Potentilla parvifolia strongly influenced soil microbial community and environmental effect along an altitudinal gradient in central Qilian Mountains in western China

The Qilian Mountains (QLMs) are an important ecological security barrier in western China and a priority area for biodiversity conservation. Potentilla parvifolia is a widespread species in the mid-high altitudes of the QLMs, that has continuously migrated to higher altitudes in recent years. Understanding the effects of P. parvifolia on microbial community characteristics is important for exploring future changes in soil biogeochemical processes in QLMs. Our study found that P. parvifolia has profound effects on the community structure and ecological functions of soil microorganisms. The stability and complexity of the rhizosphere microbial co-occurrence network were significantly higher than those of non-rhizosphere soils. There was a distinct elevation gradient in the effect of P. parvifolia on soil microbial community characteristics. At 3204 m elevation, P. parvifolia promoted the accumulation of carbon, nitrogen, and phosphorus and increased sucrase activity and soil carbon to nitrogen ratio, while significantly improving the alpha diversity index of fungi compared to bacteria and the relative abundance of Ascomycota. Further, the community similarity distance matrix of fungi showed obvious separation at 3204 m. However, over an altitude range of 3550 to 3750 m, P. parvifolia mainly affected the bacterial community characteristics. P. parvifolia positively interacted with the abundance of bacteria. Morever, the rhizosphere soil environment was conducive to the enrichment of gram positive bacteria and drove the bacterial community to shift toward high-yielding strategists (Y strategists). This is in agreement with our finding based on functional prediction that P. parvifolia favors the growth and enrichment of denitrifying flora at 3550 m and 3750 m. The results provide a scientific basis for predicting the evolutionary trends of the effects of P. parvifolia on soil microbial communities and functions and have important implications for ecological governance in QLMs.