摘要：Methane (CHsub4/sub) is one of the three most important greenhouse gases. To date, observations of ecosystem-scale methane (CHsub4/sub) fluxes in forests are currently lacking in the global CHsub4/sub budget. The environmental factors controlling CHsub4/sub flux dynamics remain poorly understood at the ecosystem scale. In this study, we used a state-of-the-art eddy covariance technique to continuously measure the CHsub4/sub flux from 2016 to 2018 in a subtropical forest of Zhejiang Province in China, quantify the annual CHsub4/sub budget and investigate its control factors. We found that the total annual CHsub4/sub budget was 1.15 ± 0.28~4.79 ± 0.49 g CHsub4/sub msup−2/sup yearsup−1/sup for 2017–2018. The daily CHsub4/sub flux reached an emission peak of 0.145 g msup−2/sup dsup−1/sup during winter and an uptake peak of −0.142 g msup−2/sup dsup−1/sup in summer. During the whole study period, the studied forest region acted as a CHsub4/sub source (78.65%) during winter and a sink (21.35%) in summer. Soil temperature had a negative relationship (ip/i 0.01; Rsup2/sup = 0.344) with CHsub4/sub flux but had a positive relationship with soil moisture (ip/i 0.01; Rsup2/sup = 0.348). Our results showed that soil temperature and moisture were the most important factors controlling the ecosystem-scale CHsub4/sub flux dynamics of subtropical forests in the Tianmu Mountain Nature Reserve in Zhejiang Province, China. Subtropical forest ecosystems in China acted as a net source of methane emissions from 2016 to 2018, providing positive feedback to global climate warming.
