Chambers, B. MacBryde, and W.L. Thomas. 1983. Genetics and Conservation: A Reference for Managing Wild Animal and Plant Populations. Menlo Park, CA: Benjamin/Cummings. Senner, J.W. 1980. Inbreeding Depression and the Survival of Zoo Populations. Pages 209-24 in M.E. Soule and B.A. Wilcox (eds.), Conservation Biology: An Evolutionary-Ecological Perspective. Sunderland, MA: Sinauer Associates, Inc., 395 pp. Shaffer, M.L. 1981. Minimum Population Sizes for Species Conservation. BioScience 31: 131-34. Simpson, G. 1940. Mammals and Land Bridges. Journal of the Washington Academy of Science 30: 137-63. Simpson, G. 1965. The Geography of Evolution. Philadelphia, PA: Chilton Books, 249 pp. Small, M.F., and W.N. Johnson, Jr. 1985. Wildlife Management in Riparian Habitats. In J. Bissonette (ed.), Proc. of Symp.: Is Good Forestry Good Wildlife Management? Smith, R.L. 1966. Wildlife and Forest Problems Appalachia. Trans. N. Amer. Wildl. and Nat. Res. Conf. 31: 212-26. Soule, M.E. 1980. Thresholds for Survival: Maintaining Fitness. Pages 151-72 in M.E. Soule and B.A. Wilcox (eds.), Conservation Biology: An Evolutionary-Ecological Perspective. Sunderland, MA: Sinauer AssOCiates, Inc., 395 pp. Soule, M.E. 1986. Conservation Biology: The Science of Scarcity and Diversity. Sunderland, MA: Sinauer Associates. Soule, M.E., and D. Simberloff. 1986. What Do Genetics and Ecology Tell Us About the Design of Nature Reserves? Biological Conservation 35: 19-40. Soule, M.E., and B.A. Wilcox. 1980. Conservation Biology: An EvolutionaryEcological Perspective. Sunderland, MA: Sinauer Associates. Sousa, W.P. 1984. The Role of Disturbance in Natural Communities. Ann. Rev. Ecol. Syst. 15: 353-91. Sparrowe, R.D., and P.F. Springer. 1970. tailed Deer in Eastern South Dakota. Seasonal Activity Patterns of WhiteJ. Wildl. Manage. 34: 420-31. Speake, D.W., J.A.McGlincy, and T.R. Colvin. 1978. Ecology and Management of the Eastern Indigo Snake in Georgia: a progress report. Pages 64-73 in

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159 R.R. Odum and L. Landers (eds.), Proceedings of the Rare and Endangered Wildlife Symposium, Aug. 3-4, 1978. Georgia Dept. of Nat. Res. Tech. Bull. WL 4. Sprock, C.M., W.E. Howard, and F.C. Jacob. 1967. Sound as a deterrent to rats and mice. J. Wildl. Manage. 31:729-41. Stauffer, D.F. 1978. Habitat Selection by Birds of Riparian Communities: Evaluating the Effects of Habitat Alteration. MS Thesis. Ames, IA: Iowa State University. Stauffer, D.F. and L.B. Best. 1980. Habitat Selection by Birds of Riparian Communities: Evaluating Effects of Habitat Alterations. J. Wildl. Manage. 44: 1-15. Sullivan, A.L., and M.L. Shaffer. 1975. Biogeography of the Megazoo. Science 189: 13-17. Swift, L.W., and K.R. Knoerr. 1973. Estimating Solar Radiation on Mountain Slopes. Agric. Meteorol. 12: 329-36. Tassone, J.F. 1981. Utility of Hardwood Leave Strips for Breeding Birds in Virginia's Central Piedmont. MS Thesis. Blacksburg, VA: Virginia Polytechnic and Institute and State College, 83 pp. Temple, S.A. 1986. Predicting Impacts of Habitat Fragmentation on Forest Birds: a Comparison of Two Models. Pages 301-04 in J. Verner, M.L. Morrison and C.J. Ralph (eds.), Wildlife 2000: Modeling Habitat Relationships of Terrestrial Vertebrates. Madison, WI: The University of Wisconsin Press. Terborgh, J. 1974. Preservation of Natural Diversity: The Problem of Extinction-Prone Species. BioScience 24: 715-22. Terborgh, J., and B. Winter. 1980. Some Causes of Extinction. Pages 119-33 M.E. Soule and B.A. Wilcox (eds.), Conservation Biology: An Evolutionary-Ecological Perspective. Sunderland, MA: Sinauer, Associates. Terborgh, J., and B. Winter. 1983. A Method for Siting Parks and Reserves with Special Reference to Columbia and Ecuador. BioI. Conserv. 27: 45-58. Thomas, J.W., C. Maser, and Thomas (ed.), Wildlife Oregon and Washington. D.C. J.E. Rodiek. 1979. Edges. Pages 48-59 J.W. Habitats in Managed Forests: the Blue Mountains of U.S. For. Servo Agr. Handbook No. 553, Washington, Tinkle, D.W. Swamp. 1959. Observations of Reptiles and Amphibians in a Louisiana Am. MidI. Nat. 62(1): 189-205. Trela, J.J., and L.A. Douglas. 1978. SOils, Septic Systems, and Carrying Capacity in the Pine Barrens. Natural and Cultural Resources of the New Jersey Pine Barrens. Proceedings of First Annual Pine Barrens Resources Conference, Atlantic City, New Jersey. Pomona, NJ: Center for Environmental Resources, Stockton State College.

PAGE 152

160 Trimble, G.R., and R.S. Sartz. 1957. How Far From a Stream Should a Logging Road Be Located? Journal of Forestry 55: 339-41. Trimble, G.R., and E.H. Tryson. 1966. Crown Encroachment into Openings Cut in Appalachian Hardwood Stands. Journal of Forestry 64(2): 104-08. U.S. Department of Agriculture, Soil Conservation Service. 1979. S.C.S. Engineering Field Manual for Conservation Practices. Washington, DC: U.S. Government Printing Office. USDA (United States Department of Agriculture). 1960. Soil Survey of Seminole County, Florida. U.S.G.P.O., Washington,D.C. USDA (United States Department of Agriculture). 1966. Soil Survey of Orange County, Florida. U.S.G.P.O.,Washington, D.C. van Aarde, R.J. 1980. The Diet and Feeding Behavior of Feral Cats, (Felis catus) at Marion Island. S. Afr. J. Wildl. Res. 10(3/4): 123-28. van der Zande, A.N., W.J. ter Keurs and W.J. van der Weijden. 1980. The Impact of Roads on the Densities of Four Bird Species in an Open Field Habitat: Evidence of a Long-Distance Effect. BioI. Conserv. 18: 299-321. Verme, L.J. 1961. Production of White-Cedar Browse by Logging. J. Forestry 59: 589-91. Verme, L.J. 1965. Swamp Conifer Deeryards in Northern Michigan: Their Biology and Management. J. Forestry 63: 523-29. Vickers, C.R., L.D. Harris, and B.S. Swindel. Resulting from Ditching of Cypress Ponds Forest Ecology and Management 2: 17-29. 1985. Changes in Herpetofauna in Coastal Plains Flatwoods. Wales, B.A. 1967. Climate, Microclimate, and Vegetation Relationships on North and South Forest Boundaries in New Jersey. William J. Hutcheson Memorial Forest Bulletin 2(3): 1-60. Wales, B.A. 1972. Vegetation Analysis of North and South Edges in a Mature Oak-Hickory Forest. Ecological Monographs 42(4): 451-71. Wanielista, M.P. (ed.). 1975. Proceedings: Stormwater Management Workshop. Florida Technological University. Orlando, Fl. Wang, F.C. 1978. Impacts of Drainage Canals in Surface and Subsurface Hydrology of Adjacent Areas in South Florida. In H.T. Odum and K.C. Ewel (eds.), Cypress Wetlands for Water Management, Recycling, and Conservation. Fourth Annual Report to the National Science Foundation and The Rockefeller Foundation, Center for Wetlands, Univ of Fl, Gainesville, FL, pp. 827-61. Wang, F.C. and A.R. Overman. 1981. Impacts of Surface Drainage on Groundwater HydrauliCS. Water Resources Bulletin, Vol 17(6): 971-977.

PAGE 153

161 Warner, R.E. 1985. Rural Illinois. Demography and Movements of Free-Ranging Domestic Cats in J. Wi1dl. Manage. 49: 340-46. Watts, W.A. 1980. The late Quaternary vegetation history United States. Ann. Rev. Ecol. Sys. 11:387-409. of the southeastern Watts, W.A. and B.C.H. Hansen. In Press. Environments of Florida in the Late Wisconsin and Holocene. Wet Site Archaeology (B. Purdy, ed.). (in press) Webb, D.S., and K.T. Wilkins. 1984. Historical Biogeography of Florida Pleistocene Mammals. Special Publication of the Carnegie Museum of Natural History. Wegner, J.F., and H.G. Merriam. 1977. Movements by Birds and Small Mammals between a Wood and Adjoining Farmland Habitats. Journal of Applied Ecology 16: 349-58. Weiner, F.M., and D.N. Keast. 1959. Sound Propagation over Terrara. Journal of the Acoustical Society of America, June 1959: 732. Weller, M.W. 1978. Wetland Habitats. Pages 210-34 in P.E.Greeson, J.R. Clark, and J.E. Clark (eds.), Wetland Functions and Values: the State of Our Understanding. Proceedings of the National Symposium on Wetlands, Nov. 7-10, 1978. Minneapolis, MN: American Water Resources Association. Weller, M.W. 1978. Management of Freshwater Marshes for Wildlife. Pages 276-84 in R.E. Good, D.F. Whigham, and R.L. Simpson (eds.), Freshwater Wetlands: Ecological Processes and Management Potential. New York, NY: Academy Press. Weller, M.W., and C.S. Spatcher. and Abundance of Marsh Birds. Report 43, 31 pp. 1965. Role of Habitat in the Distribution Iowa Ag. and Home Ec. Exp. Stn. Special Wharton, C.H., W.M. Kitchens, E.C. Pendelton, and T.W. Sipe. 1982. The Ecology of Bottomland Hardwood Swamps of the Southeast: a Community Profile. U.S. Fish and Wildlife Service, Biological Services Program, Washington, D.C. FWS/OBS-81/37, 133 pp. Wharton, C.H., V.W. Lambour, J. Newsome, P.V. Winger, L.L. Gaddy; and R. Mancke. 1981. The Fauna of Bottomland Hardwoods in Southeastern United States. Pages 87-160 in J.R. Clark and J. Benforado (eds.), Wetland Bottomland Forests. Proceedings of a Workshop on Bottomland Hardwood Forest Wetlands of the Southeastern United States. Amsterdam: Elsevier Scientific Publishing Company. Whitcomb, R.F. 1977. Island Biogeography and "Habitat Islands" of Eastern Forest. Amer. Birds 31: 3-5. Whitcomb, R.F., J.F. Lynch, P.A. Opler, and C.S. Robbins. 1976. Island Biogeography and Conservation: Strategy and Limitations. Science 193: 1030-32.

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162 Whitcomb, R.F., C.S. Robbins, J.F. Lynch, and B.L. Whitcomb, K. Klimkiewicz, and D. Bystrak. 1981. Effects of Forest Fragmentation on Avifauna of the Eastern Deciduous Forest. Pages 125-205 in R.L. Burgess and D.M. Sharpe (eds.), Forest Island Dynamics in Man-Dominated Landscapes. New York, NY: Springer-Verlag. White, D.C., R.J. Livingston, R.J. Bobbie, and J.S. Nickels. 1979. Effects of Surface Composition, Water Column Chemistry and Time of Exposure on Composition of the Microflora and Associated Macrotauma in Apalachicola Bay, Florida. White, P.S. 1979. Pattern, Process, and Natural Disturbance in Vegetation. Bot. Rev. 45: 229-99. Whitney, G.G., and J.R. Runkle. 1981. Edge Versus Age Effects in The Development of a Beech-Maple Forest. Oikos 37: 377-81. Wilcove, D.S. 1985. Nest Predation in Forest Tracts and The Decline of Migratory Songbirds. Ecology 66: 1211-14. Wi1cove, D.S., and R.M. May. 1986. National Park Boundaries and Ecological Realities. Nature 324: 206-07. Wilcove, D.S., C.H. McLellan, and A.P. Dobson. 1$86. Habitat Fragmentation in The Temperate Zone. Pages 237-56 in M.E. Soule (ed.), Conservation Biology: The Science of Scarcity and Diversity. Sunderland, MA: Sinauer Associates. Wilcox, B.A. 1980. Insular Ecology and Conservation. Pages 151-72 in M.E. Soule and B.A. Wilcox (eds.), Conservation Biology: An Evolutionary-Ecological Perspective. Sunderland, MA: Sinauer Associates, Inc., 395 pp. Williams, L.E. 1978. Florida Black Bear. Rare and Endangered Biota of Florida: Pages 23-5 in J.N. Layne (ed.), Mammals. Gainesville, FL: University Presses of Florida. Wilson, E.O., and E.O. Willis. 1975. Applied Biogeography. M.L. Cody and J.M. Diamond (eds.), Ecology and Evolution Cambridge, MA: Belknap Press of Harvard University Press. Pages 522-34 in of Communities. Wittaker, R.H. 1978. Handbook of Vegetation Science. Part V. In W. Junk (ed.), Ordination of Communities. The Netherlands: The Hague Press. Wolfe, R.W. 1987. Seed Dispersal and Wetland Restoration. MS Thesis (CFW-87-15). Gainesville, FL: Univ of FL, 93 pp. Wright, S.J., and S.P. Hubbell. a Focal Species Approach. 1983. Stochastic Extinction and Reserve Size: Oikos 41: 466-76. Yoakum, J., and W.P. Dasmann. 1971. Habitat Manipulation Practices. Pages 173-231 in R.H. Giles (ed.), Wildlife Management Techniques. Washington, DC: The Wildlife Society.

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163 Yoho, W.H. and E.C. Pirkle. 1985. Natural Landscapes of the United States (Fourth Edition). Kendall/Hunt Publ. Co., Dubuque, Iowa. Zampella, R.A., and C.T. Roman. 1983. Wetlands Protection in the New Jersey Pinelands. Wetlands 3: 124-33.

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APPENDIX A WILDLIFE ASSOCIATED WITH WEKIVA RIVER BASIN

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TABLE A-l. Fish species of the Wekiva River Basin area. Scientific Name Amia calva AngUilla rostrata Aphredoderus sayanus Dorosoma cepedianum Dorosoma petenense Elassoma evergladei Elassoma okefenokee Enneacanthus gloriosus Enneacanthus obesus Erimyzon sucetta Esox americanus niger Etheostoma fusiforme Fundulus chrysotus Fundulus lineolatus Fundulus seminolis Gambusia affinis Heterandria formosa Ictalurus brunneus Ictalurus catus Ictalurus nebulosus Ictalurus punctatus Jordanella floridae Labidesthes sicculus LepisosteuB oaseus Lepisosteus platyrhincus Lepomis auritus Lepomis gulosus Lepomis macrochirus Lepomis marginatus Lepomis microlophus Lepomis punctatus Lucania goodei Micropterus salmoides Morone saxatilis Mugil cephalus Notemigonus crysoleuca Notropis chalybaeus Notropis emiliae Notropis hyPselopterus Common Name Bowfin American eel Pirate perch Gizzard shad Threadfin shad Everglades pygmy sunfish Okefenokee pygmy sunfish Bluespotted sunfish Banded sunfish Lake chubsucker Redfin pickerel Chain pickerel Swamp darter Golden topminnow Lined topminnow Seminole killifish Mosquitofish Least killifish Snail bullhead White catfish Brown bullhead Channel catfish Flagfish Brook silverside Longnose gar Florida spotted gar Redbreast sunfish Warmouth Bluegill Dollar sunfish Redear sunfish Spotted sunfish Bluefin killifish Largemouth bass Striped bass Striped mullet Golden shiner Ironcolor shiner Pugnose minnow Sailfin shiner

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TABLE A-l. Fish species of the Wekiva River area (continued). Scientific Name Notropis maculatus Notropis petersoni Notropis welaka Noturus gyrinus Noturus lephtacanthus Percina nigrofasciata Poecilia latipinna Pomoxis nigromaculatus Common Name Tail light shiner Coastal shiner Bluenose shiner Tadpole madtom Speckle mad tom Blackbanded darter Sail fin molly Black crappie

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TABLEA-2. Relative abundance of amphibian species in Wekiva River Basin habitats.* Scientific Name Acris gryllus Amphiuma means quericus Bufo terrestris Desmognathus auriculatus Eleutherodactylus planirostris Eurycea quadridigitata Gastrophryne carolinensis Hyla cinerea Hyla crucifer Hyla femoralis Hyla gratiosa Hyla sQuirella Limnaoedus ocularis Notophthalmus perstriatus Notophthalmus viridescens Pseudacris nigrita Pseudacris ornata Pseudobranchus striatus areolata Rana catesbeiana Rana grylio Rana heckscheri Rana utricularia holbrooki Siren intermedia Siren lacertina HH = Hydric hammock habitat HS = Hydric swamp habitat CS = Cypress swamp habitat ST = Swamp thicket habitat Common Name Cricket frog Amphiuma Oak toad Southern toad Dusky salamander Greenhouse frog Dwarf salamander Narrowmouth toad Green frog Spring peeper Pinewoods tree frog Barking tree frog Squirrel treefrog Little grass frog Striped newt Penninsula newt Southern chorus frog Ornate chorus frog Dwarf siren Gopher frog Bullfrog Pig frog River swamp frog Leopard frog Spadefoot toad Lesser siren Greater siren Habitat Types HH HS CS ST c c u u c c u c u u u c cue c u c c c u u u u c c c u u u u u u u c u u u u c u u u u u u u u u c c u c u u u c c c u u u c = All species wetland dependent c = Common u = Uncommon = Possible but no data available

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TABLE A-3. Relative abundance of reptile species in Wekiva River Basin habitats. Scientific Name Agkistrodon piscivorus* Alligator mississipiensis* Anolis carolinensis Cemophora coccinea Chelydra serpentina* Cnemidophorus sexlineatus Coluber constrictor Crotalus adamanteus Deirochelys reticularia* Diadophis punctatus Drymarchon corais Elaphe guttata Elaphe obsoleta Eumeces egregius Eumeces inexpectatus Farancia abacura* Farancia erytrogramma* Gopherus polyphemus Heterodon platyrhinos Heterodon simus Kinosternon bauri* Kinosternon subrubrum* Lampropeltis getulus Lampropeltis triangulum Masticophis flagellum Micrurus fulvius Neoseps reynoldsi Nerodia cyclopion* Nerodia fasciata* Nerodia taxispilota* Opheodrys aestivus Ophisaurus attentuatus Ophisaurus ventralis Pituophis melanoleucus Pseudemys floridana* Common Name Eastern cottonmouth American alligator Green anole Scarlet snake Snapping turtle Six-lined racerunner Black racer E. diamondback rattlesnake Chicken turtle Southern ringneck snake Indigo snake Red rat snake Yellow rat snake Mole skink Five-lined skink Mud snake Rainbow snake Gopher tortoise Eastern hognose snake Southern hognose snake Striped mud turtle Florida mud turtle Florida king snake Scarlet kingsnake Eastern coachwhip Coral snake Sand skink Green water snake Banded water snake Brown water snake Rough green snake Slender glass lizard Eastern glass lizard Pine snake Florida cooter Habitat Types HH HS CS ST c u c u c c c c c c c c c u c c u c u u c c u u u u u u u c c u u u u u u u u u u u u u u u u u u u u u u c u c u c c u u

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TABLE A-3. Relative abundance of reptile species in Wekiva River Basin habitats (continued). Scientific Name Pseudemys nelsoni* Regina alleni* Rhadinaea flavilata Rhineura floridana Sceloporus undulatus Sceloporus woodi Scincella laterale Seminatrix pygaea* Sistrurus miliarius Sternotherus odoratus* Storeria dekayi Storeria occipitomaculata Tantilla coronata Terrapene carolina Thamnophis sauritus Thamnophis sirtalis Trionyx ferox* HH = Hydric hammock habitat HS = Hydric swamp habitat CS = Cypress swamp habitat ST = Swamp thicket habitat Habitat Types Common Name HH HS CS ST Florida red-bellied turtle Striped swamp snake Pine woods snake Florida worm lizard Southern fence lizard Florida scrub lizard Ground skink Black swamp snake Dusky pygmy rattlesnake Stinkpot turtle Brown snake Red-bellied snake Southeastern crowned snake Box turtle Ribbon snake Eastern garter snake Florida soft shell turtle c c = Wetland dependent species c = Common u = Uncommon u c u u u u u u u u u u u u u u u u u u u = Possible but nO data available u u u c u

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TABLE A-4. Relative abundance of bird species in Wekiva River Basin habitats. Scientific Name Accipiter cooperii Accipiter striatus Actitus macularia* Agelaius phoeniceus* Aimophila aestivalis sponsa* Ammodramus henslowii# Ammodramus leconteii*# Ammodramus savannarum Anas amaricana*# Anas clypeata*# Anas crecca*11 AruiS discors* fulvigula* Anhinga anhinga* Anthus spinoletta*# Aphelocoma coerulescens Aramus guarauna* Archilochus colubris Ardea herodias* Athene cunicularia Aythya collaris* Bombycilla cedrorum# Botaurus lentiginosus* Bubo virginianus Bubulcus ibis Buteo braCtryTUrus* Buteo jamaicensis Buteo lineatus* Butorides virescens* Cairina moschata* Calidris alba*# Calidris aJ)):ina*# Calidris mauri*# Calidris minutilla*# Common Name Cooper's hawk Sharp-shinned hawk Spotted sandpiper Red-winged blackbird Bachman's sparrow Wood duck Henslow's sparrow LeConte's sparrow Grasshopper sparrow American widgeon Northern shoveler Green-winged teal Blue-winged teal Mottled duck Anhinga Water pipit Scrub jay Limpkin Ruby-throated hummingbird Great blue heron Burrowing owl Ring-necked duck Cedar waxwing American bittern Great horned owl Cattle egret Short-tailed hawk Red-tailed hawk Red-shouldered hawk Green heron Muscovy duck Sanderling Dunlin Western sandpiper Least sandpiper Habitat Types HH HS CS ST c c u c c u u u c u c c c u c c c u c u u c c u u c c u c u c u c u u c u u u c u u u c u

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TABLE A-4. Relative abundance of bird species in Wekiva River Basin habitats (continued). Scientific Name Campephilus principalis* Caprimulgas carolinensis Caprimulgas vociferus# Cardinalis cardinalis Carduelis tristis# Carpodacus purpureus# Casmerodius albus* Cathartes aura Catharus Catharus guttatus# Catharus ustulatus# Ceryle alcyon* Chaetura pelagica Charadrius vociferus* Chordeiles minor Circus cyaneus* Cistothorus platensis*# Coccyzus americanus Colaptes auratus Colonus virginianus Columbina passerina Conotopus virens Coragyps atratus Corvus brachyrhynchos Corvus ossifragus* Cyanocitta cristata Dendroica caerulescens# Dendroica coronata# Dendroica discolor Dendroica dominica* Dendroica magnolia# Dendroica palmarum# Dendroica petechia Dendroica pinus Dendroica striata# Common Name Ivory-billed woodpecker Chuck will's widow Whip-poor-will Northern Cardinal American goldfinch Purple finch Great egret Turkey vulture Veery Hermit thrush Swainson's thrush Belted kingfisher Chimney swift Killdeer Common nighthawk Northern harrier hawk Sedge wren Yellow-billed cuckoo Common flicker Bobwhite Ground dove Eastern wood peewee Black vulture Common crow Fish crow Blue jay Black-throated blue warbler Yellow-rumped warbler Prairie warbler Yellow-throated warbler Magnolia warbler Palm warbler Yellow warbler Pine warbler Blackpoll warbler Habitat Types HH HS CS ST c c c c u c c c u u c c c c c c c u u u u c c c c c c c c u u u u c u c u u u u c c c c c c u u u c c c c u c c u u u u u u c c c c

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TABLE A-4. Relative abundance of bird species in Wekiva River Basin habitats (continued). Scientific Name Dendroica tigrina# Dryocopus pileatus* Dumetella carolinensis Elanoides forficatus* Empidonax virescens* Eudocimus albus* Euphagus carolinus*# Falco sparverius Florida caerulea* Fulica americana*# Gallinago gallinago*# Gallinula chloropus* Gelochelidon nilotica* Geothlypis trichas* canadensis* Haliaeetus leucocephalus* Himantopus mexicanus* Hirundo rustica Hydranassa tricolor* Hylocichila mustelina* Ixobrychus exilis* Lanius ludovicanus Larus delawarensis*# Laterallus jamaicensis* Leucophoyx thula* Limnodromus griseus*# Limnodromus scolopaceus*# Limnothlypis swainsonii* Lophodytes cucullatus* Melanerpes erythocephalus Meleagris gallopavo* Melospiza georgiana*# Melospiza melodia# Mimus polyglottus Mniotilta varia# Common Name Cape May warbler Pileated woodpecker Gray catbird Swallow-tailed kite Acadian flycatcher White ibis Rusty blackbird American kestrel Little blue heron American coot Common snipe Common gallinule Gull-billed tern Common yellowthroat Sandhill crane Bald eagle Black-necked stilt Barn swallow Tricolored heron Wood thrush Least bittern Loggerhead shrike Ring-billed gull Black rail Snowy egret Short-billed dowitcher Long-billed dowitcher Swainson's warbler Hooded merganser Red-bellied woodpecker Turkey Swamp sparrow Song sparrow Mockingbird Black and white warbler Habitat Types HH HS CS ST c c u c c u u c c c u u c u u c u u c c c c u c c u u c u c u c c c u c c u c c u u c u c u c c u u u u u c c c u

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TABLE A-4. Relative abundance of bird species in Wekiva River Basin habitats (continued). Scientific Name Molothrus Mycteria americana* Myiarchus crinitus* Numida meleagris Nycticorax nycticorax* Nycticorax violacea* Otus asio ----Pandion haliaetus* Parula americana* Parus bicolor Parus carolinensis Passer domesticus Passerculus sandwichensis*# Passerina cyanea Phalacrocorex auritus* Pheucticus ludovicianus# Picoides borealis Picoides pubescens Picoides villosus Pipilo erthophthalmus Piranga rubra Plegadis falcinellus* Pluvialis squatarola*# Podilymbus podiceps* Polioptila caerulea Pooecetes gramineus# Porphyrala martinica* Porzana carolina*# Progne subis* Protonotaria citrea* Quiscalus major Quisculus guiscula Rallus elegans* Rallus limicola* Regulus calendula# Common Name Brown-headed cowbird Wood stork Great-crested flycatcher Guinea fowl Black-crowned night heron Yellow-crowned night heron Screech owl Osprey Northern parula Tufted ti tmouse Carolina chickadee House sparrow Savannah sparrow Indigo bunting Double crested cormorant Rose-breasted grosbeak Red cockaded woodpecker Downy woodpecker Hairy woodpecker Rufous-sided towhee Summer tananger Glossy ibis Black-bellied plover Pied-billed grebe Blue-gray gnatcatcher Vesper sparrow Purple gallinule Sora Purple martin Prothonotary warbler Boat-tailed grackle Common grackle King rail Virginia rail Ruby-crowned kinglet Habitat Types HH HS CS ST c c c c c c c c c c c c c u u c c c c c c c c u c c c c u c c c c c c u c c c u c c u c u c c c u c c c u c

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TABLE A-4. Relative abundance of bird species in Wekiva River Basin habitats (continued). Scientific Name Rostrhamus sociabilis* Rynchops niger* Sayornis phoebell Scolopax minor* Seiurus aurocapillusll Seiurus motacilla* Seiurus noveboracensis*1I Setophaga ruticilla Sialia sialis Sphyrapicus variusll Spizella passerinall Sterna antillarum* Sterna forsteri* Strix varia* Sturnella magna Sturnus vulgaris Tachycineta bicolor*1I Thryothorus ludovicianus Toxostoma rufum Trigna flavipes*1I Trigna melanoleuca*# Troglodytes aedonll Turdus migratorius Tyrannus tyrannus Tyto alba Vermivora celatall Vermivora ruficapillall Vireo flavifrons Vireo griseus Vireo olvaceous Vireo solitarius# Wilsonia citrina* Zenaida macroura Zonotricha albicollisll HH = Hydric hammock habitat HS = Hydric swamp habitat CS = Cypress swamp habitat ST = Swamp thicket habitat Common Name Everglades kite Black skimmer Eastern phoebe American woodcock Ovenbird Louisiana waterthrush Northern water thrush American redstart Eastern bluebird Yellow-bellied sapsucker Chipping sparrow Least tern Foster's tern Barred owl Eastern meadowlark European starling Tree swallow Carolina wren Brown thrasher Lesser yellowlegs Greater yellowlegs House wren American robin Eastern kingbird Barn owl Orange-crowned warbler Nashville warbler Yellow-throated vireo White-eyed vireo Red-eyed vireo Solitary vireo Hooded warbler Mourning dove White-throated sparrow II = Migrant species Habitat Types HH HS CS ST c u c c u c c c c c c c c u u u c c c c c c u u u u cue u c c c u u u c c u u c cue c c u c c c u c u u c = Wetland dependent species c = Common u = Uncommon = Possible but no data available

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TABLE A-S. Relative abundance of mammal species in Wekiva River Basin habitats. Scientific Name Blarina carolinensis CryPtotis parva Dasypus novemcinctus Didelphis virginiana Eptesicus fuscus Geomys pinetis Glaucomys volans Lasiurus intermedius Lasiurus seminolus Lutra canadensis* rufus Mephitis mephitis Mustela frenata Myotis austroriparius Neofiber alleni* Neotoma floridana Nycticeius humeralis Ochrotomys nuttalli Odocoileus virginianus Oryzomys palustris* Peromyscus floridanus Peromyscus gossypinus Peromyscus polionotus Pipistrellus subflavus* Plecotus rafinesguii Procyon lotor* Reithrodontomys humulis Scalopus aguaticus Sciurus carolinensis Sciurus niger Sigmodon hispidus Spilogale putorius Sorex longirostris Sus scrofa EG2fvilagus floridanus Common Name Short-tailed shrew Least shrew Armadillo Opossum Big brown bat Pocket gopher Flying squirrel Yellow bat Seminole bat River otter Bobcat Striped skunk Long-tailed weasel Southeastern myotis bat Florida muskrat Wood rat Evening bat Golden mouse White-tailed deer Rice rat Florida mouse Cotton mouse Oldfield mouse Southern pipistrele bat Eastern big-eared bat Raccoon Eastern harvest mouse Eastern mole Gray squirrel Fox squirrel Cotton rat Spotted skunk Southeastern shrew Feral pig Cottontail rabbit Habitat Types HH HS CS ST u c u c c u c c c c u c c c u c u u c u u u u c c u u c u c c c c c c c c u c u u c u c c u u u c u c c c c c

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TABLE A-S. Relative abundance of mammal species in Wekiva River Basin habitats (continued). Scientific Name Sylvilagus palustris* Tadarida brasiliensis Trichechus manatus* Urocyon cinereoargenteus Ursus americanus* Vulpes vulpes HH HS CS ST = = = = Hydric hammock habitat Hydric swamp habitat Cypress swamp habitat Swamp thicket habitat Habitat Types Common Name HH HS CS ST Marsh rabbit Free-tailed bat West Indian manatee Gray fox Black bear Red fox c c = Wetland dependent species c = Common u = Uncommon u u c = Possible but no data available c

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TABLE A-6. Designated plant and animal species of the Wekiva River Basin. Scientific Name Plants Bonamia grandiflora Dennstaedtia bipinnata Dryopteris ludoviciana Encyclia tampensis Habenaria repens Nemastylis floridana Ophioglossum palmatum Phlebodium aureum Rhapidophyllum hystrix Sabal minor Spiranthes sp. Thelypteris hispidula Thelypteris interrupta Thelypteris ovata Tillandsia fasciculata Tillandsia setacea Tillandsia utriculata Zamia floridana Invertebrates Aphaostracon asthenes Aphaostracon monas Gincinnatia parva Gincinnatia ponderosa Cincinnatia wekiwae Procambarus acherontis Amphibians Rana areolata Reptiles Alligator mississipiensis Drymarchon corais couperi Gopherus polyphemus Neoseps reynoldsi Pituophis melanoleucus mugitus Sceloporus woodi Common Name Florida bonamia Cuplet fern Florida shield fern Butterfly orchid Water spider orchid Fall-flowering ixia Hand adder's tongue fern Golden polypody Needle palm Bluestem palmetto Ladies tresses Hairy tri-vein fern Spready tri-even fern Ovate maiden fern Stiff-leaved wildpine Needle-leaved wildpine Giant wildpine Florida coontie Blue spring aphaostracon Wekiwa spring aphaostracon Blue spring snail Ponderous spring snail Wekiwa spring snail Orlando cave crayfish Gopher frog American alligator Eastern indigo snake Gopher tortoise Sand skink Pine snake Florida scrub lizard Designation A E E T T T E E T T T T T T C T G G B URI UR2 UR5 UR5 UR2 UR2 UR2 UR2 UR2 UR SSC UR2 SSG T T T SSC UR2 T UR2 SSC UR2 UR2 C II II II II II

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TABLE A-6. Designated plant and animal species of the Wekiva River Basin (continued) Scientific Name Birds Aimophila aestivalis Aphelocoma coerulescens coerulescens Aramus guarauna Athene cunicularia Campephilus principalis Circus cyaneus Falco sparverius paulus Falco sparverius sparverius Florida caerulea canadensis pratensis Haliaeetus leucocephalus Hydranassa tricolor Leucophoyx thula Mycteria americana Pandion haliaetus Picoides borealis Rostrhamus sociabilis Sterna antillarum KaaDals Lutra canadensis rufus Mustela frenata penninsulae Myotis austroriparius Neofiber alleni Peromyscus floridanus Peromyscus polionotus decoloratus Plecotus rafinesguii Sciurus niger shermani Trichechus manatus latirostris Ursus americanus floridanus DESIGNATION: Common Name Bachman's sparrow Florida scrub jay Limpkin Burrowing owl Ivory-billed woodpecker Marsh hawk American kestral Eastern kestral Little blue heron Florida sandhill crane Bald eagle Tricolored heron Snowy egret Wood stork Osprey Red cockaded woodpecker Snail kite Least tern River otter Bobcat Florida weasel Southeastern myotis bat Florida muskrat Florida mouse Pallid beach mouse Eastern big-eared bat Sherman's fox squirrel West Indian manatee Florida black bear Designation A T SSC SSC B URZ T E E C II II T UR2 II II SSC T II T E I SSC SSC E E T II T E T E E URZ UR2 URZ SSC UR2 E UR3 URZ SSC URZ E E T URZ II II I A = Florida Game and Fresh Water Fish Commission (animals) or Florida Department of Agriculture and Consumer Services (plants) B = United States Fish and Wildlife Service C = Convention on International Trade in Endangered Species (CITES)

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CODES: E = Endangered T = Threatened SSC = Species of special concern C = Commercially exploited I = Appendix I species II = Appendix II species URl = Under review for federal listing, with substantial evidence in existence indicating at least some degree of biological vulnerability. UR2 = Under review for listing, but substantial evidence of biological vulnerability and/or threat is lacking. UR3 = Still formally under review for listing, but no longer being considered for listing due to existing pervasive evidence of extinction. UR5 = Still formally under review for listing, but no longer considered for listing because recent information indicates species is more widespread or abundant than previously believed.



