Although the effects of grazing on soil respiration are well understood, there is still a lack of understanding about the mechanisms underlying the effects of grazing intensity on soil respiration. In addition, the response of soil respiration to the grazing season, such as warm- and cold-season grazing, remains unclear. To determine how grazing intensity (no, light grazing, moderate grazing, heavy grazing) and grazing season (warm-season grazing, WG; cold-season grazing, CG) affect soil respiration, we conducted soil respiration measurements in two long-term grazed grasslands under CG and WG from 2010 to 2011. Our results showed that light, moderate, and heavy grazing significantly increased soil respiration relative to no grazing in 2010, but grazing intensity had little effect on soil respiration in 2011. With the increase in grazing intensity, soil respiration decreased by 10–17% at the WG site but increased by 23–30% at the CG site. Structural equation modeling analysis indicated that grazing intensity indirectly affected soil respiration by altering aboveground and soil microbial biomass carbon. CG enhanced soil respiration by 22% relative to WG. Grazing season-induced soil moisture, soil temperature, soil microbial biomass carbon and nitrogen could be mechanisms underlying increased soil respiration under in grazed grasslands. Precipitation had a strong correlation with soil respiration. Our results highlight the importance of grazing season altering soil respiration in semiarid grassland ecosystems and indicate that interactive effects of grazing season and precipitation events on soil respiration need to be considered in the future.

尽管人们已经很好地了解了放牧对土壤呼吸的影响，但是，仍然缺乏对放牧强度对土壤呼吸影响的机理的认识。此外，尚不清楚土壤呼吸对放牧季节的响应，例如暖季和冷季放牧。为了确定放牧强度（否，轻度放牧，中度放牧，重度放牧）和放牧季节（暖季放牧，WG；冷季放牧，CG）如何影响土壤呼吸，我们在两次长期放牧中进行了土壤呼吸测量CG和WG下的草原在2010年至2011年之间。我们的研究结果表明，轻度，中度和重度放牧相对于2010年没有放牧，显着提高了土壤呼吸，但放牧强度对2011年的土壤呼吸影响不大。 ，WG处土壤呼吸减少了10–17％，而CG处增加了23–30％。结构方程模型分析表明，放牧强度通过改变地上和土壤微生物生物量碳间接影响土壤呼吸。相对于WG，CG使土壤呼吸增强了22％。放牧季节引起的土壤水分，土壤温度，土壤微生物生物量碳和氮可能是草场下土壤呼吸增加的潜在机制。降水与土壤呼吸密切相关。我们的结果凸显了半干旱草原生态系统中放牧季节改变土壤呼吸的重要性，并指出未来需要考虑放牧季节和降水事件对土壤呼吸的相互作用。