Effects of Grazing Intensity on Soil Microbial Community Characteristics in Desert Steppe

[Objective] Investigating the response mechanism of soil microbial communities to changes in grazing intensity can provide scientific theoretical and technical support for ecological protection and restoration of desert steppe. [Methods] Taking the desert steppe in Inner Mongolia as the research object, we studied the effects of different grazing intensities (no grazing, light grazing, medium grazing, and high grazing) on soil physicochemical properties and the composition and diversity of soil microbial communities at different soil depths (0—20 cm and 20—40 cm), the interactions between soil physicochemical properties and soil microbial communities were analyzed. [Results] Compared to no grazing, medium grazing significantly (p<0.05) reduced the soil total nitrogen (TN) content (by 17.99%) and soil organic carbon (TOC) content (by 19.23%) at 0—20 cm depth. The maximum value of soil bulk density (SBD) appeared under high grazing conditions. The soil physicochemical properties at 20—40 cm depth showed no differences (p>0.05) under different grazing intensities. In addition, grazing decreased the abundance and diversity of bacterial communities at 20—40 cm depth, while increased the abundance and diversity of bacteria communities at 20—40 cm depth. Under light and moderate grazing conditions, the abundance and diversity of soil fungal communities at 0—20 cm depth increased, with no significant effect (p>0.05) on the abundance and diversity of soil fungal communities at 20—40 cm depth. [Conclusion] Mantel tests showed that total nitrogen of desert steppe soil was the primary factor influencing the change of desert steppe soil bacterial abundance with grazing intensity. The research results contribute to understanding the ecological sensitivity of soil microbes and offer scientific guidance for achieving sustainable management in desert steppe ecosystems.