Vegetation and Soil Nutrient Dynamics, and Carbon Sequestration Potential at Central Wisconsin Wetland Restoration Locations

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VEGETATION AND SOIL NUTRIENT DYNAMICS, AND CARBON SEQUESTRATION POTENTIAL AT CENTRAL WISCONSIN WETLAND RESTORATION LOCATIONS

NICHOLAS J. BESASIE

A Thesis

Submitted in partial fulfillment of the requirements of the degree

MASTER OF SCIENCE

NATURAL RESOURCES (SOIL SCIENCE)

College of Natural Resources

University Of Wisconsin

Stevens Point, Wisconsin

December 2010

ABSTRACT

Wetlands provide many valuable functions on the landscape, but many wetlands have been severely altered over the last two centuries by changes in land use. Farm bill programs such as the Wetland Reserve Program (WRP) and Conservation Reserve

Program have allowed wetlands to be restored or protected. Studies have indicated overall landowner satisfaction with the programs, but scientists have not done significant monitoring to determine if the wetlands are functioning properly. This study seeks to evaluate the state of wetland restoration attempts in central Wisconsin and establish baseline data to enhance and enable future comparison. Two separate investigations into the success of wetland restorations were conducted.

In the first investigation to better understand the success of restoration attempts, two young restorations and a native wetland were surveyed for vegetation, soil physical characteristics (bulk density, depth of organic rich horizons), and soil nutrient levels

(nitrogen [N], phosphorus [P], sulfur [S], and carbon [C]). Analysis revealed that vegetative communities differed between native and restored wetlands, with native wetlands having the greatest biodiversity and species richness. However, planting of vegetation appears to increase biodiversity and vegetative community structure within restorations. Comparison of soil physical parameters demonstrated that native wetlands have deeper organic horizons and lower soil bulk density. Analysis of soil nutrient levels showed that native wetlands overall have greater and less varied amounts of N, S, and C.

The historical shift of native wetlands to agriculture has lead to the depletion of organic soil carbon. Restoring wetlands may shift carbon from the atmosphere back to

iii the soil. The second part of this study seeks to quantify the amount of organic soil carbon that has accumulated since restoration of WRP sites. Composite soil samples have been taken from 32 different WRP sites (varying in age from pre-restoration to 16 yrs post restoration) located in Central Wisconsin. The success of the restoration efforts, in terms of organic soil carbon content, were determined through comparison to several undisturbed wetlands within the same geologic area. The soil organic carbon

(SOC) concentration was quantified through combustion of organic materials using a

Carbon and Nitrogen Analyzer. Soil organic carbon concentration levels were highly variable throughout the study area (22 to 305 g kg-1). A weak positive correlation (r2 =

0.28) between SOC concentration and time since restoration at WRP sites with histosols or histic epipedons was discovered. No significant trend was found for total carbon content of the soil profile and time at WRP locations. Depth of organic rich horizons appears to be limiting the recovery of SOC content. Given the relatively young age of the restorations in this study it is possible that the level of pre-restoration disturbance is still the dominating factor determining SOC levels.

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Table of Contents

Abstract ii

List of Figures vii

List of Tables viii

Acknowledgements ix

Chapter 1 – Introduction and Literature Review 1 Literature Review 1 The Wetland Reserve Program 2

Key Concepts of Wetland Restorations 4

Wetland Hydrology 5

Wetland Vegetation 6

Soil Organic Carbon and Benefits to Wetland Soil Development 7

Soil Nitrogen and Wetlands 13

Soil Phosphorus and Wetlands 14

Soil Sulfur and Wetlands 16

Soil Physical Properties at Wetland Restorations 17

Objectives 19

Chapter 2 – Analysis of vegetative communities and wetland soil properties 20 at two central Wisconsin restored wetlands

Literature Review 20

Key Concepts of Wetland Restorations 21

Wetland Vegetation 22

Soil Carbon and Wetlands 23

Soil Nitrogen and Wetlands 26

Soil Phosphorus and Wetlands 28

Soil Sulfur and Wetlands 30

Soil Physical Properties at Wetland Restorations 31

Objectives 32

Materials and Methods 33

Site Location 33

Present Conditions 34

Data Collection and Analysis 36

Vegetation Sampling 36

Soil Property Analysis 38

Soil Nutrient Analysis 39

Results and Discussion 40

Plant Surveys and Diversity 40

Soil Physical Property Analysis 43

Soil Nutrients and pH 45

Nitrogen 45

Sulfur 46

Phosphorus 47

Soil Organic Carbon 48

Soil pH 48

Conclusions 49

Chapter 3 – Carbon sequestration potential at central Wisconsin Wetland 53

Reserve Program sites

Literature Review 53

The Wetland Reserve Program 53

Soil Organic Carbon and Benefits to Wetland Soil Development 55

Objectives 61

Materials and Methods 62

Site Locations 62

Climate 64

Data Collection 64

Data Analysis 66

Results and Discussion 67

Soil Organic Carbon Concentration 67

Organic Horizon Development 70

Bulk Density 71

Soil Organic Carbon Content 72

Soil Nitrogen 74

Conclusions 74

Chapter 4 – Overall Conclusions 88

Chapter 5 – Literature Cited 90

Appendix A – Lost Creek and Buena Vista Study Location Maps 100

Appendix B – Soil Descriptions 104 Appendix C – Wetland Reserve Program Site Locations 107 Appendix D – List of Observed Plant Species 110

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List of Figures

1. Figure 3.1. Relationship between soil organic carbon (SOC) concentration by mass and time for all Wetland Reserve Program sites and native wetland locations. Data are summarized in Tables 2.2 and 2.3 77

2. Figure 3.2. Mean of soil organic carbon concentration by mass for each five year interval age of restoration for A1 and A2 hydric soil designations. Included are the 95% confidence intervals for each interval of wetland restorations 78

3. Figure 3.3. Relationship between soil organic carbon (SOC) content by mass and time for all Wetland Reserve Program and native wetland locations 79

4. Figure 3.4. Relationship between soil organic carbon (SOC) concentration and total SOC content and time for Wetland Reserve Program locations with A1/A2 hydric soil designations 80

5. Figure 3.5. Relationship between depth of organic horizon and time for all Wetland Reserve Program locations with A1/A2 hydric soil designations 81

6. Figure 3.6. Relationship between bulk density and time since restoration for all Wetland Reserve Program locations 82

7. Figure 3.7. Relationship between bulk density and soil organic carbon concentration for all Wetland Reserve Program locations and native wetland locations 83

8. Figure 3.8. Relationship between organic nitrogen concentration and soil organic carbon concentrations for all Wetland Reserve Program locations and native wetland locations 84

9. Figure 3.9. Relationship between surface horizon bulk density and overall depth of organic horizons for all Wetland Reserve Program locations 85

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viii

List of Tables

1. Table 2.1. Alpha numeric designations assigned to the hydric soils at WRP and Native locations in Central Wisconsin 51

2. Table 2.2. Vegetation Diversity Summary for Lost Creek Buena Vista and Native Locations 51

3. Table 2.3. Buena Vista Restoration Planting Success Analysis 52

4. Table 2.4. Soil Physical Properties at Native and Restored Locations 52

5. Table 2.5. Nitrogen, Sulfur, Phosphorus, Carbon, and pH for the Native and Restored Locations 52

6. Table 3.1. Alpha numeric designations assigned to the hydric soils at WRP and Native locations in Central Wisconsin 86

7. Table 3.2. Summary of SOC Concentration and Total SOC Content for Native and Wetland Reserve Program locations meeting A1/A2 hydric soil designations. Lower case letters a and b denote significant differences (p < 0.05) between the means of native and restored wetlands 86

8. Table 3.3. Summary of SOC Concentration and Total SOC Content for Native and WRP locations meeting S1/S4 designations. Lower case letters a and b denote significant differences (p < 0.05) between the averages of native and restored wetlands 87

9. Table 3.4. Soil Physical Properties at Native and Restored Locations 87

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ACKNOWLEDGEMENTS

I would like to thank the many landowners who allowed the study of their wetlands to make this research possible. I would also I like to recognize the contributions of NRCS technical staff to this research namely Scott Doherty. I want to thank Dr. Meghan Buckley, the University of Wisconsin-Stevens Point Soils Discipline, and my graduate committee for their help with this research. Lastly, I want to thank my loving wife, Amy, who stood by and supported me the last two years.

Chapter 1 – Introduction and Literature Review

Wetlands are an integral part of the landscape, and their functions provide many services (Mitsch et al., 1998). Anthropogenic activities have altered the state of the majority of our nation‟s wetlands. In an effort to dampen the loss of wetlands from

America‟s and Wisconsin‟s landscape, many dedicated non-profit groups (e.g. Ducks

Unlimited, Wisconsin Wetlands Association, Wisconsin Waterfowl Association) and government agencies (e.g. Natural Resources Conservation Service [NRCS], Army

Corps of Engineers) are actively involved in restoring wetlands.

Restoring wetlands is a comparatively young science, and as such is ever evolving. Each scenario requires a different set of objectives, along with a need to be adaptive in management strategies. Given the importance of wetlands and the very nature of wetland restoration, additional research is required to gauge the success of wetland restorations and to identify the shortcoming of these efforts.

Literature Review

2 settlement only 5 million acres remain (Wisconsin Wetland Association, 2009).

Presently, it is federal government policy from executive order under President George

H.W. Bush that when wetlands are altered for construction or farming, new wetlands must be created or previously degraded wetlands must be restored so that there is no further net loss of wetlands (USFWS, 1994).

Several government agencies in Wisconsin actively restore wetlands such as the

Department of Transportation (DOT) and Natural Resource Conservation Service

(NRCS, 2009a). Under farm bill programs such as Wetland Reserve Program,

Emergency Watershed Protection Plan and the Conservation Reserve Program, wetlands are restored or protected with minimal cost to the owner of the property

(NRCS, 2009a). In addition to farm bill programs, riparian areas and wetlands along floodplains can be protected under easements purchased through the Emergency

Watershed Protection Plan as stipulated in Section 382 of the Federal Agriculture

Improvement and Reform Act of 1996 (NRCS, 2009b).

The Wetland Reserve Program

Several government agencies such as the Department of Transportation (DOT) and Natural Resource Conservation Service (NRCS) actively restore wetlands. Under farm bill programs such as Wetland Reserve Program, Emergency Watershed

Protection Plan, and the Conservation Reserve Program, wetlands are restored or protected with minimal cost to the owner of the property (NRCS, 2009a; NRCS, 2009b).

The Wetland Reserve Program (WRP) is an American Farm Bill program established in 1995. Wetland Reserve Program is a voluntary program that farmers can

3 enroll in. Via provisions in the bill, conservation easements are purchased on areas of land. A conservation easement allows the landowner to continue to own and recreate on the land, but gives administrative control of the land use to the Natural Resources

Conservation Service (NRCS, 2009a). The NRCS can offer 30-year easements as well as permanent easements. The value paid to the landowner depends on the length of the easement and property value of the land being included in the easement.

Landowners wishing to enroll lands in WRP must have areas of wetlands that have been degraded by agriculture and have owned the property for at least seven years.

Nationwide, 179,417 acres of wetlands have been restored under the WRP provision of the Farm Bill with 7,353 acres of wetlands being restored in Wisconsin as of December

2009. One of the largest contiguous tracks of WRP, Duffy Marsh, resides in Central

Wisconsin (NRCS, 2009c).

The goal of this program is to preserve, protect, and restore wetlands that have been adversely affected by agriculture. The program mandate includes creating wildlife wetland habitat, namely for migratory waterfowl. However, the program mandate fails to address the return of other wetland ecosystem functions (e.g. nutrient cycling, flood control) as a necessary requirement (King and Keeland, 1999; King et al., 2006). In the studies that have been done to indicate the success of these programs, overall satisfaction of the property owner has been noted, but little monitoring has been done to determine if the wetlands are functioning properly (Forshay et al., 2004).

Key Concepts of Wetland Restorations

Previous research in the field of wetland restoration has outlined the need for case by case goals and monitoring of ecological data to assess the success of the restoration efforts at a given site (Euliss et al., 2008; Ehrenfeld, 2000; Zedler, 2000).

The nature of wetland restoration must be guided by the definition of wetlands having hydric soils, wetland hydrology, and a water tolerant plant community. Restoration efforts should seek to restore these characteristics as primary management goals

(Richardson and Vepraskas, 2001). When considering a wetland restoration timeline, results are generally demanded in a timely fashion. However, when restoring ecosystem functions, a more realistic timetable must be set. Wetlands take years to decades to establish nutrient cycling regimes and formation of hydric soils. While wetlands may be delineated based on presence of water at or near the surface, restoring hydrology should not be the only goal of restoration. Restoring ecosystem functions (i.e. hydrology, vegetation, soils) takes longer than what are public expectations for the desired results to be witnessed on the landscape. Wetlands take a particularly large amount of time to establish nutrient cycling regimes and formation of hydric soils (Lal, 2007).

As stated before, no two restoration attempts are identical and many require adaptive management (Wagner et al., 2008), but certain underlying principles hold true for all forms of restoration efforts. It is the policy of the United States Fish and Wildlife

Service to approach conservation from the ecosystem management perspective

(USFWS, 2009). Ecosystem management approaches arose in the early 1990‟s and are described as tailoring management and restoration efforts to maintain the ecological

5 integrity of natural systems as a whole (Grumbine, 1994). With this in mind, restoration efforts should focus on restoring ecosystem functions in addition to fauna and flora.

Management goals that not only focus on hydrology, but also vegetative communities, nutrient cycling, and soil formation should be included in management plans for wetland restorations.

Wetland Hydrology

Wetlands are defined by the presence of water in the upper part of the soil profile. Water has significant effects on soil properties as well as on vegetative communities. Considering that water is the inherent underlying factor of wetlands, wetland restoration attempts begin with considerations to return the former hydrology to the restoration area.

