BIOGEOCHEMICAL SURVEY OF WETLANDS IN SOUTHWESTERN INDIANA By DAVID A. STUCKEY A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2006
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BIOGEOCHEMICAL SURVEY OF WETLANDS IN SOUTHWESTERN INDIANA
By
DAVID A. STUCKEY
A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE
UNIVERSITY OF FLORIDA
2006
Copyright 2005
by
David A. Stuckey
This document is dedicated to my parents, Robert and Jean Stuckey, my loving wife, Sandra, and our two fine sons, Samuel and Dean, source of constant encouragement and
support.
iv
ACKNOWLEDGMENTS
I thank my parents, Robert and Jean Stuckey, for introducing me to the world of
natural science at an early age, and for their continuous support and encouragement
throughout my lifetime.
My wife, Sandra, and sons, Samuel and Dean, sacrificed their time and assisted in
the field work throughout this project. They provided the inspiration for continuing my
education in this field, and I am forever indebted.
I thank Dr. Mark W. Clark, my academic advisor at the University of Florida, for
his enabling character that made my participation in this research possible. His balanced
perspective of science, education and common sense was invaluable. My gratitude is
likewise extended to the other distinguished members of my graduate committee, Dr. K.
Ramesh Reddy, Chairman, and Dr. Matthew J. Cohen, for their ongoing support and
assistance.
I am indebted to my colleagues at the University of Florida, Ms. Stacie Greco and
Mr. Jeremy Paris. As a subset of their research project, they both provided much time
and assistance as contacts and facilitators of sampling activities and data collection. I
wish to acknowledge the analysts at the UF Wetland Biogeochemistry Laboratory for
their hard work in generating the analytical data from the project sampling.
v
TABLE OF CONTENTS page
ACKNOWLEDGMENTS ................................................................................................. iv
LIST OF TABLES............................................................................................................ vii
LIST OF FIGURES ........................................................................................................... ix
ABSTRACT....................................................................................................................... xi
Sampling Site Selection..............................................................................................15 Sampling and Analytical Methods..............................................................................18 Data Analysis..............................................................................................................25
Spatial Study Results ..................................................................................................27 Temporal Study Results..............................................................................................46
4 DISCUSSION AND CONCLUSIONS ......................................................................58
Objective One (Results)..............................................................................................58 Objective Two (Results) .............................................................................................60 Objective Three (Results) ...........................................................................................60 Objective Four (Results).............................................................................................62 Conclusion ..................................................................................................................64
vi
APPENDIX
A PROFILES OF SAMPLED WETLANDS .................................................................65
B SURVEYED WETLANDS DESCRIPTION AND LOCATION............................126
C PHOTOGRAPHS OF WETLANDS SURVEYED IN SW INDIANA ...................157
D WETLAND CHARACTERIZATION FORM.........................................................178
LIST OF REFERENCES.................................................................................................181
Table page 2-1 Number of wetlands surveyed in Southwestern Indiana from each wetland
community type and nutrient condition. ..................................................................17
2-2 Number of wetlands surveyed within each community type. Sites were all located in the southeastern part of Eco-region IX....................................................17
2-3 Southwestern Indiana wetland research location, sampling dates and characterization. All wetlands included in the survey are listed. ............................18
2-4 Southwestern Indiana wetland research location, sampling dates and characterization for Turkey Hill Graywood Marsh, wetland community type: Non-Riparian marsh with Least-Impacted wetland condition. ................................19
3-1 General descriptive statistics summary of water column total phosphorus and total nitrogen concentrations for wetlands surveyed in Indiana. Wetlands were aggregated using several different classification criteria. ........................................27
3-2 Statistical comparison of water column total phosphorus and total nitrogen concentrations for wetlands surveyed in Indiana, aggregated using several different classification criteria….…………........………………………………….28
3-3 General descriptive statistics summary of leaf litter total phosphorus, total nitrogen and total carbon concentrations for wetlands surveyed in Indiana. Wetlands were aggregated using several different classification criteria. ...............29
3-4 Statistical comparison summary of leaf litter total phosphorus, total nitrogen and total carbon concentrations for wetlands surveyed in Indiana, aggregated using several different classification criteria. . .................................................................30
3-5 General descriptive statistics summary of soil pH, organic matter, total phosphorus, total nitrogen and total carbon concentrations for wetlands surveyed in Indiana. Wetlands were aggregated using several different classification criteria.......................................................................................................................32
3-6 Statistical comparison summary of soil pH, organic matter, total phosphorus, total nitrogen and total carbon concentrations for wetlands surveyed in Indiana, aggregated using several different classification criteria…………..……… .......…34
3-7 General descriptive statistics summary of vegetation total phosphorus, total nitrogen and total carbon concentrations for wetlands surveyed in Indiana. Wetlands were aggregated using several different classification criteria. ...............35
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3-8 Statistical comparison summary of vegetation tissue total phosphorus, total nitrogen and total carbon concentrations for wetlands surveyed in Indiana, aggregated using several different classification criteria. . .....................................36
3-9 Summary table of nutrient indicator strata. ............................................................37
3-10 Summary statistics (mean, standard deviation, variance and 95% confidence interval) of water column samples collected during the temporal study..................50
3-11 Summary statistics (mean, standard deviation, variance and 95% confidence interval) of litter samples collected during the temporal study. . ............................53
3-12 Summary statistics (mean, standard deviation, variance and confidence interval) of soil sampled during the temporal study ...............................................................57
ix
LIST OF FIGURES
Figure page 1-1 Percentage of Wetlands Lost in the United States. ....................................................2
1-2 Draft Aggregations of Eco-regions for the National Nutrient Strategy (Source US EPA http://www.epa.gov/waterscience/criteria/nutrient/ecomap.html).............10
2-1 Photographs representing the three principal wetland community classifications surveyed in Southwestern Indiana, (A) Riparian Swamp, (B) Non-Riparian Swamp, and (C) Non-Riparian Marsh......................................................................18
3-1 Water Column Total Phosphorus Comparison between Least-Impacted Wetlands Surveyed in Southwestern Indiana and Eco-Region IX Least-Impacted Wetlands...................................................................................................................39
3-2 Water Column Total Nitrogen Comparison between Least-Impacted Wetlands Surveyed in Southwestern Indiana and Eco-Region IX Least-Impacted Wetlands...................................................................................................................40
3-3 Litter Total Phosphorus Comparison between Least-Impacted Wetlands Surveyed in Southwestern Indiana and Eco-Region IX Least-Impacted Wetlands...................................................................................................................41
3-4 Litter Total Nitrogen Comparison between Least-Impacted Wetlands Surveyed in Southwestern Indiana and Eco-Region IX Least-Impacted Wetlands. ................42
3-5 Vegetation Tissue Total Phosphorus Comparison between Least-Impacted Wetlands Surveyed in Southwestern Indiana and Eco-Region IX Least-Impacted Wetlands...................................................................................................................43
3-6 Vegetation Tissue Total Nitrogen Comparison between Least-Impacted Wetlands Surveyed in Southwestern Indiana and Eco-Region IX Least-Impacted Wetlands...................................................................................................................44
3-7 Soil Total Phosphorus Comparison between Least-Impacted Wetlands Surveyed in Southwestern Indiana and Eco-Region IX Least-Impacted Wetlands. ................45
3-8 Soil Total Nitrogen Comparison between Least-Impacted Wetlands Surveyed in Southwestern Indiana and Eco-Region IX Least-Impacted Wetlands. ....................46
x
3-9 Water Column Depth in Inches. Wetland zones sampled included the Inner Core (A) and Outer Edge (B). Mean and Standard Deviation of both zones are presented...................................................................................................................47
3-10 Water Column Field pH. Wetland zones sampled included the Inner Core (A) and Outer Edge (B). Mean and Standard Deviation of both zones are presented...48
3-11 Water Column Dissolved Oxygen, %. Wetland zones sampled included the Inner Core (A) and Outer Edge (B). Mean and Standard Deviation of both zones are presented...................................................................................................49
3-12 Water Column Total Phosphorus, mg/L. Wetland zones sampled included the Inner Core (A) and Outer Edge (B)..........................................................................49
3-13 Water Column Total Nitrogen, mg/L. Wetland zones sampled included the Inner Core (A) and Outer Edge (B)..........................................................................50
3-14 Litter Total Phosphorus, mg/kg. Wetland zones sampled included the Inner Core (A) and Outer Edge (B). ..................................................................................52
3-15 Litter Total Nitrogen, g/kg. Wetland zones sampled included the Inner Core (A) and Outer Edge (B). .................................................................................................52
3-16 Litter Total Carbon, g/kg. Wetland zones sampled included the Inner Core (A) and Outer Edge (B). .................................................................................................53
3-17 Soil Bulk Density, grams cm-3. Wetland zones sampled included the Inner Core (A) and Outer Edge (B). ...........................................................................................54
3-18 Soil Loss on Ignition, %. Wetland zones sampled included the Inner Core (A) and Outer Edge (B). .................................................................................................55
3-19 Soil Total Phosphorus, mg/kg. Wetland zones sampled included the Inner Core (A) and Outer Edge (B). ...........................................................................................55
3-20 Soil Total Nitrogen, g/kg. Wetland zones sampled included the Inner Core (A) and Outer Edge (B). .................................................................................................56
3-21 Soil Total Carbon, g/kg. Wetland zones sampled included the Inner Core (A) and Outer Edge (B). .................................................................................................56
3-22 Soil pH. Wetland zones sampled included the Inner Core (A) and Outer Edge (B).............................................................................................................................57
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Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Science
BIOGEOCHEMICAL SURVEY OF WETLANDS IN SOUTHWESTERN INDIANA
By
David A. Stuckey
May 2006
Chair: Mark W. Clark Major Department: Soil and Water Science
Nutrient concentrations play a critical role in the integrity and functionality of
wetlands. To fully assess the status and condition of wetland ecosystems, knowledge of
nutrient flow and cycling is required. Although water quality nutrient data are readily
available, there is limited information regarding nutrient concentrations within the soil,
litter and vegetation at wetland sites. While it is recognized that an assessment of
wetland ecosystems can be enhanced by examination of nutrient criteria, such
biogeochemical indicators have not been standardized and there is a lack of spatial data
within the National Wetland Biogeochemical Database.
To address this need for consistency and comparability in the reporting data, a
Biogeochemical Survey of Wetlands of Southwestern Indiana was conducted. Sixteen
wetland sites were surveyed for twenty biogeochemical indicators including vegetation,
litter, soil and water column nutrient parameters. One wetland site was selected for
additional study for a period of one year to provide background information on temporal
and seasonal variability within the wetland.
xii
Based on the study results, there does not appear to be a need to sub-classify
wetlands by vegetative community type to properly assess nutrient conditions in
Southwestern Indiana’s wetlands. However, hydrologic connectivity of the wetland
should be considered in the assignment of appropriate numeric nutrient criteria.
Comparison of water column, litter, soil, and vegetation nutrient indicators between
impacted and least-impacted wetlands suggests that total phosphorus concentrations
measured in the water column, litter, and vegetation do not indicate nutrient enrichment.
The most responsive indicator stratum for nutrient enrichment between impacted and
least-impacted wetlands appears to be soil total phosphorus and total nitrogen.
Comparison of nutrient concentrations in Southwestern Indiana wetlands to
Southeastern U.S. Eco-region IX wetlands showed significantly higher total phosphorus
concentrations in the water column, litter and soil from Southwestern Indiana Wetlands.
The findings suggest that the establishment of numeric nutrient criteria for Southwestern
Indiana wetlands, based on reference wetlands from Eco-region IX, could be overly
protective.
1
CHAPTER 1 INTRODUCTION
Wetland Perspective and Trend
Throughout history, man’s regard for wetlands has ranged from ambivalence and
disdain of inundated areas as wastelands, to great respect as a precious resource that
enables a way of life. At the first extreme, legislation such as the Federal Swamp Lands
Acts of 1849, 1850, and 1860 encouraged the drainage or reclamation of wetlands, to
more productive, beneficial uses to society. The other extreme could be represented by
human cultures evolved within, and dependent upon wetland environments, such as the
Cajuns of Louisiana, and the Sokaogon Chippewa of Wisconsin (Mitsch and Gosselink
2000).