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Final Report AN EVALUATION OF THE APPLICABILITY OF UPLAND BUFFERS FOR THE WETLANDS OF THE WEKIVA BASIN Mark T. Brown and Joseph M. Schaefer, Principal Investigators with K. H. Brandt, S. J. Doherty, C. D. Dove, J. P. Dudley, D. A. Eifler, L. D. Harris, R. F. Noss, and R. W. Wolfe October, 1987 Center for Wetlands University of Florida Gainesville, Florida 32611 ( 904) 392 -2424

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Acknowledgements The authors wish to express their appreciation to the staff of the Center For Wetlands, for their dedication and service way beyond the call of duty. Their attitude made completion of this report so much easier. Specifically, Jenny Carter, Staff Assistant, coordinated personnel and somehow managed to get the report finalized under difficult odds. Linda J. Crowder processed all the words over and over again as we edited and polished. Carol Cox proofread each draft. Stephen Roguski, our expert draftsperson, drafted the figures. Karla Brandt not only helped with research and writing, but did a fantastic job of final editing. Steven Tennenbaum devoted two days to derivations of the Theis Equation. We thank you for your energy. Ms. Sidney Brinson, spent a day in the field with the authors explaining the Districts methodology for wetlands determination. Staff from the Florida Department of Natural Resources, especially Ms. Deborah Shelly, provided support and transportation, Glenn Lowe, Chief Environmental Specialist a the St. Johns River Water Management District was project manager for the District and was extremely patient and effective in his support. ii

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Florida Statutes. In 373.413 and 373.416 a distinction is drawn between permits for construction and permits for operation and maintenance of water management systems. Both kinds of permits require that such systems cannot be harmful to the water resources of the District. Operation and maintenance permits are subject to an additional criterion: such activities cannot be inconsistent with the overall objectives of the District. Using one standard for construction and two for operation and maintenance is confusing. Operation and maintenance cannot be separated from construction, since once constructed, a system normally will be operated. Or to put it another way, if constructed, it seems backwards to then evaluate a permit for operation and find a system inconsistent with District objectives. Such a finding should be made prior to construction so that the project may be altered or redesigned to conform to District objectives. Thus, in our view, the review process for construction permit applications must also include operation and maintenance concerns. The District needs to review whether the constructed system will be harmful to the water resources and whether it will be consistent with the District's overall objectives during the construction permit review process. The second issue is related to the definition of "water resources." We believe that one cannot separate the waters of the District from the overall aquatic system when determining harm to the resource. The water resource must include not only the abio:ic substance (H20), but also the other abiotic substances and the biotic organisms that are carried and sustained by it. The water resource cannot be artificially dissected into parts which are regulated separat1y (although it is attempted quite often, much to the detriment of the resource); for as the water goes, so the organisms, and vice-versa." iv

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TABLE OF CONTENTS Acknowledgements . . . ii Preface iii I. INTRODUCTION .1 A. The Concept of Buffer Zones. .1 B. Buffers for Wetlands, Wildlife, and Water Quality. .2 C. Intent and Scope of the Report .5 II. REVIEW OF THE LITERATURE. .7 A. Significance of Buffer Zones 1. Ecological Significance of Transition Zones 2. Physical and Ecological Significance of Wetland 3. Water Quality Benefits of Buffer Zones. 4. Water Quantity Benefits of Buffer Zones .... 5. Edge Effects on Wildlife ... 6. Regional Habitat Needs of Wildlife: Corridors. 7. Between-Habitat Needs of Wildlife 8. Within-Habitat Needs of Wildlife. B. Review of Buffer Zone Regulations. C. Summary: Resource Buffer Zones III. LANDSCAPE ECOLOGY OF THE WEKIVA RIVER BASIN A. Landscape Perspective .. 1. Physical Description 2. Biological Description .7 7 Forest Edges. 11 14 23 26 33 38 44 50 59 67 67 67 74 B. Wetland Communities ................. 82 1. Aquatic/Marsh Communities ............... 82 2. Mixed Hardwood Swamp Community .84 3. Hydric Hammock Community. ......... 86 C. Transitional Communities: Mesic Hammock and Scrubby Flatwoods. 87 D. Upland Communities 87 1. Pine Flatwoods Communities. 88 2. Wet Prairie Communities. 90 v

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3. Pine Sandhill Communities. 4. Sand Pine Scrub Communities IV. STATUTORY & DISTRICT CRITERIA RELATED TO BUFFER ZONES A. Statutory Criteria, Sections 373.413 & 373.416, FS B. Rule Criteria, 40C-4, 40C-41 and 40C-42, FAC V. DETERMINATION OF BUFFER ZONE REQUIREMENTS 90 92 95 96 98 .111 A. Overview of the Methodology for Determination of Buffer Zones. .111 B. Determining Buffer Zone Requirements .118 C. Illustration of Buffer Zone Determinations .128 LITERATURE CITED .145 APPENDIX A. WILDLIFE ASSOCIATED WITH WEKIVA RIVER BASIN .169 vi

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I. INTRODUCTION I.A. The Concept of Buffer Zones The landscape is a mosaic of uplands and wetlands, developed lands and natural lands, and forests and fields. Somehow, without complete knowledge about how these pieces fit together, society must make decisions concerning how best to assemble the puzzle. Some decisions are easier than others, especially when there are no conflicting elements. Unlike a puzzle, however, the ease of adding a new land use to the landscape is inversely related to the number of pieces already on the board. As more and more land uses are added to the landscape, the decisions concerning placement require more and more thought. The more pieces there are on the board, the more conflicts there will be between pieces. Most often, it is at the borders between pieces where conflicts arise. Decisions are easier to make when adjoining uses are not significantly different, i.e., when the existing land uses abutting the boundaries of a decision piece are similar to the proposed use of the piece in question. However, when adjoining uses significantly different, consideration must be given to the interrelationships that are being created and to how one piece might affect surrounding pieces. When uses are significantly different, or where the potential for conflict is serious, it is common practice to create a buffer between them. Thus we have buffers around airports, nuclear power plants, and bombing ranges. Demilitarized zones (DMZ's) between warring nations are often used to maintain peace. Zoning in urban areas uses successively lower-density districts to make 1

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2 transitions between high-density land uses and low-density residential districts. Buffer zones can be relatively narrow, like the grassed shoulders of highways which separate high-energy roads from forested landscapes, or quite wide, like the DMZ between North and South Korea. Generally, as the density of activity or the potential for conflict increases, the width of the buffer necessary to contain the negative effects increases proportionally. In addition, as the difference in activity level between bordering land uses increases, the width of the border must increase, since it is not the absolute magnitude of activity but rather the relative magnitudes of activity between neighboring uses that require buffering. I.B. Buffers for Wetlands, Wildlife, and Water Quality The differences between developed lands and wild lands are significant; the more intensely developed, the more the differences. Frequently, on developed lands the native vegetation is removed and replaced with exotics, drainage is improved, soil is compacted or covered with impervious materials, wildlife habitat is replaced with human habitat, and activity levels increase 10 to 100 times those found in the wild. The gradient in the intensity of nOise, wastes, temperature, light, structure, and activity from undeveloped to developed lands is remarkable. It is this gradient that affects the edge between developed and wild lands, creating a new environment unlike the original and not at all similar to the developed land. The edge between wild lands and developed lands is characterized by overflows of materials and energy that "flow" from high density to low. Water runs off developed land, carrying sediments and nutrients. Noise from developed land intrudes into the edge, disrupts natural activity, and interferes with the less intense communications of wildlife that are cues for

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3 territorial protection and breeding. Increased temperatures caused by removing tree canopy and paving the ground surface have marked effects on the forest microclimate. Edges are common in the landscape, with or without development. In the wild landscape, however, sharp edges are hard to find. The lake edge is not a clean line; as the water level rises and falls throughout the year, it creates a littoral zone that is neither open water nor dry land, but somewhere in between. The sea edge is buffered by estuaries and coastal wetlands, which are neither open ocean nor dry land. The forest edge is a transition from the mature canopy with moist soils and minimal understory through a zone of more open canopy, with drier soils and dense understory, to the prairie with its xeric soils and lack of woody vegetation. As the landscape is developed, the wild lands that surround cities retreat. If the world was a homogeneous flat plain and development happened as a simple outward progression from the central city, the edge would constantly be moving and little need would be generated for buffer zones between developed lands and undeveloped lands. However, the world is not homogeneous, but heterogeneous, having many differences, many patches, and many obstructions to development. The development process becomes patchy, areas are skipped, wetlands left, and parks created. Areas are set aside as wildlife habitat, or protected for water quality purposes, or left undeveloped as remnants to remind us of what the landscape was once like. The patches that are created in this manner undergo constant change as they "evolve" or succeed toward ecological communities that are islands in the developed landscape. In Florida, under continuing growth pressure, the wild landscape has been mostly developed, leaving behind large and small islands of managed national, state, and local parks, along with many wetlands. Wetlands were first left

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4 behind because their development required a relatively greater commitment of funds and time than they were worth. Where the demand was high, in coastal areas for instance, wetlands were converted into dry lands and developed. Development skirted the swamps and marshes of inland areas not as a result of comprehensive planning, but because of piecemeal decisions made on a projectby-project basis. As land became more valuable and wetlands were threatened, state and local governments responded to increased pressure by enacting laws to protect the special values of wetlands recognized by society. Of primary concern was their function for maintaining clean, productive surface water and their value as very productive wildlife habitat. In the minds of many, wetlands are now "protected." The Warren S. Henderson Wetlands Protection Act of 1983 established state permitting authority over activities in wetlands by virtue of the fact that they were defined as waters of the state. A methodology for determining state waters, developed as a rule (Ch. 17-4 FAC) by the Florida Department of Environmental Regulation, was required by the Henderson Act. The rule uses vegetation as a means of determining landward extent of state waters. Plant species normally found in wetlands are sorted into three broad categories: submerged species, transitional species, and "invisible" species. All plants not found on these plant lists are considered upland species. The rule then uses simple formulas that relate dominance of these species to determine the upland edge of "state waters. II It is import-ant to note that at no time does the rule or the original legislation (except in the name of the Act) delineate "wetlands". It only refers to a selective list of plant species. The intent of the rule and legislation is to protect state waters, which include areas that are dominated by certain plant species that indicate regular and periodic inundation. Wetlands can, and do, extend landward of this jurisdictional line.

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5 The area immediately adjacent to and upland of the jurisdictional line is often a transition zone between wetlands and uplands. It is a zone that is wetland at times and upland at times, exhibiting characteristics of each and vegetated by species that are found in each. It is important to both the wetland and the upland as a seed reservoir, as habitat for aquatic and wetlanddependent wildlife species, as a refuge to wildlife species during high-water events, and as a buffer to the extreme environmental conditions of sharp vegetated edges. To protect the values and functions of areas that are waterward of the jurisdictional line, attention must be given to the area immediately upland of the line. Wholesale alteration of this edge has immediate and potentially large-scale permanent impacts on the waterward area. Wetland-dependent wildlife species that are frequent users of this area are excluded, silt laden surface waters are no longer filtered, the microclimate is greatly affected and groundwaters may be diverted or drained. In the natural state the transition zone is a buffer zone both for the adjacent wetland and state waters and for the wildlife species that inhabit them. It should be recognized as such, and afforded some degree of development control. I.C. Intent and Scope of the Report This report is intended to provide a detailed review of the existing scientific understanding of upland buffer zones, their importance to the adjacent wetlands and waters, and the effects of alterations of these transitional areas on downstream water quality and quantity, and wetland wildlife habitat values. As we researched the topic, we found a dearth of information directly addressing buffer zones. However, there has been much recent interest in the literature concerning the impacts of edges on wildlife

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6 habitat values, and some recent investigations of the extent and species composition of transitional zones between wetlands and uplands. The habitat values of transitional areas are related to between and within habitat needs of wildlife, the water quality values of buffer zones are related to protection of surface and groundwater, and their value related to water quantity issues is in their ability to mitigate adverse drainage impacts. The report is organized in five parts with an appendix that gives lists of aquatic and wetland-dependent wildlife species that are characteristic of the Wekiva Basin. After the Introduction, the second section reviews the literature and summarizes and relates it to the concept of a resource buffer zone. The third section gives a brief physical and ecological description of the Wekiva Basin. The fourth section reviews the Water Management District's statutory criteria (Chapter 373 FS) and permit criteria in 40C-4, 40C-41, and 40C-42 FAC and relates them to protection of the water resources of the Basin. The fifth section develops a methodology for determining buffer zone requirements.

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II. REVIEW OF THE LITERATURE II.A. Significance of Buffer Zones II.A.l. Ecological Significance of Transition Zones The zone that lies between what are unconditionally identified as uplands and wetlands is a zone of transition (sometimes called an ecotone). In this zone, environmental conditions resemble neither the true wetland nor upland, but fluctuate and may resemble each during different times of the year or from one year to the next. Plant species that characterize transition zones may be an assemblage of both wetland species and upland species and may contain species that are not found in either of the two adjacent zones. It has long been held that highest species diversity occurs in areas of habitat overlap (MacArther and Pianka 1966, Allen 1962, Ranney 1977). The Florida Department of Environmental Regulation (FDER), in its rules concerning the delineation and definition of landward extent of waters of the state, recognizes three main catagories of plants: submerged, transitional, and "invisible" species (Ch. 17-4.022 FAG). In an area dominated by transitional species, a preponderance of evidence that indicates it is regularly inundated is necessary before the area is considered a state water. In other words, without regular inundation, an area dominated by transitional species is not considered state waters, and by inference, therefore not a wetland. Under 17-4.022 FAG, Florida does not recognize purely transitional areas as state waters, and as a result does not recognize them as important or necessary for protection under the Warren S. Henderson Wetlands Protection Act 7

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8 (Chapter 430 Florida Statutes). However, their ecological significance as wildlife habitat and seedbanks, as well as their role in maintaining the integrity of the adjacent wetland community, is unrelated to their classification under 17-4.022 FAC. The FDER has chosen a cut-off based on dominance of "submerged" species to delineate state waters. The line so determined in most cases classifies all vegetation to the landward side as uplands. Most transition zones are to the landward side of the FDER jurisdictional line. The role of transition zones as wildlife habitat for wetland-dependent species will be reviewed in subsequent sections, as well as their role as seedbanks. Generally, their ecological value stems from (1) direct use by wildlife and (2) seed sources for plant species that are more upland in growth reqUirements, yet are found within wetlands and are an important component of the community. Transition zones occupy the key upland fringe and as a result are the main source for seed material that contributes to the spatial heterogeneity of wetlands. Wetland communities are not homogeneous. They are heterogeneous communities whose spatial variation in species composition is probably controlled by topography and ultimately by periods of inundation. Higher areas sometimes referred to as hummocks range in size from a few meters to several hectares. Hummocks have fewer periods of inundation and water depths are shallower, resulting in conditions that favor more "mesic" species. Lower areas are favored by those species that are to] ,.:, ant of flooding. This heterogeneity of the wetland landscape is (,r.,e of tte key fc:ctcrs that gives it its diversity and wildlife value. Wildlife values are greatly enhanced as a result of the increased diversity of vegetation and undulating topography.

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9 Studies of the Florida landscape indicate that the plant species diversity in transition zones is higher than the diversity of either the adjacent wetland or upland. Clewell (1982) found five community types on the Alafia River in central Florida along a gradient from wet to dry of which the "Moist Mesic Forest" seems to occupy that area that is transitional. The number of plant species found in this community exceeded all others by 25%. In Gross's (1987) study of 12 small-stream floodplain ecosystems in north and central Florida, 12 vegetation types were distinguished, using cluster analysis of which the three most diverse appeared to occur most often in the transitional areas. Studying methods for determining transition zones, Hart (1984) documented species composition of the wetland to upland continuum of eight wetland community types of north central Florida. She found that the transition zones were more diverse than either the wetland or upland and were different physiognomically from adjacent wetlands, yet were ... aligned more closely with wetlands than with uplands and were composed of species that tended to alternate between wetland and transition zones." The width of transition zones varied from a minimum of 10 m to a maximum of 30 m depending on the method used to delineate the zone and the type of wetland. Wildlife species richness shows direct spatial relationships to the increased of transition zones. Studies of forest edges (see Edge Effects on Wildlife) have documented increases in species richness and density of individuals within ecotones between habitats. Vickers et a1. (I 985) found that species richness and abundance of herpetofauna were greater along the edges of six wetlands in north central Florida than in either the wetland or upland habitat. Harris and Vickers (1984) found that virtually all mammals, because of their cursorial mode of locomotion and frequently herbivorous food habits, reside in "peripheral" areas, i.e., the transition zones. When water

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10 levels were increased, the movement of wildlife to the peripheral areas was also increased, suggesting the important role that transition zones play in providing refuge from wet-season increases in water levels in wetlands. The ecotone seems to play an even more important role when surrounded by clearcuts. Harris and McKlveen (1982) found a greater abundance and diversity of breeding birds in the ecotone between cypress wetlands and clearcut areas than in the ecotone between cypress and pinelands. Classifying the bottomland hardwood ecosystem into five classes, Wharton et al. (1981) represented the transition to upland communities as the fifth class. They listed the importance of environmental factors to fauna in each zone. Of the five classes, the transitional zone ranked highest in importance overall and highest in 18 of 27 factors, among which are: 1. Retardation of "side flooding," 2. Detritus source, 3. Diversity of oaks, 4. Availability of large variety of flora and fauna, S. Diversity of forest strata, 6. Refuge from high water, and 7. Forage and cover for upland species. The importance of the highest zones (transitional zones) of bottomland hardwoods to detrital food chains of downstream systems has been documented (Livingston et al. 1976, White et al. 1979). These studies showed that the infrequent pulses of organic matter and detritus form the higher zones in the floodplain after extreme flood and rainfall events correspond to peaks in fish production. Topography plays an important role in controlling the width of transition zones. The transition zone between wetland and upland may be only a few meters in width or may extend for several hundred meters. In areas of very low relief, where the landscape has little or no slope, the transition zone may be extensive and ill-defined; yet, in landscapes where slopes are more prominent,

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11 the transition from upland to wetland may be far more abrupt. In studies of the central Florida landscape (Brown et al. 1984, 1985, and 1986), transition zones as wide as 30 m were delineated using species composition as the controlling variable. Gross (1987) found community types using cluster analysis that were dominated by transition zone vegetation on central Florida streams as wide as 80 m, but 40-m zones were more common. II.A.2. Physical and Ecological Significance of Wetland Forest Edges When forest is cleared and some forested remnants are left, as when the landscape is developed for agriculture or urban uses or clearcut during silviculture operations, the remaining forested patches contain induced edge where there once was a forest continuum. These forested tracts develop characteristic edge habitats that differ from habitat of interior forests. Ranney (1977), in a review of the literature on forest island edges, suggested that edge habitat differed from interior forests in at least six ways: 1. Tree species composition, 2. Primary production, 3. Structure, 4. Development, 5. Animal activity, and 6. Propagule dispersal capabilities. The importance of edge is in its effects on the forested habitat and eventually on the suitability of the habitat for indigenous fauna. The conditions created when the forest continuum is cleared have detrimental long term consequences on the remaining forest system. Using current jurisdictional lines (Gh. 17-4.022 FAG) to determine the landward extent of state waters and given current development practices, the forest edge created between wetland and developed upland will coincide with the jurisdictionally determined line of regularly inundated wetland. In most instances this does not include transitional zones to the landward side of the jurisdictional line. The

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12 creation of an edge at this wetland/"upland" boundary opens the wetland to the many changes associated with edge conditions. When a forested edge is created through clearing and/or partial removal of the forest canopy, steep gradients of solar radiation, temperature, wind speed, and moisture are incurred between the relative extremes of the open land and the forest interior (Wales 1967, 1972). Studies of characteristics of newly created edges (Gysel 1951, Swift and Knoeerr 1973, Trimble and Tryson 1966, Wales 1972, 1976) suggest that solar radiation is probably the most important physical parameter influencing conditions at the forest edge. The forest edge environment is characterized by increased solar radiation which in turn increases temperatures and decreases moisture content of soils and relative humidity when combines with effects of increased wind flows. Physical and structural manifestations of these changes include increase of shadeintolerant, xeric tree and shrub species and an increase of species associated with early stages of succession (Gysel 1951, Trimble and Tryson 1966, Wales 1972) Of particular importance is the effect of increased wind speed on the newly created forest edge; especially when the edge is created at the wetland/upland interface. A major consequence of clearcutting is the loss of buffering of destructive wind speeds by the adjacent tree canopy. Tree windthrows are common along newly created edges since edge trees not exposed to wind velocities of the open landscape are not structurally prepared for them. Wetland trees do not have deep-rooted growth habits, but instead rely on a root mat very near the soil surface to provide structural support in the relatively low bearing-capacity soils of most swamps. Wind throws are relatively more common in the deep organic soils of wetland ecosystems than in forested upland

PAGE 19

communities because of soil instability and difficulty of trees to anchor sufficiently. 13 The spatial effects of forest edge conditions are variable and are highly dependent on the way the edge is maintained. Ranney (1977) summarizes the spatial influences of newly created edges as between 5 and 20 m deep from the forest edge toward the interior. In a study of microclimate on Ft. George Island near Jacksonville, Florida, Hart (1985) determined that most of the microclimatic change between cleared areas and a forest interior in north and south directions occurred within 10 m of the edge, although on western facing edges, 25 m was often required for equivalent microclimatic change. Hart notes that the eventual closure of newly created edges by shrubs and vines will ameliorate negative microclimatic conditions and suggests the planting of fastgrowing shrub species in some instances to speed up edge closure. Harris (1984) discusses the "three-tree-height" rule of thumb for the distance over which climatic effects of a surrounding clearcut will penetrate into an oldgrowth stand. Related to average tree heights of Florida wetland ecosystems, the three-tree-heights rule would suggest the penetration of influences as deep as 70 m. Conceptually, to maintain the integrity of the wetland community and to insure faunal habitat for wetland-dependent species, buffers from 5 to 70 m ,n depth are necessary. Clearing at the wetland edge opens the wetland to significant changes. However, with a buffer that encompasses the transitional zone on the landward side of the wetland, negative impacts can be avoided. Changes in abiotic parameters (due especially to increased solar radiation and wind) towards more xeric conditions along edges lead to corresponding changes in plant and animal communities (see Table 9 in Lovejoy et al. 1986) and in system properties such as nutrient cycling (Ranney 1977). Studies by

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14 Levenson (1981) and Ranney et al. (1981) in Wisconsin have documented major edge effects on the vegetation of forest islands. They found that climatic structural edge influences extend at least 10 to 15 m into a forest on the east, north, and south sides and 30 m on the west side. Once established, characteristic edge associations composed of xeric-adapted and shade-intolerant species act as sources of propagules that invade the forest interior; forest islands below a certain size (about 5 ha in Wisconsin) may be entirely edge habitat in terms of their flora and vegetation structure (Ranney et al. 1981). Such changes may be essentially permanent. In Ohio, Whitney and Runkle (1981) found that small but persistent environmental differences associated with forest edges have greater long-term effects on tree species composition and structure than did severe but relatively brief disturbances associated with logging. II.A.3. Water Quality Benefits of Buffer Zones The water quality benefits of buffer zones are related to the ability of the zone to abate destructive water velocities and quantities of pollutants carried by surface runoff from uplands that may have a negative impact on downstream water quality, flora, and fauna. Soils of transitional areas are generally characterized by a low accumulation of organic matter (Gross 1987, Clewell 1982) but have accumulations of organic debris on the order of 1 to 5 tons per ha, depending on vegetative cover (Hewlett 1982). This organic debris can absorb about 98% of rainfall energy, minimizing erosion potential. Known as litter detention storage, it disperses the energy of water that would otherwise break bonds of soil materials and produces a slurry of mud and eroded soil. The kinetic energy of sediment transport increases rapidly as the second power of water velocity (Hewlett 1982) suggesting that as a slope increases or

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15 loses obstructions (such as vegetation) to uninterrupted flow, erosion potential increases dramatically. occupying topographic lows in the landscape, wetlands are particularly susceptible to erosional deposition from higher grounds and to erosional scouring as a result of increased water velocities from mismanaged upland surface waters. Maintaining undisturbed vegetation in transition zones can help to minimize these destructive forces. The Florida Division of Forestry's Silviculture Best Management Practices (BMP) Manual 1979) recommends a Discretionary Zone (DZ) for land occurring within 300 ft of a watercourse. This 300-foot-wide strip of land is considered the zone most influential to surface water quality. Recommendations are given for varying site sensitivities regarding the intensity level of activities such as construction of roads, site preparation, and harvesting practices. Within the DZ, two Streamside Management Zones (8MZ) are further delineated: a fixed primary and a variable secondary zone, each of which has been assigned special management criteria. The primary zone is 10 m from the edge of the watercourse ,1 while the secondary zone is from 10 to about 50 m from the water's edge. The width of the secondary zone is determined by the soil and topographic characteristics of the site. Within each of the 8MZ's, recommendations for site preparation and harvesting are given relative to slope and soil erodibility. Since the main objective of Silviculture BMP's is to minimize negative impacts on water quality, and since silviculture, by definition, is the l80metimes the border of the 8MZ's are referred to as ..... the edge of the watercourse or lake ..... (Florida Division of Forestry 1979); other times the 8MZ is "adjacent to perennially open waters" (Riekerk and Winter 1982); still others as a II strip of forest land surrounding all perennial streams and lakes 10 acres or larger" or as "a vegetated strip adjacent to a watercourse ... or as occurring ... along all perennial and intermi ttent streams ..... (Florida Division of Forestry 1979). A strict definition of the watercourse's edge as related to 17-4 FAC may be important to help determine from what point the 8MZ should be applied.

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16 management of forests for their wood fiber, the BMP's are designed to maximize the forest area that can be harvested. If the goal was to minimize negative impacts on state water resources,2 the primary and secondary zones would begin at the wetland edge and extend upland. In this manner the zones would occupy the area that is commonly termed the transition zone between upland and wetland and would insure minimum impacts to state waters. It is generally agreed that the more sensitive a site is to sediment production, the wider the undisturbed vegetative buffer should be. Since sediment production can result in the deposition of materials in locations where they may have negative impacts, and since sediments provide a major vehicle by which pollutants are transported, every effort should be made to encourage the use of vegetative buffers to minimize sediment deposition in wetlands and water courses. The width and efficiency are variable. Karr and Schlosser (1977), relying on the work of Trimble and Sartz (1957), suggest a minimum width of buffers for conditions encountered in IImunicipal conditions" as 15 to 20 m for lowest (0 to 3%) slopes and as high as 80 m for slopes of 60%. There has been much research on the effects of logging in close proximity to streams, especially in the northwest United States. Erman et a1. (1977), in of logged landscapes with and without streamside buffers, found that buffers were very important in minimizing negative impacts as a result of erosion from logged lands, and that streams with narrow (less than 30 m) buffers showed effects comparable to streams with no buffers. Generally, their 2Waters of the state are those lands that are regularly and periodically inundated as defined by 17-4.022 FAC which includes areas dominated by "submerged" wetland vegetation. Thus to protect state waters and achieve Best Management Practices as they relate to these waters, the discretionary zone, primary zone, and secondary zone should be measured as distance from the edge of the wetland instead of the edge of the watercourse.

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17 research on 62 northern California streams showed a strong correlation between buffer width and stream community diversity index. Streams with highest diversity indices had buffers greater than 50 m in width. Streamside buffers in the high-relief landscapes that characterize most of the continental United States are generally measured from the channel bank. Where landscape relief is high, channel slopes are high, and associated floodplain ecosystems are narrow; and as a consequence, streamside buffers measured in this way probably adequately protect the resource. However, where landscape relief is low, as in the Southern Coastal Plain, terrain is flatter, stream channel slopes are lower, and associated riparian ecosystems are wider. The measurement of streamside buffers in low relief landscapes needs to reflect these important differences and begin at the upland edge of the riparian ecosystem. Effects of Construction Activities Darnell et al. (1976) summarized the effects of construction activities on riparian ecosystems and grouped them into three time related catagories: 1. Direct and immediate results which take place during the construction process; 2. Effects which occur during the period of stabilization following completion of the construction; and 3. Long-term effects of more or less permanent changes brought about by the construction itself or by subsequent human use and environmental management occasioned by the constructed facilities. The water quality effects of construction activities within upland boundaries of riparian ecosystems can be grouped into the same time-related catagories, although for the sake of simplicity, the first two may be combined. The overall impacts of any construction activity vary depending on environmental features (e.g., physical characteristics such as slope, soils,

PAGE 24

18 and vegetative cover), timing, type of' construction activity, and the care taken during the active construction phases. Long-term impacts associated with subsequent uses vary depending on environmental features, intensity of uses, and management practices. During and immediately following construction the major impacts on water quality can be grouped into three broad classes: 1. Impacts associated with erosion of loose soils and their subsequent deposition in downslope wetlands; 2. Suspended sediment increases in surface waters, resulting in increased turbidity; and 3. Introduction of unusual levels of chemical compounds that may have negative effects on resident fish and wildlife populations. The most obvious results of the deposition of eroded sediments in wetlands are the impacts associated with filling. When wetland soils are covered with additional depths of fill material, the most serious impact is loss of oxygen penetration to the root zone and resulting stress on vegetation. If the accu-mulation of sediment is deep enough, or if the sediment is fine enough to plug up soil pores so as to effectively starve roots of oxygen, death of vegetation results. Secondary impacts are experienced by wildlife as a result of the loss of habitat. The authors have on numerous occasions witnessed the results of inad-vertent filling along wetland edges throughout Florida. In most cases these results were caused by erosion of unstable soils during clearing and con-struction activities. The deposition of eroded material resembles a wedge of sediments where the bigger particles drop out of the sediment stream first and successively finer materials drop out farther into the wetland system. Depths of sediment are greatest along the periphery and taper off to shallower and shallower accumulations as the sediment stream penetrates into the wetland. In

PAGE 25

19 most instances the effects are immediate and dramatic. Where sediment depths are greatest, both understory and canopy plants are killed, and as the sediment wedge tapers off, tree kills are less noticeable, but the many varieties of understory vegetation with their shallower root systems are killed. Finally, at the farthest extreme of the sediment wedge, only the herbaceous vegetation is affected. The net result of the deposition of eroded sediments within the limits of wetland communities is to shift the conditions of the transitional edge farther into the wetland. Dead and dying vegetation is replaced over time by early successional upland vegetation. The impacts are less a loss of water storage capacity (since the volume of sediments may be small compared to the overall volume of water stored in the wetland) as they are a loss of valuable wetland function and wildlife habitat. If the disturbed area is close enough to surface waters, or if the configuration of the wetland is such that stormwater runoff from the upland edge can collect and form an intermittent stream, sediments eroded during construction phases may directly affect aquatic environments. In their review of impacts of construction activities in wetlands, Darnell et al. (1976) grouped the biological impacts of suspended and sedimented solids Under the topics of turbidity, suspended solids, and sedimentation. Within each group they review the biological effects that have been documented in the literature. Their review is summarized in Table II.A.l. The final water quality effect during the construction phase is related to the release of chemicals, the levels of which may be harmful to downstream fish aand wildlife or negatively affect ecosystem function. When areas are cleared, runoff increases, carrying with it increased volumes of soil and sediment. Large quantities of dissolved cations and other minerals are lost from the

PAGE 26

20 Table II.A.I Biological Effects of Sediments and Suspended Solids on Aquatic Environments (after Darnell et al. 1976) Topic Biological Effect Turbidity Suspended Solids Sedimentation Reduction of photosynthesis -eliminates phytoplankton, attached algae, and rooted vegetation, thus eliminating base of aquatic food chain Decreased visibility -interferes with normal behavior patterns of higher aquatic organisms Temperature effects -water absorbs more radiant energy, inhibiting vertical mixing in calm waters or uniformly heating moving waters modifying oxygen content Oxygen reduction -through inhibition of photosynthesis, heating, or increased COD and BOD Reduction of primary production -inhibits light penetration, absorption of critical nutrients, removal of algae and zooplankton from suspension through adherence to particles Effects on respiration -oxygen reduction can selectively eliminate aquatic animals that require oxygen for respiration, suffocation through clogging of gill filaments Other effects -potential starvation of filter feeding animals, decreased visibility, interference with migration patterns of fish Primary production -smothering and scour,ng, physical barrier to gas exchange Bottom animals -scouring and blanketing with sediments Fish populations -reduction of food supply, destruction of habitat, elimination of spawning areas, smothering of eggs and larvae

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21 cleared areas and deposited in downstream areas. Borman et al. (1968) found cation losses from 3 to 20 times greater from clearcut watersheds than from undisturbed control watersheds. Riekerk et al. (1980) showed significant increases in sediment and higher nutrient cation loading of runoff from a clearcut; relatively low-gradient watershed after one year, but no significant differences after the second year. In watersheds composed of wet savanna forests of Florida's Lower Coastal Plain, Hollis et al. (1978) recorded significant loss rates of dissolved minerals including ammonium-nitrogen as well as phosphorus and suspended sediments. Of less concern, unless a large-scale accident occurs, is the increase in petroleum products that may pass from construction sites into downstream wetlands and watercourses. Spills in maintenance yards and the general operation of equipment in and near wetlands increases the likelihood of increased contamination. In all, however, contamination from petroleum products during the construction phase should be of minor concern if proper care is taken. Effects of Operation and Maintenance Long-term water quality impacts associated with construction activities in areas adjacent to wetlands and watercourses is a function of subsequent human uses and management. Stormwaters running off developed lands carry both organic and inorganic materials, both suspended and in solution. Many of the organics are degraded through biological pathways or through chemical oxidation. As degradation occurs, oxygen is consumed causing decreases in available oxygen. Thus the breakdown of these compounds "demands" oxygen. Their presence and potential for negative water quality impacts is measured by tests for Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD).

