Long-abandoned mining environments reshape soil microbial co-occurrence patterns, community assembly, and biogeochemistry

The diversity of microbial communities is crucial for maintaining ecological balance in mining ecosystems. Although changes in soil microbial communities in mining areas have been widely studied, there is still a lack of systematic understanding of how long-abandoned mining sites influence microbial co-occurrence patterns, community assembly processes, and biogeochemical cycles. Based on soil samples from long-abandoned mining areas, this study comprehensively investigates the impacts of environmental factors on microbial co-occurrence networks, community assembly mechanisms, and biogeochemical functions. Our results show that prolonged abandonment has significantly altered the physicochemical properties of the soil and reshaped both the structure and function of microbial communities. The community assembly processes are strongly influenced by environmental stress, leading to the enrichment of specific functional microbial taxa. Notably, in highly polluted areas, bacterial communities demonstrate enhanced interspecies mutualism and increased network connectivity as adaptive strategies to cope with heavy metal stress. High concentrations of heavy metals were found to suppress microbial carbon fixation and denitrification potential, while enhancing their capacity for sulfide removal. This study fills a key knowledge gap regarding the effects of long-term mining abandonment on microbial ecology and offers new insights into the mechanisms underlying ecological restoration. It highlights the potential role of microbial communities in the remediation of degraded mining sites and provides a novel theoretical foundation for future ecological restoration efforts in such environments.