Patterns and Driving Mechanisms of β-Diversity in Mountain Plant Communities of Arid Regions

Arid mountain ecosystems are characterized by unique environmental stresses and high biodiversity. However, knowledge regarding the distribution patterns, multidimensional characteristics, and shaping forces of plant community β-diversity-especially under extreme environmental conditions-remains insufficient. In this study, we focused on the northern slope of the central Kunlun Mountains, an extremely arid region, and analyzed plant community survey data from 72 sites. By applying β-diversity partitioning and multiple regression analyses, we systematically identified the patterns of both taxonomic and phylogenetic β-diversity and their components and evaluated the relative importance of geographic, climatic, and topographic distances in shaping β-diversity. The results showed that species turnover is the primary force structuring both taxonomic and phylogenetic β-diversity, and that these diversity indices increase substantially with elevational differences. The combined influence of geographic, climatic, and topographic distances explained 46.4% of the variability in taxonomic β-diversity and 53.6% in phylogenetic β-diversity. Variance partitioning analysis showed that β-diversity patterns were shaped predominantly by climatic distance, while the contributions of geographic and topographic distances were limited. Among climatic variables, mean annual temperature emerged as the most influential determinant. This study not only deepens our understanding of biodiversity maintenance mechanisms under extreme environmental conditions but also provides important scientific evidence for the formulation of biodiversity conservation and management strategies in this region, particularly for optimizing the spatial layout of multiple small nature reserves under a turnover-dominated β-diversity pattern.