Microbial Mechanisms Underlying Soil Nutrient Availability in Vegetation Reconstruction of an Open-Pit Mining Area in Inner Mongolia
Open-pit coal mining severely damages soil and plant community structure and function, causing soil nutrient loss and ecological degradation. Vegetation reconstruction is a key measure for restoring degraded mining ecosystems, with the core challenge being the selection of suitable plant species and optimization of plant configurations. This study focused on the degraded ecosystem of the Baiyinhua open-pit mine in Inner Mongolia, screening native plant species for vegetation reconstruction experiments to investigate early-stage changes in soil nutrient availability and the underlying microbial mechanisms. Results showed that soil physicochemical properties and fungal community diversity exhibited strong adaptability during early reconstruction. However, soil fungal community composition and the relative abundance of saprotrophic fungi differed significantly among plant configurations. Leymus chinensis significantly increased the proportion of soil saprotrophic fungi from 67.28% in the control to 81.63%, while reducing the relative proportion of pathogenic fungi from 15.63% to 4.33%, demonstrating its potential to enhance soil health. Medicago rivularis improved soil microbial community composition and increased soil available phosphorus content, highlighting its capacity as an excellent pioneer species for optimizing soil nutrient availability. Furthermore, mixed sowing of grasses and legumes showed potential to enhance the nitrogen-fixing effect of legumes. Given the significant positive correlation between soil fungal community composition and total nitrogen and available nitrogen, the effects of different plant configurations on soil nutrient availability and biological health likely stem largely from the regulation of soil fungal community composition. In conclusion, achieving the goal of selecting optimal plant configurations still requires long-term continuous observation and analysis, particularly for optimizing configurations between high-quality grasses like Leymus chinensis and legumes.