This polarity of values continues today as development interests compete with
environmental conservationists for the right to develop, versus the preservation, of
wetland areas. Within the last twenty years, as wetland values have been further
recognized and promoted, legislation has been enacted to help protect diminishing
wetland resources not just from direct infill or drainage, but also from indirect
degradation and impacts to wetland functions and quality.
At the heels of this legislation are challenges to the rules and laws promulgated to
protect wetlands. A climate of judicial challenge and litigation reinforce the need for
clarity in delineation, scope and application of the wetland subject areas. The more that
is understood about wetlands, the better their chances for protection.
2
Figure 1-1 illustrates the percentage of wetland acreage in the United States that
were lost over the 200 year period between the 1780’s and the 1980’s. The State of
Indiana lost 87% of its wetlands during this period. According to estimates based on
hydric soils assessments by the USDA Soil Conservation Service, approximately
5,600,000 acres of wetlands were present in Indiana in the 1780’s, comprising 24.1% of
the total land area. The existing 813,000 acres of wetlands now cover only 3.5% of the
land area in the state. Among the 50 states, Indiana ranks 4th in proportion of wetlands
lost (Dahl 1990). Clearly, this negative trend needs to be reversed if the plant and animal
communities and the physical landscape are to receive future benefits provided by
wetland ecosystems.
Indiana’s wetlands are impacted today by agricultural activities, commercial and
residential development, road construction, water development projects, groundwater
withdrawal, loss of instream flows, water pollution and vegetation removal (IDNR 1996).
Figure 1-1. Percentage of Wetlands Lost in the United States.
3
Wetland Benefits
Wetlands have been described as the kidneys of the landscape for their abilities to
absorb, filter, stabilize and buffer nutrients, pollutants, groundwater, floodwater and other
upstream native and anthropogenic inputs. Wetlands function as sources, sinks and
transformers of chemical and biological materials. Among the most productive
ecosystems worldwide, wetlands support broad biodiversity ranging from microbial
organisms to mammals.
Wetlands play a key role in atmospheric air quality through carbon sequestration.
Conversely, drainage and destruction of wetlands can release carbon dioxide, a
greenhouse gas (Klein et al. 2005).
The ability of wetlands to perform the valuable functions of source, sink and
transformer is dependent upon their condition. Limited monitoring information is
available to assess wetland ambient and seasonal conditions, or the affects of ecosystem
stressors that may degrade wetland condition. As of 1998, only 4% of the nation’s
wetlands had been surveyed. Of those wetlands surveyed, the majority of data was
generated through dredge and fill permit requirements (USEPA 2002b).
Regulatory Authority
In 1972, Congress enacted the Clean Water Act (CWA) to “restore and maintain
the chemical, physical, and biological integrity of the Nation’s waters.” While the term
“wetland” is absent from the entire statute, Section 404 of the CWA is the primary
Section 402 of the Clean Water Act prohibits the discharge of pollutants from a
point source, into waters of the United States, unless a permit has been issued. Section
404 authorizes the U.S. Army Corps of Engineers to issue permits for the discharge of
4
dredged or fill material into navigable waters. The application and jurisdiction of
navigable waters has been the source of considerable litigation throughout the history and
development of water law in the United States. The recent proximity requirement of
navigable waterways in the designation of regulated wetlands has had the affect of
excluding many isolated and often critical wetland areas from regulatory protection
(Klein et al. 2005).
Since the implementation of the Clean Water Act in 1970, the focus of water
quality protection has been aimed primarily toward lakes, rivers and streams, while
wetland protection efforts concentrated on preventing the conversion of existing wetlands
to uplands. Although the rate of wetland loss has decreased, significant opportunities
exist to assess and ultimately protect wetland quality condition.
Water Quality Standards
Under Section 303(c) of the Clean Water Act (CWA), states are assigned primary
responsibility for enacting water quality standards that are protective of designated uses.
Section 304(a) of the CWA provides assistance to states through the Environmental
Protection Agency’s development of water quality criteria. The EPA provides this
guidance as a starting point for states in the development of water quality criteria and
standards.
Water quality standards consist of three major elements: (1) designated uses, (2)
narrative and numeric water quality criteria for supporting each designated use, and (3)
an antidegradation statement (USEPA 2002a).
Designated Uses
Environmental goals are defined or classified as designated uses for water
resources by states. Examples of typical water body designated uses include: public
5
water supply, primary contact recreation, aquatic life support, wildlife habitat, and fish
consumption. The unique functions and values of wetlands may require the
establishment of designated uses much different from typical water bodies. In the
absence of a state specified designated use for a water body, including wetlands, the
default designated use assigned by EPA is aquatic life support. In most instances states
have not actively designated uses for wetlands and therefore, for regulatory purposes,
support of aquatic life dictates selection of narrative and numeric criteria.
Water Quality Criteria
In 1998, The Clean Water Action Plan was introduced by the U.S. EPA and the
Department of Agriculture as a blueprint to protect and restore the nation’s water
resources. An element of the Plan was to define nutrient reduction goals by establishing
numeric criteria for nutrients (i.e. phosphorus and nitrogen) that reflect the different types
of water bodies and different eco-regions of the country to assist states and tribes in the
adoption of numeric water quality standards based on these criteria (EPA and USDA).
Water quality criteria are narrative or numeric descriptions of the chemical,
physical or biological conditions found in minimally-impacted, reference sites. Using
appropriate criteria, states can compare the condition of a wetland to the reference criteria
to determine if the wetland is supporting its designated uses.
Narrative Criteria
Narrative water quality criteria are statements to protect and support the
antidegradation of water resources and their designated uses. They define conditions
necessary to sustain designated uses. For example, a general narrative statement would
be: “maintain natural hydrologic conditions, including hydroperiod, hydrodynamics and
6
natural water temperature variations necessary to support vegetation which would be
present naturally” (USEPA 2002a).
Antidegradation Policy
An antidegradation policy established by a state would include provisions for full
protection of existing uses, maintenance of water quality of high-quality waters, and a
prohibition against lowering water quality in outstanding resource waters. The policy
would also address fill activities in wetlands to ensure that no significant degradation
occurs as a result of the fill activity (USEPA 2002a)
Numeric Criteria
Numeric water quality criteria define the specific numeric limits for physical,
chemical and biological parameters established by states to protect designated uses of
water resources. Because current assessment methods do not describe many biological
and physical impacts to wetlands, and numeric parameters are not yet established,
narrative criteria are primarily used for wetlands. For wetlands, states have historically
relied upon designated uses and criteria previously developed for lakes and streams,
although the ecological conditions of wetlands differ from lakes and streams.
In addition, the physical and chemical criteria were based on sampling from the
ambient water column. Since the presence of a water column in a wetland can be highly
variable, inference of water column parameters alone in determining the condition of a
wetland can be inconclusive. Since wetland characteristics can be quite different from
typical water bodies, numeric criteria for physical and chemical parameters of other
strata, specific to wetlands are needed (USEPA 2002a).
Other strata that serve as response indicators to causal variables such as nutrient
loading in wetlands include: vegetation, leaf litter and soil. Wetland vegetation responds
7
to nutrient additions by increasing the storage of nitrogen and phosphorus in plant tissue,
and increasing net primary production (NPP), and decomposition (Craft and Richardson
1998). The ratio of carbon to nitrogen (C: N) present in leaves or aboveground biomass
can be used as an indicator of nutrient enrichment. Plants assimilate more nitrogen under
conditions of nitrogen enrichment, increasing leaf nitrogen and decreasing the C: N ratio
(Shaver and Melillo 1984, Shaver et al. 1998). Phosphorus-enriched environments result
in increased leaf tissue phosphorus and decreased carbon to phosphorus ratios (C: P)
(Craft et al. 1995). To determine these affects on the C: N and C: P ratios require
knowledge of the baseline nutrient concentrations prior to enrichment.
Leaf litter is another stratum that can be used as an indicator of nutrient loading,
especially in forested wetlands with little or no herbaceous vegetation. Since woody
plants grow slower and have a longer life cycle than herbaceous vegetation, litterfall is a
slower response variable to measure nutrient use efficiency through net primary
productivity (Chapman 1986).
Wetland soils provide both the medium where many wetland chemical
transformations take place, as well as the primary storage location for available chemicals
for most wetland plants. Biogeochemical cycling, the transport and transformation of
chemicals in ecosystems, involves a number of interrelated processes highly influenced
by system hydrology. These chemical, physical and biological processes result in
changes to chemical forms and spatial movement of materials within wetlands. The
exchange of nutrients at the water-sediment interface, plant uptake, and nutrient inputs
and exports, determine overall wetland productivity. Relatively large amounts of
nutrients are tied up in wetland sediments as compared to terrestrial and deepwater
8
aquatic systems (Mitsch and Gosselink 2000). The use of soil sampling as an indicator of
nutrient enrichment in wetlands can provide information on the status of a wetland’s
function as a sink, source, or transformer of nutrients. The relative permanence of this
stratum in the wetland as compared to water column, vegetation and litter, contribute to
its favorability as an indicator.
Evaluation of Wetland Condition
The physical and chemical characteristics of a watershed’s landscape topography,
underlying geology and hydrology, contribute to the plant and animal community species
that can survive in a location. The collective interaction of these communities with their
physical and chemical environments can form wetlands, and provide valuable functions
from both economic and ecological perspectives. Wetlands can support high levels of
primary production, provide habitat for numerous species of wildlife, and mediate a range
of biochemical transformations that contribute to improved water quality (Findlay et al.
2002). The complex biological community’s presence in a wetland demonstrates its
resilience to normal variation in the environment (Karr and Chu 1999).
The severity, frequency and duration of human activities or disturbances within a
wetland, or its watershed can result in conditions where changes in the biological
community occur. A challenge to wetland scientists is the need to develop practical
measurements of wetland condition to assist resource managers in their decisions and
actions to minimize wetland loss in acreage and function (USEPA 2002a). In spite of
heightened awareness of wetlands functions and values, the ability to protect, manage and
restore these systems remains fairly poor due to a lack of tools to rapidly yet plausibly
assess their value (Findlay et al. 2002).
9
The EPA’s Office of Water has established a strategy to implement the Clean
Water Action Plan, by the development of regional nutrient criteria for each aquatic
resource type. Using comparisons to local reference or background conditions, nutrient
criteria can be developed within designated spatial areas, yielding a regionalization of
nutrient criteria. Reference data sets allow more objective and realistic selection of goals
for wetland maintenance or restoration (Findlay et al. 2002).
Numeric Nutrient Criteria
Nearly half the surface waters surveyed in the United States do not meet water
quality standards because of excessive levels of nutrients. Nutrient enrichment affects
both structural and functional attributes of wetlands. Structural affects can include shifts
in plant species composition with replacement of nutrient-tolerant species with species
more adaptive to high nutrient conditions. Wetland functional changes include increased
nitrogen and phosphorus uptake, net primary productivity, decomposition, and
eutophication (USEPA 2002c).
States consistently cite excessive nutrients as a major obstacle to water quality
attainment, and EPA expects to develop numeric nutrient criteria that cover the four
major types of water bodies – lakes and reservoirs, rivers and streams, estuarine and
coastal areas, and wetlands. The criteria will first be recommended by EPA across the
fourteen major eco-regions of the United States illustrated in Figure 1-2, below. These
recommended criteria must either be adopted by state and tribal governments or
scientifically-based alternative criteria must be proposed that is mutually agreed upon by
the local government and EPA.
10
Figure 1-2. Draft Aggregations of Eco-regions for the National Nutrient Strategy (Source US EPA http://www.epa.gov/waterscience/criteria/nutrient/ecomap.html)
To support and enable the development of numeric nutrient criteria by States and
authorized Tribes, a series of Technical Guidance Manuals has been developed by EPA.
To provide flexibility in adopting nutrient criteria into their water quality standards, the
following approaches, in order of preference, are recommended:
1) Whenever possible, develop nutrient criteria that fully reflect localized conditions and protect specific designated uses using the process described in EPA’s Technical Guidance Manuals for nutrient criteria development. Such criteria may be expressed either as numeric criteria or as procedures to translate a State or Tribal narrative criterion into a quantified endpoint in State or Tribal water quality standards.
2) Adopt EPA’s section 304(a) water quality criteria for nutrients, either as numeric criteria or as procedures to translate a State or Tribal narrative nutrient criterion into a quantified endpoint.
