Grazing Stocking Rate and Rainfall Jointly Regulate Soil Methane Uptake in a Temperate Meadow Steppe, but Do Not Reverse Net Methane Emissions

ABSTRACT Grasslands are widely recognized as important sinks of methane (CH 4 ). However, their CH 4 uptake capacity has been increasingly weakened driven by human activities and changes in precipitation regimes. In particular, the rapid expansion of livestock grazing can lead to substantial increases in CH 4 emissions. For the Eurasian grasslands that have been subject to long‐term grazing, how well they currently function and will continue to function as CH 4 sinks under the changing precipitation regimes remains uncertain. Here we conducted an 11‐year grazing‐gradient experiment to assess the combined effects of grazing intensity and precipitation variability on grassland CH 4 fluxes. We measured soil CH 4 uptake in a manipulative grazing experiment in both wet and dry years, estimated livestock‐derived CH 4 emissions, and examined a range of biotic and abiotic drivers, including vegetation attributes, soil properties, and microbial biomass, for short‐ (prior to the onset of the lagged response) and long‐term (the entire experimental period) influences on the dynamics of CH 4 uptake in temperate meadow grasslands. Over the long term, CH 4 fluxes are jointly regulated by precipitation and grazing, with overgrazing amplifying the suppressive effect of rainfall on CH 4 uptake. Soil CH 4 uptake showed a lagged response to grazing, which may have been triggered by extreme rainfall events. While moderate grazing sustained the long‐term CH 4 uptake, it fails to offset livestock‐derived CH 4 emissions. In the short term, CH 4 fluxes are primarily governed by grazing, whereas in the long term they are jointly regulated by precipitation and grazing intensity. These results offer a new perspective for understanding the source–sink CH 4 dynamics of grasslands in the context of ongoing climate change.