M~vmNST F WEIE CS IN FIERIIu ;
A CMllalW OMR 1MEQN'I E
RICeRD J. CIAZREN, JR.
rE BwOICAL MML ISI ASSOCIMIS, INC.
3819 ERST 71 AvsU
AaJM, FII 33605
Florida has between 2.5 and 2.75 million acres of freshwater systems which
account for an abundance of wetland habitat. Freshwater wetlands in Florida are
highly variable in form and function. The degree of variability is influenced on
a local level by soils, topography and hydrology. Freshwater wetland conmcnities
vary significantly in ouaposition from region to region as they are affected by
climate and hydrologic regimes.
Defining wetlands and determining their extent has became a universal dilemma
for numerous entities in the state. Differences in philosophy, methodology and
Special interests continue to promote subjective ambiguity in the quest for
a perfected quantitative approach for defining and delineating wetlands. Regional
differences in species composition, soils and hydrology hinder the applicability
of a statewide methodology that relies on a master plant species list and
generalized hydrologic guidelines.
II. WE1LAND DIVERSITY AND THEIR VARIABLES
Wetlands are generally recognized as areas where the water table is at, near
or above land surface for a significant part of the year (Anderson, 1975). Water
is the primary factor controlling wetland envir moments and their associated flora
and fauna (Niering, 1985). Several regulatory agencies have adopted their own
definitions of wetlands and supported them with legislation. Presently there are
two Federal definitions for wetlands. One was established by the U.S. Fish and
fr Wildlife Service for mapping and classifying wetlands. The second definition
employed by the U.S. Army Cops of Engineers and the Environmental Protection
Agency for regulation is more restrictive. The differences in the two definitions
accounted for the USFWS estimating there were 99 million acres of wetlands in the
lower 48 states in the mid-1970's while the U.S. Army Corps of Engineers (ODE)
concurrently estimated the acreage at 64 million acres (Gibbons, 1984).
Currently, anywhere in Florida there are at least three overlapping wetland
regulatory agencies with varying definitions of wetlands and methodologies for
their delineation. They include, but are not restricted to the ODE, Florida
Department of Enviraental Regulatio (IER) and the Water Management Districts
(WMD). Numerous local governments have even more inclusive criteria for
determining wetland limits specified in ordinances and rules.
The focus and protection afforded freshwater wetlands is to preserve the
tangible and intangible benefits they provide for our environment. Those benefits
include but are not limited to:
recharge groundwater and piezometric supplies
enhance water quality
reduce air pollution
The benefits realized from each type of wetland may vary significantly with the
inherent dynamics of the biotic and physical characteristics of the system.
Freswater wetlands are generally classified as lacustrine (associated with
lakes), riverine (river floodplain) or palustrne (marshes and swamps). There are
many variations of each classification. Those variations are recognized by
differences in the floral constituency which are the result of subtle differences
in hydrology, soils, topography, and water chemistry. Under varying conditions
the above parameters promote the dominance of certain species and the exclusion of
others. The physical parameters of freshwater wetlands in Florida differ
significantly from region to region, particularly when ccuparing the southern
portion of the state with the Panhandle.
III. FIRIDA'S DIVERSE PHYSICAL CONDITIONS AND WETLANDS
Florida is characterized by a diverse climatic, geologic and biotic
conditions. Peninsular Florida is only 100 miles from the tropics. The sub-
tropical climate of South Florida is very different from the temperate conditions
in North Florida. Florida's average annual rainfall of 53 inches is variable from
coast to coast.
Coastal areas in all parts of the state average slightly warmer temperatures
in winter and cooler temperatures in summer than inland areas at the same
latitude. Ihe Gulf Stream on the east coast and Gulf of Mexico on the west coast
buffer coastal temperatures. Average winter temperatures vary by about 10 degrees
from north to south (Marth, 1985). The most significant climatic influence on the
distribution of biotic cauinities is the freguncy of freezes. Occurrence of
hard freezes below the middle latitudes of the state are uncrmon.