3) Develop nutrient criteria protective of designated uses using other scientifically defensible methods and appropriate water quality data (EPA 2000c).
11
Developing Numeric Nutrient Criteria
EPA plans to recommend numeric criteria for wetlands based on eco-regions, but
unlike other surface water bodies, limited information exists. Heterogeneity among
wetlands and within eco-regions is uncertain and therefore needs to be assessed.
Baseline conditions for least-impacted wetlands need to be determined, or in areas
where few impacted sites exist, an assessment of background conditions is required.
Data from this study could be used to increase the overall data set that is available to EPA
to set numeric criteria using their 25% or 75% method adopted when using whole
population or least impacted wetlands, respectively.
Temporal Variability
Ecosystem influences are affected by temporal variability, and include the
chemical, physical, biotic, hydrologic, energy and habitat factors that combine to
determine the biogeochemical integrity of a wetland system. Spatial and temporal
variability in hydrology and soils in an isolated basin marsh in New Hampshire found
that vegetation fell into five wetland zones, and hydrologic variability resulted in
temporal and spatial variability of vegetative communities as greater plant diversity and
increased plant seedlings resulted from dry years (Owen Koning 2004). Studies of
temporal and spatial patterns of root nitrogen concentration and root decomposition have
shown that root nitrogen decreased through the growing season in live roots but increased
in dead roots. Live root nitrogen concentrations were found to be the highest in the most
mesic landscape positions while dead root nitrogen concentrations were highest in
Water depth was confirmed as the main predictor of species distribution, and
reduced trophic status was found to increase species richness in submerged macrophytes.
12
Mineralogical variations in sediment composition represented allogenic and autogenic
sediment sources, and their distribution corresponded with predicted species richness and
distribution (Schmieder 2004). Nutrient bioavailability in wetlands has been shown to be
largely independent of the acidity-alkalinity gradient, and the distribution of vascular
plants was influenced primarily by nutrient availability (Bragazza and Gerdol 2001).
Temporal variation of nitrogen and phosphorus uptake in two New Zealand streams
showed that range and variation of nutrient uptake in some streams can be quite large. It
was recommended that within-stream variation be considered in comparing other streams
and to help in the understanding of factors that drive nutrient uptake (Simon et al. 2004).
Although this specific research focused on stream flow, the implication of similar affects
within the wetland water column is reasonable, especially among riparian wetland
systems.
Nutrient concentrations of biomass have been shown to be more constant spatially
and temporally than indicators such as biomass production, due to variability among sites
and across years. Nutrient cycling processes in vegetation are established quickly
following wetland restoration. Therefore, nutrient characteristics of vegetation in
wetlands could be a useful metric in the evaluation of wetland restoration success
(Whigham et al. 2002).
While nutrient characteristics of vegetation could be indicative of wetland
condition, the seasonal availability of vegetation for sampling limits its value as a
universal metric for year-round monitoring. The temperate climate of the survey area of
this study precluded sampling of wetland plants due to their absence from late fall
through early spring.
13
Temporal variability reflected in the literature suggests the need for an indicator of
wetland status that is relatively independent of seasonal and hydrological changes. The
validity of a stratum to indicate differences between impacted and least-impacted sites is
important in establishing its potential value as an assessment tool for the evaluation and
monitoring of wetland condition.
Research Objectives
There were four principal objectives of this study:
Objective One
To gather information on wetlands located in Southwestern Indiana to assess the heterogeneity among wetland community types and secondarily to determine appropriate aggregation classes of wetland based on biogeochemical characteristics.
Objective Two
To determine which sampling strata: water, litter, soil, or vegetation, are most responsive to nutrient enrichment.
Objective Three
To contrast Southwestern Indiana least-impacted (reference) wetlands to Southeastern US Wetlands in Eco-region IX and to determine the validity of a single numeric criterion for this eco-region.
Objective Four
To investigate temporal variability of biogeochemical parameters within the water column, litter, soil and vegetation within one wetland over a one year period.
Hypothesis
In response to these objectives, several hypotheses were proposed.
(H1) There will be no difference in strata biogeochemistry among various wetland community types sampled in Indiana. It is suggested that the influence of hydrology would outweigh the characteristics and functions of wetland community types in the overall assimilation and cycling of nutrients.
14
(H2) Southwestern Indiana wetlands will have higher phosphorus and nitrogen concentrations than wetlands within the same eco-region in the Southeastern United States. These differences will occur among soil, water, litter and vegetation strata.
(H3) There will be differences in seasonal variability among water column, litter,
soil or vegetative biogeochemical parameters surveyed. The seasonal variability will be lower for the soil and higher for the water column parameters.
15
CHAPTER 3 METHODS
Sixteen wetland sites in Southwestern Indiana were surveyed and samples collected
between August 8 and September 27, 2003 to determine background concentrations of
nutrients Total Phosphorus and Total Nitrogen. Samples were analyzed for twenty
biogeochemical indicators in four different strata including plant, litter, soil and water
column nutrient parameters.
During the period from October 18, 2003 to July 5, 2004, eight additional monthly
surveys were conducted at the Turkey Hill Graywood Marsh to examine temporal
variability within a single wetland (Wetland ID Numbers IN15 and IN17 through IN23).
The same protocol used in the spatial sampling was followed for the temporal survey.
Both of these sampling methods are described in this chapter.
Sampling Site Selection
Wetland sampling sites were identified after review of topographical maps, aerial
photographs and wetland data from the United States Fish & Wildlife Service’ National
Wetlands Inventory Database and the Indiana Geological Survey’s GIS Atlas.
In addition, natural resource professionals from the U.S. Fish & Wildlife Service,
the Indiana Department of Natural Resources, and the Indiana Chapter of the Nature
Conservancy were consulted to help identify and procure permission to sample wetlands
surveyed. Both wetland community type and wetland condition were factors in site
selection (USEPA 2002d).
16
Identification of Minimally Impaired Wetland Sites
Impairment status of wetlands in the survey area was difficult to determine due to
the prevalence of agricultural, coal mining, and floodplain impacts present throughout the
geographic area. The wetlands selected were classified as either impacted or least-
impacted, based upon a 10% development criterion. Consistent with the approach of the
Southeastern Wetlands Study, if 10% or more of the landscape surrounding the wetland
were significantly altered, it was considered impacted. Of the sixteen wetlands, eleven
were identified as least-impacted, and five identified as impacted.
Identification of Wetland Community Types
Wetland sampling sites were classified by hydrologic and vegetative criteria. Sites
were first assessed using the United States Fish & Wildlife Service’(USFWS) National
Wetlands Inventory (NWI) Database, based on the USFWS Wetland and Deepwater
Habitat Classification System (Cowardin et al. 1979) and later verified during sampling.
Hydrologic Classification
For this study two hydrologic classifications for wetlands were recognized,
Riparian and Non-riparian. Riparian wetlands were identified as those located within 40
meters of a river or stream. Field classification of sites showed five Riparian and eleven
Non-Riparian wetlands were selected for the surveyed.
Vegetative Classification
Wetland sites were separated into two vegetative classes, Swamps and Marshes.
Designation between Swamps and Marshes were based on structure of dominant
vegetative species. If a woody canopy was present and intact, then the area was
designated a swamp. If there was no woody canopy or if the canopy consisted of less
17
than 10% cover, the area was designated a marsh. Using this criterion, four sites were
considered marshes and twelve sites considered swamps.
Combining the hydrologic and vegetative classification for each of the wetland
sites sampled three of the four possible community type classifications were represented
in the survey in both impacted and least impacted nutrient conditions (Table 2-1). Table
2-2 indicates the community type and impact status of wetlands surveyed in the
Southeastern United States that were used for comparative purposes in this research
(Greco 2004; Paris 2005).
Table 2-1. Number of wetlands surveyed in Southwestern Indiana from each wetland community type and nutrient condition.
Impacted Least-Impacted Riparian Swamp 3 2 Riparian Marsh 0 0 Non-Riparian Swamp 1 6 Non-Riparian Marsh 1 3 Table 2-2. Number of wetlands surveyed within each community type. Sites were all
located in the southeastern part of Eco-region IX. Eco-region IX Riparian Swamp 40 Riparian Marsh 4 Non-Riparian Swamp 14 Non-Riparian Marsh 3
Photographs of typical wetlands surveyed in the Southwestern Indiana study are
illustrated in Figure 2-1.
18
Figure 2-1 Photographs representing the three principal wetland community classifications surveyed in Southwestern Indiana, (A) Riparian Swamp, (B) Non-Riparian Swamp, and (C) Non-Riparian Marsh.
Sampling and Analytical Methods
Field sampling and laboratory methodology are described below, beginning with
Table 2-3, which provides a numerical listing, sampling date, characterization and
location coordinates for all wetlands surveyed.
Table 2-3. Southwestern Indiana wetland research location, sampling dates and characterization. All wetlands included in the survey are listed.
(A) Riparian Swamp
(B) Non-Riparian Swamp (C) Non-Riparian Marsh
19
Table 2-4 below provides a numerical listing, sampling dates, characterization and
location coordinates for the temporal portion of the survey that was conducted in the
Patoka River National Wildlife Refuge Turkey Hill Graywood Marsh.
Table 2-4. Southwestern Indiana wetland research location, sampling dates and characterization for Turkey Hill Graywood Marsh, wetland community type: Non-Riparian marsh with Least-Impacted wetland condition.
ID
Date Sampled
Wetland Community Type
Wetland Condition Location Coordinates
IN1 08/08/2003
Riparian Swamp Impacted
Millersburg- Wabash and Erie Canal/Pigeon Creek
N 38° 05.842' W 87° 23.653'
IN2 08/09/2003
Non-Riparian Swamp
Least-Impacted
IDNR* Lost Hill Wetland Conservation Area North
N 38° 11.220' W 87° 25.094'
IN3 08/09/2003
Non-Riparian Swamp
Least-Impacted
IDNR* Lost Hill Wetland Conservation Area South
N 38° 11.136' W 87° 25.114'
IN4 08/10/2003
Non-Riparian Swamp Impacted East Mount Carmel
N 38° 22.697' W 87° 43.780'
IN5 08/10/2003
Riparian Swamp Impacted
Elberfeld-Wabash and Erie Canal/Pigeon Creek
N 38° 09.692' W 87° 24.854'
IN6 08/16/2003
Riparian Swamp
Least-Impacted
Pike State Forest – Patoka River
N 38° 21.415' W 87° 08.973'
IN7 08/16/2003
Riparian Swamp Impacted Schlensker Ditch
N 38° 22.485' W 87° 16.722'
IN8 08/17/2003
Non-Riparian Marsh
Least-Impacted PRNWR* Buck's Marsh
N 38° 20.812' W 87° 19.395'
IN9 08/26/2003
Non-Riparian Swamp
Least-Impacted IDNR* Big Cypress Slough
N 37° 49.116' W 88° 00.273'
IN10 08/30/2003
Non-Riparian Marsh
Least-Impacted PRNWR* Snaky Point
N 38° 21.113' W 87° 19.161'
IN11 08/31/2003
Non-Riparian Marsh Impacted Snake Lake
N 38° 22.087' W 87° 19.551'
IN12 09/07/2003
Riparian Swamp
Least-Impacted
PRNWR* Hwy 57 @ Patoka River
N 38° 23.090' W 87° 19.888'
IN13 09/14/2003
Non-Riparian Swamp
Least-Impacted
PRNWR* Oxbow-Patoka River South Fork
N 38° 22.669' W 87° 21.405'
IN14 09/21/2003
Non-Riparian Swamp
Least-Impacted
PRNWR* North Meridian Oxbow
N 38° 23.325' W 87° 16.700'
IN15 09/21/2003
Non-Riparian Marsh
Least-Impacted
PRNWR* Turkey Hill Graywood Marsh
N 38° 22.476' W 87° 16.691'
IN16 09/27/2003
Non-Riparian Swamp
Least-Impacted
TNC* Goose Pond Cypress Slough
N 37° 54.316' W 87° 50.089'
*IDNR - Indiana Department of Natural Resources *PRNWR - Patoka River National Wildlife Refuge *TNC - The Nature Conservancy
20
Sample Locations
A targeted, stratified sampling approach was used to encompass spatial variation of
the wetlands’ inundation patterns. For all wetlands surveyed, a baseline transect was
established from the edge of the wetland toward the geographical center of the wetland.
