Defense Date
2024
Document Type
Thesis
Degree Name
Master of Science
Department
Biology
First Advisor
Scott Neubauer
Abstract
Climate change threatens the status quo of tidal freshwater wetlands by altering their hydrology and species makeup. Increases in water level within freshwater wetlands are well studied, but with the inclusion of saltwater intrusion; while common for some tidal wetlands affected by sea level rise, it is not universal. For wetlands that will experience flooding apart from increases in salinity, adequate study is lacking. For these wetlands, the effect of increasing water level is largely unknown. Thus, the aim of this study was to use an outdoor mesocosm experiment to isolate effects of flooding and communities of differing species makeups (all possible combinations of Sagittaria latifolia, Schoenoplectus tabernaemontani, and Sporobolus alterniflorus) on greenhouse gas emissions, plant growth and biomass, and soil organic matter. Higher flooding resulted in higher methane emissions but no change in carbon dioxide emissions. Both gas fluxes had a difference in emissions across community arrangements; for methane, Sporobolus monoculture had the highest emissions, and for carbon dioxide, all plant communities were similar with bare soil having far fewer emissions. Plant growth metrics had mixed results based on species. Plant density per pot in Schoenoplectus was negatively affected by increases in flooding, while height in Sagittaria and Schoenoplectus base diameter were positively affected by increases in flooding. Plant community arrangement affected growth of some species across every growth metric other than leaf metrics, height in Schoenoplectus, and stem count per pot in Sporobolus. Surface soil samples were positively affected by flooding in water content and vi affected by community arrangement in organic matter content. Aboveground biomass differed across community arrangements for Schoenoplectus and Sporobolus, and root biomass differed across plant communities. Results show that responses to flooding are heavily dependent on species, and sensitive to inter- and intraspecies competition within communities. Greenhouse gas emissions can increase in response to increased flooding through methane output, and changes in plant community through both methane and carbon dioxide output. Such changes in emissions have the potential to alter the effect a wetland has on the larger climate, with the potential for warming and emissions to feed back into each other as climate change progresses.
Rights
© The Author
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
8-9-2024