Research on optimization measures of mine slope vegetation restoration under difficult site conditions: A case study in the Baicheng coal mine on the southern slope of the Tianshan Mountain Range.

In In the arid, mountainous desert grassland of the southern Tianshan Mountains' Frontier Belt, where coal mining has severely degraded ecosystems and making vegetation restoration challenging. This study focused on the coal gangue dump at Xinjiang's Baicheng County Runhua Coal Mine and investigated 72 grassland plots on slopes, employing variance and redundancy analyses to assess the impact of topography and substrate factors on plant growth for restoration optimization. Results indicate: (1) Among topographic factors, pure sandstone substrate, slope aspect, and gradient significantly influenced vegetation coverage and diversity. Optimal slope gradients of 20°-35° yielded coverage of 24 %-27 %. (2) Under difficult site conditions, Gravel Content (>2 mm) and substrate Hardness were key substrate variables; coverage reached 27 % when Gravel Content was below 40 %. Minimizing Gravel Content and reducing Hardness through sieving fine particles is recommended. (3) A species ratio of 2 (annuals): 2 (perennials): 1 (shrubs) is optimal for rapid, stable, and sustainable vegetation recovery. Utilizing locally available sandstone as the primary planting substrate, this study proposes an integrated, optimized restoration model for water- and soil-scarce degraded sites, effectively reducing costs and preventing further ecosystem deterioration.