Three zones were then identified along each transect for survey and sampling: the core
wetland (A), edge wetland (B) and the adjacent upland (U). Within each of these zones,
perpendicular transects, parallel to the upland/wetland boundary, were used to locate
three sub-sample sites for each zone. Smaller non-riparian wetlands were sampled with
an outer ring (B) transect and an inner ring (A) sites at the center of the wetland. Each
sub-sampling location was approximately 30 meters apart. (Figure 2-3).
ID Date Sampled Coordinates
IN15 09/27/2003
N 38° 22.476' W 87° 16.691'
IN17 10/18/2003
N 38° 22.482' W 87° 16.715'
IN18 11/29/2003
N 38° 22.481' W 87° 16.715'
IN19 12/30/2003
N 38° 22.481' W 87° 16.715'
IN20 02/29/2004
N 38° 22.481' W 87° 16.715'
IN21 04/30/2004
N 38° 22.480' W 87° 16.713'
IN22 06/01/2004
N 38° 22.477' W 87° 16.693'
IN23 07/05/2004
N 38° 22.485' W 87° 16.721'
21
Figure 2-2. Wetland sub-sample locations of (a) Riparian (b) small Non-Riparian and (c) large, Non-Riparian Systems. Wetland zones sampled included the Inner Core (A), Outer Edge (B) and Adjacent Upland (U).
A Wetland Characterization Form (Appendix D) was used to guide and document
the field survey and sampling tasks. Detailed land-use and descriptive assessments of the
wetland and adjacent upland were recorded. In addition, this form included
documentation of vegetative species characterization at each of the wetland sub-samples
wetland zones. Information compiled from the Wetland Characterization Forms can be
referenced in Appendix A.
A1
A2
A3
B1
B3
B2
Upland
Edge
Center
(a)
A B 1
Upland
River Center Edge
Ecotone(Not sampled) Upland
Center
b) Small Non-Riparian
c) Large Non-Riparian
A) Riparian
B 2
B 3
A 1
A 2
A 3
A 1
A 2
A 3B 3
B 2
B 1
Edge
A1
A2
A3
B1
B3
B2
Edge
Center
(a)
A B 1
River Center Edge
Ecotone(Not sampled) Upland
Center
a) Riparian
B 2
B 3
A 1
A 2
A 3
A 1
A 2
A 3B 3
B 2
B 1
Edge
22
Water Column Physical Parameters
When water was present at the sub-sample locations, field conditions were
analyzed using a Yellow Springs Instruments YSI-556 MPS portable meter, calibrated
prior to use and at the conclusion of the day’s sampling for the following parameters:
• Temperature
• pH
• Dissolved Oxygen
• Conductivity
• Oxidation-Reduction Potential
Water Sample Collection
Where present, water samples were collected at each sub-sample location. The
three sub samples within a zone were composited into a 125 ml, acid-washed, HDPE
bottle. Before sample collection, bottles were triple-rinsed with site water. Water
samples were stored on ice for transport, frozen, then shipped to the Wetland
Biogeochemistry Laboratory at the University of Florida. Upon receipt of the samples by
the laboratory, sub-samples of the water composites were filtered through 0.45µm filter
paper and analyzed for nitrate and nitrite with a Rapid Flow Analyzer (RFA). A 10 ml
non-filtered sub-sample was digested and analyzed for Total Kjeldal Nitrogen (TKN).
The nitrate-nitrite and the TKN results were summed to determine total nitrogen
concentrations. Total phosphorus was determined using colorimetric analysis on a
Technicon AA II after sulfuric acid and potassium persulfate digestion (EPA method
365.1-1993).
23
Soil
Soil samples were collected at the sub-sample locations of each transect. A clean
7.3 cm diameter tenite butyrate sampling tube attached to a sharp coring head was driven
into the soil a minimum depth of 10 cm. After corer insertion, a rubber stopper was
placed inside the sampling tube at the base of the soil sample. The sample was then
extruded by pushing the rubber stopper against a piston rod, forcing the soil sample out of
the top of the sampling tube into a 10 cm tenite butyrate collar.
Any leaf litter at the top surface of the core was carefully removed, and the upper
10 cm of soil was sliced with a stainless steel pocketknife, and placed in a zip lock bag.
The three sub-samples from each transect were combined, yielding composite samples of
the wetland core, wetland edge and the adjacent upland transects. Samples were stored
on ice for transport to the Wetland Biogeochemistry Laboratory at the University of
Florida.
Upon receipt by the laboratory, the wet weight of the composite sample was
recorded for bulk density calculation. A sub-sample of the homogenized composite was
placed in a 250 ml shallow dish, weighed, and dried at 70° C for 48 hours. The dried
sample weight was used to calculate the percent moisture in the sample.
Dried samples were ground with mortar and pestle, followed by mechanical
grinding using a ball mill for eight minutes. These samples were passed through a 1 mm
sieve and placed into scintillation vials. Organic Matter Content was determined by Loss
on Ignition (LOI), and Total Phosphorus (TP) was analyzed using the Ignition Method
(Anderson 1976). Total Nitrogen (TN) and Total Carbon (TC) were determined using a
Carlo Erba NA 1500 CNS Analyzer (Haak Buchler Instruments, Saddlebrook, NJ).
24
Leaf Litter
Leaf litter samples were also collected at the sub-sample locations of each transect.
A 40 cm diameter PVC ring was placed on the soil surface and all loose debris within the
ring was collected until reaching a layer of fine, well-decomposed particles. Due to the
varying sources of litter and decomposition rates, it was sometimes necessary to collect
additional litter samples at the sub-sample locations to ensure adequate sample for
analysis.
As with the water and soil samples, the three leaf litter sub-samples were combined
to yield a composite sample for each of the wetland core and wetland edge transects. The
samples were placed in a Ziploc bag, sealed and stored on ice for transport to the Wetland
Biogeochemistry Laboratory at the University of Florida.
Upon receipt by the laboratory, the litter samples were placed in a paper bag and
dried for 72 hours at 60°C. The dried samples were initially ground in a Wiley mill to
pass through a 1 mm sieve. Samples were then ground a second time to pass through a
40µm sieve. Total Phosphorus was determined by the Ignition Method (Anderson 1976).
Total Nitrogen (TN) and Total Carbon (TC) were analyzed using a Carlo Erba NA 1500
Vegetation was collected on a selected species basis, sampling only from mature
leaves not subject to herbivory or senescence. Vegetation was sampled by removing the
leaf at the point where the node was attached to the stem. Leaves from multiple plants of
the same species throughout the wetland were composited.
Vegetation samples were dried for seven days at 60°C, then ground to passing a 40
µm sieve prior to analysis. Total Carbon (TC) and Total Nitrogen (TN) analysis were
25
conducted on 0.5 – 2.0 mg vegetation samples using a Carlo Erba Model 1500 NA. Total
Phosphorus (TP) content was determined by the Ignition Method (Anderson 1976) using
a Technicon II Colorimetric Auto-Analyzer (EPA Method 365-1).
Data Analysis
All statements of statistical significance are based on a significance threshold of α
= 0.05. Paired comparisons used a standard “T” test for evaluation of significant
differences. For comparison among community types, ANOVA with the Tukey-Kramer
Honestly Significant Difference (HSD) multiple comparison test was used. Most
variables required log transformation prior to statistical analysis. JMP version 4.04
statistical software and Microsoft Excel version 2003 were used in statistical analysis and
data summaries.
26
CHAPTER 3 RESULTS
Samples collected during the field surveys were analyzed for twenty
biogeochemical parameters among four different strata: plant, litter, soil, and the water
column. Because of their relative impact on wetland and water quality, the analysis of
the nutrient parameters total phosphorus and total nitrogen was the primary focus of this
report. The analytical results of all parameters are provided for informational purposes in
the interest of future study.
In Tables 3-1 through 3-8, general descriptive statistics and paired comparison t-
tests using p-values (α=0.05) calculated by the Tukey-Kramer Honestly Significant
Difference (HSD) test are presented for all wetland strata parameters, as aggregated by
the following classification criteria:
1. All Wetlands (Combined) 2. Hydrologic Connectivity (Riparian and Non-Riparian) 3. Vegetative Character (Swamp or Marsh) 4. Community Type (Riparian Swamp, Riparian Marsh, Non-Riparian
Swamp, Non-Riparian Marsh) 5. Wetland Condition (Least-Impacted and Impacted)
Table 3-9 summarizes the statistical data comparing all strata nutrient indicators
between least-impacted and impacted wetlands that were surveyed. Figures 3-1 through
3-8 provide a graphical representation with box plots showing the 10th, 25th, median, 75th
and 90th percentiles comparing nutrient indicators from sampling conducted in
Southwestern Indiana relative to the collaborative survey results in the Southeastern
United States.
27
Spatial Study Results
Water
Where present in the wetland, water samples were collected to determine nutrient
concentrations in the water column. Surveyed wetlands showed little difference in total
phosphorus when aggregated by hydrologic class, but Swamps had almost 75% higher
water column phosphorus concentration than Marshes (Table 3-1). Non-Riparian
Swamps had the highest total phosphorus concentration and Non-Riparian marshes the
lowest of wetland community type. Total Nitrogen concentration did not appear to vary
significantly regardless of class aggregation.
Table 3-1. General descriptive statistics summary of water column total phosphorus and total nitrogen concentrations for wetlands surveyed in Indiana. Wetlands were aggregated using several different classification criteria.
Pair-wise comparison of total phosphorus and total nitrogen in the water column
showed no significant differences when aggregated by hydrologic class, vegetative class,
community type, or wetland condition (Table 3-2). ANOVA of the three community
28
types surveyed showed no significant differences among the aggregation for total
phosphorus or total nitrogen.
Table 3-2. Statistical comparison of water column total phosphorus and total nitrogen concentrations for wetlands surveyed in Indiana, aggregated using several different classification criteria. A standard T-test for significant difference was used in paired comparisons, with probability ‘P’values (α=0.05) presented with bold font indicating values of significant difference. For comparison among community types, ANOVA was used (Tukey-Kramer HSD). Lower case letters denote statistically similar values.
Wetlands Classification Total Phosphorus Total Nitrogen Hydrologic Riparian vs. Non-Riparian 0.871 0.839 Vegetative Swamp vs. Marsh 0.104 0.633 Community Type 0.216 0.840 Riparian Swamp a A Non-Riparian Swamp a A Non-Riparian Marsh a A Condition Impacted vs. Least-Impacted 0.350 0.378 Leaf Litter
Leaf litter was collected at all sub-sample locations along the survey transects to
determine nutrient concentrations in this stratum. Total phosphorus concentrations
showed little difference as aggregated by hydrologic class or wetland condition, but
similar to water column results, Swamps had 70% higher phosphorus concentration in the
litter than Marshes (Table 3-3). Non-Riparian Swamps had the highest concentration of
total phosphorus, and Non-Riparian Marshes, the lowest of wetland community type.
Surveyed wetlands showed little difference in total nitrogen concentration as
aggregated by hydrologic class, but Non-Riparian Marshes had approximately 40%
higher nitrogen concentration than Swamps. Total nitrogen concentrations in Least-
Impacted wetlands were 35% higher than Impacted Wetlands.
29
There was little difference noted in total carbon concentration from litter samples as
aggregated by hydrologic and vegetative classes, or community type. Least-Impacted
sites showed nearly 30% higher total carbon concentrations than Impacted wetlands.
Table 3-3. General descriptive statistics summary of leaf litter total phosphorus, total nitrogen and total carbon concentrations for wetlands surveyed in Indiana. Wetlands were aggregated using several different classification criteria.
