Key Takeaways & Executive Findings
- •• • Leymus chinensis increased soil saprotrophic fungal proportion from 67.28% (control) to 81.63% and reduced pathogenic fungi from 15.63% to 4.33%, indicating a dual benefit for soil health and disease suppression in degraded mining soils. • • Medicago rivularis significantly enhanced soil available phosphorus content and improved microbial community composition, positioning it as a high-efficiency pioneer legume for nutrient-poor substrates. • • Mixed sowing of grasses and legumes (禾本科:豆科:菊科 = 8:4:1) demonstrated potential to amplify legume nitrogen fixation, a critical mechanism for accelerating soil organic matter accumulation in post-mining landscapes. • • Soil fungal community composition showed a significant positive correlation with total nitrogen and available nitrogen, implying that plant-driven fungal community shifts are a primary regulator of nutrient cycling during early ecological restoration.
Abstract
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.
1. Introduction
Open-pit coal mining in Inner Mongolia has historically prioritized production output, leaving vast spoil heaps with stripped topsoil, depleted nutrient pools, and dysfunctional microbial communities. Conventional reclamation efforts often fail because non-native species are planted without regard to plant–microbe–soil feedbacks, leading to poor establishment and long-term degradation. The bottleneck is not merely revegetation but the reinstatement of biogeochemical cycles—particularly nitrogen and phosphorus availability—which are governed by soil fungal communities that respond sensitively to plant identity and diversity.
This study addresses that bottleneck by systematically screening native grasses, legumes, and forbs and testing single versus mixed configurations in a controlled field experiment at the Baiyinhua mine. By quantifying soil nutrient pools, fungal community composition, and functional guilds, the authors provide mechanistic insight into how specific plant species—such as Leymus chinensis and Medicago rivularis—can steer microbial communities toward enhanced nutrient cycling and pathogen suppression. These findings offer a data-driven basis for designing resilient plant mixtures that accelerate ecosystem self-sufficiency in arid mining regions.
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GOU Tienan, SUN Guohao, LI Jingguo, ZHANG Liming, ZENG Lixue, LI Haichao, QU Laiye, ZHANG Naili (2026). Microbial Mechanisms Underlying Soil Nutrient Availability in Vegetation Reconstruction of an Open-Pit Mining Area in Inner Mongolia. Chinese Journal of Environmental Engineering. https://doi.org/10.12030/j.cjee.202503016
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Frequently Asked Questions
What are the specific functional shifts in soil fungal communities induced by Leymus chinensis, and how do they translate into measurable improvements in soil health parameters?
Leymus chinensis increased saprotrophic fungal relative abundance from 67.28% to 81.63% and decreased pathogenic fungi from 15.63% to 4.33% compared to control. This shift enhances organic matter decomposition and nutrient mineralization while suppressing soil-borne diseases, directly contributing to improved soil health and plant growth in degraded mining soils.
How does Medicago rivularis enhance soil phosphorus availability, and what is the magnitude of the effect?
Medicago rivularis significantly increased soil available phosphorus content relative to other configurations, though exact values are not provided in the abstract. This effect is likely mediated by its ability to alter microbial community composition, potentially increasing phosphate-solubilizing organisms, thereby improving phosphorus nutrition for subsequent vegetation.
What is the evidence that grass-legume mixtures enhance nitrogen fixation, and what are the practical implications for fertilizer management?
The study found that mixed sowing of grasses and legumes had the potential to enhance the nitrogen-fixing effect of legumes, as indicated by higher total nitrogen and available nitrogen in mixed plots. This suggests that well-designed mixtures can reduce the need for synthetic nitrogen fertilizers, lowering costs and environmental impacts in large-scale reclamation projects.
What are the limitations of using early-stage data to select optimal plant configurations, and what long-term monitoring is recommended?
The authors emphasize that early-stage data (one growing season) are insufficient to determine the most superior plant configuration. Long-term monitoring is required to assess plant community dynamics, soil nutrient trajectories, and microbial succession. They recommend continued observation of configurations involving Leymus chinensis and legumes to identify stable, self-sustaining mixtures.
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