Title: The Implications of Hydrology and Landscape Ecology on the Maintenance of Freshwater Wetland Ecosystems in Florida
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Permanent Link: http://ufdc.ufl.edu/WL00000857/00001
 Material Information
Title: The Implications of Hydrology and Landscape Ecology on the Maintenance of Freshwater Wetland Ecosystems in Florida
Physical Description: Book
Language: English
Spatial Coverage: North America -- United States of America -- Florida
Abstract: The Implications of Hydrology and Landscape Ecology on the Maintenance of Freshwater Wetland Ecosystems in Florida By: Kevin L. Erwin - Consulting Ecologist
General Note: Box 7, Folder 3 ( Vail Conference 1988 - 1988 ), Item 28
Funding: Digitized by the Legal Technology Institute in the Levin College of Law at the University of Florida.
 Record Information
Bibliographic ID: WL00000857
Volume ID: VID00001
Source Institution: Levin College of Law, University of Florida
Holding Location: Levin College of Law, University of Florida
Rights Management: All rights reserved by the source institution and holding location.

Full Text

(In Press: In Proceedings of National Wetlands Hydrology Symposium,
Society of State Wetland Managers, Chicago, Ill., September 1987.)



Kevin L. Erwin
Kevin L. Erwin Consulting Ecologist, Inc.
2077 Bayside Parkway
Fort Myers, FL 33901


Floridians have only recently been educated to the fact that

surface water management should be a major concern of local,

regional and national significance. Water can not be considered

a free or inexpensive resource to be rapidly drained from the

land to prepare for development. Since the early 1970's

Regulatory agencies, local governments and environmental

organizations have expended a considerable effort to protect

wetland habitats. Unfortunately at the same time surface water

drainage practices continued. Hydrology and landscape ecology

must be recognized as the most important factors to be addressed

by wetland managers as they strive to attain the goals of

preserving, creating or enhancing wetland systems, their

functions and values.

Over the last 200 years, 30 to 50% of the wetlands of the

continental United States have been destroyed for such diverse

uses as agriculture, mining, forestry, and urbanization (U.S.

Congress, 1984). Since the 1970's, government regulation of

wetlands in Florida has slowed the destruction of this habitat

Ss which has decreased by 12,000,000 acres between 1850 and 1973, a


S60 loss (Tschinkel, 1984). Based on satellite imagery taken

between 1972 and 1974, Hampson (1984) estimates that the area of

wetlands in Florida was 8.4 million acres, a decrease of 13.4
million since 1955. This figure includes the loss of tidal

estuarine wetlands such as salt marshes and mangrove swamps.

However, a significant percentage of wetlands which have been

destroyed consisted of interior freshwater wetlands. Cypress

strands, domes and forests, river swamps and flood plains, other

forested wetlands such as bay heads, gum swamps and hydric

hammocks, and marshes ranging from the small isolated variety to

large contiguous systems such as the Everglades have all been


While the major emphasis of surface water management has

focused on water quality enhancement and conservation, the major

emphasis of wetlands protection has been habitat preservation.

Since 1973, a number of State and Federal laws have been passed

which provide a great measure of protection to wetlands through

preservation or conservation efforts by requiring permit

application review for activities proposed within wetlands. This

legislation, (e.g. Section 404 of the Federal Clean Water Act

dredge and fill permitting program and the State of Florida's

1984 Henderson Wetlands Protection Act) outlines rigid guidelines

for the identification of wetlands jurisdiction mandating the

avoidance of wetlands by proposed developments. Another emphasis

on wetlands protection has been the acquisition of wetlands

s through beneficial state programs such as the Conservation and



( Recreation Lands Program managed by the Florida Department of

Natural Resources and the Save OUr Rivers Program managed by the

five Water Management Districts. On large tracts of land some
comprehensive measure of attention is directed towards the

management of the on-site wetlands either through acquisition or

as a result of the Development of Regional Impact (DRI) review

process (Chapter 380 Florida Statutes). However, over 90% of the

total number of land development projects within the state are

not DRI's and rarely are wetlands in any type of permitted

project including agriculture, acquired and/or systematically


The identification and preservation of wetlands by the

permitting process obviously will not insure the long term

Viability of these habitats or guarantee their function as

productive ecosystems which provide fish & wildlife habitat,

water storage and recreational areas. If they are not evaluated

and managed as a complete natural system, then such wetlands can

be expected to exhibit significant lower faunal and floral

species composition and diversity as a result of altered water

level and hydroperiod coupled with isolation from natural upland

habitats. The greatest short-coming of our efforts to protect

our wetlands is the current dichotomy which exists between

wetlands regulation and both surface water management and

adjacent land use planning. While preserving wetlands surrounded

by intense urban and agricultural land uses, we may be failing to

incorporate these habitats into management units which combine



f proper hydrology and upland buffers. Should we continue this

practice, the wetlands preserved through permitting will diminish

in value over time.

