How soil physicochemical properties and microorganisms change under mining activities in alpine and high-altitude regions−a case study of a copper mine area in Tibet Plateau

The exploitation of the Tibetan Plateau for metal mining is expected to cause extensive ecological challenges, such as soil erosion, soil degradation, and biodiversity loss. This study investigated the environmental impact of the surface copper polymetallic mine with the world’s highest altitude using indicators of soil physicochemical properties, vegetation index and microbial communities (e.g., diversity, composition, and co-occurrence patterns). We analyzed 22 soil samples from the mining surrounding (MS) area and 8 from natural grassland (NG) controls. We found that in early-stage alpine metal mining, the microbial community indicators exhibited more significant responses to environmental changes than the physicochemical property indicators. Compared with NG soil, the number of oligotrophic groups (mainly Acidobacteriota and Verrucomicrobiota) in MS soil significantly increased, whereas the number of copiotrophic groups (Proteobacteria and Firmicutes) significantly decreased. The microbial network in MS soil was less complex compared with that in NG soil, with fewer nodes and edges, indicating an unstable microbial ecosystem. The oligotrophic group (e.g., Chloroflexi) was identified as the key taxa responsible for stable network structures. Changes in soil properties (particularly pH) and heavy metals (particularly As and Zn) were the most critical factors influencing variations in soil communities in MS soil. Heavy metals explained 8.15 % more microbial community variations than other soil properties. Therefore, evaluating soil quality in ecologically fragile areas requires multiple indicators. Relying solely on physicochemical indicators, which change over a relatively longer period compared to microbial community composition, is insufficient for comprehensively detecting potential soil risks. Our conclusions were crucial for evaluating the environmental risks associated with early-stage alpine mining on the Tibetan Plateau, providing an approach toward investigating the natural bioremediation of soil ecosystems in alpine mining areas.