By 1980, the United States had lost over 50 percent of its original wetland resources. The U.S. National Wetland Inventory estimates that 95 percent of annual wetland losses since 1955 occurred to palustrine wetlands. The majority of these losses occurred to the three types of palustrine vegetated wetlands: emergent, forested, and shrub. The primary cause for wetland losses from the mid-1950s to the mid-1980s was agricultural conversion supported by federal agricultural policies, especially the Agricultural Conservation Program that provided significant direct and indirect support for wetland conversions. The rate of converting wetland to agriculture has declined since the mid-1950's with a significant decrease occurring between the mid-1970s and mid-1990s. Statistical analysis using correlation, regression and principal component analysis was performed to identify the major contributory factors in loss rates in the Midwest, Lower Mississippi River Valley and the Southeast United States. The variables considered are: Swampbuster provisions of the Food and Security Act of 1985, Conservation Reserve Program enrolled acreage and rental rates, Wetland Reserve Program and The Clean Water Act Section 404 permits; prices of corn, soybeans and wheat; and the percent of wetlands remaining. The results indicated agricultural policies and Clean Water Act Section 404 permits and wetland loss rates were negatively correlated and prices of corn, soybeans and wheat were positively correlated. The percentage of wetlands remaining, were also positively correlated with loss rates. Taken together, the selected agricultural policies, Section 404 permits, commodity prices and percent of wetland remaining, explain 96 percent of the variance in wetland loss rates and 94 percent of the agricultural losses nationally. These results are consistent, with minor variations, across geographic wetland strata and wetland types. Regional differences exist in the major type of wetland losses; emergent wetland losses were more prevalent in the agricultural Midwest, with forested wetland losses concentrated in the Lower Mississippi River Valley and the Southeast United States. The results of this research reflect the intricate relationships between federal legislation, regulatory programs, legal decisions, economic factors, and changes in society's view and understanding of the importance of wetlands and the need to merge conservation programs with agricultural policies. Economic factors exert a significant impact in decision-making of whether to convert or conserve wetland resources. The economic feasibility of installing drainage system to make wetlands farmable depends upon the relationship of capital investment cost and crop prices. Commodity prices impact decisions regarding enrollment into the Conservation Reserve Program and the Wetland Reserve Program; higher commodity prices can make conversion more profitable but low crop prices will make these programs more appealing economically. The Swampbuster provisions are effective in conserving wetlands if the economic penalties are significant to the individual farmer. The policy, legal and commodity variables were used to create models that explain the inter-relationship between agricultural economic factors, policy impacts and commodity prices. The models indicate how the variables could affect decision-making in determining whether to convert or conserve palustrine vegetated wetlands; increased commodity prices coupled with lower conservation program payments could jeopardize wetland conservation efforts and result in increased wetland loss rates due to increased wetland drainage and conversion.

Den biologiska mångfalden minskar i världen och i Sverige, en av orsakerna ärhabitatförlust. Våtmark är en naturtyp som minskade kraftigt i utbredning under 1800- och 1900-talen, vilket har resulterat i att stora insatser nu görs regionalt, nationellt och internationellt för att skydda våtmarker från exploatering. Det råder delade meningar om hur man på bästa sätt går till väga för att skydda flest antal arter på ett resurseffektivt sätt. En inflytelserik teori “Single Large or Several Small” (SLOSS) föreslår att ett eller några få stora sammanhängande reservat skyddar fler arter än många små av likvärdig sammanlagd yta. Genom att utgå från en inventering som gjorts av Länsstyrelsen i Dalarnas län testade jag hur SLOSS-teorin förhåller sig till fågelfaunan på Dalarnas myrar. I denna studie undersöktes 95 myrar av varierande storlek som ingick i inventeringen. Metodiken för inventeringen beskrivs som en förenklad revirkartering där man noterar hörda och sedda fåglar till antal och kön. Från datan togs sedan en art-ackumulationskurva (species accumulation curve) fram för att undersöka om få stora eller flera små myrar hade högre artrikedom generellt, och ett t-test gjordes för att kunna göra en mer realistisk jämförelse. Artackumuleringskurvan samt t-test visade att det fanns en större artrikedom hos flera små myrar tillsammans än hos några få stora. Det finns tidigare litteratur som stödjer detta, men det är sannolikt att det finns andra faktorer som den här studien inte har undersökt som påverkar artantalet på myrar utöver myrens storlek. Dessutom är fågelrikedom inte den enda faktorn som bör vägas in när man designar ett naturreservat, andra skyddsvärda taxa kan förhålla sig annorlunda till myrens storlek. Vidare studier krävs för att vägleda reservatsbildare i hur de ska prioritera habitat av olika storlek. / The biodiversity in the world and in Sweden is decreasing, and one of the driving forces is habitat loss. Wetlands are a habitat type that decreased substantially during the 19th and 20th centuries. This has led to large conservation efforts, both within Sweden and internationally, that aim to protect wetlands from exploitation. There is no scientific consensus regarding how to protect the most species in an effective way. One influential theory “Single Large or Several Small” (SLOSS) proposes that one or a few large habitats will hold more species than many small habitats of an equivalent total area. By using data from a census conducted by the County Administrative Board of Dalarna, Sweden, I tested how the SLOSS-theory relates to the bird diversity of wetlands in Dalarna. In this study, I assessed 95 wetlands of different sizes that were included in the census. The inventorying method was a simplified monitoring with visual and acoustic count of bird species and individuals within species. From this data I made a species accumulation curve to compare large wetlands to several small wetlands in general, and conducted a t-test which is a more direct approach to my study. Both the species accumulation curve and the t-test showed that many small wetlands had a higher bird species diversity than a single large wetland. This is somewhat supported by previous studies, however it is likely that other factors are at play that were not included in this study. Nature reserves are not only designed to preserve the highest number of bird species. One has to consider other endangered or otherwise protection worthy taxa that may behave differently to birds when it comes to large or small habitats. More research is needed to help nature reserve planners make informed decisions regarding how to prioritize habitats of different sizes.