When a wetland is preserved, the long term goal of

maintaining all of its vital functions at optimal levels should

be of primary concern. Hydrology is the single most important

element required for the maintenance of specific types of

wetland ecosystems and their functions. Hydrologic conditions

can directly modify or change chemical or physical properties

such as nutrient availability, degree of substrate anoxia,

sediment properties, and pH. Water inputs are invariably the

( dominant source of nutrients to wetlands; water outflows often

remove biotic and abiotic material from wetlands (Mitsch and

Gosselink, 1986). These modifications of the physio-chemical

environment, in turn, have a direct impact on the biotic response

in the wetland (Gosselink and Turner, 1978). Wetland fauna and

flora will almost always respond to even slight changes in

hydrologic conditions with substantial changes resulting in

species richness, diversity and productivity. Thus, an abrupt

and usually significant change in the functional integrity of the

wetland system results from a change in its hydrology.

In southern Florida drainage and diversion of water has

greatly reduced the amount of water held in the region and has

intensified and prolonged the normal winter dry season, which has

Sin turn has greatly increased the number and destructiveness of


S fires (Craighead, 1971). In addition, abnormally high water

levels in the Everglades water conservation areas has resulted in

dramatic adverse impacts to a wetland system of national
significance. Everglades habitats have been significantly

altered and wildlife biologists believe the artificially

increased water levels and extended hydroperiod have been a

significant factor in reducing wading bird populations by 90%.

One of the greatest threats resulting from hydrologically

altered wetlands in south and central Florida is the rapid

conversion of these wetlands to areas which will be completely

dominated by the problematic exotics Melaleuca quinquenervia and

Schinus terebinthifolius. These trees will rapidly invade

wetlands with altered hydroperiods which in a period of perhaps

less than 20 years could result in a monoculture of these species

and, except for continued water storage functions, a significant

reduction of wetland functions that had previously been provided

by those wetlands. Once established, these exotics can tolerate

flooding extremely well. Therefore, restoring hydroperiod alone

to hydrologically altered wetlands with exotic infestation by

these species is not a method of eradication. Physical removal

is often the only solution with regular follow-ups required.

Exotic infestation is one of the single greatest threats to

the long term viability of all freshwater wetlands in south

Florida. There is no reliable data which describes the acreage

and location of hydrologically altered wetlands or wetlands
Currently infested with Melaleuca and/or Schinus. However, large



Sssystems such as the Everglades National Park, Big Cypress

National Preserve and Six Mile Cypress Strand contain significant

infestations where management/eradication will require a

substantial financial commitment. Most of the isolated marshes

and cypress domes in urbanized south Florida which have been

regulated into preservation, show signs of exotic infestation.


There is a need in Florida and throughout the nation to

evaluate wetlands as whole ecosystems which may be connected by a

variety of habitats and hydrological pathways. Establishment of

a multi-objective greenway strategy should be used to insure that

r those wetlands that are preserved or created through mitigation

will be able to survive future natural and man-made perturbations

within the watershed and function at optimal levels. The

objective of a greenway is to provide a contiguous pathway,

irrespective of property or political boundaries where the

wetlands and uplands are integrated along a hydroecological

pathway conducive to the maintenance and perpetuation of the

system. Wetlands properly connected with native or restored

upland habitat will function as wildlife corridors and provide

natural low energy surface water management via storage and

sheetflow instead of ditches, dikes and pumps.

Since hydrology is the single most important element to be

considered for the optimal maintenance of wetland ecosystems

proper hydrologic analysis is imperative. The basic parameters

' to consider include: identification of the watershed and sub-

basin; computation of inflows and outflows from the property and

each wetland; a comparison of the pre- and post-development flow
characteristics identified above on a seasonal basis; the

average water depth; the maximum flooding depth; the maximum dry-

down depth; the hydroperiod or duration of flooding and the date

of normal wet-season flooding. These measurements should be

taken at a standard point at the upland edge of the wetland over

at least one typical water year which would include two wet

seasons. The collection of the hydrological data and proper

ecological evaluation will define the boundaries and design of

the greenway. Needs of particular wildlife species relate

directly to management objectives and will influence the design

of the greenway. It is obvious that the successful use of this

approach requires the evaluation of a system rather than isolated

areas limited by jurisdiction ownership or political boundaries

as is currently the result of most current dredge and fill or

water management permitting.

