Exploring Biotic and Abiotic Drivers of Ecosystem Properties: The Influence of Waterbirds and Photodegradation on Wetland Ecosystems

Wetlands provide a wide range of valuable ecosystem services: these are benefits from the environment that support human well-being, such as water filtration, fish and bird habitat, and shoreline protection. Despite their importance, wetlands are among the most threatened ecosystems, facing increasing pressure from natural and human activities. To better predict the future of wetlands and guide effective management and restoration practices, we need to understand the various forces shaping their ecological properties. In this thesis, we examined the influence of two forces: waterbirds and photodegradation (the process by which sunlight breaks down plant material). To explore each of these drivers, we first performed a meta-analysis (in which we reviewed past studies to examine the impact of waterbirds on wetlands) and second, conducted a field experiment where we measured the production of carbon dioxide (CO2) and methane (CH4) via photodegradation in a high-latitude wetland. From the metanalysis, we found that waterbirds can reduce the abundance, but not diversity, of both plants and animals. Although waterbirds did alter nutrients in the soil, these changes did not affect greenhouse gas production. In our second experiment, we found that plant litter exposed to ultraviolet (UV) radiation in high-latitude wetlands produced higher emissions of carbon dioxide and methane, suggesting that photodegradation increases greenhouse gas movement from plants into the atmosphere in this habitat. Together, these findings show that living and non-living forces, such as waterbirds and UV exposure, can have significant effects on wetland ecosystems. As climate change continues to alter bird migration patterns and UV radiation, wetland managers need to consider how these changes may reshape wetlands and the vital services they provide. This thesis represents a valuable step toward understanding how both biological and environmental drivers interact to influence wetland dynamics.