After the fall: how changes in temperate forests alter wetland communities

The composition of species is continually shifting due to natural succession, disturbance, and human influences. Predicting effects of these changes requires understanding species interactions, phenotypic traits responsible these interaction, and general relationships between diversity and ecological processes. In this thesis, I explore how changes in temperate forest tree composition alter processes within forest wetland ecosystems, the chemical traits of litter responsible for these effects, and general relationships between litter diversity and ecological processes.\ud \ud Forest wetlands often receive massive amounts of tree leaf litter, and contain diverse food webs that recycle energy and nutrients within litter into myriad inorganic and organic forms. In the first study, I hypothesized that the abiotic and biological components of forest wetlands respond to changes in the input of tree leaf litter species. I provided different litter species to wetland communities in outdoor mesocosms, using ten common deciduous tree litter species. Effects were dramatic, including variation in the biomass, density, and survival of consumers. In this study, I also demonstrate that several traits of litter explain much of the variation in these effects. In the second study, I hypothesized that variation in litter inputs also induce phenotypic changes in consumer development and morphology. Using wood frogs as a model species, I found that variation in litter species alters development rate and several morphological features, such as tail length, mouth size, and gut length. In the third study, I hypothesized that variation in litter inputs alters predator-prey interactions by changing the chemical and physical structure of wetland ecosystems. The results of this study suggest that interactions between litter resources and top-down interactions should be considered to accurately predict the consequences of shifting litter species composition. In the final study, I hypothesized that a general, positive relationship exists between litter chemical trait diversity and wetland consumer biomass. I found strong effects of trait diversity on decomposition rate, but no effects across a diverse array of consumer species. This suggests that wetland communities – although responsive to changes in single litter species chemistry – respond positively to increased litter species richness and may be resistant to fluctuations of litter chemical diversity