In central Wisconsin, the conventional form of wetland drainage is to use ditches and drain tile to depress the water table. Ditches and drain tile allow ground water to channelize and flow more rapidly than the rate at which the ground water flows naturally. The increased speed at which water leaves the area affected by ditching or tile results in a lowering of the ground water table as water is supplied slower and it is taken away.

Restoring hydrology to a drained wetland area is dependent on the mode of water removal. Ditches are plugged and filled with debris material, clay, or impervious fabricated materials. Plugging and filling a ditch will allow water to naturally diffuse back into the landscape as the affects of channelization are minimized. Drain tile does not need to be removed completely. Once sections of the drain tile are either broken or

6 removed, the tiles will no longer function properly and water will return to pre- disturbance levels.

Generally a water removal implement will affect large expanses on the landscape, involving several land owners. Restoration areas are typically small in size and involve only one landowner. Under this circumstance, it is often necessary for embankments and scrapes to be utilized. An embankment will hold water into a specified area thus only affecting the landowner who wishes to restore the wetland.

Scrapes are depressions created in the restoration area before hydrology is restored.

Scrapes allow for water to pool and create open water areas even though the water table could not be restored to natural levels.

Wetland Vegetation

Self-design is a technique for restoring wetlands that fits into the theory of ecosystem management (Mitsch et al., 1998). Self-design is allowing plants, animals, and functions to naturally develop. This technique can have setbacks for plant diversity if the vegetative community at restoration locations begins to be dominated by invasive plant species. Plantings are used to counteract the establishment of invasive species.

Planting also has other benefits. Research has indicated that planting desired vegetation has benefits such as increased nutrient storage (Callaway et al., 2003) and increased early succession plant diversity (Reinartz and Warne, 1993). However, climax communities and biodiversity are largely unaffected by plantings in the long run as colonization of dominant local plants takes over (Nedland et al., 2007; Mitsch et al.,

1998).

Colonization of wetland soils by hydrophitic vegetation happens naturally through two avenues. First, viable seeds may be retained in the seed bank even after years of degradation. Secondly, seeds from surrounding areas will move into the wetland through a variety of mechanisms such as wind dispersal. Colonization is not always by the desired species but sometimes by invasive species whether exotic (e.g. purple loosestrife [Lythrum salicaria]) or native (e.g. cattails [Typha spp.]) that can degrade the quality of restoration attempts (Zedler, 2000). Planting newly restored sites can help prevent colonization by invasive species (Perry et al., 2004; Daehler, 2003). Plantings are also done to help prevent soil erosion at the site (Zedler, 2000; USDA, 1998).

In natural systems, wetlands can be disturbed through a variety of mechanisms including flooding and drought. Vegetation will be affected in different ways by shifts in the local weather such as a drought, but restored wetlands generally have water control structures and an established draw down plan in place so shifts in vegetative types due to water table fluctuations can be planned for. Many species of wetland vegetation require periods of dry conditions to properly establish at a given site (i.e. the wetland).

Another disturbance mechanism that affects natural wetlands is fire. Fire affects nearly all terrestrial landscapes. Fire has many beneficial side effects on wetland vegetation such as increasing biodiversity and primary productivity (Middleton et al.,

2009).

Soil Organic Carbon and Benefits to Wetland Soil Development

Carbon cycles naturally through aquatic and terrestrial ecosystems. The world‟s oceans and carbonate rocks serve as the largest reserve of stored carbon on the planet

(NASA, 2008). Terrestrial wetlands in colder climates also store significant amounts of carbon. Annually, the amount of carbon contributed to the atmosphere from the soil is more than ten times the amount of carbon contributed to the atmosphere from the burning of fossil fuels, but soils can actively store carbon as well (Lal, 2007). The carbon cycle is dynamic with soil acting as both a source and a sink of atmospheric carbon depending on variables such as the exclusion of atmospheric oxygen by water inundation. Because of this, wetlands can both sequester carbon and release it to the atmosphere. As plants grow, they utilize carbon dioxide found in the atmosphere and turn this into sugar compounds through photosynthesis. As plants senesce and die, these sugar compounds are decomposed and once again contributed to the atmosphere. Under wetland conditions, plant material can take significant amounts of time to decompose due to the lack of atmospheric oxygen and anaerobic conditions created by inundation with water (Emery and Perry, 1996). Plant parts including stems, leaves, and roots can become trapped in wetlands with annual contributions of carbon to wetlands generally higher than the amount of carbon released from wetlands to the atmosphere (Armentano and Menges, 1986). In this manner, true organic soils are created. Histosols, the order in U.S. soil classification system for organic soils, are associated with wetlands. Histosols account for 23% of the carbon stored in global soils while only covering 1.3% of the globe (Brady and Weil, 2002). The shift from wet conditions that allow Histosols to store carbon to dry, aerobic conditions, allows for complex carbon compounds to be converted to carbon dioxide and lost to the atmosphere (Duff et al., 2009). This shift occurs when wetlands are drained for agriculture.

Carbon based gases such as Carbon Dioxide and Methane have been increasing in the atmosphere over the past century (EPA, 2007). The increase of these gases, in association with other “greenhouse gases”, has been blamed for the recent warming trend (EPA, 2007). The primary cause of increased atmospheric carbon has been industrial burning of fossil fuels (EPA, 2007). However, the depletion of organic soil carbon with increasing tillage operations and the shift of land use to agriculture has also contributed (Hillel and Rosenzweig, 2009). Carbon that would be stored in soil organic matter has been released to the atmosphere as carbon dioxide during aerobic decomposition. Increased aeration from practices such as tillage has increased the decomposition rate of the organic material (Brady and Weil, 2002). Cultivation is considered the most important factor in soil organic carbon loss (Lal 2004; Euliss et al.,

2006). Though this is only a secondary cause of increased carbon in the atmosphere

(contributions from automotives and industry are greater), the opposite is being looked to as a major way to slow the trend of increasing atmospheric carbon. Changing to less disruptive land uses and restoring native wetlands, grasslands, and forests may increase the amount of carbon stored in the soil, thereby decreasing atmospheric levels.

This concept has been termed carbon sequestration. Research has shown that the conversion of conventional cropland to no-till cropland, or even undisturbed land, can increase the amount of organic matter (and carbon) stored in the soil (Buckley, 2008;

Blanco-Canqui and Lal, 2008). In addition to reducing the amount of carbon in the atmosphere, increasing the soil carbon also improves soil structure and soil fertility

(Karlen et al., 1994).

Recent research from the Midwest and Wisconsin has been able to quantify anthropogenic influenced decreases in soil carbon as well as potential for restoration.

Changes in land use have resulted in the loss of up to 60% of predevelopment soil carbon levels in the Unites States (Guo and Gifford, 2002). However, the same study reported that restoration of low impact land use resulted in a 50% increase from depressed soil carbon levels.

Research has also been presented on the effect of specific land use shifts on the amount of carbon lost or sequestered. The conversion of natural areas such as prairies into agriculture has resulted in a net loss of soil carbon estimated to be between 24% and 89% (Brye and Riley, 2009; Jelinski and Kucharik, 2009). The conversion of forest land to agriculture has been reported to cause a 22% decrease in soil carbon (Murty et al., 2002). Further research has indicated that within a land use type, certain practices are more likely to result in a higher net loss of carbon than others. In agriculture, for example, the more disruptive, conventional practices (i.e. moldboard plowing) have resulted in a higher loss of soil carbon than reduced tillage methods (Jelinski and

Kucharik, 2009; Al-Kaisi et al., 2005).

11 wetlands to natural wetlands, it is essential to establish a baseline level of the amount of carbon at restoration sites before restoration began in order to better quantify the success of the restoration. Understanding that the areas receiving restoration were all at one time functioning wetlands, but have undergone varying levels of degradation, is key to identifying the success of the restoration efforts. For an area to be entered into the WRP, the site must be a wetland degraded by agricultural activity and as previously documented, different practices (e.g. moldboard plow vs. reduced tillage) can result in significantly different states of degradation (Zedler, 2003; Bruland et al., 2003).

A comparison of remnant natural prairies to restored prairies has shown that over time, restored soils have begun to function and store carbon as a natural soil (Brye and

Riley, 2009; Knops and Bradley, 2009). One study, from Wisconsin, comparing a 65- year old prairie restoration to a natural prairie remnant suggested that, over time, restorations will tend towards the natural undisturbed state, and may eventually reflect natural carbon cycling if carbon levels in the soil return to natural levels (Kucharik et al.,

2006). Another recent study has demonstrated that carbon will build up over time in reclaimed soils of all types (Knops and Bradley, 2009). Unfortunately, previous research has also indicated that the ability to continually build up carbon in soils is limited, and natural levels may never be reached. These same principles hold true for wetland areas. Research done on wetland restoration sites in Pennsylvania indicated that after a decade in restoration, soil organic matter levels had improved but not yet reached those of naturally occurring wetlands (Campbell et al., 2002).

Research in the area of wetland restoration routinely documents that the levels of organic carbon in the soils of restored wetlands are significantly less than that of natural

12 wetlands (Lal, 2004; Ballantine and Schnieder, 2009; Hunter et al., 2008; Sutton-Grier et al., 2009). One reason for this may be that restoration efforts themselves, such as earth moving and regrading, have adverse impacts on carbon cycling and microbial populations (Sutton-Grier et al., 2009). Microorganisms play a critical role both in the decomposition of fibric plant materials and the transport of carbon containing material to depth necessary to sequester carbon (Brady and Weil, 2002; Orr et al., 2007).

Research has indicated that litter decomposition and carbon cycling, and thus sequestration, is faster in natural sites than in restored or created wetlands (Fennesey et al., 2008).

Wetlands that are drained for agricultural purposes are also generally stripped of trees and other native vegetation. This poses another restriction on the success of wetland restorations. Given that native wetlands have established nutrient cycling regimes and established vegetation, research has shown that forested wetlands do not release as much carbon as non-forested wetlands when faced with drought conditions

(Sulman et al., 2009). Considering that it can take decades for restored wetlands to return to stable climax communities, young non-forested wetlands can readily lose high amounts of their stored carbon and undergo nutrient form transformation when faced with extended periods of drought conditions (Venterink et al., 2002; Gleason et al.,

2005).

13 plants (Abid and Lal, 2009; Reeder et al., 1998). Soil organic matter will retain water under drier conditions. Soil organic matter is also an important source of the Nitrogen,

Phosphorus, and Sulfur which are utilized by plants and microorganisms (Brady and

Weil, 2002; Cardon, 1996).

Soil Nitrogen and Wetlands

Carbon is not the only element of importance within the wetland soil matrix.

Nitrogen (N) levels are also indicators of shifts from disturbed to restored wetland states. Nitrogen, like carbon, cycles through the atmosphere, plant material, and soil.

The majority of N in the soil is held in organic compounds. Organic nitrogen cannot be leached to the groundwater nor can it be used by other organisms. Through mineralization organic N is converted to plant available forms. Available N (nitrates) can be leached from the soil profile and under anaerobic conditions, through the process of denitrification, can be lost to the atmosphere in the form of nitrogen gas (Brady and

Weil, 2002). Nitrate levels in groundwater are closely monitored due to health concerns associated with nitrates in drinking water (Knobeloch et al., 2000) and threat of eutrophication in lakes (Schindler et al., 2008). Wetlands have a well documented history of removing nitrates from ground water through denitrification (Orr et al., 2007).

Given that excess nitrates largely come from agricultural waste and nitrification of ammonia fertilizers and that the majority of WRP locations are in agricultural landscapes, the removal of nitrates from runoff water is a service that can‟t be ignored

(Bartzen et al., 2010; Orr et al., 2007).

Research on the behavior of nitrogen in accordance with a shift in land use mirrors that of carbon. Total nitrogen (TN) (organic and inorganic) levels in degraded soils appear to be reduced when compared to undisturbed soils and restored soils

(Knops and Bradley, 2009; Jelinski and Kucharik, 2009; Zedler and Callaway, 1999).

Inorganic forms of N can be higher at restored wetlands than native wetlands, especially in the first year after restoration. Having higher levels of soil inorganic N at restorations is generally attributed to fertilizer legacy.

Monitoring soil nitrogen and organic carbon levels is useful in assessing the condition of a soil (Zedler and Callaway, 1999). The carbon to nitrogen ratio is an indicator of soil health (Craft, 2001). Generally, soil microorganisms require eight parts carbon for every part of nitrogen that they utilize (Brady and Weil, 2002). However, microorganism only assimilate roughly one third of the carbon they metabolize.

Therefore, microorganisms require a total C:N ratio of 24:1. If the C:N ratio in the soil complex is wider than 24:1, microorganisms will utilize nearly all nitrogen leaving little soluble nitrogen for plant life to utilize. Research has shown that the increased incorporation of SOC into wetland soils increases the amount of nitrogen available to plants (Bailey and Lazarovits, 2001; Sutton-Grier et al., 2009) and improves soil C:N ratio (Craft, 2001).

Soil Phosphorus and Wetlands

Phosphorus can be used as an indicator of differences in the function of restored and native wetlands. The Phosphorus (P) cycle lacks an atmospheric component,

15 thusly P is only supplied or stored in plant material, water, or the soil itself (Richardson and Vepraskas, 2001).

Rapid fluxes in phosphorus levels are observed in parallel with plant life cycles.

Uptake by plants and adsorption to soil colloids are the primary removal mechanisms of available P forms (Orr et al., 2007). Also, P levels in wetlands can exhibit rapid change with occurrence of large runoff events (Kleinman et al., 2002). These large fluxes in P level, especially in free flowing surface and groundwater, make it more difficult to relate

P level to the health of a restored wetland (Hogan et al., 2004). Research has indicated that P levels are higher in natural wetlands than at restored wetland locations because of the amount of SOC (a source for P), but retention capabilities may be greater in restored wetland locations because of the increased ability to hold more organic matter and adsorb more P in depleted profiles (Hogan et al., 2004).