Total Phosphorus Total Nitrogen Mean + 1SD Median n Mean + 1SD Median n Wetlands Classification mg/kg g/kg All Wetlands 2661 + 763.8 2851 17 14.4 + 5.25 13.4 24Hydrologic Riparian 2875 + 831.7 2825 8 12.8 + 4.4 12.7 7 Non-Riparian 2471 + 689.2 2851 9 15.1 + 5.54 13.6 17Vegetative Swamp 2870 + 660.0 2936 14 13.1 + 3.40 13.1 18 Marsh 1685 + 318.4 1712 3 18.5 + 7.79 16.4 6 Community Type Riparian Swamp 2875 + 831.7 2825 8 12.8 + 4.42 12.7 7 Non-Riparian Swamp 2863 + 405.1 2945 6 13.3 + 2.83 13.6 11 Non-Riparian Marsh 1685 + 318.4 1712 3 18.5 + 7.79 16.4 6 Condition Least-Impacted 2464 + 706.1 2715 9 15.6 + 5.55 14.3 17 Impacted 2882 + 810.9 2951 8 11.6 + 3.25 11.8 7 Total Carbon Mean + 1SD Median n Wetlands Classification g/kg All Wetlands 295 + 85.06 318 24 Hydrologic Total Carbon Mean + 1SD Median n Wetlands Classification g/kg Riparian 262 + 86.1 277 7 Non-Riparian 308.5 + 83.4 329. 17 Vegetative Swamp 293.3 + 91.8 310 18 Marsh 300 + 67.9 331 6 Community Type Riparian Swamp 262.2 + 86.1 277 7 Non-Riparian Swamp 313.1 + 93.6 317 11 Non-Riparian Marsh 300.1+ 67.9 331 6
Paired comparisons of total phosphorus and total nitrogen in litter samples showed
no significant differences when aggregated by hydrologic class or wetland condition
(Table 3-4). Significant differences were noted in total phosphorus when aggregated by
vegetative class and community type, and in total nitrogen when wetlands were
aggregated by vegetative class. ANOVA of the three community types surveyed showed
significant differences in total phosphorus concentration between Non-Riparian Marshes
and both Non-Riparian Swamps and Riparian Swamps. Significant differences were also
noted for total carbon concentration between Riparian Swamps and both Non-Riparian
Swamps and Non-Riparian Marshes.
Table 3-4. Statistical comparison summary of leaf litter total phosphorus, total nitrogen and total carbon concentrations for wetlands surveyed in Indiana, aggregated using several different classification criteria. A standard T-test for significant difference was used in paired comparisons, with probability ‘P’values (α=0.05) presented with bold font indicating values of significant difference. For comparison among community types, ANOVA was used (Tukey-Kramer HSD). Lower case letters denote statistically similar values.
Wetlands Classification Total Phosphorus Total Nitrogen Total Carbon
Hydrologic Riparian vs. Non- Riparian 0.2904 0.3358 0.2334 Vegetative Swamp vs. Marsh 0.009 0.024 0.8701 Community Type 0.039 0.082 0.4782 Riparian Swamp a a B Non- Riparian Swamp a a A Non- Riparian Marsh b a A Condition Impacted vs. Least-Impacted 0.273 0.095 0.0578
31
Soil
Soil samples were collected at each sub-sample location of the wetland survey
transects to determine nutrient concentrations in this stratum. Soil pH mean values
generally ranged from 5.5 to 6.1 (Table 3-5). When aggregated by vegetative class,
Marshes were 0.5 pH units higher than Swamps. Similarly, Impacted wetlands were 0.5
pH units higher than Least-Impacted sites.
When aggregated by hydrologic class, organic matter content in Non-Riparian
wetlands was 75% higher than Riparian wetlands. Vegetative class aggregation found
Marshes contained 50% more organic matter than Swamps. Among community types,
Non-Riparian Marshes contained twice as much organic matter as Riparian Swamps.
Least-Impacted wetlands were 30% higher in organic matter content than Impacted sites.
Total Phosphorus concentration in surveyed wetlands showed little difference
among the various aggregations with the exception of wetland condition, where Impacted
wetlands contained 40% more total phosphorus than Least-Impacted sites.
Total nitrogen as aggregated by hydrologic class showed concentrations 88%
higher in Non-Riparian compared to Riparian wetlands. Little difference was noted when
aggregated by vegetative class. Consistent with results from the hydrologic class
aggregation, Non-Riparian Swamp and Marsh community types were over 90% higher in
total nitrogen than Riparian Swamps. Least-Impacted wetlands were over 50% in total
nitrogen than Impacted sites.
Total carbon concentrations were significantly different when aggregated by
hydrologic, vegetative, and community type classifications. Non-Riparian wetlands
contained twice as much total carbon as Riparian wetlands. Marshes contained 70%
more total carbon than Swamps, and Non-Riparian Marshes well over twice as much total
32
carbon as Riparian Swamps. While Least-Impacted wetlands showed higher total carbon
than Impacted sites, the difference was not significant.
Table 3-5. General descriptive statistics summary of soil pH, organic matter, total phosphorus, total nitrogen and total carbon concentrations for wetlands surveyed in Indiana. Wetlands were aggregated using several different classification criteria.
Paired comparisons of soil pH values showed no significant differences when
aggregated by hydrologic class, vegetative class, community type, or wetland condition
(Table 3-6). ANOVA of the three community types surveyed also showed no significant
differences in soil pH. Significant differences in organic matter content were shown for
aggregations by hydrologic class, vegetative class and community type, but not for
wetland condition. ANOVA of the three community types surveyed showed significant
differences in organic matter between Riparian Swamps and both Non-Riparian Swamps
and Marshes. There were no significant differences in total phosphorus noted by pair-
wise comparison of hydrologic class, vegetative class, or community type aggregations.
However, significant differences in total phosphorus were noted between Impacted and
Least-Impacted wetlands. ANOVA of the three community types surveyed showed no
significant differences in total phosphorus concentration.
34
Paired comparisons by both hydrologic class and community type showed
significant differences in total nitrogen between Riparian and Non-Riparian wetlands. As
aggregated by vegetative class and wetland condition, there were no significant
differences between Swamps and Marshes, or Impacted and Least-Impacted sites,
respectively. ANOVA of the three community types surveyed showed significant
differences in total nitrogen between Riparian Swamps and both Non-Riparian Swamps
and Marshes. Significant differences in total carbon content were shown for aggregations
by hydrologic class, vegetative class and community type, but not for wetland condition.
ANOVA of the three community types surveyed showed significant differences in total
carbon between Riparian Swamps and both Non-Riparian Swamps and Marshes.
Table 3-6. Statistical comparison summary of soil pH, organic matter, total phosphorus, total nitrogen and total carbon concentrations for wetlands surveyed in Indiana, aggregated using several different classification criteria. A standard T-test for significant difference was used in paired comparisons, with probability ‘P’values (α=0.05) presented with bold font indicating values of significant difference. For comparison among community types, ANOVA was used (Tukey-Kramer HSD). Lower case letters denote statistically similar values.
Wetlands Classification pH Organic Matter
Total Phosphorus
Total Nitrogen
Total Carbon
Hydrologic Riparian vs. Non- Riparian 0.756 0.001 0.166 0.003 0.003 Vegetative Swamp vs. Marsh 0.095 0.005 0.394 0.177 0.011 Community Type 0.234 0.001 0.101 0.011 0.002 Riparian Swamp a a a a a Non- Riparian Swamp a b a b b Non- Riparian Marsh a b a b b Condition Impacted vs. Least-Impacted 0.139 0.118 0.001 0.060 0.157 Vegetation
Vegetation samples were collected in the wetland survey areas to determine
nutrient concentrations in the common vegetation. No significant differences were noted
35
when aggregated by hydrologic class, community type, or wetland condition (Table 3-7).
Vegetative aggregation of the surveyed wetlands, however, indicated tissue total
phosphorus concentrations in Marshes were over 50% higher than Swamps.
Tissue total nitrogen concentration showed no significant differences when
wetlands were aggregated by hydrologic class, community type, or wetland condition.
Aggregation of the wetlands by vegetative class showed tissue total nitrogen
concentrations in Marshes were over 40% higher than Swamps.
Comparison of tissue total carbon showed no significant differences when
aggregated by hydrologic class, vegetative class, community type, or wetland condition.
Table 3-7. General descriptive statistics summary of vegetation total phosphorus, total nitrogen and total carbon concentrations for wetlands surveyed in Indiana. Wetlands were aggregated using several different classification criteria.
Table 3-7. Continued Tissue Total Carbon Mean + 1SD Median n Wetlands Classification % Vegetative Swamp 44.54 + 3.24 45.97 11 Marsh 46.2 + 2.53 47.37 10 Community Type Riparian Swamp 45.48 + 2.08 46.35 4 Non-Riparian Swamp 44.01 + 3.79 43.89 7 Non-Riparian Marsh 46.20 +2.53 47.37 10 Condition Least-Impacted 45.50 +3.37 47.37 15 Impacted 44.92 + 1.83 44.93 6
Pair-wise comparison of tissue total phosphorus showed no significant differences
when aggregated by hydrologic class, community type, or wetland condition (Table 3-8).
Significant differences were noted when aggregated by vegetative class. Tissue total
nitrogen concentrations aggregated by hydrologic class, community type, or wetland
condition showed no significant differences, while significant differences were noted in
vegetative class. Paired comparisons of wetland aggregations by hydrologic class,
vegetative class, community type, or wetland condition showed no significant differences
in total carbon concentration. ANOVA of the three community types surveyed showed
no significant differences among the aggregation for total phosphorus, total nitrogen, or
total carbon.
Table 3-8. Statistical comparison summary of vegetation tissue total phosphorus, total nitrogen and total carbon concentrations for wetlands surveyed in Indiana, aggregated using several different classification criteria. A standard T-test for significant difference was used in paired comparisons, with probability ‘P’values (α=0.05) presented with bold font indicating values of significant difference. For comparison among community types, ANOVA was used (Tukey-Kramer HSD). Lower case letters denote statistically similar values.
Wetlands Classification Tissue Total Phosphorus
Tissue Total Nitrogen
Tissue Total Carbon
Hydrologic Riparian vs. Non- Riparian 0.3568 0.3327 0.9194
37
Table 3-8. Continued Wetlands Classification Tissue Total
Phosphorus Tissue Total Nitrogen
Tissue Total Carbon
Vegetative Swamp vs. Marsh 0.038 0.025 0.2098 Community Type 0.119 0.087 0.3426 Riparian Swamp a a A Non- Riparian Swamp a a A Non- Riparian Marsh a a A Condition Impacted vs. Least-Impacted 0.569 0.301 0.6995 Summarized Nutrient Indicator Strata
Table 3-9 below summarizes the statistical data comparing all strata nutrient
indicators between least-impacted and impacted wetlands surveyed. Soil was the only
stratum that demonstrated significant differences between Impacted and Least-Impacted
wetlands was soil. Total phosphorus concentrations were higher in Impacted wetlands
and total nitrogen was higher in Least-Impacted wetlands.
Table 3-9. Summary table of nutrient indicator strata. Paired comparison standard T-tests with probability ‘P’values (α=0.05) in bold font denoting values of significant difference in nutrient indicator strata concentrations between Least-Impacted and Impacted wetlands surveyed in Southwestern Indiana.
Nutrient Indicator Strata
Nutrient Wetland Nutrient Condition
P-Values Wetland Nutrient Condition
Least Impacted Impacted Water P, mg/l 0.32 + 0.17 0.350 0.22 + 0.17 N, mg/l 2.89 + 1.63 0.378 2.11 + 1.24 Litter P mg/kg 2460 + 710 0.273 2880 + 810 N g/kg 15.6 + 5.55 0.095 11.6 + 3.3 Soil P mg/kg 600 + 120 0.001 860 + 210 N g/kg 4.2 + 1.6 0.060 2.7 + 0.7 Vegetation P % 0.23 + 0.16 0.569 0.19 + 0.09 N % 2.70 + 1.11 0.301 2.20 + 0.43
38
Comparison of SW Indiana Wetlands and SE US Wetlands in Eco-region IX
Figures 3-1 through 3-8 below illustrate the comparison of nutrient indicators in the
water column, litter, soil, and vegetative tissue from sampling conducted in the
Southwestern Indiana Wetland Biogeochemical Survey and the collaborative Eco-region
IX studies of the Southeastern United States: Southeastern Wetland Biogeochemical
Survey: Determination and Establishment of Numeric Nutrient Criteria (Paris 2005) and
A Biogeochemical Survey of Wetlands in the Southeastern United States (Greco 2004).
Box plots showing the 10th, 25th, median, 75th and 90th percentiles comparing nutrient
indicators from sampling conducted in Southwestern Indiana relative to the collaborative
survey results in the Southeastern United States are presented below. All data are
samples collected from Least-Impacted wetlands.
