Date of this Version
VanderHam, Ashley E., "Informing Flood Plain Wetland Restoration Using Amphibian Monitoring" (2014). Dissertations & Theses in Natural Resources.
Wetlands are among the most important and complex ecosystems in the world. They contribute to nutrient cycling, the hydrologic cycle, and provide critical habitat for many plants, fish, and wildlife. Channelization of Missouri River resulted in the loss of many floodplain wetlands. Despite ongoing restoration efforts, there are few ecologically-based performance guidelines, and managers need methods to quantify and assess the success of restored riverine wetland systems.
In 2008 a multi-institutional herpetofauna monitoring project, funded by the U.S. Army Corps of Engineers, was initiated in four states (Kansas, Missouri, Iowa, and Nebraska). The main goal of the project is to assess the success of previously restored wetlands and to create wetland restoration guidelines for future use. Amphibians were chosen for monitoring because they are globally declining, they integrate terrestrial and aquatic environments, and because they are good indicators of wetland restoration success. Frog call surveys and tadpole dip net surveys were conducted and analyzed using occupancy techniques to help determine restoration success. This thesis reports the results of herpetofauna monitoring from three Missouri River bends in Nebraska, a subset of the overall project.
I conducted a comparison of frog call surveys and tadpole dip net occupancy results, a novel co-occurrence analysis for frog call surveys, and a functional connectivity analysis based on anuran dispersal distances. The results of the frog call surveys and tadpole dip net surveys differed in many ways. The data from the tadpole dip net surveys produced fewer results, but these results were more accurate because of their link to reproduction and the lack of spurious data. If only one method is used it should be
the tadpole dip net surveys, but if the surveys are conducted in a drought year it is possible there will be insufficient data to conduct an occupancy analysis. Therefore, conducting both methods is the best way to produce the most accurate wetland restoration guidelines. The co-occurring species analysis of the frog call surveys was both more efficient and also produced a definition of wetland success for multiple species without the variation between species seen in the single species models. The functional connectivity analysis added a complex systems component to the wetland restoration guidelines, but also provided a method that can help focus management by identifying wetlands within and across complexes that are most important to functional connectivity. Combining the information gained from all of the analysis, it was determined that a successful flood plains wetland has aquatic vegetation, a shallow slope (less that 0.30), is ephemeral, has at least one wetland within 500 m, and is part of a compact (non-linear) wetland complex that has other successful wetlands and deeper, larger, less ideal wetlands that are all close enough to one another that habitat is provided in extreme conditions.
Advisor: Craig Allen