Phosphorus forms in soils and groundwater are highly dynamic. Soluble organic phosphorus can be leached through the soil profile as well as be transported via the groundwater into lakes and wetlands (Schoumans and Groenendijk, 2000). The amount of phosphorus in solution will depend on the amount of P that can be fixed by the soil and stored in plant material. Soil organic carbon and soil mineralogy can affect the equilibrium phosphorus concentration. Soil pH will affect the immobilization of soluble

P. The amount of P that can be adsorbed by the soil is largely dependent on the amount of oxidized iron and aluminum at low pH (Pant and Reddy, 2000). Under higher pH conditions, P will be more readily immobilized by calcium compounds

(Mallarino, 1997).

Phosphorus can also be supplied via fertilizers and agricultural wastes to wetlands (Kleinman and Sharpley, 2003). Wetlands have been branded as a potential non-point source of phosphorus on the landscape (Qui and McComb, 1994).

Depending on the environmental conditions present, wetlands may release P held in the soil or vegetation into the surrounding landscape via transport by ground or surface water. If concentrations of P in solution are less than the amount bound to soil colloids,

P will move into solution. It is important to understand that the wetlands themselves are not the initial source of this P. Excess P in the environment is potentially very damaging to all freshwater systems because P is typically the limiting nutrient in freshwater systems (Correll, 1998). Excess P will lead to the eutrophication of lakes and wetlands

(Daniel et al., 1998). The explosion of plant and algae life in wetlands can ultimately lead to the depletion of dissolved oxygen in the water column yielding ecological dead zones. As the vegetation and algae die off, microorganisms that decompose the dead vegetation utilize all the available dissolved oxygen in the water.

Soil Sulfur and Wetlands

Sulfur (S) can also be used to gauge the state of restored wetlands in comparison to natural counter parts. The S cycle is primarily driven by a series of reduction and oxidation reactions. Sulfur can be supplied to wetlands and the soil through a variety of avenues. Sulfur is predominantly provided by plant residue, but can also be supplied by fertilizers, pesticides, and atmospheric deposition (Inglett, 2008).

Additionally, mapping and quantifying soil sulfur can indicate differences in function and chemical processes within both natural and restored wetlands. Drained wetland soils will release sulfur into the environment (Zohary and Hambright, 1999). Sulfur levels in

17 the soil are positively correlated to the amount of soil organic matter (Walker and

Adams, 1958). Differences in sulfur levels between native and restored wetlands should correlate positively with the amount of organic matter found at the sites.

Sulfur has four main forms in the soil and ground water including sulfates, sulfides, organic sulfur, and mineral sulfur. In most soils, large fractions of sulfur are held in the organic form and require microorganisms to mineralize this sulfur similar to N cycling (Freney and Stevenson, 1966). When atmospheric oxygen is excluded from the system, sulfur compounds are primarily reduced into sulfides. Under this scenario, volatilization and loss of sulfur to the atmosphere is can occur (Mitsch and Gosselink,

2000). In the presence of available oxygen, oxidation occurs resulting in the shift of sulfides and elemental sulfur into the sulfate form. Sulfate is readily available to plants.

Research at restored wetlands has shown that certain early succession wetland plant species are susceptible to sulfide poisoning (Seliskar et al., 2004).

Soil Physical Properties at Wetland Restorations

As previously discussed, soil nutrient levels can differ between natural and restored wetlands. Other soil properties can also be adversely affected by the draining of wetlands and the conversion to agriculture. The activities associated with land clearing and agriculture can produce radically different soil conditions in a very short period of time as soil characteristics such as bulk density, texture, color, horizonation, and depth of organic material can all be altered.

Agricultural practices at drained wetland sites reduce the amount microtopography relief by homogenizing the soil profile through tillage (Fennessy et al.,

2008). This can cause reduction in biodiversity in both plants and organisms (Bruland and Richardson, 2005). Homogenizing soil layers can undo hundreds of years of soil development in days. Tillage, a common agricultural practice, mixes soil layers (Ellert and Janzen, 1999). This mixing will result in shifts in soil color and horizonation.

Tillage can also lead to soil compaction, which increases the bulk density of the soil.

Bulk density tends to be higher at restored wetlands than natural locations (Hogan et al., 2004; Ballantine and Schneider, 2009).

Depth of organic material will also be adversely affected by shifting the land use away from native wetland and into agriculture. Surface elevation will subside due to increased decomposition rate under aerobic conditions created by draining the wetland

(Armentano and Menges, 1986; Wild et al., 1998). Organic matter is extremely light and is easily lost due to wind erosion (Lyles and Tatarko, 1986). Organic soil profiles will collapse when water is drained because the water filled pore space supports soil solids.

Objectives

The first primary objective of this research is to gauge the success of two young restorations located in a similar geologic area and to establish baseline data to benefit future research. Specific components of this objective include:

1. Classify the vegetative communities present at Lost Creek and Buena Vista to

determine the extent of similarity between undisturbed and restored locations

as well as to determine success of plantings;

2. Quantify for comparison the following soil characteristics between the

restored and native sites: Depth of organic rich material, soil texture, soil

color, Carbon content, Nitrogen, Sulfur, and Phosphorus content, and soil pH;

3. Accurately delineate the boundaries of the different wetland habitat types

within the larger wetland assemblage.

The second primary objective of this research is to quantify the amount of organic carbon built up in the soil of a selection of central Wisconsin WRP sites. Specific components of this objective include:

1. Determine a carbon sequestration rate in these wetland restorations.

2. Postulate maximum attainable carbon levels from local undisturbed sites.

3. Compare restored wetlands to natural wetlands to postulate time to return

to native conditions.

Chapter 2 – Analysis of vegetative communities and wetland soil properties at two central Wisconsin restored wetlands

Literature Review

Wetlands serve many different functions. One of the most important is their ability to filter and trap contaminants and excess nutrients. Additionally, wetlands provide services such as carbon sequestration and flood control, with total services estimated in 1998 at almost 33 trillion U.S. dollars annually across the globe (Mitsch et al., 1998). Given the importance of wetlands, it is disturbing to realize that the majority of the wetlands present in North America pre-European settlement are no longer in existence or functioning properly (Zedler, 2004). In Wisconsin alone, it has been estimated that of the 10 million acres of wetland ecosystems present before European settlement only 5 million acres remain (Wisconsin Wetland Association, 2009).

Presently, it is federal government policy from executive order under President George

Several government agencies in Wisconsin actively restore wetlands such as the

Department of Transportation (DOT) and Natural Resource Conservation Service

(NRCS, 2009a). Under farm bill programs such as Wetland Reserve Program,

Emergency Watershed Protection Plan and the Conservation Reserve Program, wetlands are restored or protected with minimal cost to the owner of the property

(NRCS, 2009a; NRCS, 2009b). Wetland Reserve Program is a voluntary program that

21 farmers can enroll in. It is currently funded by the Farm Bill, actually entitled the Food,

Conservation, and Energy Act of 2008, which is renewed every four to six years (USDA,

2010).

Key Concepts of Wetland Restorations

Service to approach conservation from the ecosystem management perspective

(USFWS, 2009). Ecosystem management approaches arose in the early 1990‟s and are described as tailoring management and restoration efforts to maintain the ecological

22 integrity of natural systems as a whole (Grumbine, 1994). With this in mind, restoration efforts should focus on restoring ecosystem functions in addition to fauna and flora.

Management goals that not only focus on hydrology, but also vegetative communities, nutrient cycling, and soil formation should be included in management plans for wetland restorations.

Wetland Vegetation

1998).

23 loosestrife [Lythrum salicaria]) or native (e.g. cattails [Typha spp.]) that can degrade the quality of restoration attempts (Zedler, 2000). Planting newly restored sites can help prevent colonization by invasive species (Perry et al., 2004; Daehler, 2003). Plantings are also done to help prevent soil erosion at the site (Zedler, 2000; USDA, 1998).

2009).

Soil Carbon and Wetlands

Carbon cycles naturally through aquatic and terrestrial ecosystems. The world‟s oceans and carbonate rocks serve as the largest reserve of stored carbon on the planet

(NASA, 2008). Terrestrial wetlands in colder climates also store significant amounts of carbon. Annually, more than ten times the amount of carbon is lost from the soil to the atmosphere than carbon contributed to the atmosphere from the burning of fossil fuels, but soils can actively store carbon as well (Lal, 2007). The carbon cycle is dynamic with soil acting as both a source and a sink of atmospheric carbon depending on variables

24 such as the exclusion of atmospheric oxygen by water inundation which slows decomposition rate or the creation gases like methane which release carbon to the atmosphere. Because of this wetlands can both sequester carbon and release it to the atmosphere. Wetlands are generally considered net sinks for carbon.

Carbon that would be stored in soil organic matter is released to the atmosphere as carbon dioxide during aerobic decomposition of that organic matter.

Increased aeration from practices such as tillage has increased the decomposition rate of the organic material (Brady and Weil, 2002). Cultivation is considered the most important factor in soil organic carbon loss (Lal, 2004; Euliss et al., 2006). Though this is only a secondary cause of increased carbon in the atmosphere, the opposite is being looked to as a major way to slow this trend. Changing to less disruptive land uses and restoring native wetlands, grasslands, and forests may increase the amount of carbon stored in the soil and decrease atmospheric levels. This concept has been termed carbon sequestration. Research has shown that the conversion of conventional cropland to no-till cropland, or even undisturbed land, can increase the amount of organic matter (and carbon) stored in the soil (Buckley, 2008; Blanco-Canqui and Lal,

2008). In addition to reducing the amount of carbon in the atmosphere, increasing the soil carbon also improves soil structure and soil fertility (Karlen et al., 1994).

Studies have also shown that reversing soil carbon loss is possible just by shifting to less invasive land use practices such as restoring agriculture back to a natural state (Nelson et al., 2008). Conflicting research has also been presented demonstrating that while some improvement is seen, degraded wetlands may not return

25 to the natural state within a reasonable time line (Moy and Levin, 1991; Minello and

Webb, 1997).

When comparing restored wetlands to natural wetlands, it is essential to attempt to establish a baseline level of the amount of carbon at restoration sites before restoration is begun in order to better determine the success of the restoration.

Understanding the area receiving restoration was at one time a functioning wetland is key to identifying the success of the efforts as levels of degradation are not uniform.

For an area to be entered into the WRP, the site must be a wetland degraded by agricultural activity. As previously documented, different practices within a land use regime (agriculture, construction) can result in significantly different states of degradation (Zedler, 2003; Bruland et al., 2003).

A comparison of remnant natural prairies to restored prairies has shown that over time, restored soils have begun to function and store carbon as a natural soil (Brye and

Riley, 2009). One study, from Wisconsin, comparing a 65-year old prairie restoration to natural prairie remnant suggested that over time, restorations will tend towards the natural undisturbed state, and may eventually reflect true carbon cycling if carbon levels in the soil return to natural levels (Kucharik et al., 2006). Another recent study has demonstrated that carbon will build up over time in reclaimed soils of all types (Knops and Bradley, 2009). Unfortunately, previous research has also indicated that the ability to continually build up carbon in soils is limited, and natural levels may never be reached. These same principles hold true for wetland areas as well. Research done on wetland restoration sites in Pennsylvania indicated that even after more than a decade

26 in restoration, soil organic matter levels had improved but not yet reached those of naturally occurring wetlands (Campbell et al., 2002).

Research in the area of wetland restoration routinely documents that the levels of organic carbon in the soils of restored wetlands are significantly less than that of natural wetlands (Lal, 2004; Ballantine and Schnieder, 2009; Hunter et al., 2008; Sutton-Grier et al., 2009). Other research has indicated that restoration efforts themselves, such as earth moving and regrading, have adverse impacts both on carbon directly and on the microbial populations that affect carbon cycling in the soil (Sutton-Grier et al., 2009).

Increases in carbon content are not only good for the atmosphere, but also have many chemical and physical benefits to the soil profile. Increasing soil organic carbon

(SOC) has been shown to lower soil bulk density (Blanco-Canqui and Lal, 2007).

Having lower bulk density allows for better water infiltration and movement as well as increasing the rooting depth of plants (Abid and Lal, 2009; Reeder et al., 1998). Soil organic matter will help retain water under drier conditions. Soil organic matter is also an important source of Nitrogen, Phosphorus, and Sulfur which are utilized plants and microorganisms (Brady and Weil, 2002; Cardon, 1996).

Soil Nitrogen and Wetlands

Carbon is not the only element of importance within the wetland soil matrix.

Nitrogen (N) levels are also indicators of shifts from disturbed to restored wetland states. Nitrogen, like carbon, cycles through the atmosphere, plant material, and soil.

The majority of N in the soil is held in organic compounds. Organic nitrogen cannot be leached to the groundwater nor can it be used by other organisms. Through

27 mineralization, organic N is converted to plant available forms. Available N (nitrates) can be leached from the soil profile and under anaerobic conditions, and through the process of denitrification, can be lost to the atmosphere in the form of nitrogen gas

(Brady and Weil, 2002). Nitrate levels in groundwater are closely monitored due to health concerns associated with nitrates in drinking water (Knobeloch et al., 2000) and threat of eutrophication in lakes (Schindler et al., 2008). Wetlands have a well documented history of removing nitrates from ground water through denitrification (Orr et al., 2007). Given that excess nitrates largely come from agricultural waste and nitrification of ammonia fertilizers and that the majority of WRP locations are in agricultural landscapes, the removal of nitrates from runoff water is a service that can‟t be ignored (Bartzen et al., 2010; Orr et al., 2007).

(Knops and Bradley, 2009; Jelinski and Kucharik, 2009; Zedler and Callaway, 1999).

Soil Phosphorus and Wetlands

Phosphorus can be used as an indicator of differences in the function of restored and native wetlands. The Phosphorus (P) cycle lacks an atmospheric component, thusly P is only supplied or stored in plant material, water, or the soil itself (Richardson and Vepraskas, 2001).

Rapid fluxes in phosphorus levels are observed in parallel with plant life cycles.

(Mallarino, 1997).

(Daniel et al., 1998). The explosion of plant and algae life in wetlands can ultimately lead to the depletion of dissolved oxygen in the water column yielding ecological dead

30 zones. As the vegetation and algae die off, microorganisms that decompose the dead vegetation utilize all the available dissolved oxygen in the water.

