Title: A Quantitative Approach for Assessing the Character of Mitigated Fresh Water Marshes and Swamps in Florida
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Title: A Quantitative Approach for Assessing the Character of Mitigated Fresh Water Marshes and Swamps in Florida
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Language: English
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Spatial Coverage: North America -- United States of America -- Florida
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Abstract: A Quantitative Approach for Assessing the Character of Mitigated Fresh Water Marshes and Swamps in Florida, Kevin L. Erwin
General Note: Box 7, Folder 1 ( Vail Conference 1987 - 1987 ), Item 46
Funding: Digitized by the Legal Technology Institute in the Levin College of Law at the University of Florida.
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Bibliographic ID: WL00000653
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.

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A QUANTITATIVE APPROACH FOR ASSESSING THE CHARACTER OF MITIGATED

FRESH WATER MARSHES AND SWAMPS IN FLORIDA


KEVIN L. ERWIN

SYSTEMS ECOLOGIST

2077 BAYSIDE PARKWAY

FT. MYERS, FLORIDA 33901


One of the principle questions that must be addressed when

assessing the success of a completed wetland mitigation project

is, to what extent does the reclaimed wetland provide biological

and hydrological functions similar to those made by the mitigated

wetland. In order to determine what the success criteria should

be for a particular wetland habitat related impact, the natural

system must first be evaluated in order to assertain its form,

function, and contribution to the ecosystem. This evaluation of

the wetland to be mitigated is also of great importance in the

design of the reclamation project itself.

The exact duplication of a mitigated wetland is probably not

possible. Therefore, we must be able to evaluate the reclaimed

wetland in a quantitative manner to assess its similarity of form

and function with a mitigated wetland.

The quantitative approach should begin with a thorough

evaluation of the ecosystem of which the subject wetland is a

part. This ecosystem usually includes the identification and

study of a watershed or drainage basin in which the subject

wetland area is located. The various contributions made by the


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mitigated wetland must then be identified. These contributions,

many of which are typical for most wetland areas, include the

following:

Hydrological Function

The mitigated wetlands' function within the ecosystem as a

flow way (to pass surface water flows), and the wetlands' ability

to uptake and/or absorb constituents within the water is, in

part, related t.o the storage capacity and detention times of the

area. The wetland may also provide an attenuation of peak water

discharges from storm events to the receiving water bodies. The

ability of a wetland system to store surface waters through the

dry season and drought conditions can directly benefit water

resources available for human consumption and fish and wildlife

utilization.

Water Quality

The positive benefits of certain wetland systems to the

maintenance of water quality within an ecosystem is well

documented. It should be determined in what ways the mitigated

wetland performs such a function as part of a larger ecosystem.

The water quality of the subject wetland should also be evaluated

for future comparisons with the reclaimed wetland area. Once

baseline water quality data is collected, the reclaimed wetland

can be designed to replicate similar water quality conditions or

even an enhanced state.


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Fish and Wildlife Values

The habitat evaluation procedure (HEP) as developed by the

U.S. Fish and Wildlife Service should be used to accurately

describe the quality of the habitat and its particular

contribution within the ecosystem.
Floral Species Composition

The importance of an accurate description of the plant

community structure of the subject wetland is second only to

understanding the area's hydrological function. An assessment of

existing or known proposed activities within the ecosystem, in

which the wetland is located, is imperative. Cumulative impacts

and synergistic effects of certain activities may require

rethinking the values placed upon the mitigated wetland.

Ideally, mitigation plans should be developed as part of an

approved land use plan for an ecosystem or manageable subunit.

Methodology

Since the vast majority of the functions related to the

mitigated wetland are directly related to the hydrology of the

system, it is important to develop, at minimum, a basic

hydrological model for the wetland. Monitoring well and surface

water level data should be collected and whenever possible field

markings on vegetation such as lyhen lines should be marked and

the elevations recorded.

The water quality analysis in most cases follows the

criteria and procedures set forth by the Florida Department of

Environmental Regulation in Chapter 17-3, Florida Administrative


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Code. Surface and groundwater samples should be taken quarterly

for an annual cycle which includes a full wet season and dry

season.