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22 The final land use of a developed area has a marked effect on the quality of stormwater runoff. The Florida Department of Environmental Regulation (FDER) (1978) summarized the work of Sartor and Boyd (1972) that compared the total solids loading from residential, commercial, and industrial land uses. Industrial areas were shown to have the highest loadings and commercial areas to have the lowest. Another stormwater study of three sub-basins (a forested, a and an urban basin) of Lake Jackson in northern Florida as reported in Wanielista (1975) and summarized by the FDER (1978) compared mean concentrations for various constituents in stream water under stormflow and baseflow conditions. The findings showed that the export from the urban watershed was greater for all constituents than from the forested or suburban watersheds, and that mean concentrations of suspended solid loadings from the urban basins and suburban basins were approximately 10 times and 5 times, respectively, those of the forested watershed. In most time-related studies of the quality of urban runoff, a common finding is the difference in concentrations of constituents between the initial "first flush" and later runoff. Typically, the initial rainfall flushes the stormwater system, carrying with it large quantities of suspended solids and materials in solution. Later discharges have significant, but much lower, concentrations of pollutants. Stormwater management rules generally recognize the potential for downstream water quality impacts from urban and suburban areas, and while there is some variation in regulation throughout the state, generally they address the problem through retention of a prescribed amount of the initial rainfall from a storm event. This treatment method assumes that through retention of the first flush, a majority of the constituents that would enter surface waters are retained. However, most stormwater systems, while retaining this first

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23 flush, accumulate the remaining stormwater in the same retention basin, diluting initial concentrations with the added waters. Under these conditions, if the rainfall event is large enough, the diluted first flush is discharged along with remaining stormwaters to receiving water bodies. The net result is little if any retention of the pollutant carried by the storm runoff. Recently, more stringent regulations have been put into effect in the Wekiva River Basin that require off-line retention to avoid this problem. The problems associated with degradation of water quality as a result of the operation and maintenance of a stormwater management system once a development is in place may be little affected by a buffer requirement. The potential impacts on water quality from the combined effects of increased runoff and increased concentrations of pollutants that result from urbanization are not so much functions of how close the developed areas are to wetlands and watercourses as they are of land use, size of the development, and stormwater system design. However, potential impacts from systems designed to allow portions of a development to discharge without treatment may be mitigated through a buffer requirement. In many instances, where slopes prohibit stormwaters to be collected into a system, portions of the lowest areas in the development (typically those closest to and abutting the wetland/watercourse edge) may discharge directly. A buffer requirement in these situations would allow for some treatment of stormwaters if they were allowed to sheet flow through the buffer area. II.A.4. Water Quantity Benefits of Buffer Zones The construction and subsequent operation of urban land uses within areas adjacent to wetlands and watercourses affect the quantity and timing of waters that flow over the lands and often surficial groundwaters beneath the developed

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24 lands. The effects are the result of both construction-related activities and operation and management-related activities. During construction, the volume of runoff increases, since removed vegetation and surface accumulations of organic matter can no longer act to retard runoff, and transpiration is greatly reduced. Studies of water yield from watersheds having varying degrees of clearing show strong relationships between the amount of disturbance and water yield. One study in north central Florida by Riekerk et al. (1980) found water yield increases of 165% from a clearcut, highly disturbed watershed and over 65% from a minimally disturbed watershed. In a later study Riekerk (1985) found 2.5-fold and 4.2-fold increases in runoff from minimally and maximally disturbed watersheds, respectively. In most studies, the effects of disturbance on runoff volumes decreases markedly from 2 to 3 years after treatment as vegetation again plays a role in the site's hydrologic balance. The net effects of clearing are reflected in higher soil moisture levels which may contribute to higher stream base flow and greater direct runoff during storm events. Once vegetation has been removed, it is quite common for groundwater table elevations to increase as a result of decreased transpiration. In areas of existing high water tables, soils can become saturated and extremely difficult to work without extensive "drainage improvements.1I Stormwaters are often routed through temporary swales and ditches into downstream areas to minimize flooding while drainage and stormwater systems are being constructed. Such practices can add significantly to construction-related water quality impacts and alter quantity and timing of surface water discharge. Typically, areas immediately adjacent to floodplain and seepage wetlands are dominated by seasonally high water tables. This is a predominate aspect of

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25 the lands adjacent to the floodplain wetlands throughout the Wekiva River Basin. Lowering of water tables to accommodate construction-related activities and as a permanent consequence of development can reduce groundwater elevations and intercept groundwater flows to adjacent wetlands. Of all the impacts of development, when the mitigating effects on surface water of properly designed retention/detention systems are taken into account, the loss and interception of groundwaters has the most profound consequences. Drainage in areas with high water tables is a widely accepted practice that allows development of lands that would otherwise be difficult to develop. Positive drainage "dewaters" the upper portions of the soil, which lowers the surrounding groundwater elevations. The effects spread radially from the drainage system with the actual amount of decline in water table elevation dependent on the elevation of the drainage system and soil properties and topography of the surrounding lands. Wang (1978) and Wang and Overman (1981) found the effects of a lO-foot lowering of the groundwater table to extend up to 1 mile from drainage ditches in south Florida. While this is probably not typical throughout Florida, it does indicate the magnitude of the problem. The impact of lowered water tables on adjacent wetlands is a reduction in hydrologic function. Where adjacent wetlands are depressional wetlands that intercept the groundwater table, lower water table elevations reduce depths of surface waters and shorten hydroperiods. Under extreme conditions the wetland may remain dry throughout the year. In areas dominated by seepage wetlands, lowered water table elevations result in a reduction or even a cessation of groundwater seepage and subsequent drying of the wetland. The long-term, widescale effects of general drainage practices throughout the state have been discussed by Brown (1986) and are pervasive. While immediate ecological changes resulting from drainage are subt1e--to the untrained eye, no change is

PAGE 32

26 observable--the long-term consequences are loss of hydrological functions, gradual replacement of wetland vegetation with upland types, and consequent loss of habitat values for aquatic and wetland-dependent wildlife species. The maintenance of setbacks or buffers in areas immediately adjacent to wetlands and watercourses can have significant impact in minimizing these effects. A properly sized buffer between construction activities and downstream wetlands can slow down and filter runoff and mitigate the drawdown effects of drainage ditches on adjacent wetlands. It cannot be stated strongly enough that the lowering of water tables to accommodate development is probably the single most important impact affecting adjacent wetlands, and that a properly sized buffer will go a long way toward minimizing these impacts. II.A.S. Edge Effects on Wildlife The question of how wide a buffer zone must be to maintain biological integrity cannot be answered without considering the problem of edge effects. Edge is defined as the place where plant communities meet or where successional stages or vegetative conditions within plant communities come together (Thomas et al. 1979). Edge effects have been investigated intensively in wildlife management ever since 1933, when Aldo Leopold's classic text was published. Evidence of a positive edge effect (i.e., an increase in species richness or density of individuals near an edge in contrast to adjoining habitat types) has been reported for birds (Lay 1938, Beecher 1942, Galli et al. 1976, Laudenslayer and Balda 1976, McElveen 1977, Gates and Gysel 1978), mammals (Bider 1968, Forsyth and Smith 1973), and several other groups of organisms. Most of the early studies of edge effects were concerned with documenting an increase in wildlife abundance near edges. They implied that managing land

PAGE 33

27 to increase edge will also increase wildlife. Edge habitat has high cover density and food availability for many animals, and it is an index of carrying capacity for species that require two or more habitat types for survival (Johnson et al. 1979, Thomas et al. 1979). Hence, Leopold (1933) described game (wildlife) as "a phenomenon of the edge" because wildlife "occurs where the types of food and cover which it needs come together." Subsequently, edge became a fundamental principle of wildlife management (e.g., Allen 1962, Dasmann 1964), and some wildlife management texts went so far as to urge managers to "develop as much edge as possible" (Yoakum and Dasmann 1971). Ghiselin (1977) suggested that an edge index based on the amount of edge or ecotone present is useful as an indicator of relative animal productivity between similar habitats Unfortunately, these wildlife management recommendations were naive about the consequences of edge management on nongame animals, on plant communities, and on regional diversity patterns (reviewed in Noss 1983). In a management context, there are two types of edge: inherent edge and induced edge (Thomas et al. 1979). Inherent edge is a natural phenomenon that represents the juxtaposition of community types and a continuum of successional stages in the landscape mosaic. This natural heterogeneity is in large part a product of the natural disturbance regime of fire, flood, treefalls, wind throws landslides, and other events (White 1979, Sousa 1984, Pickett and White 1985). Moreover, this natural heterogeneity may be the primary determinant of wildlife composition and diversity in a region (reviewed in Noss 1987). Induced edge, on the other hand, 1S a product of manipulation of habitat by humans. It is closely tied to the process of habitat fragmentation that produces sharp contrasts between vegetation types. Simple geometry shows that small habitat islands have larger edge-to-interior ratios than do similar

PAGE 34

28 shaped large habitat islands. As a natural landscape is fragmented into disjunct pieces of habitat in a sea of developed land, the proportion of edge habitat in the landscape increases. Thus, species that are restricted to habitat interiors gradually are replaced by species characteristic of edge habitats. The latter species are generally opportunistic or "weedy" and do not need reserves for survival (Diamond 1976, Whitcomb et al. 1976, 1981, Noss 1983). Conservation biologists therefore recognize that interior species dependent on large tracts of undisturbed habitat should receive priority attention in conservation plans. The recognition of negative edge effects associated with induced edge was a major breakthrough in wildlife ecology. Until the mid-1970s, the attention of most wildlife scientists was focused on relatively small tracts of land (i.e., on local diversity) and on the small subset of animal species that could be hunted. Under these circumstances, induced edge habitat can be seen as favorable. Species such as white-tailed deer, bobwhite quail, cottontail rabbit, and ring-necked pheasant often increase under such circumstances, as does the species list of individual management units. But if one focuses on regional and global diversity, and on entire ecosystems (including nongame animals and endangered species of plants), the negative consequences of induced edge are all too clear. The end result is often a landscape that has lost its native character and is dominated by weeds that are either alien to the region or were previously restricted to recently-disturbed patches (Faaborg 1980, Samson 1980, Noss 1981, 1983, Samson and Knopf 1982, Harris 1984, Noss and Harris 1986). The negative effects of induced edge are easier to understand when one considers that edge is more than a one-dimensional boundary between habitat types. Effects of an open, disturbed habitat penetrate some distance into an

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29 adjoining wooded natural area; hence, edge has a width of influence. Much of this influence is ultimately climatic. Lovejoy et al. (1986), summarizing the status of their research on forest fragmentation and induced edge effects in Amazonia, recognize an abiotic class of edge-related changes that includes temperature, relative humidity, penetration of light, and exposure to wind. The type of habitat on the outside of a forest edge will determine the nature of edge effects. A general principle is that the greater the contrast between habitat types, the greater the edge effect (Harris 1984). When a forest is fragmented, the matrix which surrounds it is usually some type of early successional habitat. (Housing subdivisions would generally fall in this category.) This secondary successional habitat is a constant source of weedy plant and animal propagules that invade the forest fragment and alter species composition and relative abundances (Janzen 1983). Opportunistic animals that achieve artificially high densities in the early successional habitat often invade pristine areas, exerting abnormally high levels of trampling, browsing, and seed predation; this can destroy a natural area as surely as can a chainsaw (Janzen 1983, 1986). Bratton and White (1980) reported that manipulation of habitat to support a huntable deer herd can result in heavy browsing in adjacent natural areas and further endanger a number of rare plant species. The effects of habitat fragmentation and induced edge on animal communities (especially birds) has been particularly well studied over the last two decades. Application of island biogeography theory (MacArthur and Wilson 1967) to habitat islands have led to recommendations for the design of nature reserves. Nature reserves and forest fragments have been portrayed as islands because they are patches of natural habitat in a matrix or sea of culturally modified land (Terborgh 1974, Diamond 1975, Sullivan and Shaffer 1975, Wilson and willis 1975, Diamond and May 1976, Forman et al. 1976, Galli et al. 1976,

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30 and many others). Most early work on this problem was essentially a confirmation of the familiar species-area relationship (Arrhenius 1921, Gleason 1922, Preston 1960, 1962): larger pieces of habitat support more species. There are many potential explanations for the species-area relationship. Three general explanations are (1) larger areas support more kinds of habitats (and thus more habitat-specific species), (2) larger areas offer bigger "targets" for organisms dispersing across the landscape, (3) larger areas maintain larger populations that are less vulnerable to extinction due to random or deterministic population fluctuations, and (4) larger areas support animals of large territory and home range size that cannot be supported in small areas. Anyone of these explanations is powerful enough to support the general recommendation that nature reserves should be as large as possible (e.g., Soule and Wilcox 1980, Frankel and Soule 1981, Schonewald-Cox et al. 1983, Harris 1984, Soule 1986). The process of habitat fragmentation is accompanied by insularization of fragments, i.e., isolated pieces of habitat surrounded by dissimilar habitat begin to resemble islands in many of their ecological dynamics. Eventually, fewer native species will be found in a habitat islands than in sample areas of equal size within extensive blocks of habitat (Miller and Harris 1977). Alternately, species richness may not change much, or may even increase, with habitat insularization, but species composition will shift towards edge species at the expense of area-dependent interior species. These edge species are generally common in the developed landscape and do not need reserves of any kind for survival (reviewed in Noss 1983). In New Jersey, Forman et al. (1976) found that forest islands contained more bird species than did sample plots of equal size within extensive forests, but the additional species were primarily birds of the forest edge. Forest

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31 interior birds were limited to the larger forest islands. Since then, the changes in avifauna that occur with forest fragmentation have been thoroughly documented (for the most extensive treatment, see Whitcomb et al. 1981). In Florida hardwood hammocks, Harris and Wallace (1984) documented area-dependence in a number of bird species. In the Wekiva River bottomland hardwood forest, breeding bird species that have been shown elsewhere to be area-dependent and vulnerable to negative edge effects include the red-eyed vireo and the Acadian flycatcher, both near the limits of their ranges in this area (H. Kale, Florida Audubon Society, pers. comm.). More generally, the species most vulnerable to extinction in fragmented landscapes are large animals with large home ranges (i.e., top carnivores), ecological specialists, and species with variable populations that depend on patchy or unpredictable resources (Terborgh and Winter 1980, Karr 1982, Wright and Hubbell 1983). The characteristically small populations of these species are vulnerable to problems related to environmental stochasticity, demographic stochasticity, social dysfunction, and genetic deterioration brought on by inbreeding or genetic drift (Frankel and Soule 1981, Shaffer 1981, SchonewaldCox et al. 1983, Soule and Simberloff 1986). Biotic aspects of edge effects have played a major role in the ecological deterioration that accompanies fragmentation. Some effects of edge on vegetation were discussed above. Because animal communities respond to vegetation structure (e.g., MacArthur and MacArthur 1961, Roth 1976), any edgerelated changes in vegetation will cause corresponding changes in animal communities for a certain distance into a habitat interior. But there are more insidious processes at work. The opportunistic animals that are attracted to edge (or to the early successional habitat outside) often prey on, out compete

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32 or parasitize interior species, sometimes with disastrous consequences, to the latter's populations. Most of the research on faunal deterioration near edges has been done on birds. Whitcomb et al. (1976) provided evidence that, in areas where forest has been reduced to isolated fragments, avian brood parasites (brown-headed cowbirds), nest predators (small mammals, grackles, jays, and crows), and nonnative nest-hole competitors (e.g., starlings) are usually abundant in the urban-agricultural mafrix and often invade small forest tracts and narrow riparian strips. Gates and Gysel (1978) found that a field-forest edge attracts a variety of open-nesting birds, but such an edge functions as an "ecological trap." Birds nesting near the edge had smaller clutches and were subject to higher rates of predation and cowbird parasitism than those nesting in either adjoining habitat interior. Brown-headed cowbirds, which were not found east of the Mississippi River before widespread forest fragmentation, are a particularly noxious species. Half or more of the songbird nests within 200 m of the edge may be parasitized, reducing reproductive success for some species below the level of population sustainability (Brittingham and Temple 1983). Brown-headed cowbirds have been increasing in number and are moving south in Florida, and they will undoubtedly become more problematic as forests continue to be fragmented; meanwhile, the ecologically similar shiny cowbird, which has caused severe problems in parts of the Caribbean (Post and Wiley 1976, Post and Wiley 1977), has been moving north and was reported in Florida in 1986. Experimental studies of nest predation have documented significantly higher predation rates in small forests compared to large forests, in forests surrounded by suburbs compared to forests surrounded by agricultural land, and at decreasing distances to forest edge (Wilcove 1985, Wilcove et al. 1986).

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33 This abnormally high predation rate is related to the artificially high densities of many opportunistic animals near forest edges and in disturbed habitats (including suburbs; Wilcove et al. 1986). A primary reason why these opportunistic animals (which in Florida include raccoons, opossums, gray squirrels, armadillos,house cats, and blue jays) achieve such high densities is that the large predators (e.g., panthers, wolves, and bears) that once regulated their populations have been extirpated or greatly reduced (Matthiae and Stearns 1981, Whitcomb et al. 1981, Wilcove et al. 1986). The deleterious effects of increased nest predation may extend 300 to 600 m inside a forest border (Wilcove et al. 1986). More generally, Janzen (1986) suggests that managers can expect serious edge effects (including problems related to heavy use by humans and domestic animals) anywhere within 5 km of a reserve boundary. The studies discussed above suggest that any forest tract has a "core area" that is relatively immune to deleterious edge effects and is always far smaller than the total area of the forest (Temple 1986). Relatively round forest tracts with small edge-to-interior ratios would thus be more secure, whereas thin, elongated forests (such as those along riparian strips) may have very little or no core area and would be highly vulnerable to negative edge effects. II.A.6. Regional Habitat Needs of Wildlife: Corridors A great deal of recent literature in the fields of island biogeography and conservation biology has discussed the effects of inbreeding and genetic drift on wildlife due to genetic isolation and small population sizes (e.g., Miller 1979, Soule 1980, Senner 1980, wilcox 1980, and Franklin 1980). Inbreeding has the effect of decreasing population heterozygosity (genetic variation) by increasing the probability that progeny will receive duplicate alleles from a

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34 common ancestor. This loss of genetic variation can have both immediate and future implications for a species' survival. Inbreeding can lower species vigor and fecundity within a few generations (Soule 1980). The very reduced population of Florida panthers may be suffering from the effects of inbreeding. All five males examined have had greater than 93% abnormal sperm (Roelke 1986). Over the long term, inbreeding can also limit the ability of a population to evolve to meet changing environmental conditions (Soule 1980, Harris et al. 1984). Other literature has questioned the effectiveness of fragmented parks and preserves in maintaining viable populations of animals which require large home ranges or activity areas (Pickett and Thompson 1978, Lovejoy and Oren 1981, Harris and Noss 1985, Harris 1984, Noss and Harris 1986, Noss [in press]). In Florida, bears may range over 15,000 ac and bobcats over 5,000 ac. An otter may require several miles of linear river and riparian habitat (Harris 1985). To maintain viable populations of these and other far-ranging animals, large blocks of land are needed. One proposed management alternative for providing for these wildlife needs is the use of wildlife corridors (Diamond 1975, Butcher et al. 1981, Forman and Godron 1981, Harris 1983, Noss 1983, Harris 1984, Harris and Noss 1985, Noss and Harris 1986, Wilcove and May 1986, Noss [in press]). Wildlife corridors can be defined as strips or parcels of land which allow safe passage of wildlife between larger blocks of habitat. This contiguity effectively increases the size of protected lands and their ability to maintain viable wildlife populations. Genetic variation is maintained because genetic material is carried freely back and forth across the corridor and among large habitat blocks by dispersing wildlife. Dispersing animals can recolonize areas which have suffered from local extinctions (Fahrig and Merriam 1985). Large

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35 carnivores such as panthers, bears, bobcats, and otters which require large home range sizes would be free to continue their natural movement between habitat blocks which would otherwise be rendered inaccessible to them by physical barriers. They gain the increased resource base needed to support top-level carnivores. In addition to serving as travel routes, corridors also serve as habitat for some species. EVidence of wildlife use of travel corridors comes from a variety of sources at several scales. In the extreme, land bridges between continents have historically acted as wildlife corridors (Simpson 1940, Simpson 1965). The Bearing Sea land bridge allowed the migration of many animals, including man, into North America from Siberia. The Isthmus of Panama similarly allowed the migration of wildlife between North and South America. Other paleontological research has pointed to the development of a broad, flat corridor which formed along the Gulf coast of Florida during the glacial lowering of the sea level. Webb and Wilkins (1984) found that during these periods Florida's wildlife was highly influenced by fauna which had migrated into Florida from South America and southwestern North America. Riverine gallery forests in Brazil apparently act as mesic corridors which have allowed Amazonian forest species to invade and become components of the xeric cerrado fauna (Redford and da Fonseca, 1986). On a smaller scale, habitat corridors have also been shown to be important for wildlife. Riverine forest corridors are known to be important habitats for many species. The maintenance of streamside strips of vegetation is an important management tool for maintaining gray squirrel populations within pine plantations (McElfresh et a1. 1980). Turkeys have been successfully managed in a mosaic of poor habitat (short-rotation pine plantations) by maintaining hardwood and mature pine trees in travel corridors. These corridors allowed

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36 the turkeys to move widely among foraging and roosting areas (Gehrken 1975). Several species of birds have been found to regularly use fencerows and hedgerows as safe travel routes (Bull et al. 1976). MacClintock et a1. (1977) found that a small forest fragment connected by a corridor to an extensive forest block was characterized by birds typical of the forest interior, while similar but isolated forest fragments were not. Johnson and Adkisson (1985) noted that blue jays used vegetated fencerows as travel routes apparently because they afforded some escape cover from hawks. Wegner and Merriam (1977) found that small mammals and many birds travel more frequently along fence hedgerow corridors than across open fields. Wildlife populations in isolated blocks of forest have been shown to have lower growth rates than populations in forest blocks tied together by corridors (Fahrig and Merriam 1985). The relevance of wildlife corridor management to the Wekiva River Basin lies in the presence of a large number of parks and preserves in the area. Many wildlife species in Rock Springs Run State Reserve, Wekiva Springs State Park, Lower Wekiva River State Reserve, and Kelly Park will be adversely affected if an adequate corridor is not preserved. While several types of corridors have been defined (Forman and Godron 1981), two are perhaps most important for a discussion of the Wekiva River Basin. "Line" corridors are narrow and are entirely edge habitat, while "stripll corridors .. are wide enough to maintain interior conditions. This distinction between edge and interior habitat is important (see previous discussion on edge effects) as some interior species cannot live or even migrate through extensive edge habitats (Forman and Godron 1981). Edge effects are a function of corridor width. Beyond the deleterious effects of edge, width also has other effects on corridor function. A wide corridor may provide actual habitat for an animal while a narrower one may simply provide a travel route. A study of cypress domes showed that

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37 certain species of birds were excluded from smaller cypress domes (McElveen 1978). Stauffer (1978) found that bird species richness increased significantly with the width of wooded riparian habitat, where some species were restricted to wider strips. Tassone (1981) reported similar results from a study of hardwood leave strips. Interior forest species such as Acadian flycatchers were only infrequently found in corridors less than 50 m. Hairy and pileated woodpeckers required minimum strip widths of 50 to 60 m, while the parula warbler required at least 80 m. He suggested that leave strips must be a minimum of 100 m on larger streams to take advantage of their intrinsic wildlife value. Corridors which provide habitat should be much more 'effective in connecting larger habitat blocks than those which only provide paths for travel. Forman (1983) has stated that width is the most important variable affecting corridor function. An upland buffer along the Wekiva River floodplain would maintain the width of the corridor, allowing it to function more efficiently as a wildlife corridor. This would be particularly true where the r1ver floodplain is narrow. Narrow sections may act as barriers through which some animals are reluctant to pass. An upland buffer would allow continued movement and provide a refuge for some terrestrial wetland species during periods of high water. It would also encourage use of the corridor by upland species which do not make regular use of wetland habitats (Forman 1983). In addition to providing dispersal pathways for animal wildlife, floodplain corridors are also important in plant dispersal. Flood waters collect and disperse large numbers of seeds from both wetland and upland plants (Wolfe 1987, Schneider and Sharitz [in press]). This dispersal of upland seeds may be very important in maintaining the diversity of upland plant species on topographic highs or islands within the floodplain (Schneider and Sharitz [in

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38 press]). Wharton et al. (1982) noted that these upland areas within the floodplain are very important for wildlife habitat. Upland seeds carried onto the floodplain originate in the wetland-upland ecotone and from smaller tributaries feeding the river. Protection of this ecotone, which may extend 10 to 35 m in Florida (Hart 1981), and the adjacent upland would ensure continued input of seeds to the floodplain. In summary, width is probably the most important variable affecting corridor function (Forman 1983). Several forest interior species are known to be excluded when corridor width falls below a critical level, which is a function of edge effects and home range requirements. Increasing the width of the Wekiva River corridor by maintaining an upland buffer can only increase its effectiveness in providing both a travel route for dispersing wildlife and high-quality habitat. II.A.7. Between-habitat Needs of Wildlife Between-habitat needs refer to wildlife utilization of more than one habitat type to fulfill their requirements. Several authors have substantiated the close association and interaction of wildlife in wetland and adjacent upland communities. Fredrickson (1978) reported that various species more commonly associated with either wetlands or uplands depend on seasonal or daily shifts into different habitat types to escape flooding, to forage, to disperse, or to hibernate. Examples that he cited are turkey, river otter, swamp rabbit, deer, bobcat, and gray fox. Other species such as raccoon, gray squirrel, tree frogs, and many woodland bird species occur with similar frequency in both wetlands and uplands. Bottomland hardwoods are integrally coupled to the surrounding uplands (Wharton et al. 1982). Terrestrial lowland fauna may be coupled to the

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39 uplands; for example, deer base their home range in floodplains and graze in uplands. Conversely, upland forms such as the black racer, slimy salamander, and pine vole may use the floodplain during drydowns. Although many species breed in both habitat types, their densities may differ considerably between adjacent areas. However, the lower-density populations may serve as important recruitment sources. The greenbelts of bottomland hardwoods also provide routes for migration and restocking. Many semiaquatic Florida turtles, such as the mud turtle and snapping turtle, loaf and feed in marshes but need sandy upland sites to lay eggs (Weller 1978). The river cooter is an example of a turtle which is largely confined to water but must trek to adjacent' uplands to deposit eggs (Patrick et al. 1981). Documented cases of Florida aquatic turtles laying eggs several hundred yards from a river are not uncommon (P. Moler, Florida Game and Fresh Water Fish Commission, pers. comm.). Weller (1978) also indicated a need for more information relating to the wetland-upland interface. He wrote, "Upland areas often serve as buffers, nesting areas, or food resources for wetlands wildlife but their relative importance is undocumented." The eastern indigo snake is classified as a wetland species but frequently occurs in dry, sandy areas (Kockman 1978). Speake et al. (1978) found that indigo snakes concentrated on the higher ridges of sandhill habitat during winter and moved down into streambottom thickets in summer. Shelter provided by gopher tortoise burrows is critical to the survival of this snake while it in upland areas. Many wildlife species need both uplands and wetlands to satisfy their food requirements. Peak mast production occurs at different times of the year in uplands and lowlands (Harris et al. 1979). Winter and spring is the fruiting season for most bottomland species, while upland plants bear fruit in the

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40 summer and fall. Correspondingly, both upland and wetland nesting birds often concentrate in wetland areas during the non-nesting season (Wharton et al. 1981). Landers et a1. (1979) found that black bears also respond to seasonal differences in mast production. In North Carolina, they shift their food preferences from predominantly bottomland species in the winter and spring to predominantly upland fruits and nuts in summer and fall. Florida bears primarily inhabit swamps in the center of the state but are long distance travellers utilizing both wetlands and uplands (Williams 1978). They eat acorns, palmetto berries and the terminal bud (" swamp cabbage") of the cabbage palm. wild turkeys may be found in a variety of wet and dry habitats and normally depend on acorns as a staple food in Florida. But they also have been known to eat crawfish occasionally. (Wild turkeys were recently reintroduced into the Rock Springs Run State Reserve on the Wekiva River.) During the "egglaying season, female wood ducks eat a large percentage of invertebrates obtained from the wetland-upland transitional areas (Fredrickson 1979). Pileated woodpeckers nest and roost primarily in wet hardwoods and cypress habitats but forage in uplands (Hoyt 1957, Jackson 1978). Conner et al. (1975) did not find any pileated woodpecker nest trees farther than 150 m from water in southwestern Virginia. Jennings (1951) observed that gray squirrels in the Gulf Hammock region of Levy County, Florida, were dispersed through all habitats while food was plentiful in the fall. When red maple and elm began to bud and produce seed in mid-January, the squirrels began to concentrate in the hydric hammocks and swamps to utilize this food source. As upland foods became available in the spring and the lowland areas flooded, the squirrels moved to higher elevations.

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41 Kantola (1986) found higher fox squirrel densities in ecotone or transitional areas than in upland areas on the Ordway Reserve in Putnam County, Florida. But she also reported that home-range size and use within ecotones and uplands may vary with seasonal food abundance, reproductive activity, and climate. Between-habitat needs may vary among sites because of differences in habitat quality. More than 33% of the 30 small vertebrates species caught by pit-fall traps in the floodplain of the Chattahoochee River in Georgia were classified as upland species (Wharton et al. 1981). In contrast, only 14% of 21 small vertebrates sampled by the same method along the Alcovy River 1n Georgia received the same classification. This dissimilarity was attributed to vegetation structural differences in the floodplain. Numerous researchers have been interested in the response of small mammals to flooding. Most studies concluded that floodplains were marginal habitats for these species. However, Batzli (1977) found that Illinois floodplain populations of the white-footed mouse were remarkably similar in density, adult survival, and age structure to those in the adjacent upland areas. The exchange of individuals between these two communitie,s consisted mainly of a few floodplain mice occasionally moving into the uplands. He suggested that mature trees with abundant holes and cavities may be necessary refuges for small mammal survival during flooding. In a blackwater creek bottom in South Carolina's inner Coastal Plain, Gentry et al. (1968) found that the abundance of the cotton mouse, short-tailed shrew, and southeastern shrew were 2, 3, and 10 times greater, respectively, in the bottomland hardwood than in the adjacent uplands. Golden mouse specimens were collected only from the hardwoods.

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42 Because wetlands are often the last lands to be developed, some species normally considered upland wildlife are sometimes forced to adapt to wetlands that can supply their habitat needs (Schitoskey and Linder 1978). When uplands required by animals are destroyed, animals may concentrate in the nearby wetlands. Ozoga and Verme (1968) reported that deer mice, which are usually abundant in uplands, were also found in wetlands. White-tailed deer, an edge species, is known to adapt well to the swamps and lowland ar.eas (Verme 1961, Verme 1965, Sparrowe and Springer 1970). Weller and Spatcher (1965) found that upland bird species such as the meadowlark and mourning dove nested >n unflooded portions of wetlands. High densities of prey species also attract adaptable upland predators such as the skunk, raccoon, and red Bailey (1971) found that striped skunk densities were greater in narrow wetlands than in adjacent uplands where cultivation and other development adversely affected upland feeding sites. This situation is suspected to cause an abnormally high predation rate on waterfowl eggs by skunks. Bobcats in the Welaka Reserve showed a preference for bottomland hardwoods (Progulske 1982). More than 20% of the 269 recorded locations of two radiocollared bobcats from July 1980 to December 1981 were in this type of overs tory habitat. Although the other locations were spread among seven different upland habitat types, their need for wetlands is obvious. Melquist and Hornocker (1983) found that although Idaho otters generally followed stream beds, they often took shortcuts across peninsulas formed by stream meanders. Overland travel of up to about 3 km was recorded. Extensive cross-country movements considerably reduced the distance an animal would normally have had to travel to reach the same destination by water. However, these movements also subjected the animals to highway hazards. Three of nine

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known mortalities were road-kills. In Great Britain, Chanin and Jefferies (1978) reported that in some areas dead otters were found repeatedly at the same location on roads over a number of years. 43 In a report that synthesized extant literature for southeastern bottomland hardwood swamp habitats, Wharton et al. (1982) stated that bottomland animals do not occur in the same distinct zonal pattern as plants ranging from aquatic to upland ecosystems. Wetland wildlife inhabitants move freely into irregularly flooded or dry zones over the year. They also noted that some overlap among zones occurs, especially in the transitional areas characterized by periodic annual flooding and a duration of flooding during a portion of the growing season. Their examples of overlapping species that might occur along the Wekiva River are mole salamander, slimy salamander, narrowmouth toad, spadefoot toad, cricket frogs, chorus frogs, box turtle, five-lined skink, southeastern five-lined skink, brown snake, garter snake, ribbon snakes, rat snakes, kingsnake, southern black racer, coachwhip snake, barred owl, downy and red-bellied woodpeckers, cardinal, turkey, common yellowthroat, wood thrush, eastern wood peewee, white-breasted nuthatch, Swainson's warbler, carolina wren, yellow-throated vireo, cotton mouse, golden mouse, short-tailed shrew, least shrew, southeastern shrew, woodrat, marsh rabbit, pine vole, and eastern mole. The use of various bottomland hardwood ecological zones by wildlife differs by species, season and flooding regime (Larson 1981). Some are site specific during the breeding period while at other times they may use a broad range of ecological zones. Larson also referred to many of the species examples used by Wharton et al. (1981). Many studies have documented utilization of adjacent uplands by wetland wildlife species. Removal or alteration of this important habitat type could

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44 destroy critical requirements for many species and thus render the riverine system in that area no longer habitable for them. II.A.8. Within-habitat Needs of Wildlife Within-habitat needs refer to requirements of wildlife species within the habitat areas they occupy. Habitat alterations and land use changes can affect adjacent resident wildlife populations by fragmenting habitat to nonfunctional sizes and shapes and by introducing disturbance factors above the tolerance levels of some species. Because of the paucity of Florida-specific data, we authors have included information from research conducted in other states. Although not actual descriptions of local species/habitat relationships, there is no reason to believe that similar situations do not exist in Florida. Temple (1986) found that 16 of 43 bird species encountered on 49 Wisconsin study areas occurred less frequently, if at all, in smaller-sized forest fragments. Fragment-sensitive birds did not occur regularly in fragments that were large in total area but lacked a secure core area more than 100 m from edges at which forest adjoined non-forested habitat. Large stretches of linear habitats without sufficient core areas were not utilized by sensitive species which included three (hairy woodpecker, pileated woodpecker, and acadian flycatcher) that have been recorded in a partial listing of Wekiva wildlife residents (Florida Dept. of Environmental Regulation, 1983). Of the 13 other sensitive species, it is highly likely that six (tufted titmouse, blue-gray gnatcatcher, wood thrush, yellow-throated vireo, American redstart, and hooded 'warbler) nest along the Wekiva and the remaining seven (least flycatcher, veery, chestnut-sided warbler, cerulean warbler, ovenbird, mourning warbler, and scarlet tanager) overwinter along the Wekiva. Stauffer and Best (1980)

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45 predicted that the scarlet tanager would be absent from riparian strips Iowa less than 200 m wide. Galli et al. (1976) and Stauffer (1978) found the number of breeding bird species increased significantly with the width of wooded habitats in N.ew Jersey and Iowa. Of the 46 species recorded in New Jersey, 18 were size-dependent species, limited to a particular range of forest sizes from the largest down to a specific minimum size. The minimum areas varied from 0.8 to 10.3 hectares and are considered characteristic of each species. As the habitat size increased, new species appeared when their minimum habitat size requirements were fulfilled. An example of a size-dependent species that requires a large wooded riparian habitat is the red-shouldered hawk. This species, which is a common year-round resident in Florida, was not found in any of the New Jersey sites less than 10.3 hectares (about 25 ac). Of the 32 species that occurred in Iowa wooded riparian habitats, 16 restricted breeding to relatively wide plots. Bird diversity is also strongly influenced by vegetation composition and structural heterogeneity or diversity within a habitat type (MacArthur et al. 1962, MacArthur 1964, Weller 1978). This type of heterogeneity is a function of foliage height and cover diversity. The vertical and horizontal stratification of plants within a forest habitat is positively correlated with the number of bird species that reside there. Therefore, land-use conversion of the most diverse portion of a wooded riparian habitat would have significantly greater negative impacts on the overall avian community than conversion of the least diverse portion. Transition or ecotone areas containing both wetland and upland plant species are typically the most diverse (Wharton et al. 1982).

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46 Fragment-sensitive species or species that require large tracts of undisturbed, closed-canopy forest are also referred to as interior species. Tassone (1981) found that many forest interior bird species in Virginia were most common in riparian buffer widths above a mean value of 62 m, and certain species occurred very infrequently below different minima. Examples are the northern parula (80 m), yellow-throated vireo (70 m), Louisiana water thrush (60 m), hairy and pileated woodpeckers (50 to 60 m), and acadian flycatcher (50 m). All of these species also breed in Florida's riparian areas. Tassone (1981) concluded that several other species, observed too infrequently to estimate width requirements, may also be sensitive to buffer width. He suggested: Until more extensive research is done, strips should be left 60 or more meters in width if it is desired to provide breeding habitat for these species. They should also be situated as corridors between other hardwood and pine-hardwood stands whenever possible. Strips located on larger streams should be 100 or more meters in width to make full use of the intrinsic wildlife values associated with the riparian zone. Small and Johnson (1985) recommended that riparian buffer strips be 75 m wide to protect woodland bird communities in Maine. Johnson's (1986) study of the tolerance levels of some woodland breeding species supported this suggestion. Fragmentation also affects squirrel populations. In an eastern Texas study of clearcut effects conducted two to four years after tree harvest, gray and fox squirrels were abundant in mature woody riparian zones wider than 55 m but were rare in riparian zones narrower than 40 m (Hedrick 1973). The highest squirrel density index was calculated for the widest stringer study plot (185 m). The home-range Slze requirement for an individual gray squirrel is about two acres (Burt and Grossenheider 1964). Larger Wekiva wildlife residents require larger areas. For example, home-range sizes for individual gray foxes

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and bobcats in Welaka, Florida, is about 625 and 4,580 ha, respectively (Progulske 1982). Any actions that reduce suitable contiguous habitat below these home-range sizes will prevent individual animals from occupying those areas. Of course, viable self-sustaining wildlife populations require considerably larger home ranges than do of individuals. 47 Aside from the fragmentation factor, various human activities may alter behavior patterns or cause undue stress to some wildlife individuals in adjacent habitats. This is a relatively new aspect of wildlife biology, and very little research data are available regarding .the effects of specific human activities on different wildlife species. Noise associated with construction, operation, and maintenance of developments can cause harmful impacts on wildlife. Animals that rely on their hearing for courtship and mating behavior, prey location, predator detection, homing, etc., will be more threatened by increased noise than will species that utilize other sensory modalities. However, due to the complex that exist among all the organisms in an ecosystem, direct interference with one species will indirectly affect many others. Unfortunately, few data are available that demonstrate the effects of noise on wildlife. Much of what is found in the literature lacks specific information concerning noise intensity, spectrum, and duration of exposure. A few laboratory studies have documented decreased nesting and aversion reactions of small mammals in response to various sound frequencies (Sprock et al. 1967, Greaves and Rowe 1969). Other research has focused on the use of noise for damage or nuisance control. Diehl (1969), Crummett (1970), Hill (1970), and Messersmith (1970) reported on the success of using sound to repel rodents, bats, rabbits, deer, and birds.