Rainfall is a significant factor in the formation and perpetuation various
wetland types. Rainfall averages across the state are not significantly different
(Marth, 1985). The heterogeneous hydrologic conditions in the state are due to
variable topographic and other geologic features.
The greater topographic relief and more prevalent irregular contours in the
northern and central portions of the state promote the development of high
velocity, dynamic flowing systems based on spring and surface water flows. The
relatively flat basin conditions of the coastal and southern regions of the state
are typified by slow moving waterbodies fed by underground and surface water
Geologic formations account for hydrologic contributions to wetlands. Soil
types are developed from the interactions of geologic features with hydrology and
climate. The porous limestone plateau below and at land surface in various
regions of the state is dynamic. Spring flows, sinks, rock out crppings and
the broad everglades basin we all associated with the porous limestine plateau
that is "spine" of the state. These systems support specific wetland
A major influence of species richness in wetlands is spatial heterogeneity.
The mre niches the more opportunity for colonization of a new species (Jacobs,
1975). Hydrologic regime is the major factor affecting spatial diversity
(Gosselink, 1978). Flooding waters have the effect of minimizing spatial
diversity because of uniform mixing. Cmisquently, the biotic community of
an expansive flat basin wetlands such as the Everglades are depauperate in
comparison to the oommunities found in the dynamic high velocity spring runs of
central and northern Florida.
Diversity in wetlands is a function of flooding duration and depth.
Diversity generally increases with elevation. Increased water velocity also
increases plant species richness. Consequently, a hydrologic regime can promote
uniformity in the biotic system or lead to greater diversity (Gorham, 1957). The
heterogeneity of the hydrologic regimes in Florida variable species composition
and diversity within associated wetland floral communities.
Florida's freshwater wetlands are typically described to a cacmunity level
during most assesmnts. Finer distinctions can be made within communities to
emphasize dominant species. Subtle differences in climate and hydrologic regime
can affect significant changes in floral species dominance and composition.
The most ocmnanly employed classification system for freshwater wetlands is
the Florida land Use. Cover and Forms Classification System produced by the
Florida Departmnt of Trasportation. Broad classifications for wetlands
are wetland hardwood forest, wetland coniferous forest, mixed wetland forest and
vegetated non-forested wetlands. The system more specifically identifies 12
different freshwater wetland ocmunities. lhey are:
- gum swamps
m- iad hardwoods
- cypress swamps
pond pine swaps
Atlantic white cedar swamps
cypress pine cabbage palm swamps
This category is composed of dominant trees such as loblolly bay, sweetbay,
red bay, swamp bay, slash pine and loblolly pine. large gallberry,
fetterbsh, wax myrtle and titi are included in the understory vegetation
7his forest oc anmity is ccnposed of wauap tupelo (blackgum) or water tupelo
(tupelogum) which is pure or predominant. Associate species may include bald
cypress and a great variety of wet site tolerant hardwood species widely
variant in opposition.
This ocmmnity is ccmponed of often extremely dense stands of black titi and
cyrilla which are either the pure or predminant species. Major associated
species include bays, cypress, tupelos and a great variety of wetland
Stream and ake Swamps (Bottdoland)
This community, often referred to as bottmland or stream hardwoods, is
usually found on but not restricted to river, creek and lake flood plain or
overflow areas. It is a conglomeration of a wide variety of predominantly
hardwood species of which same of the more oamoon components include red
maple, river birch, water oak, sweetgum, willows, tupelos, water hickory,
bays, water ash and buttonbush. Associated species include cypress, slash
pine, loblolly pine and shortleaf pine.
Inland Ponds and Sloughs
these ocnmunities are associated with depressions and drainage areas that are
not associated with streams or lakes. On or a ocIbination of the following
species will generally be predominant: pond cypress, swap tupelo, water
tupelo, titi or willows.
Mixed Wtland Hardwoods
This category is reserved for those wetland hardwood communities which are
mnpesfi of a large variety of hardwood species tolerant of hydric conditions
yet exhibit an ill defined mixture of species.
