Diversity and Function Patterns of Soil Microbial Communities in Native and Invasive Plants Along an Altitudinal Gradient in the Qinling Mountains

Soil microbial communities are essential drivers of ecosystem functions, yet the factors shaping their structure and function, particularly at different altitudes and between invasive and native plants, remain insufficiently understood. Using high-throughput Illumina sequencing, we assessed the composition, diversity, impact factors, and functional potential of the microbial communities associated with Galinsoga quadriradiata (an invasive species) and Artemisia lavandulifolia (a native species) across an altitudinal gradient ranging from 896 m to 1889 m in the Qinling Mountains. The results revealed that both plant species and altitude significantly influenced soil bacterial diversity and community structure. Actinobacteriota, Proteobacteria, and Acidobacteriota accounted for higher proportions in the soils of G. quadriradiata and A. lavandulifolia. A linear discriminant analysis showed that the two species hosted distinct microbial communities, with variations driven by species-specific traits and environmental factors. Compared with plant parameters, environmental factors had a greater impact on plant soil bacterial abundance. Functional analysis indicated that A. lavandulifolia soils were more associated with nitrogen cycling processes, while G. quadriradiata soils contributed more to organic matter decomposition. Therefore, invasive and native plants harbored microbial flora with different nutritional preferences and metabolic characteristics. These findings advance our understanding of plant–microbe interactions along altitudinal gradients, and they have practical implications for managing invasive species and supporting ecosystem resilience.