Modeling CH4 Emissions from Natural Wetlands—Model Modification and Validation

Wetlands are one of the most important sources of atmospheric CH4, but the quantity of this source is still highly uncertain. We developed a biogeophysical model called CH4MODwetland to simulate CH4 emissions from natural wetlands based on CH4MOD that simulates CH4 emissions from irrigated rice paddies. The development of CH4MODwetland focused on the supply of methanogenic substrates, the process of vegetation growth, and the variation of soil redox potential that differ from the rice paddy. CH4MODwetland was validated against independent datasets from Sanjiang Plain and Zoigê Plateau. Model validation showed that the observed seasonal and interannual variations of CH4 emissions from marshland in northeastern China were well captured, but that from peatland in southwest plateau of China were less well; Nevertheless, modeled seasonal amount of CH4 emissions agreed observed well in the two places, yielding an R2 of 0.96 (n=7, p<0.001); The root-mean-squared error, mean deviation, and model efficiency between modeled and observed values are 14.1%， -6.7%, and 0.95, respectively.