This mcmunity is ccnposmd of pond cypress or bald cypress which is either
pure or pr edminant. In the case of pond cypress, camo associates are
suwmp tupelo, slash pine and black titi. In the case of bald cypress, camn
associates are water tupelo, swam cottomood, red maple, American elm,
pmpkin ash, Carolina ash, overcup oak, and water hickory. Bald cypress may
be associated with laurel oak, seetgum and sweetbay on less moist sites.
Note that some authorities do not distinguish between two varieties of
This category is ccnposed of pond pine which is either pure or predominant.
Its major associate is titi. Minor associates include sweetbay, loblolly
bay, red bay, and swamp tupelo.
Atlantic White Cedar
In this community, Atlantic White Cedar is the indicator species although it
may not always be the most abundant. Its omnon associates include slash
pine, cypress, swamp tupelo, sweetbay, red bay, loblolly bay, titi and red
Cypress Pine Cabbage Palm
his ocmunity includes cypress, pine and/or cabbage palm in combinations in
which neither species achieves dominance Although not strictly a wetlands
ooammnity, it forms a transition between moist upland and hydric sites.
The omamnities included in this category are characterized by having one or
more of the following species Ipedm inate:
Sawgrass mLadium mncs
cattail a inenis
Arrohbead Saaittaria sp.
Maidencane Panicum hemAitmn
Buttcnbush Oeghalanths ocidentalis
Oordgrass Spartina ba.eri
Switdgrass anicum viratum
Bulrush Scirpus americanus
Needlerush Juncus efusus
cmaon eed Phramnites commnis
Arrawroot Thalia dealata
This classification is ncupo.ai of dominantly grassy vegetation on wet soils
and is usually distinguished frc marshes by having less water and shorter
herbage. These cammities will be predaminated by one or more of the
St. Johns Wort
- Caium lamicensis
- Panicum hemitrano
- Spartina bakeri
- Eleocharis sp.
- IvreD Up.
- Dirir mga
Same of the specified camunities such as titi swamps and pond pine swamps
are restricted geographically in the state. Their limitations are a factor of the
dominant species intolerance for the sub-tropical climate in central and southern
Florida. All the other ocmunities vary within their broader classifications in
response to influential factors such as hydrologic regime, soils, climate and
Floral species dominance is readily discernable in a cursory review and
generally the basis for naming a specific wetland cx unity. Differences in
species composition and diversity within the same ammmnity in different regions
of the state is not addressed in most asaismn mnts. Recent assessments by
Biological Research Associates, Inc. (BRA) in north, central and southern Florida
have revealed as much as a 10 percent variation of species opposition in
freshwater marshes. Similar variability was observed in wet prairies and slough
Species dominance in the eootones (transitional areas) of each of the above
wetland systems investigated was variable. Slight differences in hydrologic
conditions, soils and topography influenced significant changes in composition,
and dominance in ecotone associations.
Significant fluctuations in species diversity, dominance and distribution
within most types of wetlands can occur over a relatively short period of time.
Seasonal conditions, drought and flood can affect as much as a 50 percent change
in camposition over a 12 month period in a wetland (Callahan, 1986).
Similar fluctuations in plant diversity and composition occur in non-contiguous
wetlands routinely on a seasonal basis. The most dramatic changes are observed in
IV. MAN AJERED WEMANLS
Decades of draining, mining and agricultural development have perturbed the
physical integrity of vast acres of freshwater wetlands in Florida. In addition
sane introduced exotic plant and tree species have rapidly invaded the forested
and non-forested wetlands throughout the state. The most heavily infested areas
are in South Florida where punk trees (elala inuenervia), eucalyptus
(Eucaltus app.) and Brazilian pepper (Schinus terebinthifolius) often dominate
the transition areas of wetlands.
Dematering and disruption of natural substrates and inherent seed banks
often open the door for exotic species invasion. In the absence of exotic
invaders native species opposition, diversity and cover is typified by
opportunistic invaders such as cattails (Tvha qp.), primrose willow (ITdwiMia
spp.) and torpedo grass (Panium ees). Ihese prolific plants frequently
suxeed to a near mnoculture representation in the system diminishing some of the
positive function attributed to wetlands.
