Relationship between Biomass and Biodiversity of Degraded Grassland in the Sanjiangyuan Region of Qinghai–Tibet Plateau

Abstract

Understanding the mechanisms of diversity–productivity relationships is a central question in community ecology. Grazing is the main driving force affecting biodiversity, function, and stability of grassland ecosystems, and thus should play an important role in mediating diversity-productivity relationships. In this study, we examined the effect of grazing intensity on both aboveground biomass and biodiversity and explored the relationship between them in alpine meadow ecosystems in Sanjiangyuan, which is the source of the Yangtze, Yellow, and Lancang rivers. The results showed that the aboveground biomass and species richness decreased significantly due to multi-state succession in alpine meadows caused by long-term grazing, while the Shannon–Wiener index and Pielou evenness index decreased and then increased with increasing grazing intensity. The relationship between the aboveground biomass and biodiversity was U-shaped. Our results highlighted the opposite pattern of the diversity–productivity relationship under low and medium grazing intensity versus an extremely high grazing intensity; evenness contributed largely to this pattern. This study provided a new perspective on grassland management and the relationship between productivity and biodiversity. Attention should be paid to rational grazing to restore biodiversity and ecosystem functions and services in alpine meadows.