To evaluate the seasonal and spatial variations of CH(4) emissions and understand the controlling factors, we measured CH(4) fluxes and their environmental variables from seven natural wetlands in mountainous regions in northeast China using a static chamber technique during a growing season from May to October in 2008. Four sites were significant atmospheric CH(4) sources, ranked in order from highest to lowest according to their seasonal mean CH(4) release: these sites were a marsh (34.18 mgCH(4) m(-2) h(-1)), two deciduous forested swamps (0.83-18.21 mgCH(4) m(-2) h(-1)) and a thicket swamp (0.43 mgCH(4) m(-2) h(-1)). Coniferous forested swamps, forested fens and bogs are unique wetlands in northeast China and represent large wetland coverage in this zone, but they were observed to be weak sinks of atmospheric CH(4) (-0.08 to -0.01 mgCH(4) m(-2) h(-1)). Similar seasonal variations can be observed at marsh, thicket swamp and two deciduous forested swamps sites, with peaks were observed during the summer and early autumn (July to early September). However, no seasonal pattern was found at the other three sites. Seasonal variations of CH(4) fluxes were primarily affected by the soil temperature. However, spatial variation among wetlands was mainly controlled by the water table, the soil temperature, plant aboveground biomass and potential CH(4) production. A high water table and herb-dominant sites had high potential CH(4) production rates and thus induced high CH(4) fluxes. In contrast, a low water table and tree- or moss-dominant sites had low potential CH(4) production rates and induced low CH(4) fluxes. (C) 2011 Elsevier Ltd. All rights reserved.