The current regulatory procedure on a case by case, parcel

by parcel basis will properly identify the wetland boundaries on

each property and most likely require wide spread conservation of

the wetland or mitigation of any disrupted habitat. However, the

end result is often undeveloped wetland habitat completely

surrounded by intense urban or agricultural development. The
hydrologic system and landscape ecology is obviously disrupted

o', and the upland-wetland ecotone eliminated. Habitat fragmentation



is also the most serious threat to biological diversity and is

the primary cause of the extinction crisis (Wilcox and Murphy

1985). With the absence of interconnecting wildlife corridors,
fish and wildlife values are significantly diminished. Noss

(1987) provides a comprehensive and thorough discussion of the

potential advantages of corridors to conservation of terrestrial

species and habitats in human-dominated landscapes that are not

discussed here.

An alternative to this scenario is the systematic approach

to wetlands management requiring the implementation of multi-

objective greenway. Under this approach a development permit

application for a parcel of land would be evaluated as a part of

a larger system (watershed). The parcel and proposed
development would be evaluated and properly designed to maintain

its pro rata contribution to the normal or desired carrying

capacity and resource related functions of the watershed. This

process of evaluating watersheds obviously requires a significant

expenditure of effort. However, the effort expended would

insure much improved, data based land use decisions. An

opportunity for this type of procedure currently exists. The

requirements of Florida's 1985 Local Government Comprehensive
Planning and Land Development Regulation Act (particularly

Section 1633178, Florida Statutes), and the 1986 Florida

Department of Community Affairs Minimum Criteria for Review of
Local Government Comprehensive Plans and Determination of

Compliance (Chapter 9J-5, Florida Administrative Code) can



S facilitate comprehensive data collection on a regional-watershed

basis for each municipality. This approach is currently being

utilized in Lee and Volusia Counties' Coastal Studies and should
be considered throughout the state. Since the data collected

from these efforts would be invaluable to a number of local state

and federal agencies an opportunity exists for cost sharing.

The hydrological approach to wetland evaluation and

permitting will improve wetland managers ability to retain

functioning, maintainable ecosystems. The benefits to the

general public and the landowner are obvious with less money

spent on exotic control, drainage and improved recreational

opportunities. Land use decisions based upon scientific data is

usually positively received by environmentalists, landowners,

developers and the judicial system which often must review

appeals of regulatory decisions. One major benefit however, is

that those wetlands protected, will actually continue to function

as a larger ecosystem in the future. A balance of wetland and

required upland conservation may result from utilizing greenways,

requiring some compromise on current trends towards near total

wetland preservation and high upland utilization. However, the

end result would be the retention of interconnected, functioning,

maintainable "hydro-ecological" ecosystems where the remaining

wetland and uplands function as a productive unit resembling the

original landscape.

This article is adapted from papers that will appear in the
Forthcoming Proceedings of the National Wetlands Hydrology



Symposium organized by the Association of State Wetland Managers,

September 1987 and in the November/December issue of the National

Wetlands Newsletter. The author is grateful to Courtney Hackney,

Wane Daltry, Mark Benedict, David Addison, and Hazel Groman for

reviewing an earlier draft, to Ria Brown for typing the

manuscript, and to Lyndon Lee and Jon Kusler for their



Craighead, F.C., Sr. 1971. The Trees of South Florida. Coral
Gables, Florida: University of Miami Press.

' Gosselink, J.G. and R.E. Turner. 1978. The role of hydrology in
freshwater wetland ecosystems. In Freshwater Wetlands:
Ecological Processes and Management Potential, R.E. Good,
D.F. Whigham and R.L. Simpson, eds., Academic Press, New
York, pp. 63-78.

Hampson, P.S. 1984. Wetlands in Florida. Florida Bureau of
Geology Map Series 109. Tallahassee, FL.

Mitsch, W.J. and J.G. Gosselink. 1986. Wetlands, Van Nostrand
Reinhold Company, New York, 539 p.

Noss, R.F. 1987. Corridors in real landscapes: A reply to
Simberloff and Cox. Conservation Biology. Vol. 1:2, pp

Tschinkel, V.J. 1984. Wetlands: The Importance of Our Aquatic
Ecosystem. Florida Naturalist, Spring, pp. 5-11.

U.S. Congress. Office of Technology Assessment. 1984. Wetlands:
Their Use and Regulation. Washington D.C.

Wilcox, B.A., Murphy, D.D. 1985. Conservation strategy: The
effects of fragmentation on extinction. American
Naturalist 125:879-887.


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