Defense Date


Document Type


Degree Name

Master of Science



First Advisor

Dr. Scott Neubauer

Second Advisor

Dr. Rima Franklin

Third Advisor

Dr. Julie Zinnert

Fourth Advisor

Dr. Edward Crawford

Fifth Advisor

Dr. Genevieve Noyce


High rates of carbon (C) sequestration exhibited by coastal wetlands is an important natural climate solution to global environmental change. At the same time, however, wetlands are the largest natural source of methane (CH4) to Earth’s atmosphere, a potent greenhouse gas that influences the global climate. Wetland CH4 emissions display high degrees of uncertainty in accounting for spatial and temporal variations in emissions due to the complex interactions between biotic and abiotic factors that influence methane production and transport, in addition to simultaneous influences from climate-driven effects on wetlands such as rapid sea level rise and increased atmospheric carbon dioxide concentration. Recent reports indicate that stratifying wetland CH4 emissions by dominant plant community reduces uncertainty, which is partially due to interspecific plant traits that both respond to global change factors and have direct and indirect influences on wetland methane production and emission. In this thesis, I compared CH4 flux rates between plant communities in a tidal brackish marsh that has undergone a drastic sea level rise-driven shift in plant community structure and I described CH4 flux patterns using biotic and abiotic factors known to influence CH4 production and emission. Contrary to previous reports from this system that higher elevation, Spartina patens-rich areas released more CH4 than other regions, low elevation plots composed of Schoenoplectus americanus released CH4 at the fastest rates in this study. I attributed this to the enlargement of the belowground carbon pool via Schoenoplectus radial oxygen loss (ROL) and subsequent stimulation of aerobic respiration. In addition, I provide evidence that the same mechanism of ROL-induced aerobic respiration led to greater CH4 emissions under elevated atmospheric carbon dioxide (eCO2) conditions. This work contributes to a growing body of literature that elucidates a mechanistic understanding of carbon cycling in tidal wetland ecosystems that will continue to change in plant species composition, trait adaptations, and location via upland transgression under a changing climate.


© Adam Michael Dunn

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