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Methane (CH 4) is a vital greenhouse gas with a 28-fold higher global warming potential than carbon dioxide when considering a molar basis for the time horizon of 100 years. Here, we investigated the variation of soil CH 4 fluxes, soil physiochemical properties, and CH 4-related bacteria community composition of two forests in China. We measured CH 4 fluxes using static chambers and analyzed soil bacterial communities using next-generation high-throughput sequencing in a temperate broad-leaved deciduous forest at Baotianman Nature Reserve (TBDF-BTM) and a tropical rainforest at Jianfengling National Natural Reserve (TRF-JFL). Our results showed that the soils from both sites were CH 4 sinks. Significant variation in soil CH 4 fluxes was found at TBDF-BTM exclusively, while no seasonal variation in the CH 4 uptake was observed at TRF-JFL. The CH 4 fluxes at TBDF-BTM were substantially higher than those at TRF-JFL during all seasons. One genus of methanotrophs and three genera of methylotrophs were detected at both sites, though they had no direct relationship with soil CH 4 fluxes. Water-filled pore space and soil total carbon content are the main factors controlling the soil CH 4 fluxes at TBDF-BTM. At TRF-JFL, the soil CH 4 fluxes showed no significant correlations with any of the soil properties. This study improves our understanding of soil CH 4 fluxes and their influencing factors in forests in different climatic zones and provides a reference for future investigation of forest soil CH 4 fluxes, the forest ecosystem carbon cycle, and the forest CH 4 model.