Soil Sulfur and Wetlands

Adams, 1958). Differences in sulfur levels between native and restored wetlands should correlate positively with the amount of organic matter found at the sites.

2000). In the presence of available oxygen, oxidation occurs resulting in the shift of sulfides and elemental sulfur into the sulfate form. Sulfate is readily available to plants.

Research at restored wetlands has shown that certain early succession wetland plant species are susceptible to sulfide poisoning (Seliskar et al., 2004).

Soil Physical Properties at Wetland Restorations

Agricultural practices at drained wetland sites reduce the amount microtopography relief by homogenizing the soil profile through tillage (Fennessy et al.,

Tillage can also lead to soil compaction, which increases the bulk density of the soil.

Bulk density tends to be higher at restored wetlands than natural locations (Hogan et al., 2004; Ballantine and Schnieder, 2009).

Depth of organic material will also be adversely affected by shifting the land use away from native wetland and into agriculture. Organic matter levels will subside due to increased decomposition rate under aerobic conditions created by draining the wetland

(Armentano and Menges, 1986; Wild et al., 1998). Organic matter is extremely light and

32 is easily lost due to wind erosion (Lyles and Tatarko, 1986). Organic soil profiles will collapse when water is drained because the water filling pore spaces supports soil solids.

Objectives

The primary objective of this research is to gauge the success of two young restorations located in a similar geologic area. Specific components of this objective include:

1. To classify the vegetative communities present at Lost Creek and Buena

Vista to determine the extent of similarity between undisturbed and restored

locations as well as to determine success of plantings;

2. To quantify for comparison the following soil characteristics between the

restored and native sites: Depth of organic rich material, soil texture, soil

color, Carbon content, Nitrogen, Sulfur, and Phosphorus content, and soil pH;

3. To accurately delineate the boundaries of the different wetland habitat types

within the larger wetland assemblage.

Materials and Methods

Site Location

This study was conducted by measuring variables at one native and two recently restored wetlands (Lost Creek and Buena Vista). All studied wetlands were located in

Portage County, WI.

The local climate at the study area can be classified as temperate. There is 66.7 cm (32.7 in) of rainfall annually with a mean annual temperature of 6.8 ° C (44.2 ° F).

Most of the rain falls in the spring and summer months. Typically there are 120 cm

(47.8 in) of snow accumulation. (Wisconsin State Climatology Office, 2009)

Lost Creek and the Buena Vista restorations are located in the sand-plain province of Portage County, Wisconsin. This region lies with in what used to be the edge of Glacial Lake Wisconsin. The dominant parent material for soil in this region is outwash sand. (NRCS, 2011)

The Lost Creek study site is located in Section 30 T24N R9E about ¾ of a mile

NW of the junction of County Highway J and US Highway 10 in Portage county. The restoration site covers 323 acres and is hydrologically attached to the native wetland just to the north. Figure A.1 depicts the location and the boundaries of the mitigation site as well as the location of the native site (Appendix A). The Lost Creek restoration was conducted by private consultants in association with the Army Corps of Engineers.

Data was also collected from an NRCS Wetland Reserve Program (WRP) site near the Buena Vista Marsh in Portage County. The Buena Vista WRP site is located in

Section 22 T21N R7E at the corner of town road Evergreen and County Highway F in

34 the township of Grant. This restoration site covers 270 acres and is hydrologically attached to a native wetland slightly south and west. Figure A.2 depicts the location of

Buena Vista WRP restoration. Access was not granted to test the proposed control site.

Present Conditions

The wetland restoration attempt at Lost Creek began in the fall of 2008 to reclaim a wetland that was drained for agricultural purposes. Hydrology was restored by using ditch plugs and breaking the drain tile that was used to lower the water table.

Several scrapes were also done at this site. Hydrology was restored to the Lost Creek restoration site in fall 2008. Prior to restoration, the site had been intensively farmed.

Significant topsoil mixing has occurred from both farming and the redistribution of top soil through restoration efforts. The objectives of the restoration effort were to restore hydrology, return several different wetland plant communities to the site including wet sedge meadow, shallow marsh, and deciduous lowland swamp, retain and restore hydric soil characteristics at the site, and bring back the nutrient cycling processes associated with the various wetland plant community and hydrologic wetland types.

Some tree and aquatic vegetation plantings have occurred at the Lost Creek

Restoration site. The vast majority of the Lost Creek Restoration site was allowed to grow fallow for the summer of 2009. Further, plantings and spreading of desired seed mixes occurred during the fall of 2009 and spring 2010. The wetland site was also burned during the fall/winter 2009 in an effort to propagate desired vegetation.

Eight ground water wells were established at the Lost Creek site. The wells are distributed across the site (locations shown on Figure A.3). A selection of these wells

35 served as reference points for gathering soil and vegetation samples. The addition of randomly selected points for soil pits and vegetation plots were also added to maintain uniformity of the study.

The Buena Vista restoration was completed in 2007. Similar efforts to restore hydrology were done at the Buena Vista restoration site as were done at the Lost Creek

Restoration site, including ditch plugs and vegetative planting. No ground water wells were installed at this location. This site was planted with a mix of brome grass (Bromus spp.), timothy (Phleum spp.), little bluestem (Schizachyrium scoparium), leadplant

(Amorpha canescens), round headed bush clover (Lespedeza capitata), and cream false indigo (Baptisia bracteata).

Based on reports from corresponding agency personnel, both restored sites have undergone extensive earth moving and topsoil mixing. According to NRCS soil survey, the dominant soils at both sites were Markey and Roscommon. Detailed descriptions of both series are in Appendix B. Soil investigation at the sites has indicated that the soils are no longer histosols and can be classified as either „histic epipedons‟ or „mixed mineral‟ hydric soil designations. Table 2.1 describes these designations. Soil profiles were described for color, texture, and depth of organic rich material at each location

(Appendix B).

Data Collection and Analysis

To gauge the success of the restoration efforts, measureable variables were compared to the analogous native wetland connected to the site Lost Creek restoration site. Using previously undisturbed wetland sites as a barometer of success is common practice (Ashworth, 1997; Campbell et al., 2003; Zedler, 2000). This allows for a direct comparison of local plant communities as well as comparison of local hydric soil characteristics and nutrient storage.

Data was collected on vegetation, bulk density, depth of organic rich material, soil texture, soil color, soil pH, and carbon and nutrient content. These measurements were taken to establish the amount of soil degradation that had taken place and provide baseline values to better understand the recovery of restored hydric soils during future sampling efforts. Nutrient levels were recorded to indicate how nutrient storage differs between recently restored and native wetlands. Both total nutrient content and nutrient form are reported to better understand the aerobic and anaerobic soil conditions which may affect nutrient cycling.

Vegetation Sampling

Plant samples were taken in summer and fall of 2009 at reference and randomly generated points within both the native and restored sites. Plants within 1 m by 1 m plots were tallied in an effort to determine type and composition of plant community.

Sampling effort (four 1 m by 1 m plots at each location) was constant for all sites to allow for comparative analysis. Plants were only removed from the site if field identification could not be made. Both the Shannon-Weiner biodiversity index (H‟) and

37 the Simpson diversity index (D) were used to compare the native and restored locations. Similar data collection and analysis are required for both allowing their simultaneous inclusion in this study without additional sampling or analysis effort. The

Shannon-Weiner biodiversity index uses the following formula to calculate a relative value of biodiversity:

s H' = - L (Pi lnpi) i=l [Eq. 2.1]

Where pi is the probability of witnessing that plant species at that specific location and S is species richness. Based on the relationship of pi to S, each data set has a unique maximum value for biodiversity (Hmax) which can be calculated thusly:

s 1 1 1-Imax. = - L S ln S = lnS. 1= 1 [Eq. 2.2]

A measurement of evenness (J) allows for comparison of communities based on the quotient of H‟/Hmax. Evenness is a reflection of how well each plant is represented in the community and is correlated to the total number of plants sampled. The result from the evenness calculation is reported as a value between 0 and 1, with values closer to one being a more even community. This calculation is similar to how Simpson biodiversity index is tabulated. The relationship for determining Simpson is:

[Eq. 2.3]

Where the use of S is the same as Shannon-Weiner but pi is now the proportion of each species counted based on the total number tabulated. The Simpson index provides the researcher with a relative number between 0 and 1, with values closer to 0 indicating a better measure of diversity.

Species richness and stem count were also tallied and reported to further understand differences between the wetland locations. Plant communities were compared using a simple species overlap comparison to illustrate differences and similarities between restored and control sites.

Randomly generated transects were also walked in the spring and early summer of 2010 to confirm boundaries of the different vegetative communities at the sites based off aerial photo analysis.

Soil Property Analysis

Soil pits were opened to a depth of 90 cm (36 in) or to parent material if shallower. Profile descriptions were done at randomly generated points in both control and restored areas in order to compare soil characteristics and pedological development. Depth of organic rich material and horizonation were determined for each location. Mineral layers were described for color (Munsell Soil Charts), texture, and diagnostic horizons (American system of soil classification). In addition, soil bulk density was determined at a depth of 12 cm (5 in). Organic soil layers were described based on depth of organic material, color (Munsell Soil Charts), and bulk density. Bulk density was determined in duplicate at each sampling location. Bulk density was

39 measured by determining the oven dry mass of soil in an open brass ring of known volume.

Soil Nutrient Analysis

Additional soil samples were collected at randomly generated points by taking soil cores to 25 cm (10 in) as a composite (three soil cores). These samples were used for analysis of nutrient content and carbon content. The composite samples for all analysis were stored in a freezer between field sampling and lab analysis to prevent breakdown of soil organic matter or conversion of chemical forms. Values for water content by mass, carbon content, ammonium, nitrate, pH, sulfate, and phosphorus were quantified and documented for each soil sample. Water content was determined gravimetrically after drying for 24 hours. The organic carbon content and total nitrogen

(TN) content in the soil were quantified through combustion of organic materials (Houba et al., 2000) using a Carbon and Nitrogen Analyzer (Costech Analytical Technologies

Inc., Valencia, CA).

Values for ammonium and nitrate were quantified by the steam distillation method for measuring exchangeable ammonium and nitrate (Stevenson, 1982). The amount of organic N can be estimated by subtracting the values obtained for ammonium and nitrate from TN levels. Soil pH was determined by using the 1:1 0.01M

CaCl2 method (Watson and Brown, 1998) and a Ross pH electrode (Thermo Scientific

Orion, Waltham, MA). Sulfate content of samples was determined using the turbidimetric procedure (Combs et al., 1998) including charcoal filtering to reduce the interference of organic matter. Phosphorus levels were quantified using the Olsen P test method (Frank et al., 1998).

Statistical analysis to compare nutrient levels, pH, and bulk density values between the natural to restored sites was performed. One-way ANOVA was utilized in

PASW Statistics 18 (IBM SPSS, Somers, NY, U.S.A) to determine differences between values obtained for the native wetland and each restored wetland respectively. The number of repeated measures taken at each wetland location was used as the number of replicates. Equality of variance (Levene‟s Test) and normality (Shapiro-Wilk) was confirmed for all data presented in this research. An alpha of 0.05 was used for all tests to determine significance.

Results and Discussion

Plant Surveys and Diversity

Plant communities varied from location to location. A visual comparison of the native location to the restored locations indicated that the native wetland was forested with a dense understory while the restored wetlands lacked any tree canopy cover, but were densely vegetated.

A total species richness comparison of the native location to the restored locations indicated that the native location had the most species present (19) while the

Buena Vista (14) and Lost Creek (11) locations had less species present (Table 2.2).

Similar results were observed at restored and native locations used in Chapter 3 of this work. Typically, native wetlands have greater plant species richness than do restored wetlands (Galatowitsch and Valk, 1996).

Comparison of the plant species present at the locations surveyed, indicated that only one plant species (Goldenrod [Solidago spp.]) from the native location was found at both restoration locations. Additionally, willow (Salix spp.) was found at the Buena Vista location and the native wetland. All locations had a different dominant plant species based on stem count. Lost Creek Restoration site dominant plant species was Lamb‟s

Quarters (Chenopodium album) which is commonly considered an agricultural weed

(Chomas et al., 2001). At the Buena Vista marsh WRP restoration, the dominant species was Little Bluestem grass, which was one of the species planted at the site. At the native wetland location the most numerous species was nut sedge (Cyperus esculentus). Complete plant lists can be found in Appendix D.

Total number of stems also varied from location to location. The native location had the fewest total number of stems (886) as compared with the Lost Creek location

(1801) and the Buena Vista location (1254) (Table 2.2). Canopy cover at the natural wetland was thought to have limited density of plants at the natural wetland. Grasses and weed seedlings were numerous at both restored locations resulting in a greater stem count at those locations.

The Shannon-Weiner biodiversity index revealed that the native location was more diverse than either the Buena Vista or Lost Creek restoration. Native locations have been shown to have a more diverse plant community than restored locations

(Galatowitsch and Valk, 1996). The Shannon-Weiner index does not compare locations based on similarity of the plant communities, only on the number of species and the relative distribution of the species recorded during the survey. Plant community evenness was calculated from values obtained from the Shannon-Weiner biodiversity

42 index and potential maximum value if all plant species were represented equally. On the resulting evenness scale (values range from 0 to 1), values closer to one indicate a plant community that is even in its representation of the plant species there. Lost Creek had an evenness value of 0.48 while the native location had an evenness value of 0.66.

This comparison shows that the native wetland has a more equal representation of the plant species found at the location. Buena Vista had an evenness value of 0.66 which is identical to the native location, meaning that both the native wetland and Buena Vista have equal representation of their respective plant communities (Table 2.2). The success of the plantings and that the vegetation has had three years to establish itself are potential reasons for the similar evenness values between the Buena Vista restoration and the native wetland.

