Abstract: Grasslands with high biodiversity can make full use of resources and enhance ecosystem multifunctionality. We examined the effects of phylogenetic diversity, species diversity， and environmental factors on the stability of alpine meadow in Qinghai-Tibet Plateau by multiple linear regression and structural equation model. There were positive correlations between phylogenetic diversity, species diversity, environmental factors and the stability of alpine meadow, which was scale dependent. At the small plot scale, the stability of alpine meadow was affected by species diversity (richness) and environmental factors, with coefficients of 0.237 and 0.221, respectively. Furthermore, phylogenetic diversity was mainly affected by species diversity, with effect coefficient of 0.812 (P<0.001). At the large plot scale, ecosystem stability was mainly affected by environmental factors and species diversity, with effect coefficients of 0.364 and 0.246 respectively (P<0.05). The effects of phylogenetic diversity, species diversity and environmental factors on ecosystem stability were gradually enhanced with increasing scale, with a dominant role of environmental factors. Our results highlight the role of phylogenetic diversity and species diversity in maintaining ecosystem stability of alpine meadow.

Key words: alpine meadow, phylogenetic diversity, species diversity, environmental factor, ecosystem stability.