Effects of Elevation and Vegetation on Methane Emissions from a Freshwater Estuarine Wetland

Abstract

Abstract Ma, A.; Lu, J., and Wang, T., 2012. Effects of elevation and vegetation on methane emissions from a freshwater estuarine wetland. Methane (CH4) emission rates from three different tidal elevations were measured in a freshwater wetland of the Yangtze River, China, estuary using a modified, static, closed-chamber technique. The intertidal zone covered by Phragmites australis is a source of atmospheric CH4. The site at a higher elevation had lower CH4 emissions than did a lower-elevation site (1.322 ± 1.15 mg m−2 h−1 vs. 11.66 ± 12.5 mg m−2 h−1). Methane emissions from the mudflats were negligible. Methane emissions showed remarkable seasonal variations, with the largest emissions occurring in summer and late-summer and the smallest emissions occurring in early spring. Although CH4 emissions were related to soil temperature at depths of 5–10 cm, differences in CH4 emissions among sites were mainly determined by the presence of P. australis. Simulatied experiments did not find significant differences...