Effects of grass planting substrate on vegetation restoration in the Muli mining area

The improvement of coal mine dumps is one of the main methods of vegetation restoration in mining areas. This study was conducted to investigate the effects of such improvement methods on vegetation restoration and to explore the theory of ecological sustainable restoration in alpine mining areas. The characteristics of the vegetation community and soil fertility were studied in dumps treated with mixed granular organic fertilizer and sheep manure as grass substrates. The results showed that adding granular organic fertilizer or sheep manure to dumps increased the content of organic matter, total and available nutrients, plant height, coverage, density, and biomass during the first year. The effect of both applications was better than that of a single application on plant communities and soil fertility. In the sixth year of direct grass planting in dumps, the plant coverage, yield, biomass, and density decreased, but the species and heights of plants, soil organic matter content, and total nitrogen increased with the obvious biological crust. Topdressing with nitrogen fertilizers significantly improved the characteristics of the plant community. Compared to gentle-slope land and flat land, the soil fertility of steep-slope land was better for the restoration of the plant community and soil fertility. Overall, for vegetation restoration and maintenance of the stability of plant communities in alpine mining areas, improving the fertility of dumps with organic fertilizer, sheep manure, and reshaped dumps ( < 30° slope) is of great significance. Dumps/dumps reshaping (slope < 30°) + granular organic fertilizer + sheep manure is the most suitable combination for the vegetation restoration matrix in the study area.