Located at the edge of the Tibetan Plateau, the Qilian Mountains form a significant high-altitude permafrost region. Understanding the stratification characteristics of soil carbon and the response mechanisms under altitudinal variation provides important insights into the carbon pool dynamics across the Tibetan Plateau. Potentilla parvifolia is a shrub species widely distributed at moderate and high altitudes. Recently, with the intensification of global climate change, there have been signs of migration to the high latitudes. This migration affects the microbial community structure and has influence on the soil carbon pools and the carbon cycling processes of ecosystems. In the present study, the rhizosphere soil carbon components and microbial communities of P. parvifolia were evaluated along altitudinal gradients (3204, 3350, 3550, and 3650 m) in the Qilian Mountains. We found that P. parvifolia significantly increased the biomass of soil gram-positive bacteria and fungi at medium and low altitudes (3204, 3350, and 3550 m) (p < 0.05), and significantly increased the contribution of mineral-associated organic carbon (MAOC) to the soil organic carbon (SOC) content when compared to those in bare soil (p < 0.05). Furthermore, P. parvifolia mainly increased SOC content by increasing the contribution of microbial necromass carbon, especially fungal necromass carbon, to MAOC; however, there were no significant differences at high altitudes (3650 m) (p > 0.05). This research enhances our comprehension of the impact of plant migration on SOC and its microbial mechanisms and provides a basis for the development of bioprotection strategies for alpine ecosystem conservation.

Different grazing practices can have varying impacts on soil properties and soil microbial communities, which are critical for maintaining productivity and functions of grasslands and the overall ecosystem. The Qinghai-Tibetan plateau (QTP) is the largest high-altitude grazing region on earth, and has three different grazing practices, including seasonal grazing (SG), continuous grazing (CG), and exclosure grazing (EG) for 10 years. Vegetation, soil properties from two different depths (0-0.15 and 0.15-0.30 m) and soil microbial communitiesin the surface soil layer (0-0.15 m) were measured in triplicate plots within each grazing practice. The soil conditions in the SG site were the best, the CG site was the worst, while the EG site was intermediate. Dry aboveground biomass, soil organic carbon, total nitrogen, and total phosphorus content under SG were 838 g/m2, 20.73g/kg, 1.74 g/kg, and 0.20 g/kg, respectively, and under CG were 8.80 g/m2, 8.07g/kg, 1.07 g/kg, 0.16 g/kg, respectively. There was no significant difference in the α-diversity of soil bacteria and fungi among the three grazing practices. However, the bacterial communities were significantly different from each other; only the fungal community under EG was significantly different from the other grazing practices. While the relative abundance of Basidiomycota under SG was significantly higher than that under EG, no difference was observed in the relative abundance of Ascomycota, Zygomycota, and unclassified_k_Fungi among the three grazing practices. Compared to SG, CG and EG significantly increased the relative abundance of Actinobacteria, Gemmatimonadetes, Verrucomicrobia, and Nitrospirae, but decreased the relative abundance of Proteobacteria and Bacteroidetes.