Analysis of Soil Microbial Community Structure Changes in The Drainage Field of The Shengli Coalfield Based on High-Throughput Sequencing

The study of soil environment in drainage fields is important for environmental management and ecological restoration, and there is currently a knowledge gap for understanding the impact of soil microbial communities in the Victory coalfield drainage fields and the corresponding ecological effects. To investigate the changes in rhizosphere soil microbial communities of different dominant plants after years of restoration, this study examines the improvement effects of different dominant plants on the soil environment. This study is based on high-throughput sequencing to restore the slope of coal mine spoil after 15 years as the sampling site. The rhizosphere soil of five dominant plants was selected for microbial community analysis, and functional prediction of the microbial community was conducted. The dominant plants selected included Erect Milkvetch (Astragalus adsurgens), Lemongrass (Caragana korshinskii), Alfalfa (Medicago sativa), Phyllanthus Pinnatifida (Elymus dahuricus), and Brassica Rapa (Brassica campestris). The results showed that after 15 years of restoration, the soil physicochemical properties in the Phyllanthus pinnatifida group were better than those in the other groups overall, but some of them were inferior to those in the lemon-stripped mallard group. Abundant saprophytic fungal communities were found in different dominant plant groups, mainly belonging to the phyla Ascomycota and Basidiomycota, resulting in significantly higher organic matter content in the dominant plant groups compared to the CK group. The bacterial communities were dominated by the phyla Actinobacteriota, Proteobacteria, Chloroflexi, and Firmicutes, which are more adaptable to extreme environments and can coexist in extreme environments. Among these microbial phyla, the Phyllanthus pinnatifida group had higher abundance. The microbial communities of the five dominant plant groups are mainly composed of species that have strong resistance to extreme environments. The soil properties and decomposition ability in the soil were significantly improved compared to those in the CK group. There are a large number of environment-specific bacterial species in the soil environment, leading to the phenomenon of "rare ecological circles". Taking all factors into consideration, the Phyllanthus pinnatifida group had a more significant effect on improving the soil microbial environment in the landfill site. Organic matter content and pH are the main factors influencing the composition of soil microbial communities, significantly affecting the composition of microorganisms in different groups. The bacterial community under PICRUSt2 predictive analysis was mainly dominated by metabolism function, and the soil environment in different groups might be favorable for the metabolism, growth and proliferation of target microorganisms; the fungal community under FUNGuild predictive analysis was mainly dominated by saprophytic and pathotrophic types, which is consistent with the fungal community in different groups. Overall, this study provides a preliminary reference for the changes in microbial communities in the Shengli coalfield, which helps deepen our understanding of the soil microbial environment in the Shengli coalfield spoil heap.