The Innovation Team of Grassland Ecology and Remote Sensing at the Institute of Agricultural Resources and Regional Planning (IARRP), Chinese Academy of Agricultural Sciences, recently made significant progress in the study of grassland methane cycling and grazing management. The team systematically revealed the key patterns and mechanisms by which grazing intensity and precipitation variability jointly regulate methane (CH₄) fluxes in temperate meadow steppes. The findings were published in the leading international journal in global change research, Global Change Biology.

Methane is the second most important greenhouse gas after carbon dioxide, with a high global warming potential. Grassland soils serve as a critical methane sink in terrestrial ecosystems, playing an important role in removing atmospheric methane. However, long-term human activities such as grazing, along with changes in precipitation patterns, are continuously weakening the methane uptake capacity of grassland soils. Temperate grasslands across Eurasia have long been subjected to intensive grazing pressure, and under the increasing frequency of extreme precipitation events, grassland methane sinks are facing unprecedented vulnerability risks.

Relying on the Hulunbuir Grassland Ecosystem National Field Scientific Observation and Research Station in Inner Mongolia, the research team conducted an 11-year controlled grazing gradient experiment to systematically evaluate the combined effects of grazing intensity and precipitation variability on grassland methane source–sink dynamics. The study found that overgrazing significantly amplifies the inhibitory effect of rainfall on methane uptake, increasing the instability of methane fluxes in wetter years. Although light grazing can maintain soil methane uptake to some extent, it cannot offset methane emissions from livestock, resulting in grazed grasslands functioning overall as a net methane source.

By examining both short-term and long-term timescales, the study elucidates the differentiated regulatory mechanisms of grassland methane fluxes and, for the first time, identifies the lagged triggering effect of extreme rainfall on long-term grazing impacts. The findings offer new insights for greenhouse gas mitigation, ecological restoration, and low-carbon grazing management in arid and semi-arid grasslands in northern China.

Tianqi Yu, a doctoral student at IARRP, is the first author of the paper, while Ruirui Yan and Xiaoping Xin serve as corresponding authors. The research was supported by the National Key Laboratory for Efficient Utilization of Arid and Semi-Arid Farmland in Northern China, the National Natural Science Foundation of China, and the National Key Research and Development Program. The results offer solid scientific support for compiling greenhouse gas inventories, advancing ecological conservation, and formulating low-carbon grazing policies in northern China;s grasslands.

Figure: Mechanisms of grazing and rainfall impacts on soil methane fluxes in temperate meadow steppe

Original paper link: https://doi.org/10.1111/gcb.70864