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Current research projects
Over the past 200 years, conversion of land for agricultural use, industrial development, and urban sprawl has been considered the most serious threat to biological diversity. The loss of habitat divides or fragments once-continuous natural habitats into smaller pieces that are often separated by areas unsuitable to sustain viable species populations. A central tenet of conservation biology is that connectivity among fragments of habitat and interactions with adjacent habitats are the keys to understanding the impacts of fragmentation on population dynamics, risk of extinction, and maintenance of biodiversity. The LEAP project uses large-scale field experiments and spatially-structured model simulations to increase our understanding of the effects of habitat alteration and loss in forested ecosystems on amphibians. Specifically, our research will provide new insights into local demographic processes and metapopulation dynamics in altered landscapes. Further, our research will provide pragmatic information to aid in efforts to balance conservation with sustainable land-use practices. The focus of our research is to understand how important population processes in a model system of pond-breeding amphibians are altered by land-use practices that degrade and fragment natural forested habitats. Further, because our field experiments do not allow us to explicitly measure connectivity, we will use spatially-structured simulation models to examine whether local effects of disturbance will influence large-scale distributions and abundances of amphibians. Extensive field studies and experiments strongly indicate that two processes are critical for persistence of pond-breeding amphibian populations: local population and metapopulation dynamics. Thus, LEAP research focuses on field experiments and model simulations that measure responses associated with three processes:
Land use for the production of crops and livestock represents a major impact of human populations on the natural world, with over 938 million acres in the United States devoted to some type of agriculture. In many counties in the Midwest, agricultural lands may account for over 90% of available acreage. The widespread nature of agricultural land use has led to concerns about the impacts of farms on stream and riverine resources, and associated wildlife populations. Aquatic and semi-aquatic organisms living in streams embedded in agriculturally-dominated landscapes, therefore, are exposed to complex mixtures of contaminants. Amphibians are unique organisms with which to study the impacts of agricultural runoff on wildlife: 1) due to the nature of their lifecycle, amphibians require aquatic habitats during the sensitive larval development period, 2) the peak of amphibian breeding occurs in the spring, when chemical and fertilizer application are high in agricultural landscapes, and 3) a substantial base of knowledge exists concerning both direct and indirect effects on amphibians of common agricultural chemicals. Further, it is now believed that amphibians are far more threatened than either birds or mammals, with 1,856 species (32.5%) being globally threatened. Thus, efforts to maintain biodiversity must recognize threats to amphibians and develop management solutions at local and national levels. The issue of how agricultural runoff affects amphibians is much too broad to be considered in a single experimental approach. Therefore, three approaches will be taken to address this issue over the next few years—laboratory studies, field studies, and a landscape-level study. The ultimate goal in this research is to understand the link between exposure levels in the field that are largely dependent upon patterns of land use in the surrounding landscape and direct effects of major contaminants on biologically relevant endpoints using amphibians.
Although riparian buffers have been used for several decades, they are designed for protecting water quality, and therefore, are inadequate for protecting biodiversity along headwater streams. The purpose of our study is to determine the biological criteria for riparian buffers to protect a highly diverse assemblage of Appalachian stream salamanders.
Habitat loss is probably the greatest reason for the decline of many organisms, including amphibians. The economic needs of humans are often in direct conflict with the ecological needs of other organisms. In our attempts to mitigate for habitat lost due to development, one must ask the question – do our efforts really replace what is lost in terms of the ecological needs of amphibians? And, if the answer to that question is no, then another question arises – how can we improve our efforts? It is quite likely that successful efforts at mitigation will be those that create or restore not only suitable breeding sites, but also core terrestrial habitat. This project focuses on the ecological needs of northern Missouri amphibians and how to best incorporate these needs in an applied manner while designing and building mitigation habitat. The objectives are to provide a means to analyze critical amphibian habitat, to guide future design and placement of new wetlands within the landscape to benefit amphibians, and establish experimentally proven methods to translocate rare, declining, or imperiled amphibian species. The research has three phases. The first is analyzing the effectiveness of man-made wetlands with respect to amphibian health by examining amphibian populations at many sites scattered across northern and central Missouri. These sites include Missouri Department of Transportation wetland mitigation sites, as well as “wildlife ponds” constructed at Missouri Department of Conservation areas. Local and landscape characteristics of the wetlands are being examined and correlated to the presence/absence of each amphibian species encountered.
The third phase of the project involves translocations of rare or declining northern Missouri amphibian species into the newly created experimental wetlands. When new wetlands are created, even the best design and placement in the landscape may not guarantee that species of conservation concern utilize the site. Barriers such as development, agriculture, and distance to the nearest established population may prevent colonization. Therefore, translocation of species may provide a means to establish new populations at appropriate sites. However, life stage at which the translocation takes place may play a role in establishment, as could other factors such as stocking density and predation pressures on young larvae. Therefore, this project will examine various translocation techniques in order to create scientifically tested methods for amphibian population establishment at man-made wetlands. Monitoring of the pools for will take place over a period of at least four years from the date of completion. |
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I. LEAP: Land Use Effects on Amphibian Populations
II. Assessing Ecologically Relevant Impacts of Agricultural Runoff on Amphibian Populations
III. Effectiveness of Riparian Buffers to Protect Stream Salamanders
Riparian buffer strips adjacent to streams have been used in forest management for many years. These buffer strips are used primarily to protect water quality from siltation, chemical runoff, and increasing sunlight and temperature due to activities such as agriculture and silviculture. However, these riparian buffer strips also play an essential role in the conservation of biodiversity. Many semi-aquatic organisms ranging from insects, amphibians, reptiles, birds, and mammals reside along streams. Although the riparian habitat is known to be critical for completion of their life cycle, the biological criteria to define and protect these habitats is still lacking. Typically when buffer zones are defined, they are based on criteria to protect the aquatic resources alone, and do not consider the impacts to wildlife. For conservation and management, habitats used by local species populations adjacent to streams must be delineated before they can be protected. There is currently a void of information on riparian habitat use by stream salamanders and we do not understand its importance to species persistence.
IV. Evaluating the Effectiveness of Mitigation Wetlands
The second phase of the study is the construction of new experimental wetlands that directly test specific design characteristics of man-made wetlands. The needs of amphibians are often poorly understood or overlooked when designing wetland sites. Consequently, attempts at habitat restoration and creation may not adequately meet the needs of certain species of amphibians that are rare or declining. Therefore, arrays of replicate wetland pools will be constructed at various locations to directly examine the effects of several “within wetland” characteristics on amphibian population establishment. Monitoring of the pools will take place over a period of at least four years from the date of completion.