Structural Variability in Bulk Soil and Rhizosphere Microbial Communities at Different Restoration Modes of Open-pit...

Microbial communities serve as vital indicators of ecosystem health and play a crucial role in facilitating the restoration of degraded soil ecosystems, acting as key participants in soil nutrient cycling. However, the interaction mechanisms between microbial communities and plants in different soil zones under varying restoration approaches remain unclear. This study focused on a restoration area of a decommissioned open-pit coal mine in an alpine region, comparing the microbial community structure and nutrient characteristics of rhizosphere and bulk soils under two restoration methods: herbaceous vegetation restoration and sea-buckthorn shrub restoration. The aim is to reveal the impact of different restoration measures on the soil-microorganism 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.