Abstract: Forest soils are the main sink of atmospheric methane (CH₄) in the terrestrial ecosystems. Global changes, such as increasing atmospheric CO₂ concentration, warming, changing rainfall regime, and increasing nitrogen (N) deposition, affected soil CH₄ uptake by altering soil physicochemical properties, plant growth, and soil microorganisms. In this study, we conducted a meta-analysis of the impacts of global changes on CH₄ uptake in forest soils. Based on 195 sets of data collected from 155 papers, we found that the rate of CH₄ uptake by forests decreased significantly under elevated CO₂ and N deposition, but increased under drought. There were no significant differences in CH₄ uptake rates at the annual scale in tropical, temperate, and boreal forests. Global warming did not affect CH₄ uptake rates in forest soils. Moreover, the results of seasonal and drought experiments on forest soil CH₄ uptake demonstrated that soil moisture was negatively correlated with CH₄ uptake. The linear model of CH₄ uptake in soil water balance fitted in this study did not reflect the negative correlation between soil water surplus and soil CH₄ uptake. These results indicate that soil water balance model requires more empirical data when it is applied at the global scale. Our results shed light on future experiments related to the impacts of global change on CH₄ uptake in forest soils.

Key words: climate change, meta-analysis, CO₂ concentration, soil water.