Wetland-atmosphere methane exchange in Northeast China: A comparison of permafrost peatland and freshwater wetlands

•Seasonal pattern and magnitude of CH4 fluxes from the two wetlands differed greatly.•Average soil temperature was the main factor related to CH4 flux for the peatland.•Surface soil temperature was the main factor related to CH4 flux for the marsh.•Wetland types should be considered when predicting regional CH4 emission.