Eddy Covariance Measurements of Methane Flux at a Tropical Peat Forest in Sarawak, Malaysian Borneo

Tropical biogenic sources are a likely cause of the recent increase in global atmospheric methane concentration. To improve our understanding of tropical methane sources, we used the eddy covariance technique to measure CH4 flux (F-CH4) between a tropical peat forest ecosystem and the atmosphere in Malaysian Borneo over a 2-month period during the wet season. Mean daily F-CH4 during the measurement period, on the order of 0.024 g C-CH4 center dot m(-2)center dot=day(-1), was similar to eddy covariance F-CH4 measurements from tropical rice agroecosystems and boreal fen ecosystems. A linear modeling analysis demonstrated that air temperature (T-air) was critical for modeling F-CH4 before the water table breached the surface and that water table alone explained some 20% of observed F-CH4 variability once standing water emerged. Future research should measure F-CH4 on an annual basis from multiple tropical ecosystems to better constrain tropical biogenic methane sources.