The Simpson Biodiversity Index indicated that the native location was more diverse than the Lost Creek location, but was less diverse than the Buena Vista location

(Table 2.2). The Simpson index is more akin to the measurement of evenness obtained from the Shannon Weiner index than the actual measure of diversity calculated by the

Shannon Weiner index. The scale for the Simpson index (0 to 1) holds values closer to

0 as having a more diverse community and values closer 1 having a less diverse community. The Buena Vista location had a Simpson value of 0.21 for the Buena Vista location and a value of 0.27 for the native location. The Simpson index gives no weight to plants occurring once during the sampling and also does not factor in species richness. The native wetland had several species occurring only once during the sampling efforts, causing the Buena Vista wetland to register a lower value and be considered more diverse according to this index.

Limited data is available for gauging success of plantings at both Lost Creek and Buena Vista because of incomplete records of restoration efforts, and continued vegetative restoration efforts during the sampling period (more so at Lost Creek than

Buena Vista). At the Buena Vista restoration, it was indicated that Leadplant, Smooth

Brome, False Cream Indigo, Timothy, Little Blue stem, and Round headed bush clover were planted on the site. Little Bluestem was the most numerous species of plant surveyed at the location (Table 2.3). Of the six plant varieties planted at the location, four were detected during the survey (Little Blue Stem, Timothy, Leadplant, and Smooth

Brome). These species comprise 62% of the plant community based on stem frequency (Table 2.3). No data is present for plant community composition before planting efforts were completed. The planting efforts at Buena Vista were successful for establishing the desired plants as the dominant plants at the location as the biodiversity and evenness values at the Buena Vista location had similar values to the native location. While the plant communities were very different in composition, the plantings seemed to provide the vegetative cover and variety that could be utilized by wildlife.

Soil Physical Property Analysis

Soil pit analysis showed that the restoration locations both met the criteria for hydric soils under the S1 designation (Sandy Organic rich mineral material). Organic horizons were also found at the Lost Creek and Buena Vista sites at multiple locations, but these horizons were not substantial enough to qualify these soils as A1/A2 designations. The native location met the hydric soil designation of A1 (Histosol) and

A2 (Histic epipedon) depending on sampling location. Complete soil profile descriptions are included in Appendix B.

Soil bulk density was lowest at the native wetland (0.28 g cm-3). Lost Creek and

Buena Vista had similar bulk density values of (0.83 g cm-3 and 0.94 g cm-3, respectively

(Table 2.4). Bulk density values tend to be higher at restored locations than native

(Chapter 3). This difference is commonly attributed to surface soil layers mixing with sub-soil and compaction from agricultural practices and restoration activities.

Depth of organic rich material differed between locations. The native wetland had an average depth of 100+ cm (40 in) for locations meeting A1 designations and a depth of 22 cm (8.6 in) for sites meeting the A2 designation. Lost Creek had an average organic rich material depth of 27 cm (10.6 in), while the Buena Vista location had an average depth of 20 cm (7.8 in) (Table 2.4). Subsidence of organic soils is one reason for the difference between the sampling locations. Subsidence of organic soils can be attributed to a variety of causes, including water being drained from the profile. This results in the collapse of the soil profile because water was filling pore spaces and supporting the solids. Also, organic matter is consumed more rapidly in drained soils because of the introduction of atmospheric oxygen and thus can be a cause of subsidence of organic soils. Another reason for reduced depth is that restoration and agricultural practices compact the soil. Once drained, organic soils are also highly susceptible to wind erosion (Kohake et al., 2010) resulting in further decrease in surface horizon depth.

Water content by mass also varied between locations. The native wetland had greater water content by mass than either the Lost Creek or Buena Vista wetland (Table

2.4). This difference can be attributed to the increased amount of organic matter in the

45 native soils. Organic soils have a greater water holding capacity than soils that are sandy in nature (De Kimpe et al., 1982).

Soil Nutrients and pH

Soil nitrogen (nitrate, ammonium, TN), sulfur, phosphorus, carbon, and pH were quantified for Lost Creek and Buena Vista restorations in addition to the native wetland control .

Nitrogen

Inorganic soil nitrogen forms (nitrate, ammonium) were significantly (p < 0.05) greater at the native location than at either wetland restoration attempts (Table 2.5).

Total N was also significantly (p < 0.05) greater at the native wetland than at the restoration sites (Table 2.5). These findings are supported by the work of Hogan et al.,

2004, Bishel Machung et al., 1996 and Fennessy et al., 2008. Levels of TN in the soil profile are linked directly to the amount of soil organic matter in the soil, which was greater at the native location (Table 2.5). The relationship between TN and soil organic matter suggests that the native wetland would have greater amounts of TN because of the increased amounts of soil carbon measured there. Native wetlands have the established bacterial communities needed for cycling nitrogen in addition to well established hydric regimes and plant communities allowing for the presence of both organic and inorganic forms of N in the soil profile (Windham and Ehranfeld, 2003). At restored locations, inorganic forms of N would have been quickly leached through the profile with the reintroduction of water and inorganic N would have been utilized by the propagation of dense vegetative communities.

Sulfur

Sulfate levels recorded for the restorations were more variable than nitrogen levels. The native control wetland had significantly similar, but numerically lower levels of sulfate than the Lost Creek Restoration (Table 2.5), however, sulfate levels were more variable throughout the Lost Creek (7 – 84 ppm) location than the control wetland

(21 – 40 ppm). Sulfate levels at the Buena Vista restoration were significantly (p < 0.05) lower than those of the native wetland. Sulfate levels at wetlands are driven by a variety of mechanisms including volatilization, mineralization, and uptake by plants. At the Buena Vista restoration, low levels of sulfate could have been caused by the release of sulfur to the atmosphere under anaerobic conditions as well as limited contributions of sulfate from soil organic matter. In addition, vegetation at the site may have utilized sulfate in the soil. The depression of sulfate levels at Lost Creek due to the utilization by plants may not be as exaggerated because of the limited amount of time since restoration. The large variation in sulfate levels at the Lost Creek restoration location can be explained by the very young age of the restoration resulting in the sulfur cycling being in a state of flux because recent inundation with water. The native location depicted some variation in sulfate levels, but overall was far more constant than at the

Lost Creek restoration. The presence of an established nutrient cycling regime based upon the supply of soil organic matter and presence of microbes to release sulfate even under anaerobic conditions explains the presences of sulfate (Combs et al., 1998).

Also, allowing the samples to air dry over a 24 hour period for laboratory analysis could have precipitated additional sulfate between sampling and laboratory analysis as sulfate is generated under aerobic conditions (Brady and Weil, 2002). Generation of sulfate

47 because of drying would have had the largest effect on samples from the native location given that these samples would have had the largest supply of sulfur from organic matter.

Phosphorus

Phosphorus levels were largely undetectable at both the native control wetland and Lost Creek locations. Lost Creek site had one sampling location with a quantifiable amount of 4.0 ppm P. Phosphorus levels at the Buena Vista restoration averaged 3.0 ppm (4.3 to 0.1 ppm) (Table 2.5), which is greater than values from the native wetland.

The Olsen P test is best suited for neutral and basic soils because the extracting solution (sodium carbonate) is prepared at a pH of 8.5 to facilitate the extraction of P from calcium phosphates and P adsorbed to calcium carbonates (Frank et al., 1998,

Elrashidi, 2001). In neutral to basic pH soils, the primary source of phosphate is as calcium phosphate as opposed to acidic soils, which contain aluminum, iron and manganese phosphates (Elrashidi, 2001). The Olsen method was utilized because of existing laboratory set up and budgetary confinement. The Olsen method for extracting

P is not the preferred method for these soils given that all soils tested were in the acidic pH range. Additionally, tests with 5N HCl to reveal the presence of inorganic carbon compounds such as calcium carbonate were negative. To better understand the assemblages of P at both the native and restored wetland locations, further testing of soil P is required.

Soil Organic Carbon

Soil organic carbon concentration levels were more than 4 times greater (p <

0.05) at the native location than at either restored wetland location (Table 2.5). Soil organic carbon levels exhibited minimal levels of variation (< 3%) within each wetland site.

Soil organic carbon concentration reductions between native and restored wetlands have been well documented (Hogan et al., 2004; Fennessy et al., 2008.;

Ballantine and Schnieder, 2009; Zedler, 2000). The loss of SOC to the atmosphere because of the introduction of atmospheric oxygen through drainage and tillage during prior agricultural operations at the restored sites is thought to be the primary cause for the lower soil SOC levels at restored sites (Lal, 2007).

Soil pH

Average soil pH levels recorded at all locations were acidic in nature. Soil pH values at the Lost Creek Restoration varied from 7.4 to 5.7. Soil pH levels were more consistent at the Buena Vista location varying only slightly (5.6 to 4.6). Soil pH levels at the native wetland were less variable (5.6 to 5.7) than those at restored locations. Soil pH levels were not significantly (p > 0.05) different between the Lost Creek restoration and the native wetland, but Buena Vista soil pH levels were significantly (p < 0.05) lower than those recorded at the native wetland (Table 2.5). While the variation in pH is significant, the difference is not surprising nor is it extreme enough to believe that an environmental factor is drastically lowering the soil pH at Buena Vista. Wetland soils typically have acidic pH values (Mitsch and Gosselink, 2007).

Conclusions

The wetland restorations at Lost Creek and Buena Vista are both different than the native wetland associated with the Lost Creek Restoration in terms of soils (physical properties and nutrient levels) and vegetation.

The soils at the locations had been significantly altered as compared to the native wetland. The most recent soil survey for the study area indicated similar assemblages of soils at the native and restored wetland locations. Based on comparison of soil properties such as depth of organic material and bulk density, restored soils are no longer similar to the soils at the native location.

Soil nutrient levels provided another avenue of comparison between the native and restored wetlands. Soil carbon levels were significantly greater at the native location than either of the restored wetlands. Additionally, trends in sulfur and nitrogen levels in the soil were similar to carbon and were typical of recently restored wetlands.

The failure of this research to accurately quantify the amount of phosphate in the soil highlights the need for researchers to be diligent in the selection of tests utilized for quantifying soil nutrients.

The wetland vegetative communities were very different between the locations studied. The native wetland had the most diverse plant community and had greatest number of different species. Efforts at the Lost Creek site to restore vegetation were ongoing during the sampling window limiting the conclusions that can be drawn from the data. The plantings at the Buena Vista location appeared to be successful in the fact that a majority of the species planted were captured during the survey. Additionally, the

Buena Vista location rivaled the native location in both overall diversity and evenness, but had a dissimilar overall plant community

Table 2.1. Alpha numeric designations assigned to the hydric soils at WRP and Native locations in Central Wisconsin Alpha Numeric Description of Hydric Soil Designation Listing A1 Histosol - 40 cm (16 inches) or more of the upper 80 cm (32 inches) is organic soil material. Can contain sapric, fibric, and hemic components. A2 Histic Epipedon - 20 cm (8 inches) or more of the upper 80 cm (32 inches) is organic soil material. Can contain sapric, fibric, and hemic components. S1 Sandy Organic rich materialy Mineral - Mineral soils where the organic carbon content is at least 5 percent to as high as 14 percent for sandy soils. S4 Sandy Gleyed Matrix - gleyed (colors appearing on the gley pages of the Munsel Color book) matrix present within 15 cm (6 inches) of the surface. (NRCS, 2010a)

Table 2.2. Vegetation Diversity Summary for Lost Creek Buena Vista and Native Locations Location # of Richness1 Native to Shannon S-W J Simpson Stems Restored Weiner H‟ Evenness Index 2 3 4 Overlap (H‟max) Index

Native 886 19 NA 1.95 (2.94) 0.66 0.27 Lost Creek 1801 11 1 1.16 (2.39) 0.48 0.44 Buena Vista 1254 14 2 1.76 (2.64) 0.66 0.21 1 Number of different species surveyed at that location 2 Number of species from native wetland also found at restored location 3 H‟max is largest possible value for diversity given the number of species surveyed at that location 4 S-W J refers to the Shannon-Weiner evenness scale described in methods section

Table 2.3. Buena Vista Restoration Planting Success Analysis Planted Species Stem Count Percent of Total Brome Grass 84 6.6 Timothy Grass 282 22 Leadplant 1 <1 Little Bluestem Grass 416 33 Cream False Indigo ND1 ND Round Headed Bush Clover ND ND Totals 783 62 1 None Detected

Table 2.4. Soil Physical Properties at Native and Restored Locations Location Bulk Density (g/cm3) Depth of Organic Rich Water Content by Mass (%) Horizons (cm) Native 0.28 100+ / 22* 61 Lost Creek 0.83 27 33 Buena Vista 0.94 20 29 * A1 Designation Depth / A2 Designation Depth

- Table 2.5. Nitrogen (Nitrate [NO3 ], Ammonium [NH4+}, Total Nitrogen [TN]), Sulfur (S), Phosphorus (P), Soil Organic Carbon (SOC), and pH for the Native and Restored Locations

NO3 (ppm) NH4+ (ppm) TN (g/kg) S (ppm) P (ppm) SOC (g/kg) pH Control 30.21a1 46.91a 28.92a 17.13a ND2 378a 6.33a Lost Creek 10.83b 16.65b 7.33b 18.68a ND 88b 5.66a Buena Vista 11.03b 13.48b 5.3b 1.66b 2.97 54b 5.15b 1 Lower case letters a and b reveal significant differences (p < 0.05) between the restored and control wetland 2 None Detected

Chapter 3 – Carbon sequestration potential at central Wisconsin Wetland Reserve Program sites

Literature Review

Wetlands serve many different functions. One of the most important is their ability to filter and trap contaminants and excess nutrients. Additionally, wetlands provide services such as carbon sequestration and flood control, with total annual global services estimated in 1998 at almost 33 trillion U.S. dollars (Mitsch et al., 1998). Given the importance of wetlands, it is disturbing to realize that the majority of the wetlands present in North America pre-European settlement are no longer in existence or functioning properly (Zedler, 2004). In Wisconsin alone, it has been estimated that of the 10 million acres of wetland ecosystems present before European settlement only 5 million acres remain (Wisconsin Wetland Association, 2009). Presently, it is federal government policy from executive order under President George H.W. Bush that when wetlands are altered for construction or farming, new wetlands must be created or previously degraded wetlands must be restored so that there is no further net loss of wetlands (USFWS, 1994).