These altered systems are technically wetlands in form and function, but
offer less desirability when ocupared to unpeturbed wetlands. Defining and
delineating altered wetlands is often tedious and frustrating. The merits of
identifying and protecting severely altered wetlands are questionable. When
hydrologic indicators are not conducive to perpetuating desirable wetland
attributes the system no longer functions and should not be classified or
delineated. Hydrology is the key factor in wetland development and function.
V. IMPLICATIMNS FR REGULATIONS
Regulatory groups throughout the State appear to be investigating and/or
adopting a three parameter approach to define and delineate wetlands. The
technique addresses wetlands as lands that are transitional between terrestrial
and aquatic systems with the following three conditions:' (1) at least
periodically the land supports hydryphytes; (2) the substrate is a hydric soil;
and (3) the substrate is saturated with water or covered by shallow water at same
time daring the growing season each year (Omawrdin, 1979).
SProblems arise using the three parameter approach when regulatory groups
pportunistically focus on one or two conditions for a wetland determination, in
( general all systems should eodibit the three of the above conditions to be
classified as a freshater wetland. There can be sections to this general
approach. Altered wetlands where vegetation ard/or soils have been displaced or
destroyed must be given special casideration. Hydrperiod becomes a primary
factor in assessing altered systems. Ihe likelihood that a viable wetland
cmiunity will develop from a disturbed system in a natural setting is almost
entirely dependent on hydrologic odlitions.
Another source of dispute in the three parameter approach, and almost all
other methods currently employed in the state to define and delineate wetlands is
the reliance on a state wide list of submerged and transitional indicator plant
species for dominance determinations. he criteria for determining the dominance
of transitional and submerged species under DER's regulations (17-4) are
significantly different frcu the OOE's guidelines (Section 404) as is their
respective plant lists. The presence of cosmopolitan species that frequently are
found in uplands as well as wetlands on both agencies' lists reduce the accuracy
of the methodology.
Regional variability of plant species ccaposition in various wetland
mmmunities make the utilization of a statewide methodology and plant list
questionable when considering specific local conditions. A regional program may
more aurately define and delineate wetlands considering local physical and
Anderson, J.R., Hardy, E.E., Roach, J.T., and Witmer, R.E., 1975. A Land-Use and
land-Cover Classification System for Use with Remote-Sensor Data: U.S. Geol.
Survey Circ. 727.
Callahan, R., Hanners, L., and Patton, S., 1986. Ecological Monitoring Report for
the Cross Bar Ranch Regional Wellfield. Tampa, Florida: Biological Research
Associates, Inc., Vol. 7, 124 p.
Ciwardin, L.M., Carter, V., Golet, F.C., and LaRoe, E.T., 1979. Classification of
Wetlands and Deepater Habituals of the United States, Washington D.C.: U.S.
Dept. of Interior, Offices of Biological Services Fish and Wildlife Service,
Florida land Use, Cover and Forms Classification System, 1985.
of Transportation, 33 p.
Gibbons, J.H., 1984. Wetlands: Their Use and Regulation, Was
Congress, Office of Technology Assessment, 206 p.
Gorham, E., 1957. The development of peat lands.
Quart. Rev. Biol.
Gosselink, J.G. and Turner, R.E., 1978. The role of
wetland ecosystems. Freshwater Wetlands Ecological
Potential. New York: Academic Press, pp. 63-78.
hydrology in freshwater
Processes and Management
Hartman, B., 1978. Rare and Endangered Biota of Florida. Gainesville, Florida:
University Presses of Florida. Vol. 1, pp. xxvi-xxix.
Jacobs, J., 1975. Diversity, stability, and maturity in ecosystems
human activities. Unifying concepts in Ecology. The Hague:
Publishers, pp. 187-207.
Marth, D and Marth, M., 1985. The Florida Almanac, Gretna, Louisiana: Pelican
Publishing Co., Inc., 469 p.
Niering, W.A., 1985. Wetlands, New York: Alfred A. Knhpf, Inc., 640 p.