Interest in, and rates of, wetland restoration have increased over the past several decades. However, despite proliferations of restored wetlands across the landscape, the structural and functional restoration success of these systems is unclear. Thus, understanding factors and processes that influence wetland characteristics is of considerable interest. This study focuses on herbaceous wetlands in the Mississippi River Alluvial Valley (MAV), a largely agricultural region interspersed with restored and naturally occurring wetlands. Chapter I is an introduction and provides a background to wetlands, wetland ecology, and the current state of wetland restoration in the United States. Chapter II focuses on factors which affect seedling density and similarities between standing vegetation, germinated seedlings, and early successional stage assemblages. Seedling density was heavily influenced by hydrology while richness and diversity were similar between restored and non-managed wetlands. Landscape-level factors affected seedling density, while germinated seedlings did not reflect standing vegetation in MAV wetlands. In Chapter III, I examine the impact of agricultural stressors on wetland plant assemblage development. Resulting assemblages showed strong fidelity to wetland soil site of origin while richness and diversity were negatively affected by elevated stressor levels. In Chapter IV, I compare characteristics between non-managed and restored wetlands in the MAV. These wetlands differed hydrologically, had different levels of soil organic matter, were dissimilar in plant assemblage composition, and varied by surrounding land use/cover. Finally, Chapter V is a discussion of the results and places this work within a larger context.

No description available.

The distribution and occurrence of plant species within a given region provides insight into the many environmental properties of that region. Although much research has been conducted on plant communities and associated environmental properties, few studies have been conducted on the characteristics of individual plants within those communities. Calcareous fens are wetlands formed by the upwelling of mineral-rich groundwater and often are associated with many unique plant communities and rare species of flora and fauna. Although many studies have documented the vegetation patterns and associated environmental gradients of these fens, none have isolated the specific hydrogeochemical conditions associated with individual species, nor have any studies attempted to document and compare the individual physiological response of species to elevated environmental calcium levels. This research was conducted to estimate environmental calcium requirements for rare as well as common indicator species of calcareous fens of Massachusetts and to examine the relationship between the accumulation of calcium in the tissues of these species to calcium availability in their environment. These factors will be important when determining required conditions for fen restoration and will further the understanding of why these species often only occur in calcareous fens. Eight calcareous fen study sites at three different locations were established where calciphiles occur in western Massachusetts. In each site, data were collected on the vegetation patterns and associated soil chemistry, water chemistry, and hydrology. In addition, plant tissues were collected and analyzed for calcium. Species distributions were evaluated as to whether they increased in abundance as environmental calcium did or whether they appeared to occur only once a specific calcium threshold was met. In addition, the concentrations of calcium in the tissues were used to determine the extent to which those plants accumulated calcium and how those levels related to levels of calcium in the substrate environment and to their overall distributions. It was found that certain calciphiles are calcium specialists, i.e. they are more abundant when environmental calcium levels are elevated, absorb greater quantities of calcium and those quantities correlate to the available environmental supply. These species include Parnassia glauca, Packera aurea, Geum rivale and Carex granularis. Of these, Geum rivale and Carex granularis, as well as Carex sterilis, did not occur below calcium concentrations of 48 mg.L-1. However, other calciphiles are calcium generalists, i.e. they are tolerant of elevated calcium levels but show no other relationship with respect to growth or accumulation. These species include Carex flava, Carex hystericina, Juncus nodosus, Solidago patula, Solidago uliginosa, and Symphyotrichum puniceum. In addition, some wetland generalists maintain elevated calcium levels (Symplocarpus foetidus and Mentha arvensis) whereas most others do not (Thelypteris palustris and Fragaria vesca). Of the calciphile and wetland generalist species, some appear to increase in abundance in calcareous fens in relation to increases in accessory benefits (Dasiphora fruticosa and Juncus brachycephalus with pH; Thelypteris palustris and Carex flava with magnesium and possibly Equisetum fluviatile with iron). Combined, these findings characterize the growth habits and calcium accumulation of species that grow in calcareous fens and indicate that calciphiles have varying degrees of dependence on calcium.