The Wetland Reserve Program

Protection Plan, and the Conservation Reserve Program, wetlands are restored or protected with minimal cost to the owner of the property (NRCS, 2009a; NRCS, 2009b).

The Wetland Reserve Program (WRP) is an American Farm Bill program established in 1995. Wetland Reserve Program is a voluntary program that farmers can enroll in. Via provisions in the bill, conservation easements are purchased on areas of land. A conservation easement allows the landowner to continue to own and recreate on the land, but gives administrative control of the land use to the Natural Resources

Conservation Service (NRCS, 2009a). The NRCS can offer 30- year easements as well as permanent easements. The value paid to the landowner depends on the length of the easement and property value of the land being included in the easement.

Landowners wishing to enroll lands in WRP must have areas of wetlands that have been degraded by agriculture and have owned the property for at least seven years.

Nationwide, 179,417 acres of wetlands have been restored under the WRP provision of the Farm Bill with 7,353 acres of wetlands being restored in Wisconsin as of December

2009. One of the largest contiguous tracks of WRP, Duffy Marsh, resides in Central

Wisconsin (NRCS, 2009c).

55 plant community, the restoration efforts should seek to restore these characteristics as the primary goals (Richardson and Vepraskas, 2001). Restoring ecosystem functions

(i.e. hydrology, vegetation, soils) takes longer than what are public expectations for the desired results to be witnessed on the landscape. Wetlands take a particularly large amount of time to establish nutrient cycling regimes and formation of hydric soils (Lal,

2007).

Soil Organic Carbon and Benefits to Wetland Soil Development

Carbon cycles naturally through aquatic and terrestrial ecosystems. The world‟s oceans and carbonate rocks serve as the largest reserve of stored carbon on the planet

56 to wetlands generally higher than the amount of carbon released from wetlands to the atmosphere (Armentano and Menges, 1986). In this manner, true organic soils are created. Histosols, the order in U.S. soil classification system for organic soils, are associated with wetlands. Histosols account for 23% of the carbon stored in global soils while only covering 1.3% of the globe (Brady and Weil, 2002). The shift from wet conditions that allow Histosols to store carbon to dry, aerobic conditions, allows for complex carbon compounds to be converted to carbon dioxide and lost to the atmosphere (Duff et al., 2009). This shift occurs when wetlands are drained for agriculture.

2006). Though this is only a secondary cause of increased carbon in the atmosphere

(contributions from automotives and industry are greater), the opposite is being looked to as a major way to slow the trend of increasing atmospheric carbon. Changing to less

57 disruptive land uses and restoring native wetlands, grasslands, and forests may increase the amount of carbon stored in the soil, thereby decreasing atmospheric levels.

Blanco-Canqui and Lal, 2008). In addition to reducing the amount of carbon in the atmosphere, increasing the soil carbon also improves soil structure and soil fertility

(Karlen et al., 1994).

Recent research from the Midwest and Wisconsin has been able to quantify anthropogenic influenced decreases in soil carbon as well as potential for restoration.

58 resulted in a higher loss of soil carbon than reduced tillage methods (Jelinski and

Kucharik, 2009; Al- Kaisi et al., 2005).

Land use shifts have been demonstrated to be an effective form of sequestering carbon. Studies have also shown that reversing soil carbon loss is possible just by shifting to less invasive land use practices such as restoring agriculture back to a natural state (Nelson et al., 2008). Conflicting research has also been presented demonstrating that while some improvement is seen, degraded wetlands may not return to the natural state within a time line that makes provides reasonable justification for restoration efforts (Moy and Levine, 1991; Minello and Webb, 1997). When comparing restored wetlands to natural wetlands, it is essential to establish a baseline level of the amount of carbon at restoration sites before restoration began in order to better quantify the success of the restoration. Understanding that the areas receiving restoration were all at one time functioning wetlands, but have undergone varying levels of degradation, is key to identifying the success of the restoration efforts. For an area to be entered into the WRP, the site must be a wetland degraded by agricultural activity and as previously documented, different practices (e.g. moldboard plow vs. reduced tillage) can result in significantly different states of degradation (Zedler, 2003; Bruland et al., 2003).

A comparison of remnant natural prairies to restored prairies has shown that over time, restored soils have begun to function and store carbon as a natural soil (Brye and

Research in the area of wetland restoration routinely documents that the levels of organic carbon in the soils of restored wetlands are significantly less than that of natural wetlands (Lal, 2004; Ballantine and Schnieder, 2009; Hunter et al., 2008; Sutton-Grier et al., 2009). One reason for this may be that restoration efforts themselves, such as earth moving and regrading, have adverse impacts on carbon cycling and microbial populations (Sutton-Grier et al., 2009). Microorganisms play a critical role both in the decomposition of fibric plant materials and the transport of carbon containing material to depth necessary to sequester carbon (Brady and Weil, 2002; Orr et al., 2007).

Research has indicated that litter decomposition and carbon cycling, and thus sequestration, is faster in natural sites than in restored or created wetlands (Fennesey et al., 2008).

2005).

Carbon sequestration is not only good for the atmosphere, it also has many chemical and physical benefits to the soil profile. Increasing SOC has been shown to lower soil bulk density (Blanco-Canqui and Lal, 2007). Having lower bulk density also allows for better water infiltration and movement as well increasing the rooting depth of plants (Abid and Lal, 2009; Reeder et al., 1998). Soil organic matter will retain water under drier conditions. Soil organic matter is also an important source of the Nitrogen,

Phosphorus, and Sulfur which are utilized by plants and microorganisms (Brady and

Weil, 2002; Cardon, 1996).

Objectives

It is the primary objective of this research to quantify the amount of organic carbon built up in a selection of wetland restorations in the WRP program in central Wisconsin.

Specific components of this objective include:

1. Determine the carbon sequestration rate at Central Wisconsin WRP

locations;

2. Postulate maximum attainable carbon levels from carbon content at local

undisturbed sites;

3. Determine the amount of time needed for restored wetland soils to return to

the native condition.

Materials and Methods

Wetland restoration attempts are abundant in central Wisconsin. To better understand the ability of restored wetland areas to build up organic carbon in the soil, a selection of WRP sites of different age were studied to determine the amount of organic carbon built up over time. To gauge the success of WRP efforts on central Wisconsin sandy soils, measureable variables were compared to analogous native wetlands in the same geologic area. Using previously undisturbed wetland sites as a barometer of success is common practice (Ashworth, 1997; Campbell et al., 2003; Zedler, 2000).

This allows for a direct comparison of hydric soil characteristics and carbon storage between restored wetlands and native wetlands. It is the primary objective of this research to quantify the amount carbon built up in the soil of a selection of central

Wisconsin WRP locations and compare those values to native wetlands. Specific components of this objective include determining a carbon sequestration rate, postulate maximum attainable carbon levels from carbon content at local undisturbed sites, and determine the amount of time needed for restored wetland soils to return to the native condition if restored wetlands exhibited this trajectory.

Site Locations

Composite soil samples were taken randomly from 32 WRP locations ranging in age from pre-restoration (WRP site approved for federal WRP funding, but had not experienced restoration efforts at the time of sampling) to 16 years post restoration and

5 native wetlands in the Central Sands region of Wisconsin, USA NRCS Major Land

Resource Area 89. This area lies on the edge of what is known as the “Driftless Area”

63 because it was not glaciated during the last advance nearly 10,000 years ago. Much of the area is dominated by outwash sands and was covered by Glacial Lake Wisconsin

(NRCS, 2011). The vegetative communities where sampling took place were defined by NRCS as emergent marsh and fresh meadow consisting of a mix of plant species including Cattial (typha spp.), Reed Canary Grass (Phalaris arundinacea), and Sedge

(Carex spp.).

All WRP sites one year of age or older were at one time native wetlands drained for agriculture and then restored. Pre-restoration sites had been native wetlands drained for agriculture, but had yet to be restored. Pre-restoration sites had dissimilar conditions at the time of sampling. Some locations were under fallow conditions, while others had a standing crop. Sampling was done in an effort to determine back ground levels of SOC at restoration sites and to determine the effects of restoration efforts and agricultural impact on the soil properties at the site. All sites were sampled based on availability and were not randomly selected from the population of sites within the study area. Sites were sampled in Wood, Portage, Marquette, Columbia, and Waushara counties. Site locations are indicated on Figure A.C.1 and A.C.2 (Appendix C).

Soils at the various sites were classified based upon the NRCS Field Indicators of Hydric Soils in the United States (2010). All sampled soils fell into the A1, A2, S1, or

S4 listings (Table 3.1) and were grouped into A1/A2 and S1/S4 categories for analysis and sample size considerations. Based on in-field inspection of soil pits, 13 WRP locations had A1/A2 designations and 12 WRP locations had S1/S4 designations.

Climate

The normal annual precipitation in Central Wisconsin ranges from 760 to 840 mm

(30 to 33 in). Most of the rainfall occurs as convective thunderstorms during the growing season. The annual snowfall ranges from about 90 to 125 cm (35 to 50 in) and generally occurs from October through April. The normal annual average temperature ranges from 6 to 7 degrees C (42 to 45 degrees F). The freeze-free period ranges from

135 to 165 days. (NRCS, 2011)

Data Collection

Selected WRP sites and natural wetlands were examined for the amount of organic carbon stored in the soil. Soil samples from post-restoration WRP sites for soil organic carbon testing were collected at randomly generated points in areas directly affected by the restored hydrology and containing necessary vegetative plant communities. This was determined by using site maps prepared by NRCS technical staff and the use of NRCS vegetation maps. Samples from pre-restoration sites were collected from areas that were expected to be directly affected by restored hydrology.

This was determined with the help of NRCS technical staff. Native wetlands were randomly sampled at locations clearly within the boundary of the wetland. This was determined by using the Web Soil Survey (NRCS, 2009d) and vegetation at the site. At each sampling location, data for carbon concentration, bulk density, and depth of organic rich horizons were collected to determine total amount of carbon sequestered.

Soil samples were collected by taking soil cores to 50 cm (20 in), or to parent material if shallower, as a composite (three soil cores) in 25 cm (10 in) increments. The

65 composite samples for all analysis were stored in a freezer between field sampling and lab analysis to prevent breakdown of soil organic matter.

Bulk density was determined in duplicate at each sampling location. Bulk density was measured by determining the oven dry mass of soil an open brass ring of known volume. In addition to bulk density, depth of organic rich material was noted for each sampling location.

The total (organic and inorganic) carbon concentration and total nitrogen concentration in the soil was quantified through combustion of composite soil samples

(Houba et al., 2000) using a Carbon and Nitrogen Analyzer (Costech Analytical

Technologies Inc., Valencia, CA). Soil samples were tested for the presence of inorganic carbon by the addition of 5N HCl (Schumacher, 2002) which would yield effervescence in the presence of inorganic carbon. No effervescence was noted for the soils in this study allowing the assumption that total carbon concentration as determined by the Carbon and Nitrogen Analyzer represents soil organic carbon. Samples were allowed to air dry, passed through a 2 mm sieve and ground before packaging and introduction to the Carbon and Nitrogen Analyzer. Each composite sample was homogenized and sampled in duplicate to ensure accuracy of results. Standards were included with each run of the Carbon and Nitrogen Analyzer to ensure uniformity of data collection methods.

Total organic carbon content of the soil profile was calculated as the product of carbon concentration, bulk density and depth of carbon rich soil and reported in units of g m-2.

Data Analysis

The relationship between carbon concentration and bulk density as well as the relationship between percent SOC and total nitrogen was explored (Excel 2007,

Microsoft Corporation, Redmond, WA, U.S.A). Significance of these relationships were determined using PASW Statistics 18 (IBM SPSS, Somers, NY, U.S.A) (α =0.05). A negative linear correlation between percent SOC and bulk density is well documented, and a positive linear correlation for total nitrogen and percent SOC is commonly accepted (Ballantine and Schneider, 2009; Post and Mann, 1990).

Regression analysis was used to model the relationship between carbon levels and length of time since completion of restoration for both A1/A2 and S1/S4 soils (Excel

2007). Significance of these models were determined using PASW 18 with an acceptable α level of 0.05.

Restored and native wetland soils meeting the A1/A2 designations were grouped by five year increments to maintain enough replicates for sound analysis. One- way ANOVA and Tukey‟s Post Hoc Test were utilized to compare the mean SOC concentrations and SOC content of these soils across time using PASW 18 with an acceptable α level of 0.05.

Restored and native wetland soils meeting the S1/S4 designations were grouped by ten year increments to maintain enough replicates for sound analysis. One-way

ANOVA and Tukey‟s Post Hoc Test were utilized to compare the mean SOC concentrations and SOC content of these soils across time using PASW 18 with an acceptable α level of 0.05.

Restored and native wetland soils meeting the S1/S4 designations and the A1/A2 designations were compared to each other based on SOC concentration, SOC content, bulk density, and depth of organic rich material. One-way ANOVA was utilized to verify significance in the mean difference for each of these variables using PASW 18 with an acceptable α level of 0.05. Equality of variance (Levene‟s Test) and normality (Shapiro-

Wilk) were confirmed for all data presented in this research (PASW 18).

Results and Discussion

Soil Organic Carbon Concentration

Soil organic carbon concentration at Central Wisconsin WRP locations was highly varied for all sites sampled (22 to 305 g kg-1). The variation was dampened by the division of the WRP locations based on hydric soil designations (Table 3.1).

Because of this, WRP locations will be analyzed based on the hydric soil classifications.

The A1/A2 locations had significantly (p < 0.05) greater average SOC concentration

(214 g kg-1) than the S1/S4 locations (32 g kg-1) (Figure 3.1). As the S1/S4 hydric soil designations are for mineral soils while the A1/A2 designations are for organic soils, it was expected that A1/A2 soils had more SOC. This difference between hydric soil types was verified by the finding that native locations with A1/A2 wetland soil designations also had a significantly greater (p < 0.05) SOC concentration (369 g kg-1) than native locations with S1/S4 hydric soil designations (86 g kg-1).