Water Column
Water column total phosphorus concentrations from surveyed wetlands in Indiana
were significantly different from wetlands surveyed in the other states of Eco-Region IX
(Figure 3-1).
39
Figure 3-1. Water Column Total Phosphorus Comparison between Least-Impacted
Wetlands Surveyed in Southwestern Indiana and Eco-Region IX Least-Impacted Wetlands.
Water column total nitrogen concentrations from wetlands surveyed in Indiana
were not significantly different from those wetlands surveyed in other states in Eco-
Region IX (Figure 3-2).
Tota
l Pho
spho
rus,
mg/
l
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Indiana Alabama Florida Georgia
State
b
a
a
a
40
Figure 3-2. Water Column Total Nitrogen Comparison between Least-Impacted Wetlands Surveyed in Southwestern Indiana and Eco-Region IX Least-Impacted Wetlands.
Litter
Litter total phosphorus concentrations from the Indiana wetland samples were
significantly different from wetlands surveyed in Florida and Georgia (Figure 3-3).
Wetlands in Alabama and South Carolina had similar total phosphorus concentrations to
the Indiana wetlands.
Tota
l Nitr
ogen
, mg/
l
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Indiana Alabama Florida Georgia
State
a
a
a a
41
Figure 3-3. Litter Total Phosphorus Comparison between Least-Impacted Wetlands
Surveyed in Southwestern Indiana and Eco-Region IX Least-Impacted Wetlands.
Litter total nitrogen concentrations from the Indiana wetland samples were similar
to Eco-Region IX wetlands in Alabama, South Carolina, and Georgia, but significantly
different from those in Florida (Figure 3-4).
Tota
l Pho
spho
rus
%
0
1
2
3
4
5
6
Indiana Alabama Florida Georgia South Carolina
State
a
ab
bc
c
c
42
Figure 3-4. Litter Total Nitrogen Comparison between Least-Impacted Wetlands
Surveyed in Southwestern Indiana and Eco-Region IX Least-Impacted Wetlands.
Vegetation
Vegetation tissue total phosphorus concentrations in wetlands surveyed in Indiana
were similar to Eco-Region IX wetlands in Alabama, Georgia and South Carolina, but
were significantly different from wetlands surveyed in Florida (Figure 3-5).
Nitr
ogen
, %
0
0.5
1
1.5
2
2.5
3
Indiana Alabama Florida Georgia South Carolina
State
a
b bb
ab
43
Figure 3-5. Vegetation Tissue Total Phosphorus Comparison between Least-Impacted
Wetlands Surveyed in Southwestern Indiana and Eco-Region IX Least-Impacted Wetlands.
Vegetation tissue total nitrogen concentrations from Indiana wetlands surveyed
were similar to those in Eco-Region IX wetlands in Alabama, Georgia, and South
Carolina, but significantly different from surveyed wetlands in Florida (Figure 3-6).
Pho
spho
rus,
%
0
0.1
0.2
0.3
0.4
0.5
Indiana Alabama Florida Georgia South Carolina
State
a
b b ab
ab
44
Figure 3-6. Vegetation Tissue Total Nitrogen Comparison between Least-Impacted
Wetlands Surveyed in Southwestern Indiana and Eco-Region IX Least-Impacted Wetlands.
Soil
Soil total phosphorus concentrations from surveyed wetlands in Indiana were
significantly different among all wetlands in the other Eco-Region IX states surveyed
(Figure 3-7).
Nitr
ogen
, %
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Indiana Alabama Florida Georgia South Carolina
State
a
abab
b b
45
Figure 3-7. Soil Total Phosphorus Comparison between Least-Impacted Wetlands
Surveyed in Southwestern Indiana and Eco-Region IX Least-Impacted Wetlands.
Soil total nitrogen concentrations from the wetlands surveyed in Indiana were not
significantly different from the wetlands surveyed in other states of Eco-Region IX
(Figure 3-8).
Soil
TP %
0
0.1
Indiana Alabama Florida Georgia South Carolina
State
a
a
b
c
b
46
Figure 3-8. Soil Total Nitrogen Comparison between Least-Impacted Wetlands Surveyed
in Southwestern Indiana and Eco-Region IX Least-Impacted Wetlands.
Temporal Study Results
The sampling results of the temporal study conducted in the Turkey Hill Graywood
Marsh are presented below by strata (water column, litter and soil), with XY plots of the
analytical data plotted along a temporal gradient for the sampling period September 31,
2003 to July 5, 2004. Tables summarizing the Mean, Standard Deviation, Variance and
Confidence Level of the parameters for all strata are presented at the end of each section.
Water
Water Column field parameters: pH, Dissolved Oxygen, and Depth, and nutrient
concentrations for Total Phosphorus and Total Nitrogen are presented below in Figures 3-
9 through 3-13, to illustrate the seasonal variability observed during the temporal survey.
Soil
TN
0
0.5
1
1.5
2
2.5
Indiana Alabama Florida Georgia South Carolina
State
a b
ababab
47
Water depth recorded in the wetland zones A and B illustrates the seasonal
Figure 3-9. Water Column Depth in Inches. Wetland zones sampled included the Inner Core (A) and Outer Edge (B). Mean and Standard Deviation of both zones are presented.
Water column field pH measurements (Figure 3-10) generally showed little
difference between the Inner Core (A) and Outer Edge (B) zones of the wetland, probably
due to the relative homogeneity of the water column. Those readings where differences
were noted may be due to very shallow sampling areas in the Outer Edge zone which
could have higher temperatures and magnified affects from the soil/water column
Figure 3-10. Water Column Field pH. Wetland zones sampled included the Inner Core (A) and Outer Edge (B). Mean and Standard Deviation of both zones are presented.
Water column dissolved oxygen concentrations over the temporal gradient show a
general increase through the fall and spring (Figure 3-11). This could be partially due to
decreasing seasonal temperature and increased emergent and floating vegetation (Lemna)
Figure 3-11. Water Column Dissolved Oxygen, %. Wetland zones sampled included the Inner Core (A) and Outer Edge (B). Mean and Standard Deviation of both zones are presented.
Water column total phosphorus concentration shown in Figure 3-12 reflects
variability of the seasonal hydroperiod. Outer Edge (B) total phosphorus concentrations
were well above the corresponding Inner Core (A) samples collected during the peak of
Figure 3-13. Water Column Total Nitrogen, mg/L. Wetland zones sampled included the
Inner Core (A) and Outer Edge (B).
Table 3-10 below lists the summary statistics of Water Column sample analysis for
Total Phosphorus and Total Nitrogen samples from the inner core (A) and outer edge (B)
of the wetland locations. The mean, standard deviation, variance, and 95% confidence
interval are presented. Water Column total phosphorus concentration was over 60 %
higher in the Outer Edge (B) samples. Total nitrogen concentrations in the Outer Edge
(B) were 20% higher than the Inner Core (A) wetland zone samples.
Table 3-10. Summary statistics (mean, standard deviation, variance and 95% confidence interval) of water column samples collected during the temporal study. Wetland zones sampled included the Inner Core (A) and Outer Edge (B).
. Water Column TP (mg/l) A
Water Column TN (mg/l) A
Mean 0.27 2.20 Standard Deviation 0.10 0.39 Sample Variance 0.01 0.16 Confidence Interval (95.0%) +0.119 +0.41
51
Table 3-10. Continued
Water Column TP (mg/l) B
Water Column TN (mg/l) B
Mean 0.44 2.71 Standard Deviation 0.28 0.71 Sample Variance 0.08 0.50 Confidence Interval (95.0%) +0.29 +0.74
As noted earlier, watershed hydrology exerts the most significant effect on the
availability, distribution and cycling of nutrients in the wetland landscape. In spite of this
influence as a regulator, because of seasonal flooding, drought, variable watershed inputs,
and its general, transient nature, water monitoring would not likely serve as a reliable,
more permanent indicator of wetland condition throughout the year.
Vegetation
The temperate climate of the survey area of this study precluded sampling of
wetland plants due to their absence from late fall through early spring.
Litter
Nutrient conservation in vegetation affects litter decomposition rates and soil
nutrient availability (Diehl et al. 2002). If C: N ratios in vegetative tissue are higher than
optimal, and water column nitrogen is available, litter can also integrate nitrogen from the
water column. Nutrient removal efficiency studied over a one year period in a
wastewater treatment wetland indicated that water temperature was a principle regulator
to this process (Anderson et al. 2003).
The following Figures 3-14, 3-15 and 3-16, illustrate the trends of total phosphorus,
total nitrogen, and total carbon from litter samples collected at both the inner core and
outer edge of the wetland over the temporal study period.
52
Litter total phosphorus concentrations from the Inner Core (A) samples were
consistently higher than those collected from the Outer Edge (B) of the wetland
throughout the temporal period (Figure 3-14). Concentrations from both zones (A) and
(B) were constant and showed little variation throughout the sampling period.
0
1000
2000
3000
4000
5000
6000
7000
8000
Jun-03 Oct-03 Jan-04 Apr-04 Aug-04
Litte
r TP,
%
AB
Figure 3-14. Litter Total Phosphorus, mg/kg. Wetland zones sampled included the Inner
Core (A) and Outer Edge (B).
Litter total nitrogen concentrations from samples collected in the Inner Core (A)
were consistently higher than Outer Edge (B) zone samples (Figure 3-15). The seasonal
variability of total nitrogen in litter appears to be greater as compared to total phosphorus
Figure 3-16. Litter Total Carbon, g/kg. Wetland zones sampled included the Inner Core
(A) and Outer Edge (B).
The summary statistics for litter nutrient indicators from samples collected in
wetland zones A and B during the temporal study are presented in Table 3-11. The mean,
standard deviation, variance, and 95% confidence interval for litter total phosphorus, total
nitrogen and total carbon are shown. The lowest variance occurred in litter total
phosphorus in the Inner Core (A) samples, followed by total phosphorus in the Outer
Edge (B) wetland samples over the time period of sampling. Total nitrogen also
exhibited little variability during the temporal period.
Table 3-11. Summary statistics (mean, standard deviation, variance and 95% confidence interval) of litter samples collected during the temporal study. Wetland zones sampled included the Inner Core (A) and Outer Edge (B).
Inner Core of Wetland (A) Litter TP (mg/kg) A
Litter N (g/kg) A
Litter C (g/kg) A
Mean 180 20.6 306 Standard Deviation 8 3.6 23.3 Sample Variance 0.0672 1.3 54.3 Confidence Interval (95.0%) +8 +3.8 +24.5
54
Table 3-11. Continued
Outer Edge of Wetland (B) Litter TP (mg/kg) B
Litter N (g/kg) B
Litter C (g/kg) B
Mean 230 19.6 296 Standard Error 87 1.2 10.1 Standard Deviation 230 3.2 26.6 Sample Variance 53 1.0 70.9 Confidence Interval (95.0%) +21 +2.9 +24.6 Soil
The soil, being the most permanent of the strata measured in this study,
would be expected to provide consistency for evaluation of wetland condition
throughout the year. It is reasonable that longer-term response to anthropogenic
inputs to the wetland would be indicated in the soil. The following figures
illustrate the trends of those parameters measured: Bulk Density, Loss on Ignition,
Total Phosphorus, Total Nitrogen, Total Carbon and pH. The inner core (A),
outer edge (B), and adjacent upland (c) of the wetland locations were surveyed
and sampled.
Soil bulk density values between the Inner Core (A) and Outer Edge (B)
wetland zones reversed from the fall, when Zone A showed higher bulk density
than Zone B (Figure 3-17). In late spring and summer, bulk density in Zone B
was higher than Zone A.
0
0.2
0.4
0.6
0.8
1
Jun-03 Oct-03 Jan-04 Apr-04 Aug-04
Soil
Bul
k D
ensi
ty, g
cm
-3
AB
Figure 3-17. Soil Bulk Density, grams cm-3. Wetland zones sampled included the Inner
Core (A) and Outer Edge (B).
55
A reversal in the loss on ignition (LOI) parameter was also noted between the Inner
Core (A) and the Outer Edge (B) wetland zones sampled (Figure 3-18). In the fall, Zone
B showed high LOI values than Zone A, while in late spring and early summer, Zone A
had higher LOI than Zone B.
