Geographical Patterns and Drivers of Species and Phylogenetic Diversity of Desert Plant Communities in the Hexi Corridor, Northwestern China

Desert plant communities play an irreplaceable role in maintaining the ecological balance of arid areas. Understanding the spatial distribution pattern of desert plant diversity and its environmental response mechanism is particularly important for the protection of regional biodiversity, and combining phylogenetic information can provide more in-depth insights. To this end, this study conducted a survey of desert plant communities along the southeast to northwest direction of the Hexi Corridor, revealing the variation patterns of species and phylogenetic diversity (PD) indicators along longitude, latitude, and altitude, and explored the driving factors of these patterns in combination with geographical, climatic, and soil factors. The results showed that the changes in species diversity (Shannon-Wiener and Margalef) and PD along longitude and latitude showed a unimodal model, with the highest value in the central region. The dispersion of phylogenetic structure decreases with increasing altitude, with divergent patterns at low altitudes and clustered patterns at high altitudes. In addition, we found that soil factors such as soil available phosphorus (SAP), soil total phosphorus (STP), and soil available nitrogen (SAN) dominated the variation of species diversity, and the PD was also mainly regulated by soil available phosphorus (SAP), while the main influencing factor of the phylogenetic structure was the average annual temperature (AMT), indicating that the community diversity pattern was driven by soil nutrients and climatic factors. The study reveals the relative roles of different environmental factors in shaping community diversity and provides a scientific basis for formulating effective desert ecosystem protection strategies.