Moderate grazing enhances ecosystem multifunctionality through leaf traits and taxonomic diversity in long-term fenced grasslands.

Grassland community diversity plays a vital role in maintaining the functionality of grassland ecosystems, influencing processes such as nutrient cycling and supporting ecosystem multifunctionality (EMF). Long-term fencing impacts biodiversity and nutrient dynamics, but its effects alongside grazing practices are not well understood. This study examined grazing intensity's effects on community structure, leaf traits, diversity, and ecosystem functions in a 38-year-fenced grassland, through a four-year grazing experiment. Kansu red deer (Cervus elaphus kansuensis) was chosen due to its diverse diet, tolerance to rough feeding, and high feed conversion efficiency. Results showed that grazing intensity significantly affected community structure. Moderate grazing promoted perennial grasses and legumes, boosting aboveground biomass, while heavy grazing encouraged poisonous forbs, potentially harming ecosystem health. Moderate grazing also enhanced diversity metrics such as the Shannon-Weiner index, species richness, functional richness, and functional diversity. Additionally, it improved leaf traits like community-weighted mean leaf nitrogen, phosphorus content, specific leaf area, and leaf dry matter content, all contributing to better EMF. Structural equation modeling revealed that EMF was directly influenced by grazing intensities and indirectly through changes in leaf traits and taxonomic diversity. These findings suggest that moderate grazing enhances EMF in long-term fenced grasslands by improving the distribution of functional groups, leaf traits, and community diversity. Thus, moderate grazing is an optimal strategy for maintaining community diversity and EMF, highlighting the importance of grazing management for sustainable land use and addressing ecological challenges in grassland ecosystems.