Microbial Community Structure in the Rhizosphere Soil of Reaumuria soongorica Across Heterogeneous Habitats and Its Response to Soil Nitrogen and Phosphorus

Nitrogen (N) and phosphorus (P) are key nutrients limiting ecosystem productivity, and habitat heterogeneity regulates rhizosphere microbial differentiation and N/P transformation through environmental filtering. However, inter-habitat differences in Reaumuria soongorica rhizosphere microorganisms and their association with N/P cycling remain unclear. Rhizosphere soils from Lanzhou (LZ), Wuwei (WW), and Zhangye (ZY) were analyzed for N/P contents, extracellular enzyme activities, and microbial community structure and diversity. Available phosphorus and organic carbon were highest in WW; nitrogen indices differed significantly between LZ rhizosphere and bulk soil; and in ZY only NO3−−N content and the NO3−−N/NH4+−N ratio changed significantly (p < 0.05). Rhizosphere enzyme activities exceeded bulk values in all habitats, being highest in WW. The rhizosphere was enriched in Ascomycota, Basidiomycota, Proteobacteria, Actinobacteriota, and Firmicutes, with higher abundance, diversity, and evenness than bulk soil; highest diversity in WW. Mantel analysis revealed similar dominant factors for fungi and bacteria but different importance among taxonomic levels; total nitrogen, alkaline phosphatase activity, altitude, pH, and bulk density dominated the bacterial community. In conclusion, the R. soongorica rhizosphere shows clear habitat differentiation and rhizosphere effects, with N, P, and enzyme activities playing key roles in community assembly. These findings support desert plant adaptation studies, functional microbial exploration, and ecological restoration.