Abstract
The alpine meadows of the Qinghai-Tibet Plateau have significant potential for storing soil carbon, which is important to global carbon sequestration. Grazing is a major threat to its potential for carbon sequestration. However, grazing poses a major threat to this potential by speeding up the breakdown of organic matter in the soil and releasing carbon, which may further lead to positive carbon-climate change feedback and threaten ecological security. Therefore, in order to accurately explore the driving mechanism and regulatory factors of soil organic matter decomposition in grazing alpine meadows on the Qinghai-Tibet Plateau, we took the grazing sample plots of typical alpine meadows as the research object and set up grazing intensities of different life cycles, aiming to explore the relationship and main regulatory factors of grazing on soil organic matter decomposition and soil microorganisms. The results show the following: (1) soil microorganisms, especially Acidobacteria and Acidobacteria, drove the decomposition of organic matter in the soil, thereby accelerating the release of soil carbon, which was not conducive to soil carbon sequestration in grassland; (2) the grazing triggering effect formed a positive feedback with soil microbial carbon release, accelerating the decomposition of organic matter and soil carbon loss; and (3) the grazing ban and light grazing were more conducive to slowing down soil organic matter decomposition and increasing soil carbon sequestration.