Abstract: Temperature changes affect soil methane metabolic microorganisms and related enzyme activities, which in turn affect CH₄ flux in grassland ecosystems. To clarify the trends and mechanism of CH₄ flux in Leymus secalinus grassland ecosystem under the trend of increasing temperature, the open-top chamber method was used to set up five gradient warming treatments, and the CH₄flux and its influencing factors in the growing season of each treatment were measured in the fourth year of warming. The results showed that warming significantly increased air temperature, but with the increase of air temperature, soil temperature and soil volumetric water content did not change significant. During the growing season, the ecosystem of Leymus secalinus grassland in northern Shanxi was a weak atmospheric CH₄ sink, an average absorption rate of (6.42±5.63) μg·m^-2·h^-1 CH₄. Warming significantly affected CH₄ flux and pmoA functional gene abundance. Compared with the control, only W1 treatment promoted CH₄ uptake flux. Redundancy analysis showed that soil volumetric water content was a significant factor affecting both pmoA gene abundance and CH₄ uptake rate. This study provides a theoretical basis for predicting CH₄ flux changes in grassland ecosystems under different scenarios of future climate warming.

Key words: OTC, Greenhouse gas, Functional genes, Methane uptake

摘要： 温度变化通过影响土壤甲烷代谢微生物及相关酶的活性进而影响草地生态系统CH₄通量。为明确晋北赖草（Leymus secalinus）草地生态系统CH₄通量随气温升高的变化趋势及机理，采用开顶箱法（Open top chambers，OTCs）设置5个梯度的增温处理，对增温第4年各处理生长季CH₄通量及其影响因素进行测定。结果表明：增温显著提高了空气温度，但随着空气温度的增加，土壤温度和土壤体积含水量无显著变化；生长季晋北赖草草地生态系统是弱的大气CH₄汇，其CH₄平均吸收速率为（6.42±5.63） μg·m^-2·h^-1；增温显著影响CH₄通量和pmoA功能基因丰度，与对照相比，只有W1处理促进CH₄吸收通量；冗余分析表明土壤体积含水量是同时影响pmoA基因丰度和CH₄吸收速率的关键因子。本研究可为预测未来气候变暖情境下草地生态系统CH₄通量变化提供理论依据。

关键词: OTC, 温室气体, 功能基因, 甲烷吸收