0
20
40
60
80
Jun-03 Oct-03 Jan-04 Apr-04 Aug-04
Soil
Loss
on
Igni
tion,
%
A
B
Figure 3-18. Soil Loss on Ignition, %. Wetland zones sampled included the Inner Core
(A) and Outer Edge (B).
Soil total phosphorus concentrations in the Inner Core (A) of the wetland were
higher than the Outer Edge (B) in the fall, late spring, and summer (Figure 3-19). During
the winter, however, samples from the Outer Edge (B) had higher concentrations of total
phosphorus in the soil.
0200400600800
10001200
Jun-03 Oct-03 Jan-04 Apr-04 Aug-04
Soil
TP, m
g/kg
A
B
Figure 3-19. Soil Total Phosphorus, mg/kg. Wetland zones sampled included the Inner
Core (A) and Outer Edge (B).
The soil total nitrogen temporal results between the Inner Core (A) and Outer Edge
(B) of the wetland were similar to those for total phosphorus (Figure 3-20). Total
56
nitrogen in the soil during fall, late spring, and summer were higher in Zone A than Zone
B. In the winter, Zone B showed higher total nitrogen values than Zone A.
0
2
4
68
10
12
14
Jun-03 Oct-03 Jan-04 Apr-04 Aug-04
Soil
TN, g
/kg
A
B
Figure 3-20. Soil Total Nitrogen, g/kg. Wetland zones sampled included the Inner Core
(A) and Outer Edge (B).
Soil total carbon concentration from the Inner Core (A) and the Outer Edge (B) appeared
to follow the same seasonal pattern as both total phosphorus and total nitrogen (Figure 3-
21). Total carbon concentrations were higher in Zone B than in Zone A during the winter
and higher in Zone A than in Zone B in the summer.
0
100
200
300
400
500
Jun-03 Oct-03 Jan-04 Apr-04 Aug-04
Soil
TC, g
/kg
A
B
Figure 3-21. Soil Total Carbon, g/kg. Wetland zones sampled included the Inner Core (A) and Outer Edge (B).
Seasonal trends in soil pH (Figure 3-22) were similar to the water column pH trend
(Figure 3-9), with fall and winter, pH values higher in the Inner Core (A) than the Outer
57
Edge (B) wetland zones. In the spring and summer, pH values were higher in Zone B
than Zone A.
33.5
44.5
55.5
66.5
77.5
Jun-03 Oct-03 Jan-04 Apr-04 Aug-04
Soil
pH AB
Figure 3-22. Soil pH. Wetland zones sampled included the Inner Core (A) and Outer
Edge (B).
A summary of the following statistics: mean, standard deviation, variance and
confidence level, was compiled from the soil sample analyses to provide an overall
comparison of the data. The results are shown in Table 3-12 below.
Table 3-12. Summary statistics (mean, standard deviation, variance and confidence interval) of soil sampled during the temporal study. Wetland zones sampled included the Inner Core (A) and Outer Edge (B).
The first objective was to gather information on wetlands located in Southwestern
Indiana to assess the heterogeneity among wetland community types to determine an
appropriate aggregation of wetland communities for numeric nutrient criteria
development (and monitoring) purposes. It was hypothesized that there would be no
difference in strata biogeochemistry among various wetland community types sampled in
Indiana. It was suggested that the influence of hydrology would outweigh the
characteristics and functions of wetland community types in the overall assimilation and
cycling of nutrients.
Based on the results for water column nutrients, there were no significant
differences noted between Total Phosphorus concentrations or Total Nitrogen
concentrations among the wetlands community classifications. Therefore, separation by
community type does not appear to be required for assessment within this region. It is
important to note that the sample size for certain community types was smaller, which
can contribute to increased Type II error rate in these conclusions. Where it is stated that
there are no significant differences in community parameters, there could be differences
that are not detectable due to small sample size.
Similar results were noted for vegetative nutrient indicators, finding no significant
differences in the vegetative tissue concentrations of Total Phosphorus, Total Nitrogen,
59
or Total Carbon. Separation by wetland community type for vegetative indicators does
not appear to be required for assessment.
Leaf litter nutrient content showed significant differences in leaf litter Total
Phosphorus concentrations between riparian and non-riparian wetlands. Seasonal
flooding and scouring effects of riparian systems would be expected to influence the
amount, types; transport and location of litter present in the wetland, and may account for
some differences in Total Phosphorus concentrations.
When aggregated by hydrologic class, organic matter content in Non-Riparian
wetland soils were 75% higher than Riparian wetlands. Vegetative class aggregation
found Marshes contained 50% more organic matter in the soil than Swamps. In addition,
Non-Riparian wetland soils contained twice as much total carbon as Riparian wetlands.
Marsh soils contained 70% more total carbon than Swamps, and Non-Riparian Marsh
concentrations of total carbon were twice as much as Riparian Swamps. This would
support the point that hydrologic influences in the riparian systems could increase
mineral soil fractions while reducing organic matter in the wetlands. Results from a
study of sediment and nutrient accumulation in floodplain and depressional wetlands
showed that phosphorus accumulation was 1.5 to 3 times higher in the floodplain
wetlands than in depressional wetlands (Craft and Casey 2000).
Considering the use of litter Total Phosphorus as an indicator of nutrient status, an
aggregation of community type should be considered between riparian and non-riparian
wetlands. Based on soil nutrient condition, results indicate significant differences in
Total Nitrogen concentrations between riparian and non-riparian wetlands. Separation by
hydrologic connectivity appears to be required for assessment of soil nutrient indicators.
60
Objective Two (Results)
The second objective was to determine which sampling strata: water, litter, soil or
vegetation is most responsive to nutrient enrichment.
Findings suggest that Total Phosphorus concentrations measured in the water
column, litter, and vegetation were not able to distinguish between impacted and least-
impacted wetlands. However, soil Total Phosphorus concentrations were able to
distinguish between impacted and least-impacted wetlands. A related study of Eco-
region IX wetlands also showed significant differences between total phosphorus
concentrations in least-impacted and impacted wetlands (Paris 2004).
In a study of sediment and nutrient accumulation in floodplain and depressional
wetlands, it was suggested that the degree of anthropogenic disturbance within the
surrounding watershed regulates wetland sediment, organic carbon and accumulation of
nitrogen. Riparian wetlands are ‘open’ systems, subject to watershed influxes of
sediment and phosphorus. Non-riparian ‘closed’ systems are influenced much less from
such influxes. Greater accumulation of phosphorus is found in floodplain wetlands that
have large catchments containing fine-textured sediments that are co-deposited with
phosphorus (Craft and Casey 2000).
In aquatic environments, the majority of phosphorus is bound to organic and
inorganic particles, with a relatively small fraction available in the water-soluble form.
Due to this conservative nature, it is understandable that a portion of the phosphorus from
watershed inputs to a wetland would remain there (Paris 2004).
Objective Three (Results)
The third objective was to contrast Southwestern Indiana least-impacted (reference)
wetlands to Southeastern US Wetlands in Eco-region IX to determine the validity of
61
single numeric criteria. Southwestern Indiana wetland nutrient indicators were compared
with sampling results from the collaborative studies: Southeastern Wetland
Biogeochemical Survey: Determination and Establishment of Numeric Nutrient Criteria
(Paris 2005), and A Biogeochemical Survey of Wetlands in the Southeastern United States
(Greco 2004).
It was hypothesized that Southwestern Indiana wetlands would have higher
phosphorus and nitrogen concentrations than wetlands within the same eco-region in the
Southeastern United States. These differences would occur among soil, water, litter and
vegetation strata.
Results:
• Total Phosphorus concentrations in the water column, litter, and soil samples from the Southwestern Indiana wetlands were significantly higher than the samples from wetlands in other states located within Eco-region IX.
• Total Nitrogen concentrations in the water column and soil were not significantly different between the Southwestern Indiana wetlands sampled and the wetlands surveyed in other states within Eco-region IX.
• Total Nitrogen concentrations in the litter were not significantly different from other states within Eco-region IX, with the exception of Florida.
• Total Phosphorus and Total Nitrogen concentrations in the vegetation were not significantly different from the other states within Eco-region IX, with the exception of Florida.
Significant differences in Total Phosphorus concentrations in the water column, litter,
and soil were noted between Least-Impacted Southwestern Indiana wetlands and Least-
Impacted Southeastern U.S. wetlands within Eco-region IX. Based on median values,
total phosphorus concentrations in the water column were approximately five times
higher in the Southwestern Indiana wetlands sampled than the collaborative study results
62
from other states in Eco-region IX. Soil total phosphorus concentrations in the Indiana
wetlands were twice as high as the wetlands surveyed in other Eco-region IX states.
The results suggest that a single numeric criteria established for all wetlands within Eco-
region IX could be overly protective of Southwestern Indiana wetlands.
The EPA Office of Water’s strategy to develop regional nutrient criteria uses
comparisons to local reference or background conditions to develop nutrient criteria
within designated spatial areas, to yield a regionalization of nutrient criteria. Reference
data sets allow more objective and realistic selection of goals for wetland maintenance or
restoration (Findlay et al. 2002).
EPA has recommended that nutrient criteria be based on the 25th percentile of the
nutrient concentrations measured from all wetlands in a region, or on the 75th percentile
concentration of least-impacted wetlands within a given eco-region. If the wetland
criteria are established on too broad a grouping or classification of wetlands, the natural
heterogeneity within the grouping could result in the overprotection of some wetlands,
while others in the same grouping could be under-protected (Paris 2004).
If the numeric criteria were established based on the 75th percentile phosphorus
concentration for all wetlands within Eco-region IX, the higher background phosphorus
concentrations from the Indiana sampling would be overly protective as compared to the
lower concentrations measured in the wetlands in other Eco-region IX states.
Objective Four (Results)
The objective of the temporal study was to determine the seasonal variability
among the strata parameters. Those parameters exhibiting the least variability, while also
demonstrating responsiveness to system inputs, would be expected as favorable
candidates for monitoring the wetland status throughout the year. It was hypothesized
63
that there would be differences in seasonal variability among water column, litter, soil or
vegetative biogeochemical parameters surveyed. The seasonal variability would be lower
for the soil and higher for the water column parameters due to the more permanent nature
of the sampled media.
Based on the study results, the trend data indicate that litter Total Phosphorus and
Total Nitrogen exhibit low variability among the strata parameters measured throughout
the monitoring period. Litter Total Phosphorus should be a reliable indicator, easily
sampled, that could be monitored, regardless of sampling season.
Soil Total Phosphorus and Total Nitrogen also exhibited low variability throughout
the temporal period and are likewise representative of effective monitoring parameters
for wetland condition. Advantages of soil indicators over litter may include soil’s more
permanent nature, and resistance to flooding impacts, especially in riparian wetlands. A
disadvantage is the additional collection equipment, weight, and effort required for soil
sampling in the field.
Another consideration, based on the results from Objective Two above, would be
that soil Total Phosphorus and Total Nitrogen may be more responsive than litter as an
indicator of nutrient impacts. The information derived from this temporal study,
however, was based upon sampling within a single wetland. Additional sampling over a
range of separate wetlands would be required to validate the responsiveness over a
temporal period.
Litter collection is a relatively non-intrusive method, more protective of wetland
integrity. In addition, the sample product is lightweight, occupying considerably less
space in the field gear, allowing for the collection of multiple samples during a survey.
64
Conclusion
The study results indicate that the hydrologic connectivity of a wetland system
should be considered in the assignment of appropriate numeric nutrient criteria. The
most responsive indicator stratum for nutrient enrichment between impacted and least-
impacted wetlands appears to be soil total phosphorus and total nitrogen.
The establishment of numeric nutrient criteria for Southwestern Indiana wetlands,
based on reference wetlands from Eco-region IX, could be overly protective. Study
results indicate soil total phosphorus and total nitrogen concentrations exhibited the
lowest variability during the temporal study, while demonstrating responsiveness to
nutrient enrichment between impacted and least-impacted wetlands. Therefore soils
likely provide the best overall choice as an indicator of wetland nutrient conditions and
therefore should be considered when developing numeric nutrient criteria.
Implications for EPA in Establishment of Numeric Nutrient Criteria
In summary, based on the survey results, there does not appear to be a need to sub-
classify wetlands by vegetative community type to properly assess nutrient conditions in
Southwestern Indiana’s wetlands. However, hydrologic connectivity of the wetland
should be considered in the assignment of appropriate numeric nutrient criteria. Soils
appear to provide the most sensitive indicator of nutrient impacts to wetlands as
compared to water, vegetation or leaf litter.