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48 The Environmental Protection Agency (1971), Ames (1978), and others have reported on the physiological responses of laboratory and farm animals to different noise stimuli. These data suggest that chronic sound may cause stress on wild animals which in turn may affect reproduction. Most people can easily relate to auditory interference, annoyance, hearing damage, sleep interference, and stress-related effects of noise. And in response to public demands, many noise-control ordinances have been enacted to reduce these adverse impacts. However, it is doubtful that these laws sufficiently protect wildlife species. van der Zande et al. (1980) found that breeding densities of three open grassland bird species were significantly reduced within 500 m of quiet rural roads and 1,600 m of busy highways in The Netherlands. They suggested that disturbance is also caused by farms, other buildings, and plantations. Although Robertson and Flood (1980) found no significant differences 1n several vegetation variables between developed and undeveloped sites along Ontario shoreline areas, bird species diversity was negatively correlated with disturbance. A greater number of species was found in the natural areas than along shorelines where cottages were present and boat use was high. Several species which also nest in Florida (yellow-billed cuckoo, yellow-throated vireo, American redstart, and pileated woodpecker) were more abundant in, or restricted to, the less disturbed transects. The Florida Game and Fresh Water Fish Commission is in the process of developing habitat protection guidelines for threatened and endangered species to provide land-use decisionmakers with recommendations and management practices that would integrate protection for these habitats in the context of large-scale developments. Many of these recommendations will address withinhabitat needs such as those identified in The Recovery Plan for the Bald Eagle

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49 in Florida (Murphy et al. 1984). This U.S. Fish and wildlife Service document states that no human activity should occur within 750 ft (250 m) of active eagle nests and that the building of housing developments should be restricted within 750 to 1,500 ft (500 m) of active nests. Potential bald eagle nesting sites are currently abundant along the Wekiva. Predation and harassment of wildlife by cats and dogs are other detrimental effects of development adjacent to wildlife habitat areas. Although relationships between domestic animals and wildlife are not fully understood, there is enough information in the literature to justify a legitimate concern. Several authors have documented the occurrence of wildlife prey in the diets of free-ranging cats and dogs and the effects of their predatory behavior on individual wildlife animals and populations (Errington 1936, McMurry and Sperry 1941, Bradt 1949, Hubbs 1951, Parmalee 1953, Eberhard 1954, Korschgen 1957, Smith 1966, Corbett et al. 1971, Gilbert 1971, Jackson 1971, Gavitt 1973, George 1974, Gill 1975, van Aarde 1980). Cats can be especially devastating on local wildlife populations. Hunting is a feline instinct, and predation rates are not related to hunger (Davis 1957, Holling 1966, Holling and Buckingham 1976). Bradt (1949) reported that a single cat, who regularly consumed domestic food, killed over 1,600 mammals and 60 birds in Michigan during an l8-month period. van Aarde (1980) found that free-ranging cats associated with households utilized open fields, edges, and timber areas. Home range sizes for females and males were 30 to 40 ha (about 100 ac) and four to eight square km (about four sections), respectively. In an Illinois study, the average home range for females and males was 112 and 228 ha, respectively (Warner 1985). These freeranging rural cats spent about 40% of their time on farmsteads. Approximately

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50 73% of the radiolocations of these cats occurred in edge areas such as roadsides, field interfaces, farmstead perimeters, and waterways. Beck (1973) reported that the average home range for free-ranging dogs in Baltimore was about four acres. Schaefer (1978) reported that dogs in rural Iowa traveled up to two miles to kill pastured sheep. Alteration of natural vegetation or other components of wildlife habitat may make modified areas unsuitable for some species. As these unsuitable areas encroach upon natural areas, core habitat fragments become smaller and the number of supported species is reduced. Various forms of disturbance can also adversely affect adjacent wildlife populations. An upland buffer would reduce or eliminate negative disturbance impacts associated with development. II.B. Review of Buffer Zone Regulations In this section methods and models for determining requirements and physical dimensions of buffer zones are presented. Buffer zones are normally considered to protect quality and wetland-dependent wildlife and to reduce the potential for negative impacts on a wetland resulting from adjacent upland development. The determination of buffer requirements (i.e., widths in relation to land use, soils, topography, etc.) for the most part are not quantitative, but rely on what is felt to be qualitative evidence for the necessity of buffering development impacts. Never-the-less, there are numerous rules and regulations that have been promulgated throughout the country that require buffers around wetland areas.

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51 The Pinelands Area One of the most noteworthy buffer zones is that developed by the New Jersey Pinelands Commission. The Pinelands Area (also known as the Pine Barrens) is an area of about 445,000 ha of an interrelated complex of uplands, wetlands, and aquatic communities in southeast New Jersey. It is a largely undeveloped region within the Northeast Urban Corridor and was designated as the country's first National Preserve in 1978. In the next year the State of New Jersey passed the New Jersey Pinelands Protection Act that in essence called for the preservation, protection, and enhancement of the significant values of Pine1ands land, water, and cultural resources. In response to both federal and state legislative mandates, the Pinelands Commission developed a Comprehensive Management Plan to preserve and protect the unique and essential character of the Pine1ands ecosystem. In the plan, wetlands protection is fostered through a regional land allocation program, a land acquisition program, and a wetland management program. The management program prohibits most development within wetlands and also requires an upland buffer around wetlands. The required "transition or buffer area" established between proposed development and adjacent wetlands measures 300 ft wide, and except for those regulated uses which have been described, no development may occur within the area. Rationale for the width of the Pinelands buffer is derived from areal nutrient dilution models (Harlukowicz and Ahlert, 1978; Trela and Douglas, 1979 and Browne 1980) that were used to predict the travel distance necessary for groundwaters laden with nutrients (from septic tank leachate) to be diluted to background levels. Depending on the values used for input variables to the model, it predicted distances to attain background concentrations of 2 mg/l N03 -nitrogen of between 325 ft and 600 ft.

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52 Since the implementation of the Pinelands Comprehensive Management Plan, 327 development applications that involved wetland issues have been reviewed by the Pinelands Commission. More than one third of these were considered inconsistent with the plan because they proposed development within wetlands or within 300 ft of wetlands (Zampella and Roman, 1983). Figures compiled by Zampella and Roman (1983) show that more than over half of the development applications that involved wetland issues were consistent with the wetland management provisions of the plan. However, among the conditions imposed on these projects was the need to establish and maintain a buffer adjacent to wetlands. Approximately one third of these applications were required to maintain the maximum buffer of 300 ft, while the remainder were required to maintain variously sized buffers which averaged about 135 ft 1n width. The Pinelands scheme of determining wetland buffers uses a Wetlands Buffer Delineation Model that evaluates relative wetland quality, and relative impacts of development. Prior to evaluating wetland quality a determination of the presence of threatened or endangered species is made, and if the wetland is known to support resident and/or breeding populations and if the wetland area is critical to their survival, the wetland is ranked having the maximum relative wetland value index and is, assigned a buffer of 300 ft. The following qualities, values, and functions are evaluated as part of the wetlands evaluation scheme and are evaluated after determination of presence of threatened and/or endangered species is made: Vegetation quality, Surface water quality, Potential for water quality maintenance, Wildlife habitat, and Socia-cultural value.

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53 Each of the five general factors listed above has a score from 1 to 3, where 3 is high value. A wetland is scored for each factor, and scores are summed and divided by 5 to obtain a Relative Wetland Value Index. Next, Potential for Impacts is evaluated by ranking the following factors: Potential for site-specific wetland impacts, Potential for cumulative impacts on a regional basis, and Significance of watershed-wide impacts. Once ranked, the scores for each of the potential impact factors are summed and divided by 3 to obtain an average score for the Relative Potential for Impacts Index. To assign buffer areas, the final step is to average the Relative Wetland Value Index and the Relative Potential for Impacts Index to obtain a Buffer Delineation Index. index is used to determine the buffer distance in three different Land Capability Areas using a table of assigned values. The strengths of the methodology are: (1) Wetland attributes and the potential for on-and off-site impacts are evaluated for each individual wetland and each development proposal on a case-by-case basis. Depending on the type of wetland, existing terrain, existing land use designations, and type of development, the buffer varies from a minimum of 50 ft to a maximum of 300 ft. (2) The method is quantitative and repeatable thus insuring some degree of consistency. (3) It does not require detailed scientific information about a wetland. State of New Jersey The House of the State of New Jersey has passed a bill whose short title is "Freshwater Wetlands Protection Act." As of this writing the State Senate has not acted upon the bill the ace would establish ... a transition area adjacent to all wetlands having the following purposes:

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54 (1) Ecological trans1t10n zone from uplands to wetlands which is an integral portion of the .wetlands ecosystem providing temporary refuge for wetlands fauna during high water episodes, critical habitat for animals dependent upon but not resident in wetlands, and slight variations of wetland boundaries over time due to hydrologic or climatic effects: (2) Sediment and stormwater control zone to reduce the impacts of development upon wetlands and wetland species. The bill would also establish the width of the transitional area as no greater than 150 ft and no less than 75 ft for freshwater wetlands of exceptional resource value, no greater than 50 ft and no less than 25 ft for freshwater wetlands of intermediate resource value, and no transitional area for wetlands of ordinary resource value. The act prohibits the following activities in transition areas: Removal, excavation or disturbance of the soil; Dumping or filling with any material; Erection of structures; Placement of pavements; and Destruction of plant life which would alter the existing pattern of vegetation. New York State Wetlands Protection Act The recent adoption of the Freshwater Wetlands Act (6 NYCCR) protects wetlands 12.4 ac or greater in size. The Act recognizes ten specific functions and benefits which freshwater wetlanfts provide for the public and for the environment. To achieve the goals of the Act to protect, preserve, and conserve New York's freshwater wetlands, the statute makes provisions for mapping, classification, regulation and local government protection. The act provides for the regulation, of a 100-foot buffer adjacent to wetland boundaries. Provisions exist in the law to extend the 100-foot adjacent area if necessary to protect the wetland.

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55 California Coastal Act of 1976 The California Coastal Act (Public Resources Code, Division 20) established the California Coastal Commission which in turn prolmugated the Statewide Interpretive Guidelines (SIG) to assist in the application of various Coastal Act policies to permit decisions. The SIG has set standards for siting development adjacent to environmentally sensitive habitat areas (ESHA). Wetlands are considered environmentally sensitive habitat areas, as are estuaries, streams, riparian habitats, and portions of open coastal waters. "Adjacent to" is defined as situated near or next to, adjoining, abutting, or juxtaposed to an ESHA. This usually means that any proposed development in an undeveloped area within of up to 500 ft of an ESHA will be considered to be adjacent and subject to critical review. Criteria for establishing buffer areas around ESHA's are designed to provide essential open space between the development and the ESHA. Development allowed in a buffer area is limited to access paths, fences necessary to protect the habitat area, and similar uses which have either beneficial effects or at least no significant adverse effects. The buffer is not itself part of the ESHA, but it is a "screen" that protects the habitat area from adverse environmental impacts caused by development. Widths of buffer areas are variable depending upon site analysis. It is usually a minimum of 100 ft; however, it may reduce for small projects (defined as single family home or one commercial office building). Additionally, provisions are suggested that the 100 ft may be reduced if the applicant can demonstrate that it is not necessary to protect the resource. Standards for determining the appropriate width of the buffer area: 1. Biological significance of adjacent lands, 2. Sensitivity of species to disturbance, 3. Susceptibility of parcel to erosion, 4. Use of natural topographic features to locate development,

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56 5. Use of existing cultural features to locate development, 6. Lot configuration and location of existing development, and 7. Type and scale of development proposed. Humboldt County, California Humboldt County's Southcoast Plan defines riparian corridors and limits development within them. It defines riparian corridors to include the uplands on both sides of streams as follows: Riparian corridors on all perennial and intermittent streams shall be, at a m1n1mum, the larger of the following: (i) 100 ft, measured as the horizontal distance from the stream transition line on both sides; (ii) 50 ft plus four times the average percent of slope, measured as a slope distance from the stream transition line on both sides; (iii) where necessary, the width of riparian corridors may be expanded to include significant areas of riparian vegetation adjacent to the corridor, slides, and areas with visible evidence of slope instability, not to exceed 200 ft. (Humboldt County Planning Department 1981, as cited by Ray et al. 1984) Uses in the riparian corridor have been limited to minor facilities, minimal timber harvest, maintenance of existing facilities, residential wells, road and bridge replacement, and tree removal for disease control. There must be, at a minimum, replanting of vegetation for any approved disturbance, and any trees that have visible evidence of current use as nesting sites by hawks, owls, eagles, osprey, herons, or egrets must be retained. Massachusetts Wetlands and Floodplain Protection Act The Massachusetts Wetlands and Floodplain Protection Act recognizes three types of wetlands: 1) land areas bordering water bodies; 2) land under water bodies; and 3) land subject to tidal action, coastal storm flowage, or flooding. These wetlands must border on a listed water body with 50% or more wetland vegetation or within the 100-year floodplain. Permits are required for virtually any development activity in, near, or affecting jurisdictional areas. Work within a 100-foot buffer zone around wetlands may require a permit since

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57 the Act defines "bordering" as a distance of 100 ft. The regulation provides that the extent of protection is to be 100 ft landward from wetland resources or 100 ft landward from the water elevation of the 100-year flood, whichever is Rhode Island Coastal Resources Management Program The General Laws of the State of Rhode Island, Title 46, Chapter 23, establishes the Coastal Resources Management Council (CRMC). The CRMC has developed the Coastal Resources Management Program. The Program establishes setbacks ranging from 50 to 180 ft from the inland boundary of coastal features such as beaches, wetlands, cliffs, banks, rocky shores, and existing manmade shorelines and apply to the following activities: Filling, removal, grading; Residential buildings; Sewage disposal systems; Industrial, commercial, recreational structures; and Transportation facilities. The setback minimum in areas not designated as Critical Erosion Areas is 50 ft, and within Critical Erosion Areas it is 30 times the calculated average annual erosion rate, which has been determined to vary between 75 and 180 ft. In addition to setback requirements, the program establishes Buffer Zones defined as land areas on or contiguous to a shoreline feature that is retained in its natural and undisturbed condition by the applicant. Buffer zones must be tailored to on-site conditions and the specific alterations and activities that are taking place. Further, the determination of the boundaries of a buffer zone need to balance the property owners' rights to enjoy their property with the Council I s responsibility to preserve and, .where possible, to restore ecological systems. There are four benefits of buffer zones as follows: 1. Erosion control, 2. Prevention of water body pollution,

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58 3. Preservation and enhancement of sceniC qualities, and 4. Protection of flora and fauna. The buffer zones are established according to values and sensitivities of the site as assessed by the Council's staff engineer and biologist, and the area may be wider than the setback distance. The buffer must be maintained by the applicant as an undisturbed area and in its natural condition. Marion County, Florida The Board of County Commissioners of Marion County, Florida adopted an emergency ordinance (Marion County Ordinance No. 73-4) in June of 1973 .. prohibiting dredging, filling, earth moving, and landclearing, and underbrushing except mowing, pruning, and care of existing lawns and planted trees and shrubs for a distance of 500 ft from the water's edge upon either side of Rainbow River or Blue Run in Marion County, Florida, between Rainbow Springs and the northern city limits of the city of Dunnellon ... Cross Creek Buffer Requirement In an amendment to its Comprehensive Plan", the Alachua County Commission adopted a 300-foot setback line from lakeshores for most development in a designated area in the southeast part of the county known as Cross Creek. The only construction allowed within the setback zone are structures such as docks built for access to the lake. The setback line is measured upland from the jurisdictional line set by the Department of Environmental Regulation or the St. Johns River Water Management District, or, where the lakeshore has been cleared, from the 100-year floodplain line. The setback width of 300 ft was determined qualitatively. The plan amendment is currently being rewritten. A new version expected to be completed by the second week of October 1987, may require a variable setback line based on such factors as soils, slope, habitat,

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and groundwater, with a minimum setback of 75 ft. (John Hendricks, Alachua County Department of Environmental Services, pers. comm.) Hillsborough County Wetland Buffer Requirement 59 A 3D-foot buffer around "conservation areas" and a 50-foot buffer around "preservation areas" are required by Hillsborough County. The former category includes most freshwater wetlands and Class III waters; the latter includes saltwater wetlands, Class I waters, and critical habitats. These categories originated in the Conservation Element of the county's Comprehensive plan adopted in the mid-l 970s That document set a policy to require "appropriate buffers" around those areas, but no width or formula to calculate width was set forth. However, in the definition of "natural shoreline"--another category of conservation area--a 3D-foot width was mentioned as one way to delimit natural shorelines, and that number was applied by county zoning staff in rezoning applications involving freshwater wetlands. The larger buffer was required around areas because they are considered to be more sensitive than conservation areas, but no formula was used to establish that width. Both buffers were adopted by the Hillsborough County Commission in a 1985 ordinance (revised in 1987) and as part of its zoning code. A variety of uses are permitted within the buffer zone, such as detention ponds, stilted structures, and boardwalks, but impervious surfaces are prohibited. Removal of natural vegetation is discouraged but not prohibited. (Charner Benz, Hillsborough County Planning and Growth Management Group, pers. comm.) II.C. Summary: Resource Buffer Zones Effects of activities in the upland areas immediately adjacent to floodplain wetlands may be separated into three time-related catagories:

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60 1. Direct and immediate impacts which occur during the construction phase, 2. Impacts which occur immediately following the construction phases during the period of stabilization, and 3. Long-term impacts that are permanent as a result of the alterations themselves or subsequent use and/or management of the altered areas. These development impacts affect three broad sets of parameters normally considered of particular importance from a regulatory perspective. They include: 1. Water quality, 2. Water quantity, and 3. Aquatic and wetland dependent wildlife. Thus each of these attributes may be affected during construction, immediately following or in the long term through human uses and management. Water Quality. The need for a buffer to insure that water quality is not degraded as the result of upland development in areas immediately adjacent to floodplain wetlands of the Wekiva River Basin is related to two potential sources of degraded waters. The first is sediments carried by surface waters from developed lands into down-gradient wetlands and waters. The second is dissolved pollutants and suspended particulate matter that degrade water quality through what might be termed chemical pathways. These include nutrie.nts, pesticides, and particulate organic matter which increase nutrient loading, may be harmful to aquatic plant and animal life, or increase BOD. Both sources of degraded water may come from the result of runoff during construction, during the period immediately following construction as the landscape stabilizes, or as a result of urban stormwater runoff long after the period of initial urbanization. Loss of valuable wetland functions as a result of sedimentation may be the most serious impact during construction activities. Sedimentation causes loss

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61 of soil properties and vegetation that are characteristic of wetlands and loss of wildlife habitat. In addition, sediments may carry significant amounts of pollutants and nutrients. Siltation and sedimentation of the wetland edge result from increased water velocities acting on soils susceptible to erosion, removal of ground cover in adjacent areas, or increased volumes of stormwaters entering the wetland that carry increased amounts of sediments. Where the waterward lots of a development are not incorporated into the stormwater management system, the potential for long-term decreased water quality after the construction phase is related to surface runoff from driveways and lawns and groundwaters carrying increased levels of nutrients and pesticides/herbicides from lawn care practices. While the rule criteria of the District requires specific stormwater management practices to mitigate water quality impacts from stormwaters, the rules allow 10% of the developed area to be "unconnected," that is, to receive no treatment. Water quantity. The water flowing into the waters and wetlands of the Wekiva River Basin is derived from three general sources. The first is groundwater (or surficial groundwater) that becomes surface seepage where ground surface elevations intersect the zone of saturation. This usually occurs on inclines near the base of sandy slopes and is characterized by surface soils that are saturated, shallow ponding of seepage waters, and small seeps that coalesce into undefined flowing surface streams. The second source is surface runoff as sheet flow from adjacent higher ground during and immediately following rainfall events, and the third source from artesia flow of deep groundwaters. Development in the zone immediately upland from the floodplain wetland edge may have dramatic impacts on the quantity of water from surface and surficial groundwater sources. Seepage is usually derived from rains that have

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62 recharged groundwaters in higher sandy soils and are moving downslope over a broad front thus, seepage areas tend to extend over the toe of the slope in a perpendicular line across the slope where the ground surface intersects the groundwater elevation. The site of seepage is usually dominated by floodplain vegetation. Alteration of the ground surface elevation through excavation in areas immediately upslope from the site of seepage may intersect the groundwater plain, and if positive drainage is maintained, can lower groundwater levels and essentially cut off further downslope seepage. If no positive outfall is maintained, the effects of excavations immediately upslope from seepage sites may have only minor impacts, since waters may be intercepted and discharged on the upslope side of the excavation, but may become groundwaters through recharge on the downslope side. In most areas where seepage is present, groundwater elevations immediately upslope are quite near the soil surface and are not conducive to many land uses. General engineering practices in areas with high water tables is to lower water table elevations by drainage or raise ground elevations by filling to make such areas more suitable for development. While filling may have little impact on subsurface water flows, drainage has the overall effect of short-circuiting groundwater flows, cutting off potential groundwater seepage downslope, and increasing surface discharge elsewhere. The effects of development on surface water flows in areas immediately upslope of the wetland edge are more easily seen and more direct. Impervious surfaces and sod increase runoff coefficients significantly over coefficients characteristic of natural lands. If these waters are not intercepted by a stormwater management system, they enter the wetlands and eventually the waters of the river. The increased volumes and velocities may cause significant degradation of downslope communities. However, under most development

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63 conditions, these waters are required to be routed through a stormwater management system, thus lessening the burden of the downslope communities. Yet these very requirements may in effect decrease sheet flow from rainfall events, since intercepted surface waters are routed elsewhere. The obvious implications of altered surface runoff and water quality have already been discussed. The temporal differences of impacts on ground and surface water quantity before, during, and after construction may be significantly different. Construction practices may dictate that surface waters and ground waters be routed differently than will be the case after construction, or that groundwaters be temporarily drained to facilitate construction activities. Once construction is completed and the stormwater system is under operating, the impacts on surface and groundwater quantity may vary little over time. Generally, stormwater discharge requirements within the Wekiva River Hydrologic Basin are designed to minimize negative impacts to surface waters through detention/retention, off-line treatment, and additional criteria. However, these requirements, and the fact that typically all lands within a project are engineered as part of the stormwater system, have the effect of isolating developed land. Contributions of overland flow runoff to downslope communities are minimized under such circumstances, since normal engineering practices are to discharge collected stormwaters at one or several point sources. Aquatic and Wetland-Dependent wildlife. Construction, operation, and maintenance of developed areas immediately adjacent to Wekiva River wetlands will result 1n both direct and indirect impacts on aquatic and wetland dependent wildlife. Noise during construction will interfere with vocalizations necessary for courtship, mating, prey location, and predator detection. Although this hindrance will be only temporary, there is no way to

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64 predict long-term consequences. After individuals disperse to less noisy territories, they mayor may not return. Chronic and acute noises of occupied residential communities will cause less severe impacts. However, auditory interference and stress-related effects will still occur in close proximity to these developed areas. A vegetated buffer will help to attenuate harmful sounds. Domestic animal harassment and predation on wildlife will also increase when pets are brought into adjacent developments. Development covenants and local laws usually require owners' to leash their pets. However, the probability of a few free-ranging dogs and many free-ranging cats is quite high. Because cats tend to spend most of their prey-searching time in edge areas, an upland buffer will help to alleviate cat predation on wetland wildlife species. Indirect impacts on wildlife will be related to habitat alteration resulting from construction. The removal of natural uplands vegetation adjacent to the wetlands will cause the originally mesic community along the outer edge of the wetlands to become more xeric. Drier community species will invade and eventually dominate this area. The ultimate result will be a reduction in the wetlands and a corresponding decline in those spec1es that are wetland-dependent. In some areas, the width of the wetlands may become too small, and the species composition will change because those with larger spatial requirements will no longer be present. Increased predation and parasitism associated with sharp induced edges will also encroach farther into the forest. Wetland-dependent species that require uplands to fulfill at least some of their life functions will extirpated from the Wekiva River Basin if there is no

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access to these uplands. An upland buffer adjacent to the wetlands will be needed to protect this necessary habitat element. 65

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III. LANDSCAPE ECOLOGY OF THE WEKIVA RIVER BASIN III.A. Landscape Perspective III.A.I. Physical Description Topography. The landscape of the Wekiva River Basin is a complex mosaic of wetland and upland habitats distributed over approximately 130 sq mi in north central Orange County, southeastern Lake County, and western Seminole County. The basin contains the physiogeographic province known as the Wekiva River Plain. Its topography is flat to gently rolling. Elevation declines towards the northeast, where the Wekiva Plain merges into the valley of the St. Johns River. On the western side of the upper Wekiva River, the land slopes gently upward to the sandhills, from whence it rises abruptly to elevations of 120 to 195 ft above sea level. Sandhills and sloping terraces separate large tracts of swampy lowlands and determine the circuitous route by which the waters of Rock Springs Run State Reserve flow southeastward. These waters turn north below the confluence of Wekiva Springs Run and the Little Wekiva River. North of this confluence, the floodplain narrows and turns to the northeast above State Road 46. The floodplain broadens out again where the Wekiva River joins Blackwater Creek and the St. Johns River in the Lower Wekiva River State Reserve (DNR, 1985, 1987). Along the west bank of the Wekiva River upstream (south) of its confluence with the Little Wekiva, elevation rises gradually towards the northwest from 15 ft above sea level along the river to approximately 35 ft above sea level. 67

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68 Beyond the 35-foot contour, the land surface rises abruptly into upland sandhill tracts in the north central section of Rock Springs Run State Reserve. Downstream (north) of the Wekiva/Little Wekiva confluence, the floodplain narrows abruptly, and the flow gradient increases rapidly to 1.6 ft/mi. The flow gradient in this stretch of the central Wekiva River is one of the steepest in east-central Florida, and the elevation along this section of the Wekiva rises much more steeply above the narrowed floodplain than it does in the flat swamps of the upper and lower sections. The width of the Wekiva/Little Wekiva floodplain narrows to about 1,000 ft along the central portion of the river, decreasing rapidly from its maximum dimensions of about 5 mi east/west by 3 mi north/south in the Wekiva Swamp. The floodplain broadens out once again in the Lower Wekiva River State Reserve (near the confluence with Blackwater Creek) to a width of 1 mi at the Wekiva's confluence with the St. Johns River (DNR, 1985, 1987). Blackwater Creek is a major tributary of the Wekiva which drains the watershed lying just north of the Wekiva Basin. rts watershed covers approximately 125 sq mi, nearly all of which is in southern Lake County. Blackwater Creek's headwaters are in Lake Dorr, and its floodplain varies in width from 800 ft at State Road 44A to over a mile along its upper and lower reaches. Another major tributary, Seminole Creek, joins Blackwater Creek at the eastern edge of Seminole Swamp. Seminole Swamp extends north and west from the confluence of Blackwater and Seminole creeks, covering an area of about 3 mi east/west and 1.5 to 2 mi north/south. This swamp lies between State Road 46A and State Road 44 in southern Lake County. Blackwater Creek flows into the lower Wekiva near the confluence of the Wekiva and the St. Johns. The waters of the Wekiva River Basin merge with those of the St. Johns and flow northward to enter the Atlantic Ocean at Jacksonville, Florida (DNR, 1985, 1987).

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69 The wetlands of the Wekiva Swamp's northern end connect with the lower reaches of Seminole Swamp through a narrow wetland corridor (not shown on all maps) which bisects the lands lying above the west bank of the Wekiva River and the northern borders of Wekiva Swamp. This wetland strip is an extremely important feature of the basin. It provides a wildlife corridor through which animals can move between these otherwise disjunct wetland communities (see Noss and Harris, 1986). The basin's diverse topography engenders a wide range of habitats, ranging from submerged aquatic plant associations to upland sandhill communities. Local soil characteristics and elevational effects combined with past and present disturbances influence the development of the various plant communities found within the Wekiva Basin. Geology and Hydrology. The Wekiva Plain was formed by Pleistocene terrace sands deposited during times of elevated sea level which occurred during interglacial periods of the Pleistocene. The most recent extended saltwater .incursion probably occurred during the Sangamonian interglacial about 100,000 to 200,000 years ago, when sea levels were about 20 ft above those of the present time (Bloom, 1983). Dunes were built up during the dry and windy periods of earlier and later glacial periods (Watts and Hansen, in press). These sands overlie the older marine limestones, clays, and marls of the Hawthorne Formation, which rest upon the deeper, porous Paleocene limestones and dolomites containing the Floridan Aquifer (Heath and Conover, 1981). The non-sedimentary bedrock of the Florida peninsula upon which these marine deposits have accumulated lies at least 4,100 ft below the present ground surface and ties in with the crustal rock of the continental plate. Soils in the Wekiva Basin can be grouped in five associations. The Freshwater Swamp Association occurs in the Wekiva River floodplain and the

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70 bottomlands around the upper part of Rock Springs Run State Reserve. These soils are usually saturated with water and are flooded much of the time. They are adjoined by the Manatee-Delray Association, which grades uphill into the Pompano-Delray Association. The two latter groups include soils which are sandy, nearly level, poorly drained, and subject to periodic flooding. The Myakka-Placid Association soils of the north-central and northeastern portions of the Rock Springs Run State Reserve are sandy, nearly level, poorly drained, and not normally subject to flooding. The St. Lucie-Pomello Association soils of the uplands are sandy, moderately to excessively well-drained, and not subject to flooding. They are restricted to the upland sandhill areas of the Wekiva Basin (DNR, 1985; see also USDA, 1960, 1966). Organic matter content of soils in the Wekiva Basin is high only in wetland soils. Silt deposition and decayed plant materials have formed the rich organic soils of river alluvium, swamp muds, and peat bogs in the basin. The general absence of well-developed topsoil horizons in sandy upland soils of the region encourage the rapid infiltration of rainwater. However, the lack of organic matter, clays, and silts in the surface soils restricts nutrient availability and limits the water-holding capacity of upland soils. Although highly permeable for the most part, the upper horizons of upland sandy surface soils quickly reach saturation during heavy rains, and sheetflow movement of rainwater can result. Problems associated with surface runoff and erosion may develop in conjunction with the heavy rains accompanying major storm fronts, especially in areas where the protective vegetation cover has been disturbed or removed. Ecosystem disturbnnces of historical importance to the disruption of the vegetative cover of Wekiva Basin soils include logging, livestock grazing, high-intensity recreationa; use, construction and development, and wildfire. Wildfire is by fa,the least destructive of these

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71 disturbances to the natural vegetation and wildlife. Indeed, fire is an essential ecological component of several endemic plant communities native to the region. Lakes and sinkholes are scattered throughout the basin as the result of the formation and subsequent collapse of solution cavities within the upper layer of the underlying Hawthorne Formation limestone bedrock. Sudden surface collapses due to sinkhole formation have in recent years swallowed buildings, automobiles, and sections of roads in the suburbs of nearby Orlando. The prevalence of sinkhole formations in the regions bordering the southern edge of the Wekiva Basin dictate caution in siting industrial and residential development. The same forces which create sinkhqles also created the many artesian springs for which the Wekiva Basin is renowned. The water in these springs comes from the Florida aquifer in deep Paleocene limestones and dolomites via faults in the overlying Hawthorne Formation. Crevices and solution channels have penetrated the otherwise impervious clay and marl layers of the Hawthorne Formation and dissolved the underlying limestone. These provide the means for developing surface outlets for artesian springwaters. The major springwater sources of the upper Wekiva River are Wekiva Springs (48 million gallons per day [MGD)), Rock Springs (42 MGD), Sanlando Springs (14 MGD), and Sheppard Springs (11 MGD). More than two-thirds of the Little Wekiva River's flow is provided by a combined discharge of 14 MGD from Seminole, Palm, and Starbuck Springs. Spring flows from the Floridan Aquifer comprise most of the Wekiva River's water volume, which averages 186 MGD at State Road 46 (DNR, 1986, 1987). Reductions in flow of several major springs during the past two decades have been attributed to water withdrawals from numerous deep

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72 groundwater wells in the region which supply water for residential, industrial, and agricultural uses (FWR, 1985; see also Heath and Conover, 1981). Two man-made springwel1s at Wekiva Falls with a combined flow of 40 MGD enter the Wekiva just south of State Road 46. Withdrawals from these deepwater wells may be partly responsible for the recent decrease in spring flow volume from various natural springs in the Wekiva Basin. However, cutting off upstream springflows from Wekiva Falls may not have particularly adverse effects on lower Wekiva River wetlands. The proximity of this source to the confluence of Blackwater Creek and the St. Johns River and the steep flow gradient in this section of the Wekiva River tend to reduce the importance of this water source to the ecology of the Lower Wekiva Aquatic Preserve region. The natural channelling of the river into a relatively restricted wetland zone caused by the increase in flow gradient tends to mitigate the negative. impacts on wetlands of the lower Wekiva River from reduced flows caused by the Wekiva Falls wells. Further in the regional water table due to over-exploitation of water resources from the Floridan Aquifer will have major impacts on the wetland habitats of the Wekiva Basin. Since about 70% of the Wekiva River's water comes from springs, any reduction in springflow volumes will adversely affect the size, distribution, character, and of state-domain wetlands, waterways, and aquatic habitats in the Wekiva Basin (DNR, 1987). Climate. The Wekiva Basin lies in the southernmost latitudes of the humid subtropical climate zone of the southeastern United States. About two-thirds of the precipitation in the basin falls between June and September. On average, 10 to 15% of the annual rainfall occurs from December to February. Annual rainfall averages 52 inches, with most rain deposited during brief, heavy showers and thunderstorms (Heath and Conover, 1981). Tropical storms,

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73 including hurricanes, contribute on average about 15% of the precipitation from June to November. Rainfall events greater than 30 inches within a single 24-hour period have been recorded during hurricanes at some Florida locations, and such events are possible in the basin if a severe hurricane moves through central Florida (Yoho and Pirkle, 1985). Tornadoes are not uncommon in central Florida, and torrential rains and high winds typically accompany the storm fronts which spawn these dangerous and sometimes highly destructive storms. The average temperature for the central Florida region is 72 degrees F.; ambient temperatures of 85 degrees F. or higher can occur during all months of the year. Arctic air masses sometimes penetrate into the region during winter months, bringing usually brief but occasionally intense episodes of subfreezing temperatures (Yoho and pirkle, 1985; Heath and Conover, 1981). Record freezes occurring during the past few years have devastated the citrus industry in Lake County and most of north central Florida. Tens of thousands of acres of orange groves were severely damaged or killed outright during sometimes week-long periods of sub-freezing temperatures. Whether these recent spates of unusually cold winter weather in central Florida represent a long-term trend toward harsher winter climates is unknown. The effects of these hard freezes do not seem to be as severe on native wildlife and plants as they are on agricultural crops, with one major exception. Populations of manatees (Trichechus manatus) in northern and central peninsular Florida suffer high mortality rates from cold stress and related causes during extended periods of freezing weather (T.J. O'Shea, USFWS, pers. comm.; see O'Shea et al., 1985). Although the artesian springheads of the St. Johns River valley create warm water refuges (72 degrees F.) for manatees, the animals must leave areas of warmer water to feed. As food plants become increasingly scarce near warm-water refuges, manatees are forced to

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74 travel farther and farther in search of food, increasing their exposure to colder water temperatures and the risk of collisions with boats (see Hartman, 1979). Radio-tagged manatees from Blue Spring on the St. Johns River have been sighted in the Wekiva River, and residents have reported seeing manatees in the Wekiva (Beeler and O'Shea, 1978). Solar insolation is generally high in central Florida. Clear skies predominate throughout much of the year, but morning ground fogs and rain clouds often reduce direct sunlight penetration for brief periods. The relatively high insolation and temperature regimes characteristic of Florida combine to produce high evapotranspiration rates. In peninsular Florida, surface water and groundwater losses to evaporation and transpiration may approach or exceed the amount of water gained from precipitation (Heath and Conover, 1981). The potential for such a water deficit demonstrates the importance of spring flows from the Floridan Aquifer to the maintenance of surface-water levels in the Wekiva Basin. The preservation of existing wetland ecosystems in the central and upper Wekiva River Basin is absolutely dependent on continued supply of springflow waters at present levels (DNR, 1987). III.A.2. Biological Description Ecological Communities. The Wekiva Basin is a unique natural ecosystem. It lies in the zone where tropical and temperate floras overlap. Tropical plant species at the northern limits of their range grow side by side with temperate-zone plants (DER, 1983). The distribution of plant species in var10US plant communities varies according to specific site characteristics, and species typical of one community may frequently occur in another (see Hart, 1984). Some species have fairly rigid microhabitat requirements, while others occur in wide ranges of soil, shade, and moisture conditions. The soil

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75 characteristics and disturbance history of a given area may result in the anomalous presence or absence of species or species groups. A knowledge of prior disturbance history (fires, logging, farming, ranching, etc.) is important in determining the extent to which present vegetation conditions reflect native vegetation patterns or the presence of human-altered plant communities (Noss, 1985). For example, selective logging has greatly reduced the abundance of cypress trees in the mixed hardwood swamp community of Rock Springs Run State Reserve (DNR, 1985). Rigid separations among plant communities do not typically occur within most natural biotas. The distinct edges (abrupt ecotones) associated with fire-maintained communities and human-altered landscapes are exceptions. For the most part, categories for community types are general constructs devised for analysis and identification of gross habitat characteristics. Despite the overlap between community types, these recognized associations reflect important biological differences among various communities and special interactions or among the constituent species of each community. The flows of numerous artesian springs from the Floridan Aquifer, together with groundwater drainage from the surrounding watershed, have created the vast network of stream channels and associated floodplains, lakes, and sinkholes which support extensive areas of hydric and mesic habitats in the Wekiva River Basin. The basin's landscape 1S dominated by wetland and lowland plant communities but is interdigitated by relatively limited and patchily distributed areas of transitional and upland habitats. Deep-water and shallow-water herbaceous marsh communities inhabit the stream channels and flooded regions, grading into the hardwood swamp vegetation which also occurs on permanently flooded sites. Bottomland hardwood

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76 communities (swamps and bayheads) grade into hydric hammocks where groundwater seeps riverward from upland communities and into mesic hammocks and flatwoods in areas of higher elevation. Drier upland communities in the region include pine sandhill, xeric hammock, and sand pine/oak scrub. Sinks and ponded areas support cypress domes and patches of wet prairie and mesic hammock (DNR, 1985, 1987; Brown and Starnes, 1983). wildlife. Many of the Wekiva Basin's wildlife species are locally ubiquitous mammals which are common throughout the region or not restricted to one specific plant community or habitat type. These include black bear (Ursus americanus), white-tailed deer (Odocoileus virginiana), feral hog (Sus scrofa), bobcat (Felis rufus), river otter (Lutra canadensis), striped skunk (Mephitis mephitis), opossum (Didelphis marsupial is) raccoon (Procyon lotor), two shrews, several bats, cotton mouse (Peromyscus gossypinus), wood rat (Neotoma floridiana), and two cottontail rabbits. Most of the ubiquitous species of the Wekiva Basin frequent swamps, and other species--including wood duck (Aix sponsa), pileated woodpecker (Dryocopus pileatus), and many songbirds--require forested wetlands for nesting and/or foraging habitats. Many of these species require large expanses of diversified habitat mosaics. For example, black bears, sandhill cranes and wild turkey (Meliagris gallipavo) need between-habitat diversity (presence of a patchwork of different habitats) within their home ranges to support the extensive daily or seasonal shifts in activity among various plant communities. Species such as bats, pileated woodpeckers, and water turtles, which typically forage and live within one habitat, may utilize quite different habitats for dispersal, reproduction, or hibernation. Other species, such as river otters, have large home ranges and travel widely among various habitat patches, even

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though most of their activities are conducted 1n one habitat type (in this case, aquatic wetlands). 77 In describing the faunal communities of the Wekiva Basin, the focus 'will be upon typical species associations within given habitat types. As noted in reference to plant communities, these associations are, for the most part, flexible. Overlaps and omissions in the presence of species within community types may occur. However, the upland communities of the Wekiva Basin are exceptional in having several characteristic and interdependent (commensal) species which are entirely restricted to specific upland habitats. The wetland faunal communities include many species of restricted distribution (such as fishes or the endemic snail and crayfish species), as well as a large complement of more freely ranging forms which utilize several wetland habitat types. Aquatic wildlife communities are comprised of species which are largely or entirely dependent upon aquatic ecosystems (rivers, lakes, springs, ponds: places where standing or flowing water is present to some degree at any given time) for at least part of their life cycle. These communities include animals such as toads and tree frogs which spend their adult lives in terrestrial habitats but which require aquatic habitats for breeding and the development of young (larvae or tadpoles). Aquatic communities in the Wekiva Basin region support a great diversity of wildlife, ranging from microscopic protozoans and invertebrates to the massive American alligator. Literally hundreds of species of snails, mussels, crayfish, insects, fishes, birds, amphibians, reptiles, and mammals share aquatic habitats with a broad spectrum of aquatic plant life. The aquatic plant community provides critical resources such as food, shelter, and oxygen for animals in aquatic environments and is the base of the aquatic food chain.

