Bacterial Community Characteristics of Kengyilia thoroldiana Rhizosphere Soil in Different Topographic Habitats of the Yellow River Source Region and Their Response to Vegetation-Soil Factors

This study aims to uncover the structural and functional characteristics of rhizosphere soil bacterial communities of <i>Kengyilia thoroldiana</i> under five types of topographic habitats in the source region of the Yellow River, and to explore the interaction mechanisms between bacterial communities and plant-soil factors, thereby providing microbiological support for the ecological restoration of <i>Kengyilia thoroldiana</i> artificial grasslands in alpine desert grassland. In this study, high-throughput sequencing technology was employed to compare the species composition, diversity, interaction networks, and functional characteristics of rhizosphere bacterial communities of <i>Kengyilia thoroldiana</i> across five topographic habitats in the source region of the Yellow River. Additionally, Mantel tests and redundancy analysis (RDA)) were conducted to explore the key environmental factors driving the structure of bacterial communities. The results showed that habitat differences significantly influenced the community characteristics of <i>Kengyilia thoroldiana</i> and soil physicochemical properties. The plant height, coverage, biomass, and soil carbon, nitrogen, and phosphorus contents were highest in habitats H2 and H5, while they were lowest in habitats H1 and H3. In contrast, soil pH and electrical conductivity exhibited an opposite trend. At the bacterial community level, the number of operational taxonomic units (OTUs) in habitat H5 reached 1917, with α-diversity indices such as Shannon, Ace, and Chao1 being 6.13, 1820.85, and 1844.80, respectively, significantly higher than those in habitat H1. Cluster analysis revealed that habitat H3 formed a distinct group, while the bacterial community structures in the remaining four habitats were similar. Functional prediction indicated that chemoheterotrophy and aerobic chemoheterotrophy were the dominant functions across all habitats, with functional expression values exceeding 9300 in habitats H2, H4, and H5. Redundancy analysis confirmed that soil pH and SOC were the key factors driving the structure of rhizosphere bacterial communities of <i>Kengyilia thoroldiana</i>. In summary, topographic habitats influence the growth of <i>Kengyilia thoroldiana</i> plant communities by shaping soil environmental heterogeneity, thereby regulating the structure and function of rhizosphere bacteria associated with <i>Kengyilia thoroldiana</i>.