Comparison of A1/A2 and S1/S4 to their native counterparts indicated that the shift from a natural state to agriculture significantly reduced the SOC concentration in

68 the soil (Table 3.2 and Table 3.3). Native wetlands had a significantly (p < 0.05) greater

SOC concentration than pre-restoration locations and WRP locations less than 10 years of age. This finding is supported by Hogan et al., 2004, Sigua et al., 2009, Ballantine and Schneider, 2008, and Campbell et al., 2002.

Wetland Reserve Program sites awaiting restoration had a highly variable SOC concentration ranging from 13.4 g kg-1 to 200g kg-1 with an average SOC concentration of 84 g kg-1. It is thought that intensity of agriculture and restoration activities are generally responsible for such large deviations in addition to natural environmental stochasticity (Paustian et al., 2006; Schulten and Hempfling 1992; Xu et al., 2006). This variability inhibits the ability of making accurate estimates of restoration recovery given our sample size, sampling resolution, and limited time since restoration for the other

WRP locations studied. Since pre-restoration levels of SOC concentration are significantly less than native SOC concentration levels, we can determine that restoration activities are not sole contributors to the reduction of SOC at WRP of all ages.

There was a significant (p < 0.05) increasing trend with a weak correlation (r2 =

0.28) between SOC concentration at A1/A2 WRP sites and time (Figure 3.1) The equation (y =7.53x + 152) derived from correlation of increasing SOC concentration with time allows us to estimate that restored A1/A2 wetlands will take 30 years to return to the average native SOC concentration of 369 g kg-1. Wetland soils at A1/A2 WRP sites are sequestering carbon at a rate of 7.5 g carbon per kg of soil annually. Soil organic carbon concentration (one of three factors affecting total carbon content) is trending towards the natural state after a decade in restoration. Managers must take this into

69 account when setting timelines for desired results (Zedler, 2000; Mitsch and Wilson,

1996). Previous research estimates that SOC concentrations could return to natural levels 3.3 to 300 yrs after restoration (Euliss et al., 2006; Hossler and Bouchard, 2010).

The amount of time needed for SOC concentration would depend heavily on the amount of degradation at the site and the quality of restoration efforts.

Additional evidence of SOC concentration recovery for A1/A2 soils at restored wetlands is evident in the comparison of SOC concentration levels and variability within the different age classes since restoration. Soil organic carbon concentration became less variable across the restoration classes as time since restoration increased (Figure

3.2). Analysis of SOC for A1/A2 wetland soils types indicated that restorations 10+ yr in age have significantly (p > 0.05) similar carbon concentration to native wetlands and numerically greater carbon concentration than restorations younger than 10 yr, including pre-restoration sites (Table 3.2). The S1/S4 soils display no trend toward the natural condition for SOC concentration after 10 years. This divergence from A1/A2 soils is a reflection of the natural variability found in S1/S4 types of soils and the different trajectories taken based upon the severity of degradation. Native S1/S4 wetland soil locations had a significantly (p < 0.05) higher SOC concentration than restored S1/S4 soils of all ages.

Wetland soils meeting the A1/A2 criteria of similar ages appear to be stabilizing in respect to SOC concentration as they trend toward the natural condition. As the restored wetlands age, the effects of the degradation are lessened as natural decomposition processes began to take over (Ballantine and Schneider, 2008;

Fennessy et al., 2008). Ballantine and Schneider further determined that the rate of

70 organic matter decomposition within the soil profile was the limiting factor for some wetland restorations. Increased rates of decomposition at native wetlands allow for faster incorporation of dead plant material into the soil profile.

Organic Horizon Development

Depth of organic material varied widely across the study locations. The average depth of organic rich horizons was 33.6 cm (13.2 in) with A1/A2 wetland soils (native and restored) having a significantly (p < 0.05) deeper organic rich profile (54.86 cm

[21.5 in]) compared to S1/S4 wetland soils (12.34 cm [4.6 in]) (Table 3.4). No significant trend was found for depth of organic rich horizon and time since restoration

(Figure 3.5). These results are not surprising. The restored wetlands in this study are relatively young in age. Agricultural and restoration activities can decrease depth of the surface horizon by several means including soil mixing. Native soils meeting the A1/A2 hydric soil designations were significantly deeper than their restored counterparts.

Native soils meeting the S1/S4 designations were not different than restored locations based on depth of organic rich material.

The depth of organic rich materials has an impact on the total amount of carbon sequestered in a wetland. Numerically, the A1/A2 native soils were twice as deep when compared with the restored soils. If all other soil properties were equal, this comparison of depth of organic rich material would indicate that native wetlands hold twice as much sequestered carbon as restored wetlands.

Bulk Density

Bulk density followed similar trends to carbon concentration and depth of organic rich material. The bulk density of all WRP wetland soils was highly variable (0.147 to

1.65 g cm-3). Restored A1/A2 wetland soils had a significantly (p < 0.05) smaller bulk densities than the S1/S4 wetland soils examined (Figure 3.6) (Table 3.4). Bulk density was significantly greater at restored wetlands than at native wetlands for A1/A2 wetland soils. Given that incorporation of soil organic matter into the soil profile reduces soil bulk density and native locations had more organic matter than restored, these findings are expected. Also, traffic from agriculture and restoration had a compacting (increased bulk density) effect at restored sites.

No significant trend was found for bulk density and time since restoration for either A1/A2 or S1/S4 wetland soils (Figure 3.6); this indicates that the soil properties that affect bulk density such as soil organic matter content have not fully recovered in ten years. A significant (p < 0.05) negative correlation (r2 = 0.44) was found between the average upper profile bulk density and depth of the organic rich horizon (Figure 3.9).

This relationship indicates that soil profiles that are deeper (more developed) have lower soil bulk density. The realization of this relationship reinforces the idea that the amount of soil profile degradation has an impact on soil physical properties such as bulk density.

A significant (p < 0.05) inverse exponential relationship (r2 = 0.672) was found between SOC concentration and bulk density (Figure 3.7). This finding is similar to the relationship described by Blanco-Canqui et al. (2005) and further supported by Bishel-

Machung et al. (1996). By monitoring bulk density as an indicator of invasiveness of restoration techniques and agricultural practices, we can confidently dismiss the notion that compaction had any significant effect on the wetland restorations examined. This is based on the fact that no observations of high SOC concentration were correlated with high bulk density values. While compaction did occur at the sites, the effects appear to be marginalized by the amount of organic matter in the soil.

Soil Organic Carbon Content

Soil organic carbon content was calculated as a product of SOC concentration, bulk density, and depth of organic rich horizons. Overall, total SOC content at the WRP locations studied varied from 1780 to 63700 g m-2. No significant trend was found for total SOC content for either A1/A2 or S1/S4 soils (Figure 3.3). High variability in SOC at both S1/S4 and A1/A2 sites made it harder to predict time for soil carbon levels to return to the native condition (Table 3.2 and 3.3) (Figure 3.3). These findings confirm that total amount carbon sequestration at restoration sites is highly dependent on a number of variables.

Soil organic carbon content levels were significantly greater at A1/A2 wetland restoration locations than at S1/S4 locations. This finding is supported by the prior results where A1/A2 soils had greater values for SOC concentration and depth of organic rich material as compared with S1/S4 locations. While S1/S4 wetlands had greater bulk density values, which would indicate the potential to have more carbon stored in each kilogram of soil, the increase in bulk density was not enough to offset the increases in SOC concentration and depth of organic rich material at A1/A2 sites.

The carbon content at all A1/A2 WRP sites was significantly less than that of native wetlands with similar soils (Table 3.2). The carbon content at all S1/S4 WRP sites was significantly less than that of the native wetlands with similar soils (Table 3.3).

The A1/A2 wetland soils had a significantly (p < 0.05) higher SOC content than S1/S4 organic soils. These results were expected because A1/A2 soils had greater values for both SOC concentration and depth of organic rich horizons.

A comparison of SOC concentration and SOC content was done for A1/A2 wetland soils to determine if SOC concentration would reflect SOC content of the profile

(Figure 3.4). This relationship revealed that SOC concentration is not an adequate indicator of total carbon storage. The lack of a significant correlation between SOC content and SOC concentration again emphasizes the influence that bulk density and overall depth of organic rich horizons have on SOC content.

Native wetlands meeting the A1/A2 wetland soil criteria had an average of 93.5 kg m-2 for total carbon content. This allows us to postulate that the maximum attainable value for sequestering carbon in freshwater wetlands in Central Wisconsin to be 93.5 kg m-2. Wetland areas awaiting restoration in this category had an average SOC content of 28.1 kg m-2. If these wetlands return to the native condition, 65.4 kg of carbon will be removed from the atmosphere per m-2 of wetland area restored. Similar analysis at

S1/S4 wetland soil sites indicates that those locations would be able to recover 8 to 12 kg m-2 of atmospheric carbon, if they return to the native condition.

Soil Nitrogen

Total N was significantly (p < 0.05) higher for A1/A2 wetland soils than S1/ S4 wetland soils. Native locations had the highest organic N levels (p < 0.05). This relationship is as expected because soil N is closely tied to the amount of soil organic matter. Areas, such as the A1/A2 and native wetlands, which had greater organic matter content will have greater amounts of N than areas with low organic matter content. Greater soil organic matter (SOM) content can be assumed based on the correlation of SOC concentration to SOM (SOM is considered to have 58% carbon)

(Combs and Nathan, 1998). The widely recognized correlation between organic carbon and organic nitrogen was verified (Brady and Weil, 2002; Post and Mann 1990; Batjes,

1996). Total soil Nitrogen concentration levels closely followed SOC concentration levels for all locations sampled. Soil C:N ratios for all sampled locations (including natural and restored locations) were around 12:1 (p < 0.05) (r2 = 0.9594) (Figure 3.8).

Carbon to N ratios of less than 20:1 indicate sufficient amounts of N to meet microbial needs for decomposition (Brady and Weil, 2004).

Conclusions

Converting native wetlands to an alternative land use such as agriculture has an adverse affect on soil carbon, bulk density, and depth of organic material (Hogan et al.,

2004; Campbell et al., 2002).

Wetland soils meeting the A1/A2 hydric soil designations that have been under restoration for at least a decade are similar to native wetlands in terms of SOC

75 concentration. Wetland soils meeting the A1/A2 hydric soil designations appear to be stabilizing in respect to SOC concentration as they trend toward the natural condition.

As the restored wetlands age, the effects of the degradation are lessened as natural decomposition processes began to take over (Ballantine and Schneider, 2008;

Fennessy et al., 2008). The rate of organic matter decomposition within the soil profile has been determined to be the limiting factor for some wetland restorations (Ballantine and Schneider, 2008). Horizon development (depth of organic rich material) showed no significant trend with time and may be a limiting factor of returning SOC content to the native condition. Vertical accretion of plant material, decomposition rate, hydrologic regime, microbial and vegetative community all will affect horizon development

(Fennessy et al., 2008; Craft, 2001; Mentzer et al., 2006; Fierer and Schimel, 2002;

Matthews and Spyreas, 2010).

Restored wetland soils take a significant amount of time to return to the native condition. Based on regression analysis of the SOC concentration, A1 and A2 wetland soil types should return to the native condition after 30 years. Managers must take this into account when setting timelines for desired results (Zedler, 2000).

Trends in bulk density and C:N ratio at the locations studied indicate that restored wetlands responded positively and began to reflect the conditions present at native sites in a relatively short period of time.

Data from some of the pre-restoration sites and young restorations exhibited greater carbon concentration and content than older restorations which indicated that

NRCS standards for site selection and prep have become more refined. A need for this

76 type of forward, efficient approach to wetland restoration has been previously recognized (Fennessy et al., 2008; Bedford, 1999; Zedler and Kercher, 2005)

400

350 ) 1 - y = 7.5276x + 152.29 300 R² = 0.2814

250

200

SOC ConcentrationSOC (g kg 150

100 y = -0.8547x + 37.596 R² = 0.0824 50 ■ ■

0 0 5 10 15 20 Native

Years Since Restoration

■ S1 & S4 Hydric Soil Designations A1 & A2 Hydric Soil Designations

Figure 3.1. Relationship between soil organic carbon (SOC) concentration by mass and time for all Wetland Reserve Program sites and native wetland locations. Data are summarized in Tables 2.2 and 2.3.

450

400 ... ◄► 350 ......

) 300 1

- ... .. 250 ◄► 200 ◄► .. 150 ◄► ◄► SOC ConcentrationSOC (g kg 100 ·- 50 .. ... 0 0 1-5 5-10 10+ Native

Age of Restoration (yrs)

Figure 3.2. Mean of soil organic carbon concentration by mass for each five year interval age of restoration for A1 and A2 hydric soil designations. Included are the 95% confidence intervals for each interval of wetland restorations.

120000

100000 ) 2 - 80000

y = 253.19x + 32033 60000 R² = 0.0078 A

CarbonContent (g m A 40000 ' A 20000 A A ■ y = -441.54x + 9587.4 ■ ■ R² = 0.3427 0 ■ ■ 0 5 10 15 20 Native

Years Since Restoration

■ S1 & S4 Hydric Soil Designations A1 & A2 Hydric Soil Designations

Figure 3.3. Relationship between soil organic carbon (SOC) content by mass and time for all Wetland Reserve Program and native wetland locations.

400 70000

♦ 350 y = 7.5276x + 152.29 60000 R² = 0.2814 300 ♦ ♦

) 50000

1 - 250 .. ····························••"··• 40000 E ·····································~·······:····································· ...... Cl) 200 C u0 y = 253.19x + 32033 30000 u ♦ 0 150 ♦ R² = 0.0078 (/) ♦ ♦ SOC ConcentrationSOC (g kg 20000 100

50 10000

0 0 0 2 4 6 8 10 12 14 16 18

Age of Restoration (yrs)

♦ SOC Concentration SOC Content Linear ( SOC Concentration) Linear ( SOC Content)

Figure 3.4. Relationship between soil organic carbon (SOC) concentration and total SOC content and time for Wetland Reserve Program locations with A1/A2 hydric soil designations.

