Ecological Responses of Soil Properties and Microbial Diversity to Elevational Gradients and Human Activities in the Bogda Mountains, Xinjiang

Abstract

This study explored the combined effects of elevational gradients and anthropogenic activities on soil physicochemical properties and microbial communities in the northern slope of the eastern foot of the Bogda Mountains, Xinjiang. The key objectives were to identify the dominant driving factors of soil microbial community variation and provide scientific and actionable implications for regional environmental management and ecological sustainability in arid-semiarid mountain ecosystems. Soil samples were collected from 10 sampling sites (8 distributed along the elevational gradient and 2 in human-disturbed areas) using the five-point sampling method. One-way analysis of variance (ANOVA) and redundancy analysis (RDA) were applied to quantify the variations in soil properties (moisture, pH, total nitrogen, etc.) and microbial characteristics (abundance, species richness and diversity). The results showed that soil physicochemical properties presented obvious vertical distribution patterns along the elevational gradient: the mid-altitude spruce forest zone had significantly higher soil moisture and organic matter contents, whereas the high-altitude zone exhibited extremely low levels of these two indicators; the agricultural area had a notably elevated available phosphorus content compared with natural habitats. Soil microbial communities showed distinct spatial heterogeneity: the low-altitude desert zone had the highest bacterial abundance, the mid-altitude spruce forest zone maintained the highest microbial diversity, and the high-altitude meadow/cold desert zone was characterized by the impoverishment of microbial abundance and diversity. Anthropogenic agricultural activities significantly increased soil bacterial abundance but reduced the overall microbial diversity in the affected areas. RDA further revealed that soil organic matter, total nitrogen and moisture were the core driving factors regulating the structure and diversity of soil microbial communities. In conclusion, elevational gradients and anthropogenic activities shape the distribution and variation of soil microbial communities by altering soil physicochemical properties, and irrational human disturbances would disrupt the synergistic interaction between soil properties and microbial communities. These findings provide a solid scientific basis for optimizing regional ecological protection measures, formulating sustainable agricultural practices, and constructing adaptive environmental management strategies for arid-semiarid mountainous regions.