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78 The aquatic plant communities in the rivers, springs, and floodplains of the Wekiva Basin support populations of numerous fishes, including various types of bass, sunfish, mullet, catfish, pickerel, shad, crappie, perch, shiner, topminnow, killifish, molly, and bowfin (see appendix for scientific names of species not detailed in this discussion). The wetland herpetofauna of the region is exceptionally diverse and contains many aquatic forms. Amphibians which are largely or entirely dependent upon aquatic habitats include sirens, amphiumas, newts, bullfrogs, pigfrogs, and leopard frogs. The largely aquatic reptiles of wetland habitats in the region include American alligators, softshell turtles, cooters, mud turtles, alligator snapping turtles, stinkpots, water moccasins, and several non-poisonous water snakes .. In contrast to amphibians--which typically lay their eggs in water--reptiles need terrestrial or semi-terrestrial sites in which to incubate their eggs. Some reptile species (especially turtles) must travel some distance from the water into adjacent upland habitats to find patches of sunlit, sandy soil necessary for successful nesting. Some of the invertebrates of the Wekiva Basin (including three endemic snails of the genus Cincinnatia and the threatened Wekiva Springs Aphaostracon snail) are restricted to springhead habitats. The threatened Orlando Cave crayfish is an endemic form restricted to habitats in the Little Wekiva River system. Other important invertebrates of the basin are apple snails and burrowing crayfish. The apple snail is the primary food of the limpkin, a large snipe-like bird found in wetland habitats that support populations of this golf-balI-size snail. Burrowing crayfish spend part of the year in vertical burrows which are dug in muddy soils in non-flooded wetland and transitional zones. Excavated soil from the burrow is formed into a nearly cylindrical cone rising as much as 6 inches above ground level. Crayfish

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emerge from these burrows periodically to forage and breed. Crayfish are an important food source for many larger vertebrates, including various fish, bird, and mammal species. Many species of birds found within the Wekiva Basin are dependent upon aquatic and wetland habitats for foraging and/or nesting habitats. Osprey, anhinga, wood stork, egrets, herons, ibises, bitterns, ducks, snipe, gallinules, coot, limpkin, and grebes are characteristic of the open wetland and aquatic habitats of the region. Bald eagles (USFWS: Endangered; FGFWFC: 79 Threatened) are expected to occur as transients in the aquatic communities of the area even if no resident individuals are known at the present time. The resident wood stork (Mycteria americana) has been classified as an endangered species by both state and federal agencies (FGFWFC, 1987). Sandhill cranes (threatened) utilize marsh, wetland, and upland sites in the Wekiva Basin. Other resident species such as the little blue heron (Florida caerulea), tricolored heron (Egretta tricolor), snowy egret (Egretta thula) and limpkin (Aramus guarauna) have been designated as Species of Special Concern (SSC) by the Florida Game and Fresh Water Fish Commission (FGFWFC, 1987). The wetlands bird community of the Wekiva region is exceptionally diverse. Encroachment upon wetland habitats will directly and indirectly affect these attractive and often highly visible components of the Wekiva Basin wildlife community. Typical mammals of the aquatic marsh communities in this region include river otter, round-tailed muskrat CNeofiber alIeni), raccoon, rice rat (Oryzomys palustris), and marsh rabbit (Silvilagus palustris). Otters and raccoons range widely among other habitats, while round-tailed muskrat, marsh rabbit, and rice rat are usually associated with marsh, swamp, or wet prairie communities.

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80 The bottomland hardwood associations (hardwood swamp and bayhead communities) typically occur as closed-canopy woodlands which are distributed either as extensive wetland forests in flooded basins or as gallery forests along stream and lake margins. These communities represent a transitional gradient between strictly aquatic and terrestrial environments and retain characteristics of both. Consequently, the wildlife associated with swamp and bayhead communities includes species of both aquatic and terrestrial affinities. The Wekiva Basin swamps and bottomland hardwoods support not only numerous aquatic forms, but also many typically terrestrial animals, including black bear, white-tailed deer, turkey, opossum, gray squirrel (Sciurus carolinensis), cotton mouse, wood rat, gray fox (Urocyon cinereoargentus), and striped skunk. The Wekiva Basin and the nearby southern portion of the Ocala National Forest constitute perhaps the best remaining areas of suitable bear habitat in central Florida (DER, 1983). The Florida black bear (Ursus americanus floridanus) is unique among North America I s extant black bear populations in that its large size is commensurate with that of the ancestral black bears of Ice Age times (Kurten and Anderson, 1980). Management strategies keyed to protection of black bear populations and habitat requirements should benefit virtually all other wildlife in the Wekiva Basin. The largely terrestrial habitats of the uplands include pine flatwoods, pine sandhills, and sand pine/oak scrubs. Flatwoods are used by bear, deer, spotted skunk (Spilogale putorius), cotton rat (Sigmodon hispidus), cotton mouse, diamondback rattlesnake (Crotalis adamanteus), and various other ubiquitous species. Flatwoods provide good cover and shelter for animals that forage in adjacent habitats, move between habitats, and seek refuge from high floodwaters during storms. The truly upland habitats of the region are the pine sandhill and sand pine/oak scrubs of the dry dune-ridges. Typical

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81 wildlife species of these upland habitats include the gopher tortoise (Gopherus polyphemus, SSe) and its many associated commensal (interdependent) species, including the gopher frog (Rana sphenocephala, SSe), the Florida moUSe (Peromyscus floridanus, SSe), and the eastern diamondback rattlesnake. Pocket gophers (Geomys pinetis; also known as salamander or sandy-mounder) occur in more open habitats of deep, well-drained, sandy soils on high ridges in the Wekiva Basin. Longleaf pine sandhills are the preferred habitat of the Sherman's fox squirrel (Sciurus niger shermani, sse). This species has been decimated over the past century by logging of mature pines in the sandhill communities. Reduced populations survive in remnant turkey oak forests, and the species may occur around cypress domes in flatwoods and in a few other upland ecotone situations (OER, 1983). The logging of mature longleaf pines and conversion of sandhill communities into citrus and slash pine plantations have severely affected the structure, composition, and distribution of sandhill ecosystems. The preponderance of listed species among the typical wildlife of the once widespread sandhill community is an indication of the extent to which this habitat has been disrupted by development. The sand pine/oak scrub community contains several highly specialized endemic species such as scrub lizard (Sceloporus woodi) sand skink (Neoseps reynoldsi, threatened), and Florida scrub jay (Aphelecoma coerulescens coerulescens, threatened). Many sandhill wildlife species also utilize scrub habitats and range freely between adjacent scrub and sandhill habitats. The acorns of various oak species common in these habitats are an important seasonal food for black bear, deer, turkey, and feral hog populations of the Wekiva Basin.

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82 III.B. Wetland Communities Wetlands habitats of the Wekiva Basin can be subdivided loosely into three major community types. These are the aquatic herbaceous marsh community of stream channels and springheads, the mixed hardwood swamp community of the river floodplains, and the hydric hammock community of groundwater and surface runoff seepage wetlands. Marshes and swamps are characterized by saturated or flooded soils which are subject to regular and extended periods of inundation by standing or flowing water. Hydric hammock soils are saturated but only occasionally inundated. Marsh vegetation consists of submerged, emergent, and floating herbaceous plants. Swamp vegetation consists of water-tolerant trees and shrubs. Gradual shifts in plant species composition occur according to the regularity and depth of immersion for ground-level vegetation in floodplain habitats. The presence of surface water will greatly affect the types of wildlife species which are present at any given time. III.B.I. Aquatic/Marsh Communities The freshwater marshes of Florida are critically endangered. Freshwater marshes are vulnerable to changes in water levels, water quality, hydroperiod, and fire regimes. Drainage of marshes for development and agriculture has eliminated much of Florida's freshwater marsh habitat. Heavy recreational use, particularly when associated with off-road vehicle and boat traffic, can drastically alter the structure and composition of vegetation within marshes and inhibit the vital ecosystem functions of these communities. The freshwater marsh is a critical resource for many species of birds, fishes, reptiles, mammals, and amphibians in the Wekiva Basin. Undisturbed areas of freshwater marsh provide excellent cover and travel routes for many

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83 wildlife species. The vegetation of freshwater marshes filters surface runoff that feeds rivers and lakes. Soil particles are trapped within the vegetation matrix, and plant roots stabilize the soil surface both above and below the water level. Dense rafts and mats of marsh plants protect the stream banks from strong current flows and help prevent erosion during periods of high water and storm floods. Marsh plants fix and store nutrients and soil particles filtering in from the surrounding landscape, thus helping to prevent eutrophication. The deepwater marsh communities (Water Hyacinth/Coontail/ Watergrass: Eichhornia/Ceratophyllum/Echinochloa) are dominated by rooted or free-floating aquatic herbaceous plants, and they typically occur on permanently flooded sites with water depths of 3 to 6 ft (Brown and Starnes, 1983). This community is found in the main channels and deeper sections of spring runs in the Wekiva Basin, with maximum development in sites not shaded by streamside tree canopy. These high-gradient, fast-moving streams tend to flush out the organic debris and compounds which stain the waters of blackwater swamp systems. High flow rates and steep gradients also create clearwater stream conditions within large tracts of hardwood swamps. The large spring flows of the upper Wekiva River system generate clearwater alkaline streams with high flow and clean, sandy bottoms. These calcareous spring flows are rich in phosphorous and other nutrients and support luxuriant aquatic plant growth. Other representative plants of this habitat include water lily (Nymphaea odorata), hydrilla (Hydrilla verticullata), water-lettuce (Pistia stratioides), and duckweed (Lemna spp.). The common water hyacinth (Eichhornia crassipes) is a weedy exotic which has invaded aquatic habitats throughout Florida. This species has become the dominant aquatic plant in many localities within the region, severely encroaching upon

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84 important native species such as eelgrass and coontail. of water hyacinth is a desirable but presently unachievable management goal. Shallow-water marsh communities (Cutgrass/Maidencane/Cattail/ Arrowhead: Leersia/Panicum/Typha/Sagittaria) typically occur in sites which may be flooded only seasonally but which have water depths of 6 inches or more during the growing season (Brown and Starnes, 1983). Other representative species include sawgrass (Cladium jamaicense), sedges and rushes (Juncus spp., Elocharis spp., and Rynchospora spp.) These shallow-water herbaceous plant associations typically occur in the shallower sections of stream channels and along stream margins within the Wekiva Basin. Wet prairie communities are similar to shallow marsh communities in terms of both their constituent species and flooding regimes. Water depths range from 0.5 to 2 ft in the growing season. Sometimes called grassy ponds, sloughs, or prairie lakes (DNR, 1985), the wet prairie is a grass/herb plant community associated with seasonally and permanently flooded areas of upland habitats (see below for a more detailed discussion of this community). III.B.2. Mixed Hardwood Swamp Community The shallower waters in floodplains and along the margins of lakes and streams in the Wekiva Basin support large tracts of swamp and bottomland hardwood vegetation. This community is comprised of cypress species and a variety of deciduous hardwood trees that grow on saturated and flooded soils. Nutrient availability is generally low, but wildlife habitat value is high. Swamps assimilate organic and inorganic wastes and pollutants, store water, and impede the movement of floodwaters. By slowing down the rate of water flow, swamps help to minimize erosion, promote infiltration, and facilitate the settling out of debris, silt, and nutrients carried by floodwaters. These

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85 functions improve water quality, stabilize water flows in streams and rivers, and help to maintain high groundwater levels in the region. Swamps provide habitat for many wildlife species and are used as travel corridors by wildlife in developed areas. The mixed hardwood swamp (cypress/tupelo/water ash: Taxodium/ Nyssa/Fraxinus) and bayhead (red bay/loblolly bay/pond cypress: Persea/Gordonia/Taxodium) community occurs on poorly drained sites which are regularly or permanently flooded (Brown and Starnes, 1983). Tannins and humic acids from plant debris color and acidify the waters in swamps and in their drainage streams. These blackwater systems tend to occur in the low-gradient streams and basins of cypress and hardwood swamps where organic debris accumulates on stream bottoms and in backwaters. Blackwater Creek is a typical example of this distinctive stream type. Pure stands of cypress stands and old cypress trees are no longer common in the swamps of the Wekiva Basin. Old-growth cypress has been selectively logged from swamps throughout Florida during the past century (see DNR, 1985; Monk,1968). Fluctuations in water level are required for cypress regeneration: cypress seeds must be soaked before they will germinate, but they will not germinate if they are underwater. Other important species of the mixed hardwood swamp are red maple (Acer rubrum), American elm (Ulmus americana), water hickory (Carya aquatica), buttonbush (Cephalanthus occidentalis), and bluestem palmetto (Sabal minor) (Brown and Starnes, 1983). The American elm was formerly common and widespread throughout eastern and central North America, but in the past century the introduction of Dutch Elm disease, an exotic pathogen, has nearly exterminated this species throughout much of its range (see Davis, 1981). However, this species still survives as a common element in the floodplain forests of the Wekiva Basin.

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86 III.B.3. Hydric Hammock Community In some areas between the mixed bottomland hardwoods and the upland communities along the Wekiva River, seepage of groundwater from uplands is the dominant source of water. The topography of these areas is flat, and the soils are poorly drained and almost constantly saturated with seepage water. Although subject to occasional flooding, the hydroperiod in hydric hammocks is shorter than in the adjacent swamps. Hydric hammock communities support more plant species than any other wetland type in the Wekiva Basin. Among the species are popash (Fraxinus caroliniana), live oak, laurel oak (Quercus laurifolia), red maple, southern magnolia (Magnolia virginiana), red cedar (Juniperus siliciola), cabbage palm, saw palmetto (Serenoa repens), tulip poplar (Liriodendron tulipfera), pond pine (Pinus serotina), slash pine (Pinus elliotii), sweet gum (Liquidambar styraciflua) wax myrtle (Myrica cerifera), and several vines and ferns (Brown and Starnes, 1983). The hydric hammock is excellent wildlife habitat and is used by ubiquitous mammals and birds as well as by numerous reptiles and amphibians. This community is very sensitive and vulnerable to changes in groundwater hydrology in upland areas. Drawdowns caused by nearby wells and diversion of groundwater via retention ponds and ditches in uplands can interrupt the supply of seepage water to hydric hammocks, causing the soil to dry out and, eventually, species composition to shift toward more mesic and fewer wetland species. Lowering the water table also makes hydric hammock more vulnerable to fire, a disturbance to which these ecosystems are not adapted.

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87 III.C. Transitional Communities: Mesic Hammock and Scrubby Flatwoods In the Wekiva Basin, the transitional communities between the wetlands and the uplands are largely ecotonal in character, occurring as edges or borders around the larger areas of swamp. Distinct separations between the swamp, bayhead, and lowland hammock communities occupying floodplain habitats of the Wekiva Basin are typically absent. Transitional species of the wetland/upland ecotone include hydric and mesic hammock forms such as cabbage palm, saw palmetto, tulip poplar, pond pine, slash pine, and sweet gum (Brown and Starnes, 1983). Scrubby flatwoods associations form ecotones between the mesic flatwoods and the xeric sandhill and scrub communities. Scrubby flatwoods occupy sites which are sufficiently well-drained so that there is no standing water present even under extremely wet conditions. Pines (slash, sand, and longleaf) are typically present but scattered within a matrix of shrubby oaks and palmettos. Scrub oak inopina), Chapman's oak chapmanii), and sand live oak intermix with saw palmetto and scrub palmetto (Sabal etonia) to form a generally thick shrub layer 1 to 2 m high. Herbaceous cover tends to be sparse. Lichens (Cladonia spp.) and spike moss (Selaginella arenicola) provide considerable ground cover except on recently burned sites. Fire is important in determining the structure and composition of scrubby flatwoods vegetation, which is intermediate in character between flatwoods and sandhill/scrub communities. III.D. Upland Communities The drier, sandy soils of the uplands support scrubby flatwoods on their lower edges and longleaf pine sandhill and sand pine scrub on better-drained and slightly higher sites. Longleaf pine-turkey oak sandhills and sand

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88 pine-oak scrub are distinct in structure and composition from flatwoods communities. These communities occur as savanna or scrub formations on the well-drained upland soils of the Wekiva Basin and are subject to frequent burning. Differences in past burning regimes and. local soil characteristics strongly affect the particular vegetation characteristics of these communities (see Kalisz and Stone, 1984). These habitats are home to a number of important endemic species and are particularly sensitive to changes in natural disturbance regimes (see Monk, 1968). Upland habitats have been severely disturbed by past and present management practices, and major ecological components cannot become reestablished following certain types of human-caused disturbances (Means and Grow, 1985). In many respects, these specialized uplands communities are at the greatest risk from development at present (see Means and Grow, 1985). They occupy substrates and soils which are often preferred over those of wetland sites for agriculture, silviculture, industry, and residential development. As a consequence, few large tracts of native upland vegetation and wildlife survive at the present time. Those upland communities which remain have been subjected to major changes in vegetation regimes and wildlife species diversity as the direct result of human disturbance. Such human-caused changes in the ecology of upland terrestrial communities can greatly alter the movement of water, soil, and nutrients into adjacent wetlands and regional watersheds (see Qdum, 1971, 1983). III.D.l. Pine Flatwoods Communities Flatwoods are fire-adapted communities which occur on moderately to poorly drained soils of terraced lands above the floodplain in areas subject to periodic burning. Wildfires tend to kill off most typical hardwood hammock

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89 tree species while leaving the fire-tolerant forms, especially pines and palmetto, as local dominants. Exclusion of fire will result in succession to bottomland hardwoods or mesic hammock on most flatwoods sites (Monk, 1968). The dominant species in the basin's mesic pine flatwoods community are pines, scattered oaks, and saw palmetto (Pinus spp./Quercus spp./Serenoa repens). A dense shrub layer carpets the understory level. Pines of flatwoods habitats include longleaf pine, slash pine, and pond pine. Live oak and dwarf live oak minima) are often present. Saw palmetto is usually the dominant shrub species, with dwarf live oak, fetterbush (Lyonia lucida) staggerbush (Lyonia fruticosa), dwarf huckleberry (Gaylussacia dumosa), and wax myrtle as secondary components. Saw palmetto, threeawn grass (Aristida patula), greenbriar (smilax spp.), and gallberry (Ilex glabra) are typical understory species. Flatwoods often contain patchily distributed areas of cypress dome, bayhead, mesic hammock, wet prairie, sandhill, and scrub vegetation due to variations in topography, soils, and soil moisture regimes. Standing water may be present in flatwoods during periods of high precipitation and elevated groundwater levels. Longleaf pine was formerly dominant on drier sites, while slash pine and pond pine tend to be dominant on more mesic soils. Repeated selective harvesting of longleaf pines, changes in fire regimes, and conversion of flatwoods and sandhills to agriculture during the past century have greatly affected the distribution and abundance of native longleaf pine communities (Monk, 1965, 1968; Means and Grow, 1985). Slash pine is now the dominant tree on many former longleaf sites. Pond pine becomes dominant in acidic, poorly drained flatwoods where soil pH is less than 4.5, while slash pine occurs primarily on more neutral soils (Monk, 1968).

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90 IILD.Z. Wet Prairie .Communities Wet prairies typically occur in sinks and depressions within areas of low topographic relief which receive water through runoff from adjacent higher ground. Patches of wet prairie vegetation are commonly found scattered throughout the flatwoods and sandhills of the region. Shrubs and small trees, such as primrose willow (Ludwigia spp.) and elderberry (Sambucus simpsonii), are sometimes present in wet prairies. Characteristic herbaceous plants include panicum grasses (Panicum tenerum, dichotomum, etc.), sloughgrass (Scleria spp.), swamp lily (Crinum americanum), and sundew (Drosera spp.). The wet prairie is fire-adapted, and frequent burning will maintain wet prairies on sites which would otherwise succeed to hydric or mesic woodland. These grassy patches increase habitat diversity in flatw90ds landscapes and provide accessory foraging habitats for important wetland wildlife species. Because wet prairies are dependent on surface water runoff to supply water (Brown and Starnes, 1983), drawdowns of water tables in flatwoods by ditching can eliminate wet prairies and reduce habitat diversity in upland regions. III.D.3. Pine Sandhill Communities The pine sandhill is a savanna-type formation of scattered trees and open woodlands having a well-developed ground cover of grasses, forbs, and scattered shrubs. Characteristic species are longleaf pine, turkey oak, and wiregrass (Pinus palustris/Quercus laevis/Aristida stricta). Fire is an important ecological component of sandhill environments and maintains the characteristic open pine woodland and sparse understory vegetation. Burns occur naturally in sandhill communities at about 3-to 5-year intervals, usually started by lightning strikes (Means and Grow, 1985). These frequent

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91 fires preserve the dominance of longleaf pine and inhibit succession to xeric hammock vegetation (Kalisz and Stone, 1984). Sand pine may also invade sandhill communities when fire is suppressed (Kalisz and Stone, 1984). The upland dune formations of the Wekiva Basin are dominated by pine sandhill communities containing patchily distributed areas of sand pine/oak scrub (Pinus clausa/Quercus spp.) and xeric hammock. Pines and turkey oaks are typically the principal overs tory components. The relative dominance of turkey oaks and pine species other than longleaf and the absence of old-growth longleaf in the region's sandhill communities are due to selective logging in these communities. Sandhills have a more or less continuous herbaceous ground cover dominated by wiregrass. Shrubs and hardwoods other than oaks are typically present at low densities (Laessle, 1958). Other common plants of sandhill habitats are bluestem grasses (Andropogon stolonifera, A. tenarius), persimmon (Diospyros virginiana), prickly pear (Opuntia ammophila), blueberries (Vaccinium spp.), gopher apple (Chrysobalnus oblongifolius), and spike moss. Shrub rosemary (Ceratiola ericoides) is often common in sandhill communities but does not usually occur in dense stands. Individual rosemary bushes are usually ringed by narrow perimeters of bare soil. This phenomenon is caused by the release of an allelopathic chemical from the rosemary which inhibits the growth of other plants within its imnediate vicinity. The high primary productivity of sandhill habitats provides a rich food base for a wide variety of wildlife. Turkey oak acorns are important to mast-feeders such as deer, turkey, and feral hpg. Sandhill communit ies support a characteristic fauna which includes Sherman's fox squirrel and gopher tortoise with its host of commensal wildlife species.

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92 Sand pine scrub and oak scrub occur on various upland sites within the Wekiva Basin (DNR 1985, 1987). Sand pine and oak scrub are characterized by a mixed scrub oak understory dominated by scrub live oak, myrtle oak myrtifolia), and Chapman's oak chapmanii). Sand pine is variably present in the scrub habitats of the Wekiva Basin. Differences in burning and disturbance regimes probably account for the absence of sand pine in some scrub communities of the Rock Springs Run State Preserve (DNR, 1985). Shrubs such as staggerbush, rosemary, and wild olive (Osmanthus americana) may also be present. Scrub hickory (Carya floridana), a Florida endemiC, is present in the scrub habitats of the Wekiva Basin. Common herbaceous plants of scrub habitats in the region include blueberries, gopher apple (Chrysobalnus oblongifolius), prickly pear (Opuntia compressa), spike moss, and wiregrass. Lichens (Cladonia spp., Usnea spp., and others) grow on patches of bare soil or as epiphytes on the bark of woody plants. Patches of xeric hammock (live oak/sand live oak/red oak/American holly/deer moss: Quercus virginiana/Q. falcata/Ilex opaca/Cladonia spp.) occur within the upland sandhill habitats. Pine sandhill and sand pine scrub communities will be succeeded by xeric hammock vegetation if the absence of fire is prolonged (Monk, 1968). Exclusion of fire allows regeneration of hardwoods and prevents the continued recruitment of pines. The leaf litter of xeric hammock plants is fire-resistant, so that patches of hammocks within large sandhill tracts typically remain unburned even though ground fires have spread throughout the surrounding pine-dominated landscape. The prevalence of natural and human-caused wildfires in the Wekiva Basin over the past centuries has limited the significance of this community type in the region.

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93 Sand pine scrub and oak scrub occur on various upland sites within the Wekiva Basin (DNR 1985, 1987). Sand pine and oak scrub are characterized by a mixed scrub oak understory dominated by scrub live oak, myrtle oak myrtifolia), and Chapman's oak chapmanii). Sand pine is variably present in the scrub habitats of the Wekiva Basin. Differences in burning and disturbance regimes probably account for the absence of sand pine in some scrub communities of the Rock Springs Run State Preserve (DNR, 1985). Shrubs such as staggerbush, rosemary, and wild olive (Osmanthus americana) may a1sobe present. Scrub hickory (Carya f10ridana), a Florida endemic, is present in the scrub habitats of the Wekiva Basin. Common herbaceous plants of scrub habitats in the region include blueberries, gopher apple (Chrysobalnus ob10ngifolius), prickly pear (Opuntia compressa), spike moss, and wiregrass. Lichens (Cladonia spp., spp., and others) grow on patches of bare soil or as epiphytes on the bark of woody plants. Patches of xeric hammock (live oak/sand live oak/red oak/American holly/deer moss: Quercus .. geminata/Q. falcata/Ilex opaca/Cladonia spp.) occur within the upland sandhill habitats. Pine sandhill and sand pine scrub communities will be succeeded by xeric hammock vegetation if the absence of fire is prolonged (Monk, 1968). Exclusion of fire allows regeneration of hardwoods and prevents the continued recruitment of pines (see Williamson and Black, 1981). The leaf litter of xeric hammock plants is fire-resistant, so that patches of hammocks within large sandhill tracts typically remain unburned even though ground fires have spread throughout the surrounding pine-dominated landscape. The prevalence of natural and human-caused wildfires in the Wekiva Basin over the past centuries has limited the significance of this community type in the region.

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IV. STATUTORY & DISTRICT CRITERIA RELATED TO BUFFER ZONES Questions have been raised concerning the authority of the District to enact requirements which restrict or preclude the construction and operation of systems within the Wekiva River Basin. The rulemaking related to the Wekiva Basin has been the subject of serious concern, and much debate has resulted. An earlier draft of the Wekiva Basin Rule had requirements that buffered the river from impacts, but was withdrawn following considerable controversy, and staff was directed to revisit the issue. Following several drafts of proposed language for buffer requirements, a Petition for Administrative Determination of Invalidity of Proposed Rule was filed that alleged the proposed rule constitutes an invalid exercise of delegated legislative authority or is otherwise invalid. The statutory authority granted the Governing Board of the District related to the enactment of requirements that restrict or preclude the construction, operation, or maintenance of systems is clearly stated, but somewhat general. Broad rulemaking authority has been granted by the Legislature (Chapter 373, FS). The Board may adopt reasonable rules that are consistent with the law and reasonably necessary to effectuate its powers, duties, and functions. Rules adopted by the Board must be reasonably related to the purposes of Chapter 373. The Board cannot act in an arbitrary and capricious manner and should have before it competent and substantial evidence to support a proposed rule. 95

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96 Two questions related to the statutory authority given in Chapter 373 (FS) have occurred to us. First, in Sections 373.413 and 373.416 the Legislature enacted two statutory provisions related to water management systems; the former addressing construction of systems and the later addressing operation and maintenance of systems. As a result, an arbitrary distinction is made between construction and operation and maintenance. Second, the statute does not provide a definition for the term "water resources.1t IV.A. Statutory Criteria, Sections 373.413 & 373.416, FS Sections 373.413 and 373.416 draw a distinction between permits required for construction or alteration of dams, impoundments, reservoirs, or works (373.413, FS) and permits required for maintenance and operation of same (373.416, FS). In the former, the District may require permits to assure that construction or alteration of any system will not be harmful to the water resources of the District. In the latter, the District may require permits to assure that the operation or maintenance of a system will not be harmful to the water resources of the District and will not be inconsistent with the overall objectives of the District. The distinction between the harm that may result from construction activities and harm that may arise from operation and maintenance is a confusing one in light of the review a permit application may receive. Can the District evaluate an application for construction based only on harm to water resources, or can the application also be evaluated relative to the overall objectives of the District? Conceptually it may be relatively easy to separate impacts on water resources that result from development activities into those that occur during construction and those that may result from the operation and maintenance of that which has been constructed. From a resource management perspective,

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97 however, it is not an easy distinction to make. Determining the harm to water resources during construction and following construction is not too difficult, but what is difficult is separating the consideration of these potential impacts when determining if a permit for construction should be issued. To issue a permit for construction of a system or work and evaluate only the potential impacts to water resources without evaluating its impact on the overall objectives of the District once the system is in place is like basing the decision to operate on a patient only upon his/her chances of living through the operation, with no regard as to whether the organ removed is essential for survival after the operation. The distinction is an artificial one at best. If the overall objective is to manage the water resources of the District and insure that the construction, operation, and maintenance of works are not harmful to them, the District must evaluate potential harm resulting from operation and maintenance concurrently with potential harmful impacts resulting from construction. Foregoing sections of this report have established that while impacts caused by construction and those resulting from operation and maintenance can be separated for discussion purposes, they are intimately interconnected, and they must both be considered if the potential impacts are to be evaluated, understood, and resolved. To manage the water resources of the District effectively, all relevant information and potential consequences of any decision must be evaluated during application review. To do otherwise cannot possibly result in effective resource management. In this light, when the District reviews a construction permit, not only should potential harm to water resources be evaluated (Chapter 373.413 FS), but District staff should also determine if it is consistent with the overall objectives of the District (Chapter 373.416 FS).

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98 The second question is also important in permit evaluation. In evaluating a permit for construction and/or operation and maintenance, the District strives to assure that the system or work will not be harmful to the water resources of the District. In a narrow sense, water resources can be thought of as the water only. Then harm would constitute affecting the quality or quantity of water (the abiotic substance). In a broader sense, however, water resources must be thought of as not only the water (the H20) but as the combined biotic and abiotic components--the ecological system of plant and animal life and abiotic elements that are the whole resource. It is not easily dissected or decomposed into two distinct parts for the purposes of management, since the quality of the resource is a complex functional interrelationship of abiotic substances and living organisms. The management of one aspect without regard for the other may at times run counter to sound management of the whole. A working definition of water resources should include the entire resource, and may be something like the following: Water Resource The combined abiotic substances and biotic organisms that constitute the aquatic systems of ground and surface waters. IV.B. Rule Criteria, 40C-4, 40C-4l and 40C-42, FAC Chapter 40C-4, FAC, implements the permitting program in a manner that is consistent with the Objectives and policies of the St. Johns River Water Management District and the declared water policy of the State of Florida. In essence it declares that surface water management permits will be required prior to the construction, alteration, operation, maintenance, removal, Or abandonment of any dam, impoundment, reservoir, appurtenant work, or works. To obtain a permit, each applicant must give reasonable assurance that such activity will not adversely affect navigability, recreational development, or

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99 public lands; endanger life, health, or property; adversely affect the availability of water; be incapable of being effectively operated; adversely affect existing agricultural, commercial, industrial, or residential developments; cause adverse u.pacts to the quality of receiving waters; adversely affect natural resources, fish, and wildlife; increase the potential for damage to off-site property or the public; increase the potential for flood damage; or otherwise be inconsistent with the objectives of the District, among others (emphasis added). The chapter also establishes size thresholds for which permits are required. In addition to the above, the District's Applicants Handbook states that State Water Policy (Chapter 17-40, FAC) is used as guidance to determine harm to water resource and that consideration should be given to the impacts of facilities on recreation; navigation; water quality; fish and wildlife; wetlands, floodplains, and other environmentally sensitive areas;.saltwater or pollution intrusion; reasonable beneficial uses of water; minu.um flow levels; and other factors related to the public health, safety, and welfare; among others (emphasis added). Further, the Handbook states that the District recognizes that ... wetlands are important components of the water resource because they serve as spawning, nursery and feeding habitats for many species of fish and wildlife, and because they provide important flood storage and water quality benefits. Review criteria are provided to determine whether a system will meet District objectives regarding hydrologically related environmental functions. Except when threatened or endangered species are involved, the District will only consider off-site impacts on aquatic and wetland-dependent species relative to the functions currently being provided by the wetland to these types of fish and wildlife. An applicant must provide assurance that a proposed system will not cause changes in the habitat of off-site aquatic and wetland-dependent

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100 species; the abundance and diversity of off-site aquatic and wetland-dependent species; and the food sources of off-site aquatic and wetland-dependent species. Chapter 40C-41, FAC establishes basin-specific surface water management permitting criteria for the Wekiva River Basin that are in addition to the District-wide criteria specified in Chapters 40C-4 and 40C-40, FAC. The Wekiva River Basin Rule was adopted in March 1987, establishing permitting standards as follows: 1. RECHARGE -Three inches of runoff from all directly connected impervious areas must be retained within the project area for projects or portions of projects in Most Effective Recharge Areas. As an alternative, applicants may demonstrate that the post development recharge capacity is equal to or greater than the predevelopment recharge capacity. 2. STORAGE -A system may not cause a net reduction in flood storage within the 100 year floodplain of a stream or other watercourse which has a drainage area upstream of more than one square mile and which has a direct hydrologic connection to the Wekiva or Little Wekiva Rivers or Black Water Creek. Definitions of Most Effective Recharge Areas and directly connected impervious areas are given in 40C-41, as follows: .. Most Effective Recharge Areas have been defined by the U.S. Geological Survey as areas which have 10-20 inches of recharge per year ... Most Effective Recharge Areas can be more accurately defined by soil types. The Soil Conservation Service has categorized soils according to hydrologic characteristics. Those soils determined by SCS to be Type "A" Hydrologic Soil Group shall be considered to be Most Effective Recharge Areas Directly connected impervious areas are those impervious areas which are connected to the surface water management system by a drainage improvement such as a stormwater, paved channel, or other man-made conveyance. Stormwater that is retained must be infiltrated into the soil or evaporated such that the storage volume is recovered within 14 days following a storm event.

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In addition, when stormwater management systems discharge to Class I, Class II, or outstanding Florida Waters, Chapter 40C-42, FAC provides for further treatment of stormwaters as follows: (10) Stormwater discharge facilities which directly discharge to Class I, Class II, and outstanding Florida Waters shall include an additional level of treatment equal to fifty percent of the treatment criteria specified in Section 40C-42.03S(1) (b) or Section 40C-42.04l(S) and shall provide off-line retention or off-line detention with filtration of the first one-half inch of run-off of the total amount required to be treated. 101 In all, the criteria in 40C-4l, and 40C-42 recognize the special values of the water resources of the Wekiva River Basin and were designed to afford additional protection. Rule criteria are generally designed to protect water resources (both quality and quantity of surface water and quantity of recharged groundwater) as a result of the construction, operation, and maintenance of a work or system. In most instances, however, specific construction techniques and specific engineering of a project' s stormwater management system are not adequately addressed by criteria simply because these are outside the purview of the review criteria. Language may be inserted in conditions for permits that require particular attention be paid to minimizing impacts during construction from eros loon and siltation, for example, but lIaccidents do happen." In other words, there are two s igni ficant potential gaps in the rule criteria related to water quality that an appropriately designed buffer rule will overcome. The potential gaps are as follows: 1. Water quality impacts resulting from construction activities in the areas immediately adjacent to wetland; and 2. Water quality impacts resulting from portions of projects constructed adjacent to wetlands, but not directly connected to the stormwater management system.