A biological monitoring program should be designed to

compliment the water quality monitoring within a mitigated

wetland. The use of Hester Dendy samplers in stream situations

and net and core sampling in static water systems is recommended.

Since the target of the biological sampling is generally

macroinvertebrates it must be understood that seasonality and

habitat preference of most species will influence the sampling

procedure design. Sampling should be done quarterly, if

possible, spanning the dry/wet season cycle. Net and core

sampling should be undertaken in each of the major macrophyte

communities within the wetland since compartmentalization of

species will adversely bias an inadquately sampled system (Erwin,

1985). Samples collected within each macrophyte community over

the wet/dry season cycle should provide an accurate

characterization of species richness and diversity of the

macroinvertebrate community.

The methodologies used to determine the characterization of

the wetlands floral composition depends upon whether the wetland

is a forested (swamp) or nonforested (marsh) wetland. In

nonforested wetlands line intercept transects (Phillips, 1959;

Smith, 1980) can be used to evaluate the mitigated wetland and

later provide comparison of degree of similarity with the

reclaimed system. The method consists of taking observations on

transect lines laid out over the study area. The identity of



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plant species touching, overlying, or underlying the line is

recorded along with the distance that each species covers

(intercepts) the line. In this way the line can be thought of as

a two dimensional plane extending above and below the actual

transect line. The line intercept transect should run down

slope, perpendicular to the shoreline, thus enabling correlations

to be made between the distribution of cover and water depth

and/or hydroperiod. The individual intervals are totaled by

species and by transect to yield estimates of percent cover. The

line intercept method is rapid, objective, and relatively

accurate. This method is also well adapted for measuring changes

and vegetation across transitional zones and transects can be

randomly placed and replicated to obtain the desired precision.

When the line intercept transect data is displayed graphically,

each species will have a specific signature (Figure 1). To

facilitate both an intensive, accurate and repeatable

characterization of forested wetlands, the use of the "line

strip" (elongated quadrat) technique (Lindsey, 1955; Woodin and

Lindsey, 1954) should be used. All elongated quadrats should run

parallel to the slope to allow for correlations to be made on a

gradient from flooded through moist to dry conditions within the

wetland. Separate measurements should be taken for the over, mid

and understory percent closure, height and DPH of canopy trees.

This same methodology may also be applied to the reclaimed

forested wetland and expanded so data collection may address

survivability and growth rate.










Many other methodologies for quantitative data collection

and interpretation do exist with only a few mentioned in this

discussion. The investigator must take the time to evaluate the

available methodologies and select or develop the methodology

best suited to characterize the mitigated wetland given the

limitations which always are a part of any study. In many

instances it is the limitations placed upon the investigator that

have a greater influence on the methodology to be selected than

the study area itself. Therefore, it is important to recognize

some of these limitations.

Lack of Success Criteria

Since the restoration or exact duplication of a particular

wetland is not possible, the investigator must obtain acceptable

success criteria from which to judge the similarity of form and

function between the mitigated and reclaimed wetland systems.

Time

In many instances it is not possible to provide the

investigator with the time necessary to conduct an investigation

over an annual wet/dry season cycle.

Expense

The techniques I have outlined here generally require

extensive field time and many hours of data entry and computer

analysis.

So, what have we concluded in applying this approach to

wetlands mitigation? I believe the methodologies described do

provide an adequate characterization of the wetlands form and


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function. Again, it is important that the investigator use

methodologies best suited for the particular system to be

studied.



REFERENCES



Erwin, Kevin L. 1985. Agrico Fort Green reclamation project.

Third Annual Report. Agrico Mining Company, Mulberry,

Florida.



Florida Administrastive Code, Chapter 17-3, Water Quality

Standards, 1983 Florida Department of Environmental

Regulation, Tallahassee, Florida.



Lindsey, A.A. 1955. Testing the line strip method against full

tallies in diverse forest types. Ecology 36:485-495.



Phillips, E.A. 1959. Methods of vegetation study. Holt,

Rinehart and Winston, Inc., New YOrk. 107 pp.



Smith, R.L. 1980. Ecology and field biology. Harper and

Row, New York. 805 pp.



Woodin, H.E. and A.A. Lindsey. 1954. Juniper-Pinyon east of

the continental divide as analyzed by the line strip method.

Ecology 35:474-489.





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