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Understanding the mechanisms that sustain plant diversity in arid regions is a current focus of ecological research. This study focused on the Gurbantunggut Desert, China’s largest fixed and semi-fixed desert, and systematically investigated the plant community diversity and its environmental drivers on fixed, semi-fixed, and mobile dunes. Data analysis was conducted using non-metric multidimensional scaling (NMDS) ordination, redundancy analysis (RDA), boosted regression tree (BRT), and structural equation modeling (SEM). The results indicated that taxonomic diversity (TD), functional diversity (FD), and phylogenetic diversity (PD) all exhibited consistent gradient patterns: fixed dunes > semi-fixed dunes > mobile dunes. The Net Relatedness Index (NRI) and the Nearest Taxon Index (NTI) primarily exhibited phylogenetic clustering, and habitat filtering was the dominant process in community assembly. Soil water content (SWC) and soil organic carbon (SOC) are the key drivers regulating plant diversity in this region. SWC and SOC directly and significantly influence FD and PD; however, their indirect effects on TD are weak, suggesting that species composition is also jointly constrained by abiotic processes such as dispersal limitation and interspecific competition. This study offers a theoretical foundation for differentiated ecological management of fixed, semi-fixed, and mobile dunes in the Gurbantunggut Desert.
Lin et al. (Wed,) studied this question.