The results further indicate that a single numeric criteria established for Eco-region
IX could either be overly protective or under protective of ecological integrity based on
background nutrient conditions in the wetlands sampled in Southwestern Indiana.
Figure B-59. IN16 Wetland Description and Location
156
Figure B-60. IN16 Wetland Description and Location
Figure B-61. IN16 Wetland Description and Location
157
APPENDIX C PHOTOGRAPHS OF WETLANDS SURVEYED IN SW INDIANA
158
Figure C-1. Photograph of Wetland IN1
Figure C-2. Photograph of Wetland IN1
159
Figure C-3. Photograph of Wetland IN1
Figure C-4. Photograph of Wetland IN2
Figure C-5. Photograph of Wetland IN2
160
Figure C-6. Photograph of Wetland IN3
Figure C-7. Photograph of Wetland IN3
161
Figure C-8. Photograph of Wetland IN4
Figure C-9. Photograph of Wetland IN4
162
Figure C-10. Photograph of Wetland IN5
Figure C-11. Photograph of Wetland IN7
163
Figure C-12. Photograph of Wetland IN8
Figure C-13. Photograph of Wetland IN9
164
Figure C-14. Photograph of Wetland IN9
Figure C-15. Photograph of Wetland
165
I
Figure C-16. Photograph of Wetland IN9
Figure C-17. Photograph of Wetland IN10
166
Figure C-18. Photograph of Wetland IN10
Figure C-19. Photograph of Wetland IN11
167
Figure C-20. Photograph of Wetland IN11
Figure C-21. Photograph of Wetland IN11
168
Figure C-22. Photograph of Wetland IN12
Figure C-23. Photograph of Wetland IN12
169
Figure C-24. Photograph of Wetland IN12
Figure C-25. Photograph of Wetland IN13
170
Figure C-25. Photograph of Wetland IN14
Figure C-27. Photograph of Wetland IN14
171
Figure C-28. Photograph of Wetland IN15
Figure C-29. Photograph of Wetland IN16
172
Figure C-30. Photograph of Wetland IN16
Figure C-31. Photograph of Wetland IN16
173
Figure C-32. Photograph of Wetland IN15
Figure C-33. Photograph of Wetland IN15
174
Figure C-34. Photograph of Wetland IN15
Figure C-35. Photograph of Wetland IN15
175
Figure C-36. Photograph of Wetland IN15
Figure C-37. Photograph of Wetland IN15
176
Figure C-38. Photograph of Wetland IN15
Figure C-39. Photograph of Wetland IN15
177
Figure C-40. Photograph of Wetland IN15
Figure C-41. Photograph of Wetland IN15
178
178
APPENDIX D WETLAND CHARACTERIZATION FORM
Wetland ID: Date: Start Time: Finish Time: Observer Name: Picture ID: Weather Condition: Is the wetland adjacent to a body of water? Circle the appropriate choice:
River Stream Lake Estuary Ocean None Characterization for the Entire Wetland (Please circle one of the vegetation classes)
1) Is the vegetation composed predominantly non-vascular (mosses and lichens) ...…Moss-Lichen 2) Is the vegetation herbaceous?
i) Is the vegetation dominated by rooted emergent vegetation?.....................Emergent Wetland ii) Is the vegetation predominately submergent, floating-leaved, or free-floating?....Aquatic Bed
3) Is the vegetation mostly trees and/or shrubs? i) Is it dominated by vegetation less than 6 meters tall? ………………Scrub-Shrub Wetland ii) Are the dominants 6 meters or greater? …………………………………. Forested Wetland
Land-Use Characterization 1) Circle the following land-uses that best characterizes the adjacent upland and estimate the percentage of the area that is
represented by the circled land uses: a) Commercial ______ g) Rural (scattered homes) ______ b) Industrial ______ h) Unimproved pasture______ c) Golf course ______ i) Forested or wetland ______ d)High density residential (>20 units/acre) ______ j) Pine plantations ______ e) Low density residential ______ k) Row crops ______ f) Feed lots or Dairy operations ______ l) Other ______
2) Please circle the following fire indicators present within the vegetation zone: a) Charred ground surface e)Burnt dead trees b) Burnt trees with new shoots f) Burnt crowns of trees c) Burn marks on trees and shrubs g) Burned ground with no understory d) No evidence of fire
3) Is trash present in the wetland?: Yes or No (describe) 4) Is there green algae present in the wetland?: Yes or No (describe)
5) Is there evidence of sedimentation in the wetland? Yes or No (describe)
6) Is there floating vegetation?: Yes or No (describe)
7) Circle any visible indicators of hydrologic disturbances:
a) Ditch e) Dam b) Nearby road impeding flow f) Dike c) Canals g)Piped inflows d) None noticed h) Other (describe) 8) Circle any visible indicators of vegetative disturbances:
a) Large stand of vines e) Cutting or grazing in wetland b) Cutting or grazing in adjacent upland f) Insect damage c) Large stand of exotic species g) Large % of dead trees d) None noticed h) Other (describe) 9) Circle any direct indicators of nutrient loading to the wetland a) Presence of cattle in wetland d) Yard waste dumping in/near wetland b) Fertilizer or manure application in watershed e) None noticed
c) Other (describe) 10) What is the approximate size of the wetland: ________________ Shape: _____________ (please sketch on back) 11) HGM classification (from key): _____________________________________
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Vegetation Community Characterization Form Sub-sample A (Deep Center) Wetland ID: Observer Name: Date: Photo ID:
List the dominant overstory vegetation within a 10-ft radius of sampling and the % cover they represent
% cover of understory
List the dominant understory story vegetation within a 10-ft radius of sampling and the % cover they represent
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LIST OF REFERENCES
Anderson, D.C., J.J. Sartoris, J.S. Thullen, and P.G. Reusch. 2003. The Effects of Bird Use on Nutrient Removal in a Constructed Wastewater Treatment Wetland. Wetlands: Vol. 23, No.2, pp. 423-435.
Bragazza, L. and R. Gerdol. 2001. Are Nutrient Availability and Acidity-Alkalinity Gradients Related in Sphagnum-Dominated Peatlands? Journal of Vegetation Science: Vol. 13, No. 4, pp. 473-482.
Chapman S.B. 1986. Production Ecology and Nutrient Budgets. In: P.D. Moore, S.B. Chapman (eds). Methods in Plant Ecology. Boston: Blackwell Scientific Publications, pp. 1-60.
Cowardin, L.M., V. Carter, F.C. Golet, and E.T. LaRoe. 1979. Classification of Wetlands and Deepwater Habitats of the United States. U.S. Fish and Wildlife Service, Office of Biological Services, Washington, DC, USA. FWS/OBS-79/31.
Craft, C.B., J. Vymazal, C.J. Richardson. 1995. Response of Everglades Plant Communities to Nitrogen and Phosphorus Additions. Wetlands: Vol. 15: 258-271.
Craft, C.B. and C.J. Richardson. 1998. Recent and Long-Term Organic Soil Accretion and Nutrient Accumulation in the Everglades. Soil Science Society of America Journal: Vol. 62: 834-843.
Craft, C.B. and W.P. Casey. 2000. Sediment and Nutrient Accumulation in Floodplain and Depressional Freshwater Wetlands of Georgia, USA. Wetlands: Vol. 20, No. 2, pp. 323-332.
Dahl, T.E. 1990. Wetland Losses in the United States, 1780’s to 1980’s. U.S. Department of the Interior, Fish and Wildlife Service. Washington, D.C. 13 pp.
Dress, W.J. and R.E.J. Boerner. 2002. Temporal and Spatial Patterns in Root Nitrogen Concentration and Root Decomposition in Relation to Prescribed Fire. The American Midland Naturalist: Vol. 149, No.2, pp.245-247.
Findlay, S.E.G., E. Kiviat, W.C.Nieder and E.A. Blair. 2002. Functional Assessment of a Reference Wetland Set as a Tool for Science, Management and Restoration. Aquatic Sciences: Vol. 64. pp. 107-117.
Greco, S. 2004. A Biogeochemical Survey of Wetlands in the Southeastern United States. University of Florida. Gainesville.
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Indiana Department of Natural Resources (IDNR). 1996. Indiana Wetlands Conservation Plan. Indianapolis.
Karr, J.R. and E.W. Chu. 1999. Restoring Life in Running Waters: Better Biological Monitoring. Washington, D.C: Island Press.
Klein, C.A , F. Cheever, and B.C. Birdsong 2005 Natural Resources Law A Place-Based Book of Problems and Cases Aspen Publishers, Inc.
Mitsch, W.J. and J.G. Gosselink. 2000. Wetlands. John Wiley and Sons, Inc., New York, NY, USA.
Owen Koning, C. 2005. Vegetation Patterns Resulting from Spatial and Temporal Variability in Hydrology, Soils, and Trampling in an Isolated Basin Marsh, New Hampshire, USA. Wetlands: Vol. 25, No. 2, pp. 239–251.
Paris, J.M. 2005. Southeastern Wetland Biogeochemical Survey: Determination and Establishment of Numeric Nutrient Criteria. University of Florida. Gainesville.
Schmieder, K. and A. Lehmann, 2004. A Spatio-Temporal Framework of Efficient Inventories of Natural Resources: A Case Study With Submersed Macrophytes. Journal of Vegetation Science: Vol. 15, No. 6, pp. 807–816.
Shaver, G.R. and J.M. Melillo, 1984. Nutrient Budgets of Marsh Plants: Efficiency Concepts and Relation to Availability. Ecology 65: 1491-1510.
Shaver, G.R., L.C. Johnson, D.H. Cades, G. Murray, J.A. Laundre, E.B. Rastetter, K.J. Nadelhoffer and A.E. Giblin, 1998. Biomass and CO2 Flux in Wet Sedge Tundras: Responses to Nutrients, Temperature and Light. Ecology Monograph 68: 75-97.
Simon, K. S., C. R. Townsend, B. J. F. Biggs and W. B. Bowden. 2004. Temporal Variation of N and P Uptake in 2 New Zealand Streams. Journal of the North American Benthological Society: Vol. 24, No. 1, pp. 1–18.
U.S. Environmental Protection Agency (US EPA) and U.S. Department of Agriculture (USDA). 1998. Clean Water Action Plan: Restoring and Protecting America’s Waters.
U.S. Environmental Protection Agency. 2002a. Methods for Evaluating Wetland Condition: Introduction to Wetland Biological Assessment. Office of Water, U.S. Environmental Protection Agency, Washington, DC. EPA-822-R-02-014.
U.S. Environmental Protection Agency. 2002b. Methods for Evaluating Wetland Condition: Study Design for Monitoring Wetlands. Office of Water, U.S. Environmental Protection Agency, Washington, DC. EPA-822-R-02-015.
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U.S. Environmental Protection Agency. 2002c. Methods for Evaluating Wetland Condition: Vegetation-Based Indicators of Wetland Nutrient Enrichment. Office of Water, U.S. Environmental Protection Agency, Washington, DC. EPA-822-R-02-024.
U.S. Environmental Protection Agency. Methods for Evaluating Wetland Condition: Developing Metrics and Indexes of Biological Integrity. Office of Water, U.S. Environmental Protection Agency, Washington, DC. EPA-822-R-02-016.
Whigham, D., M. Pittek, K.H. Hofmockel, T. Jordan, and A.L. Pepin. 2002. Biomass and Nutrient Dynamics in Restored Wetlands on the Outer Coastal Plain of Maryland, USA. Wetlands: Vol. 22, No. 3, pp. 562-574.
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BIOGRAPHICAL SKETCH
David A. Stuckey has been a lifelong student of natural history and the
environment, a sportsman and conservationist. In 1992, he graduated from the University
of Evansville, receiving a B.S. Degree in natural resources. In 2006, he will complete the
requirements for an M.S. degree in environmental science from the University of Florida.
His working career has included over 25 years in the fields of environmental
engineering and quality control in government, coal mining and the pharmaceutical
industry. He is currently Manager of Environmental Health and Safety for Bristol-Myers
Squibb Company’s Corporate Quality Environment, Health and Safety Group, working
toward a balanced approach to sustainable development, pollution prevention, and the