Effects of grazing on temperate grassland ecosystem based on a meta-analysis

The temperate semi-arid grassland in Inner Mongolia is primarily used for grazing, which directly and indirectly affects material circulation and energy flow. Grazing intensity plays a decisive role in the health status and direction of grassland succession. Data from 40 studies about Inner Mongolia grassland grazing intensity were analyzed via a meta-analysis. The results showed that compared to the non-grazing grassland, light grazing did not affect the above- and below-ground biomass, soil total nitrogen, and total phosphorus, but significantly increased (P < 0.05) the soil organic carbon (3.60%), microbial carbon (7.80%), bacteria (11.40%), and fungi (10.83%). Moderate grazing did not affect the below-ground biomass and the number of microorganisms, but significantly reduced (P < 0.05) the above-ground biomass (21.62%), soil organic carbon (4.44%), total nitrogen (2.15%), total phosphorus (8.35%), and microbial biomass nitrogen (6.76%). Heavy grazing significantly decreased (P < 0.05) the above- and below-ground biomass (39.72% and 16.30%, respectively), soil organic carbon (7.62%), total nitrogen (6.46%), total phosphorus (8.03%), microbial biomass carbon (8.76%), bacteria (12.92%), and actinomyces (18.27%). These findings suggest that light grazing benefits soil fertility and grassland productivity; however, the grassland ecosystem's functional capacity weakens once the grazing intensity exceeds a certain threshold. This information is useful for adapting management strategies to prevent grassland degradation.