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102 While the existing rule criteria recognize the importance of recharge in the Wekiva River Basin to maintain both the quality and quantity of groundwaters, the "discharge" of groundwaters that are of particular importance to maintenance of ecologically significant hydric hammocks and floodplain wetlands of the Basin is not addressed in the present rules. These wetland systems are particulary sensitive to the lowering of the groundwater table. The District's policy regarding the lowering of groundwater tables found in Section 10.6.3 of the Applicants handbook states: It is presumed that an adverse impact will result if the system causes the groundwater table to be lowered; a) more than an average three feet lower over the project area than the average dry season low water table; or b) at any location, more than five feet lower than the average dry season low water table; or c) to a level that would drain adjacent surface water bodies below a minimum level established by the Governing Board pursuant to Section 373.042, FS. In most instances, in areas adjacent to the floodplain wetlands of the Wekiva Basin a lowering of the water table from 3 to 5 ft would severely impact hydrologic functions, draining groundwater, disrupting seepage regimes, and diverting surface waters. The net result would be the disruption of ecological functions and loss of wildlife habitat. Thus a third potential gap in the protection of the water resources of the Wekiva River Basin and the importance of the groundwater table to seepage and floodplain wetlands that an appropriately designed buffer may overcome is as follows: 3. Water quantity impacts resulting from excavations and general lowering of the groundwater table in areas adjacent to seepage wetlands. Finally, while it is the policy of the District to evaluate permit applications uSlng reVlew criteria that expressly states consideration should be given to impacts on fish and wildlife, wetlands, floodplains, and other environmentally sensitive areas, present rule criteria in 40C-4l or 40C-42 do

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103 not address these factors. Recognizing the special significance of the wetland and wildlife resources of the Wekiva River Basin, a fourth potential gap in protection of the resources may be overcome with an appropriate buffer as follows: 4. Impacts to flora and fauna resulting from loss of habitat and disturbance as a consequence of construction, operation, and maintenance of systems in areas adjacent to wetlands. Further discussion related to water quality and water quantity issues is given next to better explain the rationale for recommending a buffer to minimize negative impacts of development in areas immediately adjacent to the wetlands and watercourses of the basin. Water Quality Issues. The potential for significant degradation of water quality during construction is directly related to the proximity to the resource and the type of construction activity. Given in Figure IV.l is a plan view of an area along a section of river typical of the Wekiva River. The figure illustrates a typical wetland/upland interface and two typical residential development patterns. In the first type of development, lots and housing units are built up to the wetland line, and some clearing of canopy and understory is required. In the second type of development, because the wetland/upland edge is generally the lowest elevation of the project site, retention/detention basins are constructed along the edge, requiring complete removal of vegetation and excavation. Both development patterns could be constructed under current permit criteria. Where lots and house construction occur adjacent to the wetland edge, typically, the downslope areas are wholly or partially excluded from the stormwater management system. This results from the fact that the edge of the floodplain generally is the lowest elevation, and either the back of lots must be filled to elevations so that surface waters flow toward the front of the

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104 lot, or the back portions of lots are excluded from the management system. The size of lots on the floodplain edge dictate to a large degree how much land is excluded from the management system and allowed to sheet flow stormwaters downslope to the wetland edge. While this development pattern may minimize disturbances along the edge from clearing and digging, surface waters running downslope from these areas are not subject to treatment by the stormwater system and can cause significant water quality problems both in the short term during construction and in the long term during use and management. If the area upslope from the wetland edge is to be excavated for detention or retention ponds, initial c1earcutting, additional heavy equipment for digging, and placement of spoils contribute additional potential water quality problems. The c1earcutting required exposes soils to even greater erosion potential since all vegetation must be removed and the ground surface is scraped clean in preparation for digging equipment. The heavy equipment associated with excavations and earthwork necessary to contour basin side slopes and surrounding lands contribute to significant potential constructionrelated "accidental infringement" into the downslope wetlands/water resources. Finally, spoil placement in adjacent areas and filling along the wetland line expose the downslope wetland/water resource to potential sedimentation from newly excavated non-stabilized soils. Figure IV.2 is a cross section of a floodplain swamp, transition zone, and uplands typical of portions of the Wekiva River Basin. In the top drawing the undisturbed condition is shown. In the bottom drawing the effects of clearing and construction activities in areas immediately adjacent to the wetland line are summarized. Under these conditions, protective ground cover and litter are scraped off the soils, leaving them bare and easily washed downslope during construction. The resulting erosion and deposition will significantly affect

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lOS Figure IV.l. Drawing of two development patterns typical of the Wekiva River Basin. The development pattern in the upper portion of the drawing has housing down to the line and stormwater retention/detention ponds in the upland portions of the development. The development in the lower portion of the drawing has stormwater retention/detention basins constructed immediately adjacent to the wetlands line. The former development scheme minimizes water quantity impacts, but may cause water quality impacts. The latter scheme will impact water quantity, but storm water system may minimize water quality impacts.

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106 those wetlands/water resources that are waterward of the construction line. While precautions might be taken, such as installation of barriers to impede and/or filter silt laden runoff, there is no assurance that the precautions will be effective or that they will remain in place long enough for the area to stabilize. Degradation of water quality as a result of construction and long-term runoff from developed lands may be easily avoided by providing a construction setback or buffer that can act as a sediment trap, dissipate destructive velocities, and minimize water quality problems through filtration of surface runoff. Water Quantity Issues. Criteria in 40C-4, 40C-41, and 40C-42 related to water quantity are generally concerned with recharge of groundwaters in areas of significant recharge potential and with surface runoff patterns. Not protected and of special significance in river systems like the Wekiva are seepage at the base of sandy slopes that maintain saturated soils and standing and flowing surface waters at seepage locations. Shown in Figure IV.3 are the groundwater relationships of the sandy, welldrained ridges along the upland fringes of the Wekiva floodplain and the seepage areas at their bases. It is at these seeps that groundwaters become surface waters and contribute base flow to the Wekiva. In the natural condition waters exiting at the seepage edge are typically low in nutrient content, having recharged through the sparse scrub vegetation of the sandhills and filtered through several hundred (or thousand) feet of well-washed sand. Upon exit from the soil, the newly emerged surface waters support a unique assemblage of vegetation (often referred to as a hydric hammock) adapted to constant saturation and periodic inundation with oligotrophic waters. The wetland line typically coincides or is just landward of these areas.

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Figure IV.2. Cross section drawing of the floodplain and adjacent uplands showing the natural condition in the upper drawing, and the consequences of clearing and development in the bottom drawing. 107

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108 The bottom drawing in Figure IV.3 summarizes the effects of excavations 1n the area immediately landward of the wetland line on the quantity of seepage water exiting in downslope locations. Where excavations are deep and interrupt groundwater flows, seepage areas are "robbed" of sustaining groundwaters, as they are routed through the stormwater management system and discharged at outfall points, or are exposed to surface evaporation in water retention/detention systems. The net effect on total quantity of water that may leave a project site when the effects of increased impervious surfaces and the stormwater management systems are factored in is not easily determined. However, it is quite apparent that the loss of seepage waters will significantly alter species composition in seepage wetlands and have potential consequences on dry season base flows of the Wekiva. Potential consequences of lowered water tables and intercepted groundwater flow to downstream hydric hammocks and floodplain forests can be mitigated through implementation of a buffer zone requirement in the Wekiva Basin. While its function will be to insure high groundwater elevations in close proximity to seepage wetlands, it may also serve a role in insuring maintenance of high water quality.

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Figure IV.3. Cross section drawing of the floodplain and adjacent uplands showing the natural condition in the upper drawing, and the effects of construction of drainage ditches or retention/detention structures in close proximity to the wetlands edge on groundwater table. 109

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V. DETERMINATION OF BUFFER ZONE REQUIREMENTS Given in this section is a description and rationale for the methodology for determining buffer zone requirements. The need for a buffer zone to effectively protect the special values of the water resources of the Wekiva Basin is based on three potential impacts of the construction, maintenance, and operation of works. They are related to impacts on water quality that result from construction and long-term use, impacts that may result from alterations of groundwater tables, and impacts on aquatic and wetland-dependent wildlife habitat. This section is organized into three parts. First an overview of the methodology is presented that discusses the parameters that control the determination of a buffer zone width. Second, methods for the determination of buffer zones are given, with formulae where appropriate. Finally, sample sections of the Wekiva River and Black Water Creek are used to describe each of the controlling parameters and to display the resulting buffer widths. V.A. Overview of the Methodology for Determination of Buffer Zones Four factors are used to determine the width of buffer zones to protect the water resources of the Wekiva River System. The four factors are (1) the Water Management District wetland line (40C-4 FAC) (2) the erodibility of soils in the zone immediately upland of the wetland line, (3) the depth of the groundwater table below the soil surface in the zone immediately upland of the wetland line, and (4) the habitat requirements of aquatic and wetlanddependent wildlife species. 111

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112 Because of the detailed nature of the data required to determine the need for and extent of upland buffers, determinations must be made on a case-by-case basis. However, in the final part of this section we have included maps and figures of the relevant data for a typical sections of the river system to illustrate the methodology's application. Controlling Parameters The parameters that control the width of the required buffer are related to the need to protect water quality and quantity and aquatic and wetlanddependent wildlife, both during and following construction of any development project in areas immediately adjacent to the floodplains of the Wekiva River System. It is important that construction and operation are considered simultaneously, since a project cannot be operated unless it is built, nor is it realistic to aSSume that it will not be operated should it be built. The descriptions and rationale for the following parameters reflect this important integration. Some parameters result from the need for protective measures during construction, others from the need for measures after construction, and still others result from both. (1) 40C-4 Wetland line. The wetland line is the landward extent of wetlands using the methodology outlined in 40C-4 (FAC) and Chapter 16 of the Applicant's Handbook. The determination is made by District staff using dominant vegetation, soils, and other indicators of wetland conditions. The line so determined in most cases is the same as the jurisdictional line set by the Florida Department of Environmental Regulation (17-4 FAC) for demarcation of the landward extent of state waters. The wetland line defines the waterward boundary of the area for which buffer zone requirements are to be determined.

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113 (2) Soil Erodibility. Soil erodibility is a function of slope and soil type. Used in combination, both factors determine the potential for soil erosion and subsequent sedimentation in downslope areas. (a) Slope. Ground surface slope is expressed as percent slope and is determined by measuring the change in elevation over a distance of 300 ft landward of the wetland line. The slope is an indicator of the erosion potential of soils during and immediately following construction activities and/or site preparation. The steeper the slope, the greater the potential for soils to be eroded by surface runoff during rainevents. (b) Soil Type. The soil type may be determined by consulting the USDA SCS Soil Survey for the county in which the development project is located, or it may be determined in the field by a qualified soil scientist. Highly erodible soils in combination with steep slopes dictate severe limitations on removal of vegetative cover; gentle slopes with highly erodible soils or steep slopes with minimally erodible soils dictate moderate limitations; and gentle slopes with minimally erodible soils dictate slight limitations. A formula is used to calculate the exact buffer requirement (see Section V .B). (3) Depth to Water Table. The depth to the groundwater table in areas immediately upland of the wetland line is an important indicator of groundwater interaction with downslope wetlands. Where the water table is near the surface and slopes toward the wetland, the area is dominated by discharging groundwaters, and a buffer to avoid drainage of the wetlands is warranted. The depth to the groundwater table may be determined by field measurements (although it should be understood that one measurement at one point in time does not give a true picture of average year-to-year, season-to-season

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114 conditions) or through field determination of soil type and interpretation of county soil survey data. Excavations in areas where the water table is near the surface in the zone immediately upslope from seepage wetlands (i.e., where the hydraulic gradient is toward the wetland area) intercept groundwater flows and have the potential to drain wetlands on the downslope side of the excavations. Where these are present, a setback is warranted to insure that proposed development activities do not diminish the quantity of water entering the downslope wetlands. (4) Wildlife Habitat Requirements. The old adage that an ounce of prevention is worth a pound of cure is particularly appropriate to wildlife conservation. Loss of habitat is the greatest threat to many of Florida's wildlife species. One approach to alleviating this threat would be to monitor each species and to take protective action if it is determined that any given species is declining. This approach is risky in that such a determination may be made too late to reverse the decline. Another approach would be to prevent any change in the amount of habitat available to each species, but this is neither practical nor possible. It is better to formulate a general method to accommodate the wildlife of a given region as a whole. The practical solution, then, is to determine the amount of harm that is acceptable and to prevent it from increasing. By far, the most common cause of wildlife population reduction is landscape alteration through agriculture, silviculture, or construction activities. Altering or changing natural conditions to which species are adapted often harms native wildlife communities by destroying key conditions that make a given site suitable habitat. An obvious example is the removal of snags (dead trees) that are essential nesting structures, food sources, and

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115 perches for many birds, mammals, reptiles, and amphibians. A common misconception is that no harm is done because there are plenty of other undeveloped areas containing the same requirements. On the contrary, other areas that have the necessary elements for a particular species are probably already occupied at a saturation level, leaving no rOom for individuals that are ousted by development occurring elsewhere. Therefore, the most effective method of protecting wildlife resources in the Wekiva River Basin would be to preserve areas in their most natural conditions and in large enough parcels so that self-sustaining populations can be maintained. Buffer requirements to protect aquatic and wetland-dependent wildlife species are related to four factors: habitat suitability; spatial requirements; access to upland and/or transitional habitat; and noise impacts on feeding, breeding, and other life functions. Wetland-dependent species are those which depend on wetland communities for at least some of their essential requirements. (a) Habitat Suitability. Food, cover, and water are life-sustaining elements for all species. If every requirement for an animal is available in a particular area, the area is considered to be suitable habitat for that species; if one or more of a species' requirements is not available, the area is unsuitable. Some species are extremely specialized. For example, the Everglades or snail kite has an exclusive diet of only one snail species, Pomus depressus. Others, such as the raccoon, are generalists and can readily substitute many items to fulfill their needs. Several methods have been developed recently to determine if sites are suitable for a given species. These methods are based on availability of food, cover and water requirements, and various parameter measurements have been

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116 shown to be associated with these requirements. Examples of the parameters used for this report are tree canopy closure and tree height. (b) Spatial Requirement. Every animal requires a certain amount of space to carry out life functions such as feeding, courtship, and nesting. Spatial needs are highly variable, even within species. Differences are associated with many factors, including sex and age of the animal, time of year, availability and distribution of food and cover, and social structures. In general, larger species tend to have greater spatial requirements. Obvious comparisons are the black bear versus the cotton mouse and the red-shouldered hawk versus the mockingbird. Also, species with more unpredictable and unevenly distributed food sources require more space to satisfy their nutritional needs. For example, marsh rabbits have small spa.tial requirements relative to their size because they eat grasses and forbs which are plentiful within small areas. Conversely, gray squirrels need relatively larger territories to find mast, which is unevenly distributed. It should be realized that the .Wekiva River acts as a border to many species living in the river basin. Even those that can swim or fly across the river are affected by the impacts of increased predation and disturbance factors associated with the edge ecotone created at the water/forest interface. Because many forest-dwelling, wetland wildlife species utilize more than one habitat type, their spatial requirements can often be satisfied even if a portion of the forested area does not fit the definition of a wetland community but does fulfill other habitat suitability criteria. In most cases, areas immediately landward of the wetland line that are cleared for agriculture or silviculture or which are planted in monocultural pine plantations will not be suitable habitat for wetland-dependent species. Where these situations occur, buffer zone requirements are not as sensitive to wildlife considerations as

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117 they might be if the area had a continuous, relatively natural, forest canopy. For this reason, it is essential that serious consideration be given to whether or not agriculture and silviculture should be exempt from buffer zone requirements where the protection of aquatic and wetland-dependent wildlife species is of particular importance. Although it is difficult to rationalize the use of wildlife considerations when the canopy has been removed, mitigation of previous adverse impacts on wildlife could be addressed by replanting the would-be buffer zone (determined by the application of the other factors) with native tree species to reestablish wildlife values. (c) Access to Upland or Transitional Habitat. Several wetland-dependent wildlife species must have access to upland or transitional habitat regardless of the landward extent of the wetlands. For example, many semiaquatic turtles need sandy and relatively warm upland sites to lay eggs. Elimination of such habitats could extirpate numerous wetland-dependent species from the Wekiva River Basin. (d) Noise Impacts. Noise can interfere with signals and directly affect wildlife behavior. Many species rely on vocalizations for warnings, mate recognition, detection of separated young, and to establish territorial boundaries. Background noise can interfere with these vocalizations and cause direct reductions in populations or dispersal to less noisy areas. Sudden loud noises can disturb or harass some individuals and cause harmful stress which affects reproduction and other life functions. To protect aquatic and wetland-dependent species from noise interference, buffer zones between the point of noise generation and the habitat are warranted. The distance of buffer necessary for protection from noise is related to both the level of noise and the space through which the noise

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118 passes. Dense vegetation diminishes the level of noise more quickly than open ground; pavement tends to propagate noise better than vegetated grasslands. The required buffer depends upon the characteristics of the intervening area. V.B. Determining Buffer Zone Requirements The order in which each of the four parameters is calculated or measured is important. The 40C-4 wetland line must be determined first, since all determinations are based on the 'establishment of this line as the waterward boundary of the buffer zone. Once the wetland line is established, the order in which the remaining parameters are determined is of little consequence. Since the requirements for a buffer zone depend on a dynamic landscape where the relationships between the controlling variables are not constant, each of the parameters must be calculated. The spatial frequency at which the calculations are made (i.e., how often the buffer zone lines need to be determined along the waterward edge of a proposed development) depends on the variation in the measured parameters. If there is no reason to believe the parameters and their relationships to each other are different along the entire length of the water-ward edge of the proposed development, each parameter needs to be determined only once. However, if the parameters appear to change significantly, more determinations are necessary. The exact number of determinations is a function of the relative changes in slope, soil type, water table elevation, and forest canopy and vegetative structure. In most cases, estimates of the relative changes in parameters can be made using topographic and soils maps and aerial photographs. Final buffer zone widths are set by determining the controlling parameter, i.e., the parameter that results in the widest buffer zone. The following

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119 paragraphs detail methods for determining buffer widths based on each of three parameters (water quality, water quantity, and wildlife habitat suitability). (1) 40C-4 Wetland line. The wetland line is determined using the methodology outlined in Part III, Section 16 of the Applicants Handbook. (2) Water Quality Maintenance. The requirement for a buffer zone for maintenance of water quality is related to the filtering capacity and roughness of natural undisturbed vegetation to minimize inputs of sediments and destructive velocity of waters. The potential for erosion and subsequent sedimentation is a function of the erodibility of soil and slope. The velocity of water varies as the square root of slope (Manning's formula), and the potential for a particle of soil to be moved is a function of erodibility and velocity of water over the surface. Thus a simple relationship of slope and e,odibility may be used to determine buffer widths as follows: where: Bw = Sl/2 E Bw = the width of the buffer in ft; S = average slope of the land in ft per 100 ft; and (1) E = erodibility factor; use 4 for soils with SCS erosion factors (k) of 0.1, use 3 for soils with k = 0.15, use 2 for soils with k = 0.17, and 1 for soils with k> 0.17. using Equation I, the required buffer for an average slope of 3% and soils with low erodibility factor (E = 4) would be 43 ft. The buffer required for soils with the same slope and erodibility factors of 3 and 2 are 57 ft and 87 ft, respectively. Table V.l lists pertinent soil properties for many soil types found in and adjacent to wetlands in the Wekiva River System. It highlights some of the important constraints likely to be encountered within the Basin. The second column lists k factors (erosion factors) that can be used in determining the erodibility factor.

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120 Table V. 1. Soil properties and interpretation. K Depth t0 2 Limitations 2 Soil type Erosion 1 W. Table Group S.Tank Bldg. Excav. Albany sand, 0-5%1 .10 15-40" C M M M Anclote fine sand .10 0-10" 0 S S S Anclote & Myakka .10 0-10" 0 S S S Astatula sand, dark, 0-5% .10 >120" A Sl Sl M Blanton fine sand, high, 0_5%3 .17-.28 18-30" A Sl Sl S Blanton fine sand, low, 0_5%3 .17-.28 1B-30" A M M S Cassia sand .10 10-40" C S S S Delray fine sand3 .15 +12-0" AID S S S Delray fine sand, NA 0 NA VP IN Delray fine sand, high .15 0-12" AID S S S Emeralda fine .10 0 0 S S S relda fine sand 3 .17-.28 0-12" BID S S S Immokalee fine sand .17-.20 0-12" AID S S S Iberia & .10-.28 0 0 S S S Immokalee sand .17-.20 0-12" AID S S S Leon fine sand3 .17-.20 0-12" AID S S S Leon fine sand, 0_2%3 .17-.20 0-12" AID S S S Myakka sand .10 0-10" 0 S S S Myakka & Placid sands, 2-8% .10 0-10" 0 S S S Ocilla sand .10 40-60" C M M M Paola sand, 0-5% .10 >80" A Sl Sl Sl Plummer fine .17-.28 0-12" AID S S S Pomello fine sand .17-.20 12-30" A M Sl S Pomello fine sand, 0_5%3 .17-.20 12-30" A M Sl S Pomello sand .10 30-40" C M M M Pompano fine sand3 .15 0-12" AIO S S S Pompano fine sand, shallow phase .10 0 0 VP IN Placid sand .10 0 0 S S S Pompano fine sand3 3 .15 0-12" AIO S S S Sandy alluvial land S S S Swamp .10 +24"-0 0 +S +S +S Tavares sand .10 40-60" C Sl Sl M Tavares sand, white subsurf. .10 40-60" C Sl M M Wabasso sand .10 0-10" 0 S S S Wauchula sand .10 0-10" 0 S S S

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Table V. 1. Continued. (footnotes) 1K Erosion is a measure of the rate at which a soil will erode. Values are expressed as tons of soil loss per acre per unit of R (rainfall factor) from continuous fallow on a 9% slope 73 feet long. Hydrologic Group is a relative index of runoff rate. A = low runoff potential, B = moderately low runoff potential, C = moderately high runoff potential, and 0 = high runoff potential. When two letters are given, the first applies to the drained condition while the second applies to the natural condition. Source for K factors and hydrologic groups, unless otherwise noted: U.S. Soil Conservation Service Soil Interpretation Sheets (provided by SCS office in Gainesville, Florida, September 1987) for lake, Orange, and Seminole counties. 2 Oepth to water table = depth to seasonally high water table. The range reflects yearto-year variation. Standing water above the soil surface is indicated by a "-". limitations apply to septic tank drainage fields, dwellings without basements or foundations for low buildings, and shallow excavations (ponds or below-ground basements). Sources for depth to water table and limitations are the Soil Survey of Orange County, Florida (1960), Soil Survey of Seminole County, Florida (1966), or Soil Survey of lake County Area, Florida (1975) except where otherwise noted. 51 = slight, M = moderate, 5 = severe, and _5 = very severe. The Orange County Soil Survey does not include a rating for building suitability. Ratings for septic tank drainage fields range from very poor (VP) to poor (P) to fair (F) to good (G). It does not rate soils for excavated ponds, but only describes the elevation [high (H) or medium (ME)], shallow water table (SH), or inundated (IN). 3 Source: Soil Survey Supplement, Seminole County, Florida (1975). 121

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122 The above formula is included as a means of providing a framework from which hydrologists, soil scientists, and engineers working in conjunction might develop nomographs or equations better suited for the conditions encountered in the Wekiva River Basin. A derivation of the Universal Soil Loss Equation, while requiring very specific information, may be a better means of determining buffer zone widths for protection of water quality if an allowable field soil loss can be established, although any soil erosion has the potential to cause disruption of downstream waters and wetlands. Without the detailed analysis required by the more sophisticated methodologies, the above equation is given as an example for determining the buffer requirements for protection of water quality. (3) Water Quantity Maintenance. The buffer width required for protecting water quantity is related to the drainage impacts of lowered water tables on adjacent wetlands. The lowering of groundwater tables is accomplished through drainage structures that cause transient groundwater flows toward the structure in the upper portions of the shallow aquifer (water table aquifer). The effect of water table drawdown diminishes with distance from the structure. Current regulations of the District allow an average drawdown of 3 ft throughout a development project, with no one area having a drawdown greater than 5 ft. The width of the buffer depends on the drawdown anticipated as a result of the drainage structures and the hydraulic conductivity of the soil. Using a design drawdown (depth to which groundwaters are to be lowered) in the vicinity of a structure, the buffer required to minimize drawdown effects on adjacent wetlands can be calculated using a derivation of the Theis equation as follows: ho -h = (2.3 Q/4 p. K D)(log [2.25 T t/r2 nl) (2) and substituting: Q = K sOL (3)

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and t = 4 D n/pi K s2 (4) where: ho -h = Q = D = L = K = s = T = t = S = r = acceptable drawdown at wetlands edge taken as 0.25 ft. discharge depth of ditch or basin length of ditch or basin hydraulic conductivity, taken as 10 ft/day slope of water table surface K x depth of ditch time in days coefficient of storage, taken as 0.2 distance radially from ditch or basin n = porosity. 123 Equation 2 may be simplified and rearranged to solve for the distance, r, where the drawdown will be equal to 0.25 ft in terms of the length, L, of ditch or basin. Substituting the buffer width, B w for the distance, r, the equation then stated as follows: Bw = (1.69D/S)(10-[1.3/SL]) (5) The solution of Equation 5 is trivial for very small ditch lengths. The assumption is made that a drawdown of 0.25 ft at the wetland edge is acceptable. The buffer distances for drawdowns of 1, 2, 3, and 5 ft with a ditch length of 300 ft are 78, 156, 235, and 392 ft, respectively. Determining drawdowns in unconfined water table aquifers where conditions vary from one site to the next is a very complex task, and the methodology presented here is likely to be controversial. Be that as it may, the above formula may be used to determine a buffer width based on gross assumptions concerning such factors as hydraulic conductivity and coefficient of storage, among others. It is a much simplified version of much more complex relationships. Without a detailed analysis of the conditions and soils characteristic of the Wekiva Basin--which are beyond the scope of this report--the simplified relationships expressed in Equation 2 may be used as guides to

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124 determine effective setbacks to minimize drawdown effects. The authors suggest that groundwater hydrologists, engineers and ecologists be consulted to better define parameters more precisely and to formulate an acceptable methodology for determining drawdown effects. (4) Maintaining Habitat Suitability Specific quantitative data are not currently available for all of the wildlife species in the Wekiva River Basin. However, we were able to obtain information on several of the more sensitive forest-dwelling wetland-dependent species which would be adversely affected by landscape alterations (Table V.2). Areas that are suitable for these species would, of course, also be suitable for less sensitive species. The following are minimum standards that are required for an area to be considered suitable for a full spectrum of wildlife along the Wekiva River. 1. Tree canopy height greater than 50 ft; 2. Tree canopy greater than 70%; 3. Average tree. crown diameter greater than 15 ft; 4. More than 3 trees of at least 20 inches dbh/ac; 5. More than 0.1 snags greater than 20 inches dbh/ac; 6. Average shrub height greater than 2 ft but less than 15 ft; and 7. Shrub canopy closure greater than 70%. (a) Calculating Spatial Requirements. The amount of suitable contiguous habitat required to support at least one individual of most species living in the Wekiva River Basin is a circular area of 5.17 ac (diameter = 536 ft). This was derived by combining information from several references (see Table V.2). First of all, many forest interior songbirds do not live in plots smaller than 1 ac (diameter = 236 ft). Other data suggest that individuals found in some of the smallest plots were probably living in stressful and unhealthy environments. Negative edge effects have been shown to affect species within 300 ft of forest boundaries. Ideally then, the minimum diameter

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Table V.2. Minimum habitat suitability and spatial requirements of some of the most sensitive wetland dependent wildlife species in the Wekiva River Basin. Species Florida cooter and other 1 aquatic turtles 2 wood stork Pileated 3 4 woodpecker hawk Song birds4,5,8,9 10 Indlgo snake Habitat Types aquatic, all wetlands, sandy uplands cypress swamps, shallow fresh water all forested wetlands all forested wetlands Minimum Habitat Suitability uplands for nesting, water for food large cypress trees for nesting, water for food -tree canopy closure > 25% -> 3 trees of at least 20 in. dbh/acre -> 0.1 snags (>20 in. dbh)/acre -tree canopy height > 17.7 m -tree canopy closure > 70% -avg. tree crown diam. > 8 m -shrub canopy closure > 20% -avg. shrub ht. > 0.5 m but < 5.0 m wetlands for most of the year but gopher tortoise burrows in winter Minimum Spatial Requirements in Suitable Habitat Areas Distance Upland from Total Width River Edge of Timber Including River (50 ft of uplands) 197 ft 795 ft 236 ft 300 ft from large cypress trees 4,221 ft 2,606 ft (300 ft of uplands) ,... N '"

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Table V.2 (page 2 of 2) lWeller, M.W. 1978. Management of Freshwater Marshes for Wildlife. Pages 276-84 in R.E. Good, D.F. Whigham, and R.L. Simpson (eds.), Freshwater Wetlands: Ecological Processes and Management Potential. New York, NY: Academy Press. 2palmer, R.S. Flamingos. 1962. Handbook of North American Birds: Volume 1, Loons through Yale University Press, New Haven. 567 pp. 3Schroeder, R.L. 1983. Habitat suitability index models: U.S. Dept. Int., Fish. wildl. Servo FWS/OBS-82/10.39. Pileated woodpecker. 15 pp. 4Tassone, J.F. 1981. Utility of Hardwood Leave Strips for Breeding Birds in Virginia's Central piedmont. MS Thesis. Blacksburg, VA: Virginia Polytechnic Institute and State College, 83 pp. 5Galli, A.E., C.F. Leck, and R.T.T. Forman. 1976. Avian distribution patterns in forest islands of different sizes in central New Jersey. Auk 93:356-64. 6Bryant, A.A. 1986. Influence of selective logging on red-shouldered hawks, Buteo lineatus, in Waterloo Region, Ontario, 1953-1978. Canadian Field 100(4):520-25. 7Bednarz, J.C. and J.J. Dinsmore. 1982. Nest-sites and habitat of redshouldered and red-tailed hawks in Iowa. Wilson Bull. 94(1):31-45. 8Sousa, P.J. 1982. Habitat suitability index models: Veery. U.S. Dept. Int., Fish. Wildl. Servo FWS/OBS-82/10.22. 12 pp. 9remple, S.A. 1986. predicting impacts of habitat fragmentation on forest birds: A comparison of two models. Pages 301-04 in J. Verner, M.L. Morrison and C.J. Ralph (eds.), Wildlife 2000: Modeling Habitat Relationships of Terrestrial Vertebrates. Madison, WI: The University of Wisconsin Press. 10Speake, D.W., J.A. McGlincy, and T.R. Colvin. 1978. Ecology and management of the eastern indigo snake in Georgia: A progress report. Pages 64-73 in R.R. Odum and L. Landers (eds.), Proceedings of the Rare and Endangered Wildlife Symposium, Aug. 3-4, 1978. Georgia Dept. Nat. Res. Tech. Bull. WL 4. ,... N a-

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127 of a stress-free suitable habitat area should be 836 ft (300 ft + 236 ft + 300 ft). However, it is assumed that edge effects along the river are not as severe as those along the uplands, and the average of 236 flnd 836 (536 ft) is recommended as the minimum width necessary to prevent harmful effects of development on individual wetland-dependent animals. Self-sustaining populations require suitable areas many times larger. Their spatial needs can be easily satisfied by protecting a minimum width of 536 ft of suitable habitat landward from the edge of the forest along both sides of the river. In some situations, the wetland area will be sufficient and no upland buffer is needed to fulfill this requirement. Where wetlands are relatively narrow but forest canopy continues into the uplands, an upland buffer will be needed. Although some large species such as the hawk need correspondingly wider areas, it is our opinion that the requirements of these low-density nesting birds are satisfied by the large wetland areas within the existing designated wetlands along the Wekiva River. The 536-foot width is believed to be sufficient contiguous habitat to satisfy corridor requirements of large mammals such as black bear, river otter, and bobcat. (b) Calculating Necessary Access to Uplands or Transitional Habitat. Enough upland or transitional habitat must be preserved adjacent to the wetlands so that semiaquatic turtles can find suitable safe areas to lay their eggs. Although a narrow upland strip of sandy soil would provide the necessary substrate, nests constructed in this type of environment would be subjected to high predation rates associated with edges. A minimum 50-foot upland buffer along the entire length of the river is recommended for turtles. Areas where gopher tortoises are present within 300 ft of the adjacent wetlands should be protected so indigo snakes in the wetlands can continue

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128 their seasonal movements into upland gopher tortoise burrows. In these situations, the buffer should include the entire gopher tortoise area. (c) Calculating Buffers for Noise Impacts. The effects of noise on wildlife breeding, feeding, and territorial protection is not completely understood, although data suggest that noise more than human presence that drives wildlife from areas surrounding developed land. A simple method proposed by Brown (1981) for determining buffer sizes necessary to attenuate highway noise to acceptable levels was to utilizes forested areas to reduce noise levels to background levels. Using the following equation,3 noise level at the source can be related to vegetation of the buffer zone to determine buffer width necessary to reduce noise levels to background (40 dBA). where: Bw = In (40/Ni)/-Ac (6) Bw = Ac = N' 1 = buffer width in ft attenuation coefficient. Use .002 for paved buffer, .0037 for nonforested buffer, and .0053 for heavily forested buffer noise level of source. Use 50 dBA for residential areas, 60 dBA for nonarterial general traffic, 70 dBA arterial traffic, and 70 dBA for commercial areas The required buffers to reduce average residential noise levels (50 dBA) to background (40 dBA) is 60 ft when the buffer is cleared or 42 ft when the buffer is forested. V.C. Illustration of Buffer Zone Determinations Given in this section are several maps of portions of the Wekiva River Basin and Black Water Creek Basin depicting relevant information and highlighting examples of buffer width determinations for controlling 3 The equation is derived from data presented in several studies (Eyring 1946, Weiner and Keast 1959, Embleton 1963, and a summary by Robinette 1972).

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129 parameters. The information shown on each of the maps has been derived from aerial photographs, USDA SCS soil surveys, and USGS topographic maps. The scale of the original information determines the resolution at which buffer widths can be graphically depicted. As a result, the resolution of these maps is not sufficient to locate buffer requirements accurately at a scale that is suitable for actual determinations. Instead, maps and data should be compiled at a scale of about I" = 100 ft, or possibly 1" = 200 ft, to render the zone in which buffer determinations are to be made in sufficient detail. The areas chosen for these illustrations were selected because of the variety of conditions that are illustrated within relatively small geographic locales. Whether these areas can ultimately be developed was not taken into consideration, so to the astute observer, it may be obvious that portions of the areas are in state ownership. No attempt has been made to single out these areas for any purpose other than for their illustrative value. Tables V.3, V.4, and V.5 list ranges of buffer widths generated using the above equations and a given set of parameter values. It is important to note that there is an infinite range of buffer widths and that the values shown are only representative possibilities. The variables. in the equations are to be determined in the field on a site-by-site basis. (1) 40C-4 Wetland Line. Given in Maps V.1 and V.6 are simplified vegetation maps to show the forest canopy and wetland line. The wetland line was drawn from interpretation of aerial photographs and is an estimate of the line that would be determined using field verification of the dominance of wetland vegetation (2) Wildlife Habitat Suitability. Also shown on Maps V.1 and V.6 are the three habitat buffer zones. When forest canopy is absent, the buffer zone resulting from spatial requirements of wildlife is not determined and is only

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130 shown when the wetland line is waterward of the necessary 536 ft. The transitional habitat buffer is shown as a SO-foot zone landward of the wetland line, and the noise attenuation buffer is drawn based on the vegetative characteristics of the intervening area between the habitat line and the area reserved for development. The most landward line is then drawn as the wildlife buffer. (3) Water Quality Buffer. Shown on Maps V.2, V.3, V.7, and V.8 are slope and generalized soil characteristics derived from SCS soil surveys that are used in calculating buffer zone requirements to minimize erosion and sedimentation. The indicated buffer zone requirement is a function of the erodibility of the soil and slope of the ground surface in the area immediately landward of the wetland line. Where two or more soil types occur along the 300-foot survey swath, either the dominant type was used or an average value was taken if the soils were evenly distributed. (4) Water Quantity Buffer. Shown on Maps V.4 and V.9 are generalized water table characteristics that are used to determine the buffer zone required to minimize adverse impacts from water table drawdown. A design drawdown of 3 ft was used to calculate buffer zone requirements. The assumption was made that if water table elevations were between 0" and 12", then a full drawdown of 3 ft was necessary. In like manner, if the water table elevation was between 12" and 24" or between 24" and 36", the drawdown was taken as 2 ftand 1 foot, respectively. (5) Composite Buffer. Given in Maps V.5 and V.lO are the composites derived by taking the most landward buffer boundary determined by each of the four controlling parameters.

