Structural variability in bulk soil and rhizosphere microbial communities at different restoration modes of open-pit coal mine

Abstract methods herbaceous revegetation (O) and shrub (specifically Hippophae rhamnoides, S) revegetation. The aim was to elucidate the impact of different restoration measures on soil-microbe interactions. The results demonstrated that soil organic carbon (SOC), total nitrogen (TN), available nitrogen (AN), total potassium (TK), and available potassium (AK) contents were significantly higher in the herbaceous restoration area (O) than in the seabuckthorn area (S), by 51.7%, 88.6%, 38.2%, 13.1%, and 4.7%, respectively. Compared to bulk soil, rhizosphere soil exhibited higher microbial community diversity and richness. Furthermore, seabuckthorn rhizosphere microbial diversity surpassed that of herbaceous rhizosphere. Different restoration areas (DRE) significantly (p < 0.05) influenced the relative abundances of Actinobacteria, Proteobacteria, Chloroflexi, and Acidobacteria. The seabuckthorn area showed higher proportions of Proteobacteria (26.48 ~ 42.86%) and Actinobacteria (28.26 ~ 45.19%) compared to the herbaceous area. Functional gene prediction revealed that the seabuckthorn area expressed significantly higher abundances of core metabolic functional genes related to energy production and conversion (C), amino acid transport and metabolism (E), carbohydrate metabolism (G), and lipid metabolism (I) than the herbaceous area. Additionally, a symbiotic functional guild comprising animal pathogens, endophytes, lichen parasites, plant pathogens, and wood saprotrophs was formed in the seabuckthorn area. Redundancy analysis (RDA) indicated significant positive correlations (p < 0.05) between Acidobacteria, Chloroflexi, Actinobacteria, and Ascomycota and the contents of SOC, TN, and total phosphorus (TP). Bacterial networks formed with Actinobacteria as the core hub, comprising 300 edges connecting 50 nodes, while fungal networks were dominated by Ascomycota. Based on these findings, this study proposes a synergistic restoration strategy characterized by "herbaceous-induced short-term priming" coupled with "seabuckthorn-driven long-term stability." This strategy provides a theoretical foundation for the targeted microbial regulation of ecological restoration in mining areas.