• • y = 1.2383x + 37.034 • 70 R² = 0.1245

60 • 50 •

30 • • Depthof Organic Rich Horizon (cm) • • 20 • 10

0 0 2 4 6 8 10 12 14 16 18 Age of Restoration (yrs)

Figure 3.5. Relationship between depth of organic horizon and time for all Wetland Reserve Program locations with A1/A2 hydric soil designations.

1.8

1.6

1.4 y = -0.0209x + 1.1193 R² = 0.1919 1.2 ) 3 - ■ ■ 1 ■ ■ ■ ■ 0.8 • • •

Bulk Density Density Bulk (g cm ■ • ■ 0.6 ■ • • 0.4 • • • y = -0.007x + 0.5378 0.2 • • • • R² = 0.0273 0 0 5 10 15 20 25 Age of Restoration (yrs)

A1/A2 Bulk Density ■ S1/S4 Bulk Density •

Figure 3.6. Relationship between bulk density and time since restoration for all Wetland Reserve Program locations.

400

♦ •• 350 ♦ ♦

300 ♦ )

1 ♦ ♦ - 250 ♦

200 ♦ y = 437.71e-2.377x ♦ R² = 0.672 150 ♦ ♦ SOC ConcentrationSOC (g kg 100 ♦•• ♦ 50 ♦ ~ ♦ ♦ • 0 •• 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 Bulk Density (g cm-3)

Figure 3.7. Relationship between bulk density and soil organic carbon concentration for all Wetland Reserve Program locations and native wetland locations.

500

450 ) 1 -

400 ♦ ♦ 350 ••• ♦ ♦ 300 ♦ •• y = 11.851x + 3.011 250 R² = 0.9594 SOC ConcentrationSOC (g kg 200

150

100

0 0 5 10 15 20 25 30 35 40 Nitrogen Concentration (g kg-1)

Figure 3.8. Relationship between organic nitrogen concentration and soil organic carbon concentrations for all Wetland Reserve Program locations and native wetland locations.

1.6

♦ ♦ 1.4 ♦ y = 1.0541e-0.016x )

3 1.2 R² = 0.4365 - ♦ ♦ ♦ ♦ 1 ♦ ♦ ♦♦

0.8

0.6 SurfaceBulk Density (g cm 0.4

0.2

0 0 20 40 60 80 100 120

Depth of Organic Material (cm)

Figure 3.9. Relationship between surface horizon bulk density and overall depth of organic horizons for all Wetland Reserve Program locations.

Table 3.1. Alpha numeric designations assigned to the hydric soils at WRP and Native locations in Central Wisconsin Alpha Numeric Description of Hydric Soil Designation Listing A1 Histosol - 40 cm (16 inches) or more of the upper 80 cm (32 inches) is organic soil material. Can contain sapric, fibric, and hemic components. A2 Histic Epipedon- 20 cm (8 inches) or more of the upper 80 cm (32 inches) is organic soil material. Can contain sapric, fibric, and hemic components. S1 Sandy Organic rich materialy Mineral - Mineral soils where the organic carbon content is at least 5 percent to as high as 14 percent for sandy soils. S4 Sandy Gleyed Matrix - gleyed (colors appearing on the gley pages of the Munsel Color book) matrix present within 15 cm (6 inches) of the surface. (NRCS, 2010a)

Table 3.2. Summary of SOC Concentration and Total SOC Content for Native and Wetland Reserve Program locations meeting A1/A2 hydric soil designations. Lower case letters a and b denote significant differences (p < 0.05) between the means of native and restored wetlands. Age of Restoration (yr) 0 (n = 3) 1-5 (n = 3) 5-10 (n = 3) 10+ (n = 7) Native (n = 3)

Soil Organic Carbon Mean 158.5 a 155.7 a 203.6 a 251.2 ab 368.6 b -1 Concentration (g kg ) Std. Err 32.0 24.5 40.3 30.1 5.7

Total Organic Carbon Mean 28100a 35800a 29500a 33600a 95300b -2 Content (g m ) Std. Err 7300 6300 9400 6700 5000

Table 3.3. Summary of SOC Concentration and Total SOC Content for Native and WRP locations meeting S1/S4 designations. Lower case letters a and b denote significant differences (p < 0.05) between the averages of native and restored wetlands. Age of Restoration (yrs) 0 (n = 4) 1-10 (n = 5) 10+ (n = 7) Native (n = 2)

Soil Organic Carbon Mean 28.0a 43.1a 26.6a 86.3b -1 Concentration (g kg ) Std. Err 5.4 8.1 5.7 0.65

Total Organic Carbon Mean 8475a 8844a 4257a 16700b -2 Content (g m ) Std. Err 1041 2576 885 150

Table 3.4. Soil Physical Properties at Native and Restored Locations. Location Bulk Density Depth of Organic Rich 3 (g/cm ) Horizons (cm) Native A1/A2 0.28a1 100a Restored A1/A2 0.45b 45b Native S1/S4 0.84c2 22c Restored S1/S4 0.99c 21c 1 Lower case letters a and b denote significant differences (p < 0.05) between the averages of native and restored wetlands with A1/A2 designations and S1/4 designations. 2 No significant differences were between S1/S4 native and restored wetlands

Chapter 4 – Overall Conclusions

Wetland restoration is a comparatively young science and is evolving as research sheds new light on areas of deficiency.

Restoring wetlands to a similar state as before degradation by drainage and agriculture takes a great deal of time. This research demonstrated that wetland vegetation, hydric soil physical properties, and soil nutrient levels are impacted adversely by the conversion of native wetlands into alternative land uses. However, analysis of the data revealed that wetland vegetation responds positively when efforts to plant and establish vegetation at restoration sites are carried out. Furthermore, even though all the restoration studied were relatively young, a trend in the recovery of soil organic carbon (SOC) concentration levels was detected at a selection of Wetland

Reserve Program (WRP) locations. The recovery of SOC concentration levels will result in the enhanced availability of soil nutrients and recovery of soil bulk density, but the recovery of SOC concentration is not enough to return SOC content levels of the soil profile back to the native condition.

This study also recognized that wetland restorations in Wisconsin are becoming more adaptive and selective. Trends in the data revealed that locations being enrolled into WRP are substantially better suited to wetland restoration than areas that were restored previously. Natural Resource Conservation Service personnel have indicated that the intensive investigation into the success of wetland restorations and being adaptive in management strategies enhances both our understanding and the quality of restorations themselves.

Future research is required to better understand the recovery of hydric soils at wetland restoration attempts. Sampling before restoration attempts have begun, immediately after completion, and after significant amount of time has passed will provide the best insights into developing better restoration practices. Replication of this study in the future would provide valuable insight into the ongoing effectiveness of wetland restorations, and would provide another opportunity to better estimate the ability of wetland functions to return.

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Appendix A – Lost Creek and Buena Vista Study Location Maps

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Figure A.A.1. Lost Creek Restoration and Native Wetland Boundaries Porta e Count , WI, USA

1:11,005 Legend N D Native Wetland ~ Lost Creek Restoration +

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Figure A.A.2. Buena Vista Wetland Restoration Boundary Porta e Count , WI, USA ..__ lr;;l":'l!lll~,t'l';.'~1l'J'~"!'.ll-

1:1 0,532 N Legend

~ Buena Vista Restoration +

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Figure A.A.3. Known Well Locations at Lost Creek Restoration

1:9,825 Legend N

O Known Well Location ~ Lost Creek Restoration +

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Appendix B – Soil Descriptions

Dominant Soil Series Descriptions

According to the most recent soil survey the site contains Markey, Markey shallow, and Roscommon organic rich material as the most dominant soils (Web Soil

Survey, 2009). The Markey Series (Ma) (Sandy or sandy-skeletal, mixed, euic, frigid

Terric Haplosaprists) consists of very deep and very poorly drained organic soils.

Markey soils can be over one hundred inches deep. They form from organic matter that overlies sandy outwash. Markey can be found on depressions on outwash plains, lake plains, flood plains, river terraces, valley trains, and moraines. Slopes range from 0 to 2 percent. Mean annual precipitation is about 76 cm (30.4 in). Mean annual air temperature is about 6 degrees C (43 degrees F). The Markey series have relatively slow decomposition rates as compared to similar soils farther south. This is because of the colder climate. A typical profile for Markey soils contains four organic layers over sand. The Oa1 horizon is 0 – 23 cm (0 – 9 in) with a moist color of 10YR 2/1-2. The Oa2 horizon is 23-30 cm (9 - 12 in) with a moist color of 10YR 3/2. The Oa3 horizon is 30 –

61 cm (12- 24 in) with a moist color of 10YR 2/2. The Oa4 horizon is 61- 80 cm (24 - 32 in) with a moist color of 10YR 2/1. These layers differ in only slightly few select areas

(color & Rubbed fiber content). Overall Markey soils are comprised of sapric materials or highly decomposed plant material. These materials are also diagnostic to Markey

Organic rich material. They exist in the landscape as bog soils with prominent aquatic type surface vegetation.

Roscommon series (Rm) (mixed frigid Mollic Psammaquents) consists of very deep, very poorly drained organic rich materialy sand soil. The soil predominantly forms

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105 on slopes of less than 1 % under forest canopy. Typically Rm is found in sandy deposits on lake plains, outwash plain, lake basins, and glacial drainage ways. Mean annual precipitation is 85 cm (30 in) and mean annual air temperature is 6 degrees C

(43 degrees F). The typical profile for Rm is A, Cg, finally followed by a C layer. The A layer is 0 to 23.5 cm (0 - 9 in) with a moist color of 10YR 3/1. Generally it is characterized as slightly acidic, very friable with weak coarse subangular blocky structure. The Cg layer is 23.5 cm to 35 cm (9 -14 in) with a moist color of 10YR 6/2.

This single loose grain sand layer is slightly acidic. The C layer is 35 cm to 150 cm (14

– 60 in) with a moist color of 10YR 5/3. This soil series supports predominantly lowland tree species such as northern white cedar and yellow birch.

Control Site Profile Description

The soils at the control site were Markey and Markey shallow series. Soil colors were typically 10YR 2/1. Depths of the organic matter ranged from 22 cm (8.6 in) to

100 cm (40 in). Color differences and organic matter consistency were more uniform at the soil profiles examined than how the soils were described in the Official Series

Descriptions for Markey and Markey shallow (NRCS, 2010b). Woody debris material was found until a depth of 26 cm (10 in) at one location. Parent material was sand with a color of 10YR 4/3.

Lost Creek Restoration Profile Description

The soils at the Lost Creek restoration site showed signs of anthropogenic influence. It was indicated that the topsoil at the restoration was consolidated and uniformly distributed about the location. A typical profile was a organic rich materialy

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106 sand A horizon 27 cm (10.6) over a sandy to sandy loam C horizon with evidence of water inundation by the presence of mottles or gleying. The boundary between the A and C horizon was abrupt. Numerous sand ribbons and thin buried organic horizons were described at the location. The origin of the sand and organic matter inclusions was thought to be the result of the top soil mixing that occurred at the location because of this soil colors ranged from 10YR 4/3 to 10YR 2/1.

Buena Vista Restoration Profile Description

The soils at the Buena Vista restoration were very similar to the soils found at the

Lost Creek restoration. The typical soil examined at this location had a organic rich material sandy A horizon that was 20 cm (7.8 in) deep with a color of 10YR2/1. This horizon overlaid a C sandy horizon with a color of 10YR4/4 and massive structure. A buried organic horizon was indentified at one soil pit. Additionally, mixing of the A and

C horizons at the boundary was typical.

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Appendix C - Wetland Reserve Program Site Locations

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Figure A.C.1. Native and Wetland Reserve Program Locations by County, WI, USA

1 :3, 145,022

Legend LJ Wisconsin State and County Borders D Counties Containing Wetlands Surveyed

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Figure A.C.1. Wetland Reserve Program Locations Central Wisconsin, USA

0 0 0 0

0 0 0

0 0 00

0 oi 0

0 +N

Legend

[O l Wetland Location 1:747,740 LJ Counties Containing Wetlands Surveyed

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Appendix D- List of Plant Species by Location

Native Wetland

Red Maple Acer rubrum Wild Columbine Aquilegia canadensis Paper Birch Betula papyrifera Bearded Short Husk Brachyelytrum erectum Nut sedge Cyperus esculentus Jewelweed Impatiens capensis Wild Lily of the Valley Maianthemum canadense Sensitive Fern Onoclea sensibilis Cinnamon Fern Osmunda cinnamomea Switch Grass Panicum virgatum Buckthorn Rhamnus cathartica Black berry Rubus allegheniensis Raspberry Rubus idaeus Willow Salix spp. Golden Rod Solidago spp. Skunk cabbage Symplocarpus foetidus Poison Ivy Toxicodendron radicans American Elm Ulmus Americana Stinging Nettle Urtica dioica

Lost Creek Restoration

Common Yarrow Achillea millefolium Ragweed Ambrosia artemisiifolia Lamb's Quarters Chenopdium album Crab Grass Digitaria spp. Foxtail Grass Hordeum jubatum Lady's Thumb Persicaria vulgaris Evening Lynchs Silene latifolia Golden Rod Solidago spp. Tansy Tanacetum vulgare Cow Vetch Vicia cracca Barren Strawberry Waldsteinia fragarioides

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Buena Vista Restoration

Leadplant Amorpha canescens Smooth Brome Bromus spp. Wild strawberry Fragaria virginiana Timothy Phleum pratense Cottonwood Populus deltoides Cinquefoil Potentilla spp. Willow Salix spp. Little Blue Stem Schizachyrium scoparium Orange Hawk Weed Schizachyrium scoparium Golden Rod Solidago spp. Dandelion Taraxacum officinale Yellow Goats Beard Tragopogon pratensis Common Mullein Verbascum thapsus Cow Vetch Vicia cracca

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