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Table V.3. Sample buffer widths (ft) determined by water quality criteria (refer to Equation 1, Section V.B.2) Erodibility* Slope % ** 1 2 3 4 3.9 198 99 66 49 6.9 263 131 88 67 7.9 281 140 94 70 10.0 316 158 105 79 Erodibility factors are interpreted as follows: 131 1) Most erodible soils (K > 0.17) or no. 2 soils with no vegetative cover. 2) Soils with (K = 0.17) conditions or medium soils (3) with no vegetation. 3) Medium erodibility (K = 0.15) or good soils (4) with no vegetative cover. 4) Good soils (K = 0.10) with vegetative cover. ** Numbers shown represent upper limits of slope categories.

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132 Table V.4. Sample buffer widths (ft) determined by water quantity criteria (refer to Equation 5, Section V.B.3) Drawdown (ft) Slope % '* 1 2 3 5 3.9 56 112 168 280 6.9 28 57 85 142 7.9 24 49 73 121 10.0 19 37 56 93 Numbers shown represent upper limits of slope categories. The slope of the groundwater table was assumed to equal that of the ground surface in the area immediately adjacent to the wetland line.

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Table V.5. Sample buffer widths (ft) determined by noise attenuation criteria (refer to Equation 6, Section V.B.4) Noise Level (dBA) Buffer Type 50 60 70 Canopy 42 76 105 No Canopy 60 110 151 Paved 112 203 280 133

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LITERATURE CITED Allen, D.L. 1962. Our Wildlife Legacy. New York, NY: Funk and Wagnalls. Ames, D.R. 1978. Physiological responses to auditory stimuli. J.L. Fletcher and R.G. Busnell (eds.), Effects of noise on wildlife. New York: Academic Press. Arrhenius, o. 1921. Species and Area. J. Ecol. 9: 95-99. Bailey, T.N. Marsh. 1971. Biology of Striped Skunks on a Southwestern Lake Erie J. Wildl. Manage. 85: 196-207. Batzli, G.O. 1977. Population Dynamics of the White-Footed Mouse in Floodplain and Upland Forests. Amer. MidI. Natl. 97(1): 18-32. Beck, A.A. 1973. The Ecology of Stray Dogs: a Study of Free-Ranging Urban Animals. Baltimore, MD: York Press, 98 pp. Beecher, W.J. 1942. Nesting Birds and Vegetative Substrate. Chicago, IL: Chicago Ornithol. Soc. Beeler, I.E., and T.J. O'Shea. 1987. Distribution and Mortality of the West Indian Manatee (Trichechus manatus) in the Southeastern United States: A Compilation and Review of Recent Information. Vol. 1: The Atlantic Coast. U.S. Fish and Wildlife Service Contract Report, Contract /114-16-0009-861815. Prepared for the U.S. Army Corps of Engineers, Jacksonville District. 328 pp. Bider, J.R. 1968. Animal Activity in Uncontrolled Terrestrial Communities as Determined by a Sand Transect Technique. Ecol. Monogr. 38: 269-308. Bloom, A.L. 1983. Sea Level and Coastal Morphology of the United States Through the Late Wisconsin Glacial Maximum. Pages 215-219 in Late Quaternary Environments of the United States, Vol I: The Pleistocene (S.C. Porter, ed.). University of Minnesota Press, Minneapolis. Borman, F.H., G.E. Likens, D. W. Fisher, and R.S. Pierce. 1968. Nutrient Loss Science 159: 882-884. Acceleration by Clearcutting of a Forest Ecosystem. Bradt, G.W. 1949. Farm Cat as Predator. Michigan Conserv. 18: 23-25. Bratton, S.P., and P.S. White. 1980. Rare Plant Management--After Preservation What? Rhodora 82: 49-75. Brittingham, M.C., and S.A. Temple. 1983. Have Cowbirds Caused Forest Songbirds to Decline? BioScience 33: 31-35. Brown, M.T. 1981. The Use of Planted Pines for Highway Noise Reduction. Working Paper. Gainesville, FL: Center for Wetlands, Univ of FL. 145

PAGE 138

146 Brown, M.T. 1986. Cumulative Impacts in Landscapes Dominated by Humanity. Pages 33-50 in E.D. Estevez, J. Miller, J. Morris, and R. Hamman (eds.), Managing Cumulative Effects in Florida Wetlands: Conference Proceedings. New College Environmental Studies Program Publication No. 37 (Sarasota, FL). Madison, WI: Ominipress. (CFW-86-09.) Brown, M.T., G.R. Best, B. Coggins, C. Diamond, B. Dunn, F. Gross, J. Sendzimir, P. Straub, M. Sullivan, R. Tighe, and P. Wallace. 1984. Development of Techniques and Guidelines for Reclamation of Phosphate Mined Lands as Diverse Landscapes and Complete Hydrologic Units. First Annual Report to Florida Institute of Phosphate Research, Bartow, FL. Gainesville, FL: Center for Wetlands, Univ of FL, pp. 51. (CFW-84-07.) Brown, M.T., G.R. Best, M. Davis, F. Gross, R. Hassoun, H. Riekerk, P. Straub, M. Sullivan, and W.T.S. Swank. 1985. Development of Techniques and Guidelines for Reclamation of Phosphate Mined Lands as Diverse Landscapes and Complete Hydrologic Units. Second Annual Report to Florida Institute of Phosphate Research, Bartow, FL. Gainesville, FL: Center for Wetlands, Univ of FL, pp. 184. (CFW-85-04.) Brown, M.T., G.R. Best, H. Riekerk, M. Davis, F. Gross, M. Sullivan, R. Tighe, and S. Roguski. 1986. Development of Techniques and Guidelines for Reclamatiori of Phosphate Mined Lands as Diverse Landscapes and Complete Hydrologic Units. Preliminary Third Annual Report to Florida Institute of Phosphate Research, Bartow, FL. Gainesville, FL: Center for Wetlands, Univ of FL, pp. 92. (CFW-86-08.) Brown, M.T., and E.M. Starnes (with C. Diamond, B. Dunn, P. McKay, M. Noonan, S. Schreiber, J. Sendzimer, S. Thompson, and B. Tighe). 1983. A Wetlands Study of Seminole County. Center for Wetlands and Department of Urban and Regional Planning, University of Florida, Gainesville. Technical Report 41. iv + 284 pp. Browne, K.W., and Associates. 1980 An Assessment of the Impact of Septic Leach Fields, Home Fertifications, and Agricultural Activities on Groundwater Quality. Final Report to the New Jersey Pinelands Commission. Bull, A.L., C.J. Meade, and K. Williamson. in Relation to Agricultural Changes. 1976. Bird-Life on a Norfolk Farm Bird Study 23: 163-82. Burt, W.H. and R.P. Grossenheider. 1964. A Field Guide to the Mammals. Boston, MA: Houghton Mifflin Co., 284 pp. Butcher, G.S., W.A. Niering, W.J. Barry, and R.H. Goodwin. 1981. Equilibrium Biogeography and the Size of Nature Preserves: An Avian Case Study. Oecologia 49: 29-37. Chanin, P.R.F., and D.J. Jefferies. 1978. The Decline of the Otter (Lutra lutra L.) in Britain: An Analysis of Hunting Records and Discussions of Causes. BioI. J. Linn. Soc. 10: 305-28. Clewell, A.F., J.A. Goolsby, and A.G. Shuey. South Prong Alafia River System, Florida. 1982. Riverine Forests of the Wetlands 2: 21-72.

PAGE 139

147 Conner, R.N., R.G. Hooper, H.S. Crawford, and H.S. Mosby. 1975. Woodpecker Nesting Habitat in Cut and Uncut Woodlands in Virginia. J. Wildl. Manage. 39(1): 144-50. Corbett, R.L., R.L. Marchinton, and C.E. Hill. 1971. Preliminary Study of the Effects of Dogs on Radio-Equipped Deer in Mountainous Habitat. Proc. Ann. Conf. of S.E. Assoc. Game and Fish Comm. 25: 69-77. Crummett, J.G. 1970. Acoustic information denial as a means for vertebrate pest control. Paper presented at the 80th meeting of the Acoustical Society of America, Houston, November, 1970. Darnell, R.M., W.E. Pequegnot, B.M. James, F.J. Benson, and R.A. Defenbaugh. 1976. Impacts of Construction Activities in Wetlands of the United States. U.S. EPA, Office of Resesrch and Development, Corvallis ERL. Corvallis, OR. Dasmann, R.F. 1964. Wildlife Biology. New York, NY: John Wiley and Sons. Davis, D.E. Mammal. 1957. The Use of Food as a Buffer in a Predatory-Prey System. 38: 466-72. J. Davis, M.B. 1981. Pages 132-153 H.H. Shugart, Quaternary history and the stability of forest communities. in Forest Succession: Concepts and Application (D.C. West, and D.B. Botkin, (eds.) Springer-Verlag, New York. DER (Department of Environmental Regulation, State of Florida). 1983. Report to the Environmental Regulation Commission on Extending the Boundaries of the Outstanding Florida Water Designation Within the Wekiva River System. Victoria J. Tschinke1, Secretary. DER, Tallahassee. Diamond, J.M. 1975. Studies for the 129-46. The Island Dilemma: Lessons of Modern Biogeographic Design of Natural Preserves. Biological Conservation 7: Diamond, J.M. 1976. Island Biogeography and Conservation: Strategy and Limitations. Science 193: 1027-29. Diamond, J.M., and R.M. May. 1976. Island Biogeography and the Design of Natural Reserves. Pages 163-86 in R.M. May (ed.), Theoretical Ecology: Principles and Applications. Philadelphia, PA. Diehl, F.P. 1969. Sound as a rodent deterrent. Pest control. 37: 36-34. DNR (Department of Natural Resources, State of Florida). 1985. Rock Springs Run State Reserve Unit Plan. Bureau of Land and Aquatic Resource Management, Division of Recreation and Parks. Tallahassee. DNR (Department of Natural Resources, State of Florida). 1987. Wekiva River Aquatic Preserve Management Plan, June 1987 (DRAFT) Bureau of Land and Aquatic Resource Management, Division of Recreation and Parks. Tallahassee.

PAGE 140

148 Eberhard, T. 1954. Food Habits of Pennsylvania House Cats. J,.Wildl. Manage. 18: 284-86. Environmental Protection Agency. 1971. Effects of noise on wildlife and other animals. NTID 300.5. 74 pp. Erman, D.C" J.D. Newbold, and K.B. Roby. 1977. Evaluation of Streamside Bufferstrips for Protecting Aquatic Organisms. Davis, CA: California Water Resources Center, Univ of CA. Errington, P.L. 1936. Notes of Food Habits of Southern Wisconsin House Cats. J. Mammal. 17: 64-65. Eyring, C.F. 1946. Jungle Acoustics. Journal of the Acoustical SOCiety of America, October 1946: 731. Faaborg, J, 1980. Potential Uses and Abuses of Diversity Concepts in Wildlife Management. Trans. Missouri Acad. Sci. 14: 41-49. Fahrig, L., and G. Merriam. 1985. Habitat Patch Connectivity and Population Survival. Ecology 66: 1762-68. Florida Department of Environmental Regulation. 1983. Extending the Boundaries of the Outstanding Florida Water Designation within the Wekiva River System. Report to the Environmental Regulation Commission. Tallahassee, FL: State of Florida Department of Environmental Regulation, 44 pp. Florida Division of Forestry. 1979. Silviculture Best Management Practices Manual. Tallahassee, FL: Florida Department of Agriculture and Consumer Services, Division of Forestry, Collins Bldg. FGFWFC (Florida Game And Fresh Water Fish Commission). 1987. Official lists of endangered and potentially endangered fauna and flora in Florida. GFC #86{7-050, Tallahassee. Florida Department of Environmental Regulation. 1978. Non-point Source Management: A Manual of Reference Management Practices for Urban Activities. Bureau of Water Analysis FDER. Tallahassee, FL. 96 p. Forman, R.T. 1983. Corridors in a Landscape: Their Ecological Structure and Function. Ecology (CSSR) 2(3): 375-87. Forman, R.T.T, A.E. Galli, and C.F. Leck. Diversity in New Jersey Woodlots with Oecologia 26: 1-8. 1976. Forest Size and Avian Some Land Use Implications. Forman, R.T.T., and M. Godron. 1981. Patches and Structural Components for a Landscape Ecology. BioScience 31: 733-40. Forman, R.T.T., and M. Gordon. 1986. Landscape Ecology. New York, NY: John Wiley & Sons, 619 pp.

PAGE 141

149 Forsyth, D.J., and D.A. Smith. 1973. Temporal Variability in Home Ranges of Eastern Chipmunks (Tamias straitus) in a Southeastern Ontario Woodlot. Am. MidI. Natl. 90: 107-17. Frankel, O.H., and M.E. Soule. 1981. Conservation and Evolution. Cambridge, England: Cambridge University Press. Franklin, I.R. 1980. Evolutionary Change in M.E. Soule and B.A. Wilcox (eds.), Evolutionary-Ecological Perspective. Inc., 395 pp. in Small Populations. Pages 209-24 Conservation Biology: An Sunderland, MA: Sinauer Associates, Fredrickson, L.H. 1979. Floral and Faunal Changes in Lowland Hardwood Forests in Missouri Resulting from Channelization, Drainage, and Impoundment. U.S. Fish and Wildl. Servo FWS/OBS-78/91. 130 pp. Fredrickson, L.H. 1978. Lowland Hardwood Wetlands: Current Status and Habitat Values for Wildlife. Pages 296-306 in P.E. Greeson, J.R. Clark and J.E. Clark (eds.), Wetland Functions The State of Our Understanding. Proceedings of the National Symposium on Wetlands, Nov. 710, 1978. Minneapolis, MN: American Water Resources Association. FWR (Technical Committee of THE FRIENDS OF THE WEKIVA RIVER, INC.). 1985. The Wekiva River Basin: A Resource Endangered. Friends of the Wekiva River, Inc. 36 pp. text + appendices. Galli, A.E., C.F. Leck, and R.T.T. Forman. 1976. Avian Distribution Patterns in Forest Islands of Different Sizes in Central New Jersey. Auk. 93: 356-64. Game, M., and G.F. Peterken. 1984. Nature Reserve Selection Strategies in the Woodlands of Central Lincolnshire, England. BioI. Conserv. 29: 157-81. Gates, J.E., and L.W. Gysel. 1978. Avian Nest Dispersion and Fledgling Success in Field-Forest Ecotones. Ecology 59: 871-83. Gavitt, J.D. 1973. Disturbance Effects of Free-Running Dogs on Deer Reproduction. MS Thesis. Blacksburg, VA: VPI and State University. Gehrken, G.A. 1975. Travel Corridor Technique of Wild Turkey Management. Pages 113-17 in L.K. Halls (ed.), Proceedings of the National Wild Turkey Symposium. Austin, TX: Wildlife Society, Texas Chapter. Gentry, J.B., F.B. Golley, and M.H. Smith. 1968. An Evaluation of the Proposed International Biological Program Census Method for Estimating Small Mammal Populations. Acta Theriologica 13(18): 313-27. George, W.G. 1974. of Raptor Prey. Domestic Cats as Predators and Factors in Winter Shortages Wilson Bull. 86: 384-96. Ghiselin, J. 1977. Analyzing Ecotones to Predict Biotic Productivity. Environ. Manage. 1: 235-38.

PAGE 142

150 Gilbert, F.F. 1971. Analysis of Deer Mortality Other Than Legal Kill. Maine No W-67-R2: Job No. 1-3. Maine Dept. Inland Fisheries and pp. Fed. Aid Proj. Game. Memo. 12 Giles, R.H. (ed.). 1971. Wildlife Management Techniques. Washington, D.C.: The Wildlife Society. Gill, D. 1975. The Feral House Cat as a Predator of Varying Hares. Can. Field-Nat. 89: 78-79. Gleason, H.A. 1922. On the Relationship Between Species and Area. Ecology 3: 158-62. Gottfried, B.M. 1979. Small Mammal Populations in Woodlot Islands. Amer. MidI. Nat. 102: 105-12. Greaves, J.H. and F.P. Rowe. 1969. Responses of confined rodent populations to an ultrasound generator. J. Wildl. Manage. 33: 409-17. Gross, F.E.H. 1987. Characteristics of Small Stream Floodplain Ecosystems in North and Central Florida. MS Thesis (CFW-87-01). Gainesville, FL: Univ of FL, pp. 167. Gysel, L.W. 1951. Borders and Openings of Beech-Maple Woodlands in Southern Michigan. Journal of Forestry 49: 13-19. Harlukowicz, T.J., and R.C. Ahlert. 1978. Effects of Septic Effluent on Groundwater Quality in the New Jersey Pine Barrens. Final Report to The Rockefeller Foundation. New Brunswick, NJ: College of Engineering, Bureau of Engineering Research, Rutgers. Harris, L.D. 1983. An Island Archipelago Model for Maintaining Biotic Diversity in Old-Growth Forests. Pages 378-82 in New Forests for a Changing World, Proceedings of the 1983 SAF National Convention. Harris, L.D. 1984. Preservation of Press, 211 pp. The Fragmented Forest: Island Biogeography Theory and the Biotic Diversity. Chicago, IL: University of Chicago Harris, L.D. 1985. Conservation Corridors: A Highway System for Wildlife. Winter Park, FL: Environmental Information Center of the Florida Conservation Foundation, Inc., ENFO report 85-5, 10 pp. Harris, L.D., D.H. Hirth, and W.R. Marion. Silvicultural Systems for Wildlife. Louisiana State University. 1979. The Development of The 28th Annual Forestry Symposium. Harris, L.D., and J.D. McElveen. 1982. Effects of Edge Type on North Florida Breeding Birds. Gainesville, FL: School of Forest Resources and Conservation, Univ of FL (unpublished manuscript). Harris, L.D., M.E. McGlothlen, and M.N. Manlove. 1984. Genetic Resources and Biotic Diversity. Pages 94-107 in L.D. Harris (ed.), The Fragmented

PAGE 143

Forest: Island Biogeography Theory and the Preservation of Biotic Diversity. Chicago, IL: University of Chicago Press, 211 pp. Harris, L.D., and R.F. Noss. 1985. Problems in Categorizing the Status of Species: Endangerment with Best of Intentions. l 16th IUCN Technical Meeting, Madrid, Spain. November 1984. 151 Harris, L.D., and C.R. Vickers. 1984. Some Faunal Community Characteristics of Cypress Ponds and the Changes Induced by Perturbations. Pages 171-85 in K.C. Ewel and H.T. Odum (eds.), Cypress Swamps. Gainesville, FL: University Presses of FL. (CFW-84-36.) Harris, L.D., and R. Wallace. 1984. Breeding Bird Species in Florida Forest Fragments. Proc. Ann. Conf. S.E. Assoc. Fish Wildl. Agencies 38: 87-96. Hart, R. 1981. Regulatory Definitions of Wetlands: Do They Maximize Wetland Function? Pages 273-83 in P. McCaffrey, T. Breemer, and S. Gatewood (eds.), Progress in Wetlands Utilization and Management. Proceedings of a Symposium, June 9-22, 1981. Coordinating Council on the Restoration of the Kissimmee River Valley and Taylor Creek--Nubbin Slough Basin. Hart, R.L. 1984. Evaluation of Methods for Sampling Vegetation and Delineating Wetlands Transition Zones in Coastal West-Central Florida, January 1979-May 1981. Technical Report Y-84-2 U.S. Army Engineer Waterways Experiment Station. Washington, DC: NTIS. Hart, R.L. 1985. Microclimate Studies, Volume 3: Terrestrial Ecology Appendix 3B. Fairfield, FT. George Island Master Resource Management Plan, ESE #83-612-0610-0120. Gainesville, FL: Environmental Sciences and Engineering Inc. Hartman, D.S. 1979. Ecology and behavior of the manatee (Trichechus manatus) in Florida. Amer. Soc. Mammal. Spec. Publ. 5: 1-153. Lawrence, Kansas. Heath, R.C. and C.S. Conover. 1981. Hydrologic Almanac of Florida. United States Department of Interior Geological Survey, Open-File Report 81-1107. USGS, Tallahassee. Hedrick, L.D. 1973. Silvicultural Practices and Tree Squirrels. MS Thesis. Texas A&M University. 97 pp. Hewlett, J.D. 1982. PrinCiples of Forest Hydrology. Athens, GA: Univ of Georgia Press. Hill, E.P. 1970. Bat control with high frequency sound. Pest Control. 38: 18. Holling, C.S. 1966. The Functional Response of Invertebrate Predators to Prey Density. Mem. Entomol. Soc. Can. 48, 88 pp. Hollis, C.A., R.F. Fisher, and W.L. Pritchett. 1978. Effects of Some Silvicultural Practices on Soil Site Properties in the Lower Coastal Plains. In Youngberg, C.T., (ed.), Forest Soils and Land Use. Forest and Wood SCiences, Colorado State University, Fort Collins, CO., pp. 585-607.

PAGE 144

152 Hoyt, S.F. 1957. The Ecology of the Pi1eated Woodpecker. Ecology 38(2): 246-56. Hubbs, E.L. 1951. Food Habits of Feral House Cats in the Sacramento Valley. Calif. Fish and Game 37: 177-89. Hunt, R. 1984. Evaluation of Methods for Sampling Vegetation and Delineating Wetlands Transition Zones in Coastal West-Central Florida, January 1979-May 1981. U.S. Army Engineer Waterways Experiment Station. Springfield, VA: NTIS, Technical Report Y-84-2. Jackson, J.A. 1978. Competition for Cavities and Red-Cockaded Woodpecker Management. Pages 103-12 S.A. Temple (ed.), Endangered Birds. Madison, WI: University of Wisconsin Press. Jackson, L.W. 1971. Annual Deer Mortality in Malone. Fed. Aid Proj. No. W89-R-15: Job No. XI-4. New York, NY: New York State Dept. Env. Cons. Delmar. 9. Janzen, D.H. 1983. No Park is an Island: Increase in Interference from Outside as Park Size Increases. Oikos 41: 402-10. Janzen, D.H. 1986. The Eternal External Threat. Pages 286-303 in M.E. Soule (ed.), Conservation Biology: The Science of Scarcity and Diversity. Sunderland, MA: Sinauer Associates. Jennings, W.L. 1951. Squirrel (Scirus Gainesville, FL: A Study of the Life History and Ecology c. carolinensis Gmelin) in Gulf Hammock. Univ of FL, 151 pp. of the Gray MS Thesis. Johnson, W.C., R.K. Schreiber, and R.L. Burgess. 1979. Diversity of Small Mammals in a Powerline Right-of-Way and Adjacent Forest in East Tennessee. Am. MidI. Nat. 101: 231-35. Johnson, W.C., and C.S. Adkisson. 1985. Dispersal of Beech Nuts by Blue Jays in Fragmented Landscapes. American Midland Naturalist 113: 319-24. Johnson, W.N., Jr. 1986. Avian Use of a Lakeshore Buffer Strip in Eastern Maine. MS thesis. Orono, ME: University of Maine, 63 pp. Johnston, V.R. Illinois. 1947. Breeding Birds of the Forest Edge in East-Central Condor 49(2): 45-53. Kalisz, P.J. and E.L. Stone. 1984. Longleaf pine islands of the Ocala Ecology 65(6): 1743-1754. National Forest: a soil study. Kantola, A.T. 1986. Fox Squirrel Home Range and Mast Crops in Florida. Thesis. Gainesville, FL: Univ of FL, 68 pp. MS Karr, J.R. 1982. Population Variability and Extinction in the Avifauna of a Tropical Land Bridge Island. Ecology 63: 1975-78.

PAGE 145

153 Karr, J.R., and I.J. Schlosser. 1977. Stream Morphology on Water Quality Environmental Resource Lab, Office Impact of Nearstream Vegetation and and Stream Biota. Athens, GA: U.S. of Resources and Development. Kockman, H.I. 1978. Eastern Indigo Snake. Pages 68-9 in R.W. McDiarmid (ed.), Rare and Endangered Biota of Florida: Amphibians and Reptiles. Gainesville, FL: University Presses of Florida. Korschgen, L.J. Missouri. 1957. Food Habits: Coyotes, Foxes, House Cats, Bobcats in Mo. Conserv. Comm. Bull. 15, 64 pp. B., and E. Anderson. 1980. Pleistocene mammals of North America. Columbia Univ. Press, New York. 442 pp. Laessle, A. M. 1958. The origin and successional relationships of sandhill vegetation and sand pine scrub. Ecol. Monog. 28: 361-387. EPA Landers, J.L., R.J. Hamilton, A.S. Johnson, and R.L. Marchington. 1979. Foods and Habitat of Black Bears in North Carolina. J. Wildl. Manage. 43: 143-53. Larson, J.S. 1981. Transition from Wetlands to Uplands in Southeastern Bottomland Hardwood Forests. Pages 225-74 in (eds.), J.R. Clark and J. Benforado, Wetland Bottomland Hardwood Forests. Proceedings of a Workshop on Bottomland Hardwood Forest Wetlands of the Southeastern United States. Amsterdam: Elsevier Scientific Publishing Company. Lavdenslayer, W.F., and R.P. Balda. Juniper-Ponderosa Pine Ecotone. 1976. Breeding Bird Use of a PinyonAuk 93: 571-86. Lay, D.W. 1938. How Valuable are Woodland Clearings to Birdlife? Wilson Bull. 45: 254-56. Leopold, A. 1933. Game Management. New York, NY: Charles Scribners Sons. Levenson, J.B. 1981. Woodlots as Biogeographic Islands is Southeastern Wisconsin. Pages 12-39 in R. L. Burgess and D. M. Sharpe (eds.), Forest Island Dynamics in Man-Dominated Landscapes. New York, NY: Springer Verlag. Livingston, R.J., R.L. Iverson, and D.C. White. 1976. Energy Relationships and Productivity of Apalachicola Bay. Final Research Report to Florida Sea Grant College. Tallahassee, FL: Florida State Univ. Lovejoy, T.E., and D.C. Oren. 1981. The Minimum Critical Size of Ecosystems. Pages 7-12 in R.L. Burgess and D.M. Sharpe, (eds.), Forest Island Dynamics in Man-Dominated Landscapes. New York, NY: Springer-Verlag. Lovejoy, T.E., R.O. Bierregaard, A.B. Rylands, J.R. Malcolm, C.E. QUintela, L.H. Harper, K.S. Brown, A.H. Powell, G.V.N. Powell, H.O.R. Schubart, and M.B. Hays. 1986. Edge and Other Effects of Isolation on Amazon Forest Fragments. Pages in M.E. Soule (ed.), Conservation Biology: The Science of Scarcity and Diversity. Sunderland, MA: Sinauer Associates.

PAGE 146

154 Lyle, Jr., E.S. 1987. Surface Mine Reclamation Manual. New York, NY: Elsevier. Lynch, J.F., and D.F. Whigham. 1984. Effects of Forest Fragmentation on Breeding Bird Communities in Maryland, USA. BioI. Conserv. 28: 287-324. MacArthur, R.H. 1964. Environmental Factors Affecting Bird Species Diversity. Ecology 42: 594-98. MacArthur, R.H., and J.W. MacArthur. 1961. On Bird Species Diversity. Ecology 42: 594-98. MacArthur, R.H., J.W. MacArthur, and J. Preer. 1962. On Bird Species Diversity. Amer. Naturalist 66: 167-74. MacArthur, R.H., and E.R. Pianka. 1966. On Optimal Use of a Patchy Environment. Am. Nat. IOU(916): 603-09. MacArthur, R.H., and E.O. Wilson. 1967. The Theory of Island Biogeography. Princeton, NJ: Princeton Press. MacClintock, L., R.F. Whitcomb, and B.L. Whitcomb. 1977. Evidence for the Value of Corridors and Minimization of Isolation in Preservation of Biotic Diversity. American Birds 31: 6-16. Matthiae, P.E., and F. Stearns. 1981. Mammals in Forest Islands in Southeastern Wisconsin. Pages 55-66 in R.L. Burgess and D.M. Sharpe (eds.), Forest Island Dynamics in Man-Dominated Landscapes. New York, NY: Springer-Verlag. McElfresh, R., J. Inglis, and B.A. Brown. Hardwood Ravines in Pine Plantations. Symp. 29: 79-89. 1980. Gray Squirrel Usage of Louisiana State Univ. Forestry McElveen, J.D. Florida. 1977. The Edge Effect on a Forest Bird Community in North Proc. S.E. Assoc. Fish Wildl. Agencies 31: 212-15. McElveen, J.D. 1978. The Effects of Different Types of Edge Types and Habitat Sizes on the Distribution of Breeding Birds in North Florida. MS Thesis. Gainesville, FL: Univ of FL, pp. 47. McMurry, F.B., and C.C. Sperry. 1941. Food of Feral House Cats in Oklahoma, a Progress Report. J. Mammal. 22: 184-90. Means, D.B. and G. Grow. 1985. The endangered longleaf pine community, ENFO 85(4): 1-12. Florida Conservation Foundation, Winter Park. Melquist, W.E. and M.G. Hornocker. 1983. Ecology of River Otters in West Central Idaho. Wildl. Monogr. 83: 1-60. Messersmith, D.H. 1970. Control of bird depredation. Agric. Dept. Coop. State Research. Serv., Maryland.

PAGE 147

155 Miller, R.I. 1979. Conserving the Genetic Integrity of Faunal Populations and Communities. Environmental Conservation 5: 191-95. Miller, R.I., and L.D. Harris. 1977. Isolation and Extirpations in Wildlife Reserves. Bid. Conserv. 12: 311-15. Mitsch, W.J., M.D. Hutchison, and G.A. Paulson. 1979. The Momence Wetlands of the Kankakee River in Illinois: An Assessment of Their Value. Chicago, IL: Illinois Institute of Natural Resources Doc 79/17; 55 pp. Monk, C.D. 1965. Southern mixed hardwood forest of north central Florida. Ecol. Monog. 35(4): 335-354. Monk, C.D. 1968. Successional and environmental relationships of the forest vegetation of north central Florida. Amer. MidI. Nat. 79(2): 441-457. Moore, N.W., and M.D. Hooper. 1975. On the Number of Bird Species in British Woods. BioI. Conserv. 8: 239-50. Murphy, T.M., F.M. Bagley, W. Dubuc, D. Mager, S.A. Nesbitt, W.B. Robertson, and B. Sanders. 1984. Southeastern States Bald Eagle Recovery Plan. Atlanta, GA: U.S. Fish and Wildlife Service. Noss, R.F. 1981. The Birds of Sugarcreek, an Ohio Nature Reserve. Ohio J. Sci. 81: 29-40. Noss, R.F. 1983. A Regional Landscape Approach to Maintain Diversity. BioScience 33(11): 700-06. Noss, R.F. 1985. Characterizing pre-settlement vegetation: how and why. Natural Areas Journal 5(1): 5-19. Noss, R.F. 1987. Corridors in Real Landscapes: A Reply to Simberloff and Cox. Conservation Biology Journal. (in press.) Noss, R.F. 1987. From Plant Communities to Landscapes in Conservation Inventories: press.) A Look at the Nature Conservancy (USA). BioI. Conserv. (in Noss, R.F. and L.D. Harris. 1986. Nodes, networks, and MUM's: preserving diversity at all scales. Environmental Management 10:299-309. Noss, R.F., and L.D. Harris. Diversity at All Scales. 1986. Nodes, Networks, and Mums: Preserving Environmental Management 10(3): 299-309. Odum, E.P. 1971. Fundamentals of Ecology, Third Edition. W.B. Saunders, Inc., Philadelphia. Odum, E.P. 1978. Ecological Importance of the Riparian Zone. Proc. of Symposium: Strategies for Protection and Management of Floodplain Wetlands and other Riparian Ecosystems. USDA For. Servo Gen. Tech. Rep. WO-12, 410 pp. Odum, E.P. 1983. Basic Ecology. W.B. Saunders, Inc., Philadelphia.

