Doctor of Philosophy, The Ohio State University, 2017, Environment and Natural Resources

Few studies investigate the intricate effects that the plant community has on amphibian populations. Plants shape ecosystems, affecting both physical and chemical attributes of the landscape. Conspicuous artifacts of the plant community include canopy cover, physical structure, and modified temperature and moisture profiles. However, less conspicuous artifacts of the tree community, namely the physiochemical characteristics of their resulting leaf litter, have the ability to shape their ecosystem just as greatly as their more conspicuous traits. Leaf litter represents the primary energy source in vernal pools and other aquatic systems that are critical amphibian breeding habitat. As plant communities shift across the landscape due to ecosystem degradation, invasion by nonnative species, climate change, and shifting disturbance regimes, there is a critical need to investigate how these potential changes can influence the amphibian community and the mechanisms by which they occur. My research investigates how the vernal pool breeding amphibian community responds to differing plant communities across a heterogeneous forested landscape and throughout their life cycle. As such, my overall objectives are multi-faceted: (1) to determine if the tree community impacts colonization and use of vernal pool-breeding amphibians (2) to scale up mesocosm studies that document the strong regulatory response tree litter inputs can have on growth and development of amphibian larvae to a field setting (3) to determine if small, constructed ridge-top pools are a viable option for enhancing amphibian populations in the landscape, particularly with regards to increasing functional connectivity and maintaining diverse amphibian communities, and (4) to establish a landscape-level study design for conducting future, field-based experiments that can serve as a baseline to document changes in forest ecosystems. These objectives are addressed within each of my primary research pursuits below (open full item for complete abstract)

Committee: Stephen Matthews (Advisor); H. Lisle Gibbs (Committee Member); P. Charles Goebel (Committee Member); Roger Williams (Committee Member) Subjects: Biology; Climate Change; Ecology; Environmental Management; Environmental Science; Forestry; Freshwater Ecology; Wildlife Conservation; Wildlife Management

Doctor of Philosophy, University of Akron, 2013, Integrated Bioscience

Climate change threatens to alter the current distribution, productivity, and community composition of wetlands in the Midwestern United States. Increasing rainfall variability and rising temperatures will yield unique stresses for wetland vegetation, including an increase in flooding severity and a higher frequency of potentially harmful heat events. This dissertation explores the interactions and impacts of climate warming and hydrologic variability on productivity, morphological plasticity, reproduction, and functional composition within wetland communities, followed by an evaluation of the connection between wetland distribution and climate on a regional scale. Climate warming led to depressions in productivity during the warmest months while hydrologic variation consistent with climate projections yielded decreases in spring production and peak biomass. Reproductive allocation and other functional trait differences suggested that the future climate will limit productivity in many wetland ecosystems in the Midwest. A distribution model based on Artificial Neural Networks projected significant increases in flooding leading to wetland expansion concentrated in the Midwestern Corn Belt and potential declines in wetland area in Minnesota and northern Michigan. These results suggest that, though wetland area is projected to increase for the Midwest, without hydrologic management, many wetland systems are at risk of community turnover and degradation resulting from a shifting climate.

Committee: Randall Mitchell Dr. (Advisor); Linda Barrett Dr. (Committee Member); Lauchlan Fraser Dr. (Committee Member); Stephen Weeks Dr. (Committee Member); Gregory Smith Dr. (Committee Member); John Senko Dr. (Committee Member) Subjects: Ecology; Geographic Information Science; Geography