PARENT SESSION
Poster Session 32: Biogeochemistry
Thursday, August 11, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal

Atlantic White Cedar swamp: Effects of temperature and water table position on decomposition.

Brunie, Lisa ^{1, 2}, ¹ Mount Holyoke College Department of Earth and Environment, South Hadley, Massachusetts, USA² Ecosystem Center, Woods Hole, Massachusetts, USA

ABSTRACT- Atlantic Cedar swamps are peat-based wetlands. That store large amounts of carbon dioxide as a result of slow and incomplete decomposition. The anoxic nature of these wetlands forces microbes to use alternative electron acceptors, resulting in methane emission. In this study, the effects of water level and temperature on decomposition and release of these greenhouse gases were examined. Ten peat cores collected from Hidden Swamp, a Cedar swamp in Falmouth, Massachusetts on Cape Cod, were incubated in various temperature treatments of 4, 10, and 21.1 C. In the 4 and 21.1 C temperature treatments 650ml of water was drained from the peat. The flux data showed that the 21.1 C temperature incubations had larger emissions of both carbon dioxide and methane. The largest flux of carbon dioxide was measured from the dry core and the largest flux of methane from the saturated core with in the 21.1 C temperature treatment (1.5 gC/m2/day). Dissolved inorganic nitrogen (DIN) measurements demonstrated that higher temperatures cause more loss of nitrogen, either through the process of denitrification or immobilization. Extrapolations were made based on the flux rates and calculated Q10 values to estimate the global warming potential for the various scenarios of saturated and unsaturated at the base temperatures and with an increase in temperature of five degrees. A Q10 value for the saturated and dried cores for carbon dioxide was 2.89 and 3.29 respectively. The Q10 value of methane for the saturated core was 4.97 and the dried was 1.23. The largest global warming potential was calculated for the scenario of unsaturated with an increase in five degrees (276.87 carbon dioxide equivalents). This data has large implications for global warming and decomposition of the peat within these systems.

Key words: Atlantic White Cedar swamp, Decomposition, Global Warming Potential, Dissolved inorganic nitrogen