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156 O'Shea, T.J., C.A. Beck, R.K. Bonde, H.I. Kochman, and D.K. Odell. 1985. An analysis of manatee mortality patterns in Florida, 1976-1981. Journal of Wildlife Management 49(1): 1-11. Ozoga, J.J., and L.J. Verme. 1968. Small Mammals of Conifer Swamp Deeryards in Northern Michigan. Michigan Academy Sci., Arts, and Letters 53: 37-49. Parmalee, P.W. 1953. Food Habits of the Feral House Cat in East-Central Texas. J. Wildl. Manage. 17: 375-76. Patrick, W.H., Jr., G. Dissmeyer, D.D. Hook, V.W. Lambou, H.M. Leitman, and C.H. Wharton. 1981. Characteristics of Wetlands Ecosystems of Southeastern Bottomland Hardwood Forests. Pages 276-300 in J.R. Clark and J. Benforado (eds.), Wetland Bottomland Hardwood Forests.--Proceedings of a Workshop on Bottomland Hardwood Forest Wetlands of the Southeastern United States. Amsterdam: Elsevier Scientific Publishing. Pickett, S.T., and J.N. Thompson. 1978. Patch Dynamics and the Size of Nature Reserves. Biological Conservation 13: 27-37. Pickett, S.T.A., and P.S. White. 1985. The Ecology of Natural Disturbance and Patch Dynamics. Orlando, FL: Academic Press. Post, W., and J.W. Wiley 1976. The Yellow-Shouldered Blackbird: Present and Future. American Birds 30(1): 13-20. Post, W., and J.W. Wiley. 1977. The Shiny Cowbird in the West Indies. The Condor 79(1): 119-21. Post, W., and J.W. Wiley. 1977. Reproductive Interactions of the Shiny Cowbird and the Yellow-Shouldered Blackbird. The Condor 79(2): 176-84. Preston, F.W. 1960. Time and Space and the Variation in Species. Ecology 41: 611-27. Preston, F.W. 1962. The Canonical Distribution of Commonness and Rarity. Ecology 43: 185-215, 410-32. Progulske, D.R., Jr. Eastern Florida. 1982. Spatial Distribution of Bobcats and Gray Faxes in MS Thesis. Gainesville, FL: Univ of FL, 63 pp. Ranney, J.W. 1977. Forest Island Edges: Their Structure, Development and Importance to Regional Forest Ecosystem Dynamics. Oak Ridge, TN: Oak Ridge National Laboratory, Env. Sciences Div., Pub. No. 1069. Ranney, J.W., M.C. Bruner, and J.B. Levenson. 1981. The Importance of the Structure and Dynamics of Forest Islands. Pages 67-95 in R.L. and D.M. Sharpe (eds.), Forest Island Dynamics in Man-Dominated Landscapes. New York, NY: Springer-Verlag. Edge in Burgess Ray, D., W. Woodroof, and R.C. Roberts. 1984. Management of Riparian Vegetation in the Northcoast Region of California's Coastal Zone. Pages 660-685 in R.E. Warner and K.M. Hendrix (eds.), California Riparian

PAGE 149

157 Systems: Ecology, Conservation, and Productive Management. Berkeley, CA: University of California Press. Redford, K.H., and G.A.B. da Fonesca. 1986. The Role of Gallery Forests in the Zoogeography of the Cerrado's Non-Volant Mammalian Fauna. Biotropica 18(2): 126-35. Riekerk, H. 1985. Water Quality Effects of Pine Flatwoods Silviculture. Journal of Soil and Water Conservation. Vol 40(3): 306-09. Riekerk, H., B.F. Swindel, and J. A. Replogle. 1980. Effects of Forestry Practices in Florida Watersheds. Proceedings of the Symposium on Watershed Management. ASCE. pp. 706-20. Riekerk, H., and D.K. Winter. 1982. Forest Water Management Principles in Florida. Proceedings Specialty Conference on Environmentally Sound Water and Soil Management. Orlando, FL: ASCE. Robbins, C.S. 1980. Effect of Forest Fragmentation on Bird Populations. Pages 198-212 in R.M. DeGraaf and K.E. Evans, Compilers. Management of North Central and Northeastern Forests for Nongame Birds. U.S. Dept. Agric., Forest Service General Technical Report NC-51. Robertson, R.J., and N.J. Flood. 1980. Effects of Recreational Use of Shorelines on Breeding Bird Populations. Can. Field. Nat. 94(2): 131-38. Robinette, F.O. 1972. Plants, People, and Environmental Quality. Washington, DC: Department of the Interior, National Park Service, p 41. Roelke, M.E. 1986. Medical Management, Biological Findings, and Research Techniques for the Florida Panther. Pages 7-14 in W.V. Branan (ed.), Survival of the Florida Panther: A Discussion and Accomplishments. Tallahassee, FL: Florida Defenders of the Environment. Roth, R.R. 1976. Spatial Heterogeneity and Bird Species Diversity. Ecology 57: 733-82. Rusterholz, K.A., and R.W. Howe. 1979. Small Islands in a Minnesota Lake. Species-Area Relations of Birds on Evolution 33: 468-77. Samson, F.B. 1980. Island Biogeography and the Conservation of Nongame Birds. Trans. N. Am. Wildl. and Nat. Res. Conf. 45: 245-51. Samson, F.B., and F.L. Knopf. 1982. In Search of a Diversity Ethic for Wildlife Management. Trans. N. Am. Wi1dl. and Nat. Res. Conf. 47: 421-31. Sartor, J.D. and G.B. Boyd. 1972. Water Pollution Aspects of Street Surface Contaminants. U.S. EPA-R2-72-081. Washington, D.C. Schaefer, J.M. 1978. Coyote and Dog Depredation on Sheep in Southern Iowa. MS Thesis. Iowa State University, 140 pp. Schitoskey, Jr., F., and R.L. Linder. 1978. Use of Wetlands by Upland Wildlife. Pages 307-11 in P.E. Greeson, J.R. Clark and J.E. Clark (eds.),

PAGE 150

158 Wetland Functions and Values: the State of Our Understanding. Proceedings of the National Symposium on Wetlands, Nov. 7-10, 1978. Minneapolis, MN: American Water Resources Association. Schneider, R.L., and R.R. Sharitz. In press. Hydrochory and Swamp Forest Regeneration. Ecology. Schonewald-Cox, C.M., S.M. Chambers, B. MacBryde, and W.L. Thomas. 1983. Genetics and Conservation: A Reference for Managing Wild Animal and Plant Populations. Menlo Park, CA: Benjamin/Cummings. Senner, J.W. 1980. Inbreeding Depression and the Survival of Zoo Populations. Pages 209-24 in M.E. Soule and B.A. Wilcox (eds.), Conservation Biology: An Evolutionary-Ecological Perspective. Sunderland, MA: Sinauer Associates, Inc., 395 pp. Shaffer, M.L. 1981. Minimum Population Sizes for Species Conservation. BioScience 31: 131-34. Simpson, G. 1940. Mammals and Land Bridges. Journal of the Washington Academy of Science 30: 137-63. Simpson, G. 1965. The Geography of Evolution. Philadelphia, PA: Chilton Books, 249 pp. Small, M.F., and W.N. Johnson, Jr. 1985. Wildlife Management in Riparian Habitats. In J. Bissonette (ed.), Proc. of Symp.: Is Good Forestry Good Wildlife Management? Smith, R.L. 1966. Wildlife and Forest Problems Appalachia. Trans. N. Amer. Wildl. and Nat. Res. Conf. 31: 212-26. Soule, M.E. 1980. Thresholds for Survival: Maintaining Fitness. Pages 151-72 in M.E. Soule and B.A. Wilcox (eds.), Conservation Biology: An Evolutionary-Ecological Perspective. Sunderland, MA: Sinauer AssOCiates, Inc., 395 pp. Soule, M.E. 1986. Conservation Biology: The Science of Scarcity and Diversity. Sunderland, MA: Sinauer Associates. Soule, M.E., and D. Simberloff. 1986. What Do Genetics and Ecology Tell Us About the Design of Nature Reserves? Biological Conservation 35: 19-40. Soule, M.E., and B.A. Wilcox. 1980. Conservation Biology: An EvolutionaryEcological Perspective. Sunderland, MA: Sinauer Associates. Sousa, W.P. 1984. The Role of Disturbance in Natural Communities. Ann. Rev. Ecol. Syst. 15: 353-91. Sparrowe, R.D., and P.F. Springer. 1970. tailed Deer in Eastern South Dakota. Seasonal Activity Patterns of WhiteJ. Wildl. Manage. 34: 420-31. Speake, D.W., J.A.McGlincy, and T.R. Colvin. 1978. Ecology and Management of the Eastern Indigo Snake in Georgia: a progress report. Pages 64-73 in

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159 R.R. Odum and L. Landers (eds.), Proceedings of the Rare and Endangered Wildlife Symposium, Aug. 3-4, 1978. Georgia Dept. of Nat. Res. Tech. Bull. WL 4. Sprock, C.M., W.E. Howard, and F.C. Jacob. 1967. Sound as a deterrent to rats and mice. J. Wildl. Manage. 31:729-41. Stauffer, D.F. 1978. Habitat Selection by Birds of Riparian Communities: Evaluating the Effects of Habitat Alteration. MS Thesis. Ames, IA: Iowa State University. Stauffer, D.F. and L.B. Best. 1980. Habitat Selection by Birds of Riparian Communities: Evaluating Effects of Habitat Alterations. J. Wildl. Manage. 44: 1-15. Sullivan, A.L., and M.L. Shaffer. 1975. Biogeography of the Megazoo. Science 189: 13-17. Swift, L.W., and K.R. Knoerr. 1973. Estimating Solar Radiation on Mountain Slopes. Agric. Meteorol. 12: 329-36. Tassone, J.F. 1981. Utility of Hardwood Leave Strips for Breeding Birds in Virginia's Central Piedmont. MS Thesis. Blacksburg, VA: Virginia Polytechnic and Institute and State College, 83 pp. Temple, S.A. 1986. Predicting Impacts of Habitat Fragmentation on Forest Birds: a Comparison of Two Models. Pages 301-04 in J. Verner, M.L. Morrison and C.J. Ralph (eds.), Wildlife 2000: Modeling Habitat Relationships of Terrestrial Vertebrates. Madison, WI: The University of Wisconsin Press. Terborgh, J. 1974. Preservation of Natural Diversity: The Problem of Extinction-Prone Species. BioScience 24: 715-22. Terborgh, J., and B. Winter. 1980. Some Causes of Extinction. Pages 119-33 M.E. Soule and B.A. Wilcox (eds.), Conservation Biology: An Evolutionary-Ecological Perspective. Sunderland, MA: Sinauer, Associates. Terborgh, J., and B. Winter. 1983. A Method for Siting Parks and Reserves with Special Reference to Columbia and Ecuador. BioI. Conserv. 27: 45-58. Thomas, J.W., C. Maser, and Thomas (ed.), Wildlife Oregon and Washington. D.C. J.E. Rodiek. 1979. Edges. Pages 48-59 J.W. Habitats in Managed Forests: the Blue Mountains of U.S. For. Servo Agr. Handbook No. 553, Washington, Tinkle, D.W. Swamp. 1959. Observations of Reptiles and Amphibians in a Louisiana Am. MidI. Nat. 62(1): 189-205. Trela, J.J., and L.A. Douglas. 1978. SOils, Septic Systems, and Carrying Capacity in the Pine Barrens. Natural and Cultural Resources of the New Jersey Pine Barrens. Proceedings of First Annual Pine Barrens Resources Conference, Atlantic City, New Jersey. Pomona, NJ: Center for Environmental Resources, Stockton State College.

PAGE 152

160 Trimble, G.R., and R.S. Sartz. 1957. How Far From a Stream Should a Logging Road Be Located? Journal of Forestry 55: 339-41. Trimble, G.R., and E.H. Tryson. 1966. Crown Encroachment into Openings Cut in Appalachian Hardwood Stands. Journal of Forestry 64(2): 104-08. U.S. Department of Agriculture, Soil Conservation Service. 1979. S.C.S. Engineering Field Manual for Conservation Practices. Washington, DC: U.S. Government Printing Office. USDA (United States Department of Agriculture). 1960. Soil Survey of Seminole County, Florida. U.S.G.P.O., Washington,D.C. USDA (United States Department of Agriculture). 1966. Soil Survey of Orange County, Florida. U.S.G.P.O.,Washington, D.C. van Aarde, R.J. 1980. The Diet and Feeding Behavior of Feral Cats, (Felis catus) at Marion Island. S. Afr. J. Wildl. Res. 10(3/4): 123-28. van der Zande, A.N., W.J. ter Keurs and W.J. van der Weijden. 1980. The Impact of Roads on the Densities of Four Bird Species in an Open Field Habitat: Evidence of a Long-Distance Effect. BioI. Conserv. 18: 299-321. Verme, L.J. 1961. Production of White-Cedar Browse by Logging. J. Forestry 59: 589-91. Verme, L.J. 1965. Swamp Conifer Deeryards in Northern Michigan: Their Biology and Management. J. Forestry 63: 523-29. Vickers, C.R., L.D. Harris, and B.S. Swindel. Resulting from Ditching of Cypress Ponds Forest Ecology and Management 2: 17-29. 1985. Changes in Herpetofauna in Coastal Plains Flatwoods. Wales, B.A. 1967. Climate, Microclimate, and Vegetation Relationships on North and South Forest Boundaries in New Jersey. William J. Hutcheson Memorial Forest Bulletin 2(3): 1-60. Wales, B.A. 1972. Vegetation Analysis of North and South Edges in a Mature Oak-Hickory Forest. Ecological Monographs 42(4): 451-71. Wanielista, M.P. (ed.). 1975. Proceedings: Stormwater Management Workshop. Florida Technological University. Orlando, Fl. Wang, F.C. 1978. Impacts of Drainage Canals in Surface and Subsurface Hydrology of Adjacent Areas in South Florida. In H.T. Odum and K.C. Ewel (eds.), Cypress Wetlands for Water Management, Recycling, and Conservation. Fourth Annual Report to the National Science Foundation and The Rockefeller Foundation, Center for Wetlands, Univ of Fl, Gainesville, FL, pp. 827-61. Wang, F.C. and A.R. Overman. 1981. Impacts of Surface Drainage on Groundwater HydrauliCS. Water Resources Bulletin, Vol 17(6): 971-977.

PAGE 153

161 Warner, R.E. 1985. Rural Illinois. Demography and Movements of Free-Ranging Domestic Cats in J. Wi1dl. Manage. 49: 340-46. Watts, W.A. 1980. The late Quaternary vegetation history United States. Ann. Rev. Ecol. Sys. 11:387-409. of the southeastern Watts, W.A. and B.C.H. Hansen. In Press. Environments of Florida in the Late Wisconsin and Holocene. Wet Site Archaeology (B. Purdy, ed.). (in press) Webb, D.S., and K.T. Wilkins. 1984. Historical Biogeography of Florida Pleistocene Mammals. Special Publication of the Carnegie Museum of Natural History. Wegner, J.F., and H.G. Merriam. 1977. Movements by Birds and Small Mammals between a Wood and Adjoining Farmland Habitats. Journal of Applied Ecology 16: 349-58. Weiner, F.M., and D.N. Keast. 1959. Sound Propagation over Terrara. Journal of the Acoustical Society of America, June 1959: 732. Weller, M.W. 1978. Wetland Habitats. Pages 210-34 in P.E.Greeson, J.R. Clark, and J.E. Clark (eds.), Wetland Functions and Values: the State of Our Understanding. Proceedings of the National Symposium on Wetlands, Nov. 7-10, 1978. Minneapolis, MN: American Water Resources Association. Weller, M.W. 1978. Management of Freshwater Marshes for Wildlife. Pages 276-84 in R.E. Good, D.F. Whigham, and R.L. Simpson (eds.), Freshwater Wetlands: Ecological Processes and Management Potential. New York, NY: Academy Press. Weller, M.W., and C.S. Spatcher. and Abundance of Marsh Birds. Report 43, 31 pp. 1965. Role of Habitat in the Distribution Iowa Ag. and Home Ec. Exp. Stn. Special Wharton, C.H., W.M. Kitchens, E.C. Pendelton, and T.W. Sipe. 1982. The Ecology of Bottomland Hardwood Swamps of the Southeast: a Community Profile. U.S. Fish and Wildlife Service, Biological Services Program, Washington, D.C. FWS/OBS-81/37, 133 pp. Wharton, C.H., V.W. Lambour, J. Newsome, P.V. Winger, L.L. Gaddy; and R. Mancke. 1981. The Fauna of Bottomland Hardwoods in Southeastern United States. Pages 87-160 in J.R. Clark and J. Benforado (eds.), Wetland Bottomland Forests. Proceedings of a Workshop on Bottomland Hardwood Forest Wetlands of the Southeastern United States. Amsterdam: Elsevier Scientific Publishing Company. Whitcomb, R.F. 1977. Island Biogeography and "Habitat Islands" of Eastern Forest. Amer. Birds 31: 3-5. Whitcomb, R.F., J.F. Lynch, P.A. Opler, and C.S. Robbins. 1976. Island Biogeography and Conservation: Strategy and Limitations. Science 193: 1030-32.

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162 Whitcomb, R.F., C.S. Robbins, J.F. Lynch, and B.L. Whitcomb, K. Klimkiewicz, and D. Bystrak. 1981. Effects of Forest Fragmentation on Avifauna of the Eastern Deciduous Forest. Pages 125-205 in R.L. Burgess and D.M. Sharpe (eds.), Forest Island Dynamics in Man-Dominated Landscapes. New York, NY: Springer-Verlag. White, D.C., R.J. Livingston, R.J. Bobbie, and J.S. Nickels. 1979. Effects of Surface Composition, Water Column Chemistry and Time of Exposure on Composition of the Microflora and Associated Macrotauma in Apalachicola Bay, Florida. White, P.S. 1979. Pattern, Process, and Natural Disturbance in Vegetation. Bot. Rev. 45: 229-99. Whitney, G.G., and J.R. Runkle. 1981. Edge Versus Age Effects in The Development of a Beech-Maple Forest. Oikos 37: 377-81. Wilcove, D.S. 1985. Nest Predation in Forest Tracts and The Decline of Migratory Songbirds. Ecology 66: 1211-14. Wi1cove, D.S., and R.M. May. 1986. National Park Boundaries and Ecological Realities. Nature 324: 206-07. Wilcove, D.S., C.H. McLellan, and A.P. Dobson. 1$86. Habitat Fragmentation in The Temperate Zone. Pages 237-56 in M.E. Soule (ed.), Conservation Biology: The Science of Scarcity and Diversity. Sunderland, MA: Sinauer Associates. Wilcox, B.A. 1980. Insular Ecology and Conservation. Pages 151-72 in M.E. Soule and B.A. Wilcox (eds.), Conservation Biology: An Evolutionary-Ecological Perspective. Sunderland, MA: Sinauer Associates, Inc., 395 pp. Williams, L.E. 1978. Florida Black Bear. Rare and Endangered Biota of Florida: Pages 23-5 in J.N. Layne (ed.), Mammals. Gainesville, FL: University Presses of Florida. Wilson, E.O., and E.O. Willis. 1975. Applied Biogeography. M.L. Cody and J.M. Diamond (eds.), Ecology and Evolution Cambridge, MA: Belknap Press of Harvard University Press. Pages 522-34 in of Communities. Wittaker, R.H. 1978. Handbook of Vegetation Science. Part V. In W. Junk (ed.), Ordination of Communities. The Netherlands: The Hague Press. Wolfe, R.W. 1987. Seed Dispersal and Wetland Restoration. MS Thesis (CFW-87-15). Gainesville, FL: Univ of FL, 93 pp. Wright, S.J., and S.P. Hubbell. a Focal Species Approach. 1983. Stochastic Extinction and Reserve Size: Oikos 41: 466-76. Yoakum, J., and W.P. Dasmann. 1971. Habitat Manipulation Practices. Pages 173-231 in R.H. Giles (ed.), Wildlife Management Techniques. Washington, DC: The Wildlife Society.

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163 Yoho, W.H. and E.C. Pirkle. 1985. Natural Landscapes of the United States (Fourth Edition). Kendall/Hunt Publ. Co., Dubuque, Iowa. Zampella, R.A., and C.T. Roman. 1983. Wetlands Protection in the New Jersey Pinelands. Wetlands 3: 124-33.

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APPENDIX A WILDLIFE ASSOCIATED WITH WEKIVA RIVER BASIN

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TABLE A-l. Fish species of the Wekiva River Basin area. Scientific Name Amia calva AngUilla rostrata Aphredoderus sayanus Dorosoma cepedianum Dorosoma petenense Elassoma evergladei Elassoma okefenokee Enneacanthus gloriosus Enneacanthus obesus Erimyzon sucetta Esox americanus niger Etheostoma fusiforme Fundulus chrysotus Fundulus lineolatus Fundulus seminolis Gambusia affinis Heterandria formosa Ictalurus brunneus Ictalurus catus Ictalurus nebulosus Ictalurus punctatus Jordanella floridae Labidesthes sicculus LepisosteuB oaseus Lepisosteus platyrhincus Lepomis auritus Lepomis gulosus Lepomis macrochirus Lepomis marginatus Lepomis microlophus Lepomis punctatus Lucania goodei Micropterus salmoides Morone saxatilis Mugil cephalus Notemigonus crysoleuca Notropis chalybaeus Notropis emiliae Notropis hyPselopterus Common Name Bowfin American eel Pirate perch Gizzard shad Threadfin shad Everglades pygmy sunfish Okefenokee pygmy sunfish Bluespotted sunfish Banded sunfish Lake chubsucker Redfin pickerel Chain pickerel Swamp darter Golden topminnow Lined topminnow Seminole killifish Mosquitofish Least killifish Snail bullhead White catfish Brown bullhead Channel catfish Flagfish Brook silverside Longnose gar Florida spotted gar Redbreast sunfish Warmouth Bluegill Dollar sunfish Redear sunfish Spotted sunfish Bluefin killifish Largemouth bass Striped bass Striped mullet Golden shiner Ironcolor shiner Pugnose minnow Sailfin shiner

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TABLE A-l. Fish species of the Wekiva River area (continued). Scientific Name Notropis maculatus Notropis petersoni Notropis welaka Noturus gyrinus Noturus lephtacanthus Percina nigrofasciata Poecilia latipinna Pomoxis nigromaculatus Common Name Tail light shiner Coastal shiner Bluenose shiner Tadpole madtom Speckle mad tom Blackbanded darter Sail fin molly Black crappie

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TABLEA-2. Relative abundance of amphibian species in Wekiva River Basin habitats.* Scientific Name Acris gryllus Amphiuma means quericus Bufo terrestris Desmognathus auriculatus Eleutherodactylus planirostris Eurycea quadridigitata Gastrophryne carolinensis Hyla cinerea Hyla crucifer Hyla femoralis Hyla gratiosa Hyla sQuirella Limnaoedus ocularis Notophthalmus perstriatus Notophthalmus viridescens Pseudacris nigrita Pseudacris ornata Pseudobranchus striatus areolata Rana catesbeiana Rana grylio Rana heckscheri Rana utricularia holbrooki Siren intermedia Siren lacertina HH = Hydric hammock habitat HS = Hydric swamp habitat CS = Cypress swamp habitat ST = Swamp thicket habitat Common Name Cricket frog Amphiuma Oak toad Southern toad Dusky salamander Greenhouse frog Dwarf salamander Narrowmouth toad Green frog Spring peeper Pinewoods tree frog Barking tree frog Squirrel treefrog Little grass frog Striped newt Penninsula newt Southern chorus frog Ornate chorus frog Dwarf siren Gopher frog Bullfrog Pig frog River swamp frog Leopard frog Spadefoot toad Lesser siren Greater siren Habitat Types HH HS CS ST c c u u c c u c u u u c cue c u c c c u u u u c c c u u u u u u u c u u u u c u u u u u u u u u c c u c u u u c c c u u u c = All species wetland dependent c = Common u = Uncommon = Possible but no data available

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TABLE A-3. Relative abundance of reptile species in Wekiva River Basin habitats. Scientific Name Agkistrodon piscivorus* Alligator mississipiensis* Anolis carolinensis Cemophora coccinea Chelydra serpentina* Cnemidophorus sexlineatus Coluber constrictor Crotalus adamanteus Deirochelys reticularia* Diadophis punctatus Drymarchon corais Elaphe guttata Elaphe obsoleta Eumeces egregius Eumeces inexpectatus Farancia abacura* Farancia erytrogramma* Gopherus polyphemus Heterodon platyrhinos Heterodon simus Kinosternon bauri* Kinosternon subrubrum* Lampropeltis getulus Lampropeltis triangulum Masticophis flagellum Micrurus fulvius Neoseps reynoldsi Nerodia cyclopion* Nerodia fasciata* Nerodia taxispilota* Opheodrys aestivus Ophisaurus attentuatus Ophisaurus ventralis Pituophis melanoleucus Pseudemys floridana* Common Name Eastern cottonmouth American alligator Green anole Scarlet snake Snapping turtle Six-lined racerunner Black racer E. diamondback rattlesnake Chicken turtle Southern ringneck snake Indigo snake Red rat snake Yellow rat snake Mole skink Five-lined skink Mud snake Rainbow snake Gopher tortoise Eastern hognose snake Southern hognose snake Striped mud turtle Florida mud turtle Florida king snake Scarlet kingsnake Eastern coachwhip Coral snake Sand skink Green water snake Banded water snake Brown water snake Rough green snake Slender glass lizard Eastern glass lizard Pine snake Florida cooter Habitat Types HH HS CS ST c u c u c c c c c c c c c u c c u c u u c c u u u u u u u c c u u u u u u u u u u u u u u u u u u u u u u c u c u c c u u

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TABLE A-3. Relative abundance of reptile species in Wekiva River Basin habitats (continued). Scientific Name Pseudemys nelsoni* Regina alleni* Rhadinaea flavilata Rhineura floridana Sceloporus undulatus Sceloporus woodi Scincella laterale Seminatrix pygaea* Sistrurus miliarius Sternotherus odoratus* Storeria dekayi Storeria occipitomaculata Tantilla coronata Terrapene carolina Thamnophis sauritus Thamnophis sirtalis Trionyx ferox* HH = Hydric hammock habitat HS = Hydric swamp habitat CS = Cypress swamp habitat ST = Swamp thicket habitat Habitat Types Common Name HH HS CS ST Florida red-bellied turtle Striped swamp snake Pine woods snake Florida worm lizard Southern fence lizard Florida scrub lizard Ground skink Black swamp snake Dusky pygmy rattlesnake Stinkpot turtle Brown snake Red-bellied snake Southeastern crowned snake Box turtle Ribbon snake Eastern garter snake Florida soft shell turtle c c = Wetland dependent species c = Common u = Uncommon u c u u u u u u u u u u u u u u u u u u u = Possible but nO data available u u u c u

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TABLE A-4. Relative abundance of bird species in Wekiva River Basin habitats. Scientific Name Accipiter cooperii Accipiter striatus Actitus macularia* Agelaius phoeniceus* Aimophila aestivalis sponsa* Ammodramus henslowii# Ammodramus leconteii*# Ammodramus savannarum Anas amaricana*# Anas clypeata*# Anas crecca*11 AruiS discors* fulvigula* Anhinga anhinga* Anthus spinoletta*# Aphelocoma coerulescens Aramus guarauna* Archilochus colubris Ardea herodias* Athene cunicularia Aythya collaris* Bombycilla cedrorum# Botaurus lentiginosus* Bubo virginianus Bubulcus ibis Buteo braCtryTUrus* Buteo jamaicensis Buteo lineatus* Butorides virescens* Cairina moschata* Calidris alba*# Calidris aJ)):ina*# Calidris mauri*# Calidris minutilla*# Common Name Cooper's hawk Sharp-shinned hawk Spotted sandpiper Red-winged blackbird Bachman's sparrow Wood duck Henslow's sparrow LeConte's sparrow Grasshopper sparrow American widgeon Northern shoveler Green-winged teal Blue-winged teal Mottled duck Anhinga Water pipit Scrub jay Limpkin Ruby-throated hummingbird Great blue heron Burrowing owl Ring-necked duck Cedar waxwing American bittern Great horned owl Cattle egret Short-tailed hawk Red-tailed hawk Red-shouldered hawk Green heron Muscovy duck Sanderling Dunlin Western sandpiper Least sandpiper Habitat Types HH HS CS ST c c u c c u u u c u c c c u c c c u c u u c c u u c c u c u c u c u u c u u u c u u u c u

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TABLE A-4. Relative abundance of bird species in Wekiva River Basin habitats (continued). Scientific Name Campephilus principalis* Caprimulgas carolinensis Caprimulgas vociferus# Cardinalis cardinalis Carduelis tristis# Carpodacus purpureus# Casmerodius albus* Cathartes aura Catharus Catharus guttatus# Catharus ustulatus# Ceryle alcyon* Chaetura pelagica Charadrius vociferus* Chordeiles minor Circus cyaneus* Cistothorus platensis*# Coccyzus americanus Colaptes auratus Colonus virginianus Columbina passerina Conotopus virens Coragyps atratus Corvus brachyrhynchos Corvus ossifragus* Cyanocitta cristata Dendroica caerulescens# Dendroica coronata# Dendroica discolor Dendroica dominica* Dendroica magnolia# Dendroica palmarum# Dendroica petechia Dendroica pinus Dendroica striata# Common Name Ivory-billed woodpecker Chuck will's widow Whip-poor-will Northern Cardinal American goldfinch Purple finch Great egret Turkey vulture Veery Hermit thrush Swainson's thrush Belted kingfisher Chimney swift Killdeer Common nighthawk Northern harrier hawk Sedge wren Yellow-billed cuckoo Common flicker Bobwhite Ground dove Eastern wood peewee Black vulture Common crow Fish crow Blue jay Black-throated blue warbler Yellow-rumped warbler Prairie warbler Yellow-throated warbler Magnolia warbler Palm warbler Yellow warbler Pine warbler Blackpoll warbler Habitat Types HH HS CS ST c c c c u c c c u u c c c c c c c u u u u c c c c c c c c u u u u c u c u u u u c c c c c c u u u c c c c u c c u u u u u u c c c c

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TABLE A-4. Relative abundance of bird species in Wekiva River Basin habitats (continued). Scientific Name Dendroica tigrina# Dryocopus pileatus* Dumetella carolinensis Elanoides forficatus* Empidonax virescens* Eudocimus albus* Euphagus carolinus*# Falco sparverius Florida caerulea* Fulica americana*# Gallinago gallinago*# Gallinula chloropus* Gelochelidon nilotica* Geothlypis trichas* canadensis* Haliaeetus leucocephalus* Himantopus mexicanus* Hirundo rustica Hydranassa tricolor* Hylocichila mustelina* Ixobrychus exilis* Lanius ludovicanus Larus delawarensis*# Laterallus jamaicensis* Leucophoyx thula* Limnodromus griseus*# Limnodromus scolopaceus*# Limnothlypis swainsonii* Lophodytes cucullatus* Melanerpes erythocephalus Meleagris gallopavo* Melospiza georgiana*# Melospiza melodia# Mimus polyglottus Mniotilta varia# Common Name Cape May warbler Pileated woodpecker Gray catbird Swallow-tailed kite Acadian flycatcher White ibis Rusty blackbird American kestrel Little blue heron American coot Common snipe Common gallinule Gull-billed tern Common yellowthroat Sandhill crane Bald eagle Black-necked stilt Barn swallow Tricolored heron Wood thrush Least bittern Loggerhead shrike Ring-billed gull Black rail Snowy egret Short-billed dowitcher Long-billed dowitcher Swainson's warbler Hooded merganser Red-bellied woodpecker Turkey Swamp sparrow Song sparrow Mockingbird Black and white warbler Habitat Types HH HS CS ST c c u c c u u c c c u u c u u c u u c c c c u c c u u c u c u c c c u c c u c c u u c u c u c c u u u u u c c c u

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TABLE A-4. Relative abundance of bird species in Wekiva River Basin habitats (continued). Scientific Name Molothrus Mycteria americana* Myiarchus crinitus* Numida meleagris Nycticorax nycticorax* Nycticorax violacea* Otus asio ----Pandion haliaetus* Parula americana* Parus bicolor Parus carolinensis Passer domesticus Passerculus sandwichensis*# Passerina cyanea Phalacrocorex auritus* Pheucticus ludovicianus# Picoides borealis Picoides pubescens Picoides villosus Pipilo erthophthalmus Piranga rubra Plegadis falcinellus* Pluvialis squatarola*# Podilymbus podiceps* Polioptila caerulea Pooecetes gramineus# Porphyrala martinica* Porzana carolina*# Progne subis* Protonotaria citrea* Quiscalus major Quisculus guiscula Rallus elegans* Rallus limicola* Regulus calendula# Common Name Brown-headed cowbird Wood stork Great-crested flycatcher Guinea fowl Black-crowned night heron Yellow-crowned night heron Screech owl Osprey Northern parula Tufted ti tmouse Carolina chickadee House sparrow Savannah sparrow Indigo bunting Double crested cormorant Rose-breasted grosbeak Red cockaded woodpecker Downy woodpecker Hairy woodpecker Rufous-sided towhee Summer tananger Glossy ibis Black-bellied plover Pied-billed grebe Blue-gray gnatcatcher Vesper sparrow Purple gallinule Sora Purple martin Prothonotary warbler Boat-tailed grackle Common grackle King rail Virginia rail Ruby-crowned kinglet Habitat Types HH HS CS ST c c c c c c c c c c c c c u u c c c c c c c c u c c c c u c c c c c c u c c c u c c u c u c c c u c c c u c

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TABLE A-4. Relative abundance of bird species in Wekiva River Basin habitats (continued). Scientific Name Rostrhamus sociabilis* Rynchops niger* Sayornis phoebell Scolopax minor* Seiurus aurocapillusll Seiurus motacilla* Seiurus noveboracensis*1I Setophaga ruticilla Sialia sialis Sphyrapicus variusll Spizella passerinall Sterna antillarum* Sterna forsteri* Strix varia* Sturnella magna Sturnus vulgaris Tachycineta bicolor*1I Thryothorus ludovicianus Toxostoma rufum Trigna flavipes*1I Trigna melanoleuca*# Troglodytes aedonll Turdus migratorius Tyrannus tyrannus Tyto alba Vermivora celatall Vermivora ruficapillall Vireo flavifrons Vireo griseus Vireo olvaceous Vireo solitarius# Wilsonia citrina* Zenaida macroura Zonotricha albicollisll HH = Hydric hammock habitat HS = Hydric swamp habitat CS = Cypress swamp habitat ST = Swamp thicket habitat Common Name Everglades kite Black skimmer Eastern phoebe American woodcock Ovenbird Louisiana waterthrush Northern water thrush American redstart Eastern bluebird Yellow-bellied sapsucker Chipping sparrow Least tern Foster's tern Barred owl Eastern meadowlark European starling Tree swallow Carolina wren Brown thrasher Lesser yellowlegs Greater yellowlegs House wren American robin Eastern kingbird Barn owl Orange-crowned warbler Nashville warbler Yellow-throated vireo White-eyed vireo Red-eyed vireo Solitary vireo Hooded warbler Mourning dove White-throated sparrow II = Migrant species Habitat Types HH HS CS ST c u c c u c c c c c c c c u u u c c c c c c u u u u cue u c c c u u u c c u u c cue c c u c c c u c u u c = Wetland dependent species c = Common u = Uncommon = Possible but no data available

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TABLE A-S. Relative abundance of mammal species in Wekiva River Basin habitats. Scientific Name Blarina carolinensis CryPtotis parva Dasypus novemcinctus Didelphis virginiana Eptesicus fuscus Geomys pinetis Glaucomys volans Lasiurus intermedius Lasiurus seminolus Lutra canadensis* rufus Mephitis mephitis Mustela frenata Myotis austroriparius Neofiber alleni* Neotoma floridana Nycticeius humeralis Ochrotomys nuttalli Odocoileus virginianus Oryzomys palustris* Peromyscus floridanus Peromyscus gossypinus Peromyscus polionotus Pipistrellus subflavus* Plecotus rafinesguii Procyon lotor* Reithrodontomys humulis Scalopus aguaticus Sciurus carolinensis Sciurus niger Sigmodon hispidus Spilogale putorius Sorex longirostris Sus scrofa EG2fvilagus floridanus Common Name Short-tailed shrew Least shrew Armadillo Opossum Big brown bat Pocket gopher Flying squirrel Yellow bat Seminole bat River otter Bobcat Striped skunk Long-tailed weasel Southeastern myotis bat Florida muskrat Wood rat Evening bat Golden mouse White-tailed deer Rice rat Florida mouse Cotton mouse Oldfield mouse Southern pipistrele bat Eastern big-eared bat Raccoon Eastern harvest mouse Eastern mole Gray squirrel Fox squirrel Cotton rat Spotted skunk Southeastern shrew Feral pig Cottontail rabbit Habitat Types HH HS CS ST u c u c c u c c c c u c c c u c u u c u u u u c c u u c u c c c c c c c c u c u u c u c c u u u c u c c c c c

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TABLE A-S. Relative abundance of mammal species in Wekiva River Basin habitats (continued). Scientific Name Sylvilagus palustris* Tadarida brasiliensis Trichechus manatus* Urocyon cinereoargenteus Ursus americanus* Vulpes vulpes HH HS CS ST = = = = Hydric hammock habitat Hydric swamp habitat Cypress swamp habitat Swamp thicket habitat Habitat Types Common Name HH HS CS ST Marsh rabbit Free-tailed bat West Indian manatee Gray fox Black bear Red fox c c = Wetland dependent species c = Common u = Uncommon u u c = Possible but no data available c

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TABLE A-6. Designated plant and animal species of the Wekiva River Basin. Scientific Name Plants Bonamia grandiflora Dennstaedtia bipinnata Dryopteris ludoviciana Encyclia tampensis Habenaria repens Nemastylis floridana Ophioglossum palmatum Phlebodium aureum Rhapidophyllum hystrix Sabal minor Spiranthes sp. Thelypteris hispidula Thelypteris interrupta Thelypteris ovata Tillandsia fasciculata Tillandsia setacea Tillandsia utriculata Zamia floridana Invertebrates Aphaostracon asthenes Aphaostracon monas Gincinnatia parva Gincinnatia ponderosa Cincinnatia wekiwae Procambarus acherontis Amphibians Rana areolata Reptiles Alligator mississipiensis Drymarchon corais couperi Gopherus polyphemus Neoseps reynoldsi Pituophis melanoleucus mugitus Sceloporus woodi Common Name Florida bonamia Cuplet fern Florida shield fern Butterfly orchid Water spider orchid Fall-flowering ixia Hand adder's tongue fern Golden polypody Needle palm Bluestem palmetto Ladies tresses Hairy tri-vein fern Spready tri-even fern Ovate maiden fern Stiff-leaved wildpine Needle-leaved wildpine Giant wildpine Florida coontie Blue spring aphaostracon Wekiwa spring aphaostracon Blue spring snail Ponderous spring snail Wekiwa spring snail Orlando cave crayfish Gopher frog American alligator Eastern indigo snake Gopher tortoise Sand skink Pine snake Florida scrub lizard Designation A E E T T T E E T T T T T T C T G G B URI UR2 UR5 UR5 UR2 UR2 UR2 UR2 UR2 UR SSC UR2 SSG T T T SSC UR2 T UR2 SSC UR2 UR2 C II II II II II

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TABLE A-6. Designated plant and animal species of the Wekiva River Basin (continued) Scientific Name Birds Aimophila aestivalis Aphelocoma coerulescens coerulescens Aramus guarauna Athene cunicularia Campephilus principalis Circus cyaneus Falco sparverius paulus Falco sparverius sparverius Florida caerulea canadensis pratensis Haliaeetus leucocephalus Hydranassa tricolor Leucophoyx thula Mycteria americana Pandion haliaetus Picoides borealis Rostrhamus sociabilis Sterna antillarum KaaDals Lutra canadensis rufus Mustela frenata penninsulae Myotis austroriparius Neofiber alleni Peromyscus floridanus Peromyscus polionotus decoloratus Plecotus rafinesguii Sciurus niger shermani Trichechus manatus latirostris Ursus americanus floridanus DESIGNATION: Common Name Bachman's sparrow Florida scrub jay Limpkin Burrowing owl Ivory-billed woodpecker Marsh hawk American kestral Eastern kestral Little blue heron Florida sandhill crane Bald eagle Tricolored heron Snowy egret Wood stork Osprey Red cockaded woodpecker Snail kite Least tern River otter Bobcat Florida weasel Southeastern myotis bat Florida muskrat Florida mouse Pallid beach mouse Eastern big-eared bat Sherman's fox squirrel West Indian manatee Florida black bear Designation A T SSC SSC B URZ T E E C II II T UR2 II II SSC T II T E I SSC SSC E E T II T E T E E URZ UR2 URZ SSC UR2 E UR3 URZ SSC URZ E E T URZ II II I A = Florida Game and Fresh Water Fish Commission (animals) or Florida Department of Agriculture and Consumer Services (plants) B = United States Fish and Wildlife Service C = Convention on International Trade in Endangered Species (CITES)

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CODES: E = Endangered T = Threatened SSC = Species of special concern C = Commercially exploited I = Appendix I species II = Appendix II species URl = Under review for federal listing, with substantial evidence in existence indicating at least some degree of biological vulnerability. UR2 = Under review for listing, but substantial evidence of biological vulnerability and/or threat is lacking. UR3 = Still formally under review for listing, but no longer being considered for listing due to existing pervasive evidence of extinction. UR5 = Still formally under review for listing, but no longer considered for listing because recent information indicates species is more widespread or abundant than previously believed.