Bioavailable metals and soil general properties co-mediate microbial communities in uncovered and vegetated areas during different seasons in an abandoned Mo-Ni mining area

Although vegetation restoration is known to reshape the soil environment in abandoned mining areas, the relative importance and combined effects of environmental factors such as bioavailable metals and soil general properties on the microbial communities during this process are not well understood. The chemical fractions of nine metals (Mo, Ni, Cu, Zn, Pb, Cd, Cr, As, and Hg), general properties, and microbial communities of soil in uncovered and vegetated areas under wet and dry seasons from an abandoned Mo-Ni mining area were investigated. The results indicated that soil properties was improved in vegetated areas with higher pH, OM, TN, and TP, and lower metal concentrations compared to uncovered area. The OM, TN, TP in vegetated areas were higher in the dry season than those in the wet season. Cd exhibited the highest proportion of exchangeable fraction and ecological risk. Actinobacteriota (20.5%∼36.8%), Chloroflexi (15.0%∼35.8%), and Proteobacteria (13.4%∼26.2%) were the top three dominant phyla of bacteria. The relative abundances of Chloroflexi and Ascomycota in dry and wet seasons in uncovered area were significantly higher than those in the three vegetated areas. The bacterial and fungal communities between dry and wet seasons clustered together in uncovered area, while they were separated clearly in vegetated areas. The α-diversity of bacteria and fungi showed a significant positive correlation with pH, OM, TN, and TP. However, it was negatively correlated with EC and bioavailable Zn, Pb, Ni, Cu, Cr, and Cd. The shared effect of bioavailable metals and general properties on microbial communities was greater than the independent effect in the abandoned Mo-Ni mining area. These findings enhance our understanding of the effects of bioavailable metals and soil general properties on microbial communities and provide a foundation for vegetation restoration strategies in the abandoned Mo-Ni mining area.