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ABSTRACT PHYSIO-CHEMICAL EVALUATION AND FUNCTIONAL ASSESSMENT OF NATIVE WETLAND SOILS AND ORGANIC AMENDMENTS FOR FRESHWATER MITIGATION WETLANDS MAY 2007 EMILY K.D. STOCKMAN, B.S., UNIVERSITY OF MASSACHUSETTS AMHERST M.S., UNIVERSITY OF MASSACHUSETTS AMHERST Directed by: Dr. Peter Veneman Due to the history of wetland loss within the United States a National “No Net Loss” policy was adopted in 1988. This policy requires the creation of mitigation wetlands to replace lost and/or damaged natural wetlands. The role of soil in natural wetland systems is key in providing a number of ecology functions, such as the supply of wetland plant nutrients and the retention of nonpoint source pollutants. Nonetheless, Federal and Massachusetts guidelines regarding the creation of soil and the utilization of organic amendments in mitigation wetlands lack specific parameters and thresholds. This research compares the chemical and physical properties of two commercially available composts and two natural wetland soils and evaluates these materials as possible pollutant sources and sinks. The results of the characterization study demonstrate significant differences between the compost samples and the wetland soils in regards to the following properties: organic matter content, pH, polarity, total nutrients (P, K, B, Zn, Fe, Al, Cd, Ni, Cr) and extractable nutrients (P, K, Ca, B, Mn). These physio-chemical properties influence the functions of supplying plant nutrients and retaining nonpoint source pollutants such as excessive nutrients and herbicides. The results of the nutrient release studies indicate that the compost samples behave as potential sources of excessive levels of phosphorus and nitrate. In addition, the pollutant retention studies concluded that the compost samples sorbed lower amounts of phosphorus under aerobic conditions and lower amounts of the commonly-used herbicide, 2,4-D, as compared to the wetland soils. Overall, the differences in both physio-chemical properties and the behavior of the composts as compared with the wetlands soils as well as each other, substantiate the necessity to re-evaluate Federal and Massachusetts guidelines pertaining to mitigation wetland soil and amendments. Based on the results of this study the following minimal analyses are recommended: organic matter content, pH, total nutrients and extractable nutrients. In addition, based on the phosphorus release and retention studies the following thresholds are recommended to prohibit the release of excessive levels of phosphorus into the mitigation wetland and adjacent aquatic systems: Morgan’s extractable P content ≤ 25 mg kg-1 and/or the total P content ≤ 1286 mg kg-1.

No description available.

Agriculture has diminished shorebirds’ natural habitat in the Mississippi Alluvial Valley. Remaining natural stopover sites are supplemented with agricultural fields during the fall and winter. This study evaluates the impact of 4 different post-harvest water management strategies on shorebird food abundance and potential agrochemical biomagnification. Chironomid samples estimated abundance, biomass, and chironomid agrochemical concentration in each field. A risk assessment of agrochemical biomagnification to shorebirds was made across all treatments. Of treatments represented on all study sites, winter treatment had greatest chironomid abundance and biomass. Models indicated that days since flood initiation, start date, and temperature are significant predictors of chironomid abundance and biomass. Risk assessment results indicate low risk to shorebirds across all treatments for agrochemicals measured in this study. This study shows that flood timing is more important to providing shorebird resources than trends in abundance and biomass of chironomids, and shorebird risk from agrochemicals measured was minimal.