Integrated ecological restoration techniques system for waste dumps of typical open-pit coal mine in alpine grassland: A case study of a six-year restoration project in Huolinhe South open-pit mine

The alpine grasslands of Eastern Inner Mongolia, located in a typical ecologically fragile zone within the “Northern sand prevention belts,” serve as both a crucial open-pit mineral energy base in China and a site of significant ecological challenges. Open-pit mining supports the nation's energy needs but poses threats to local environmental security. Integrated ecological restoration, as opposed to traditional single-target strategies that exhibit limited effectiveness, emerges as a viable solution to address environmental issues in open-pit mines and waste dump areas, while ensuring the sustainability of the surrounding alpine grassland ecosystem. Given the unique characteristics of the alpine grassland and the limited access to advanced, integrated restoration concepts, our study has concentrated on the ecological rehabilitation of the Huolinhe South open-pit mine in Eastern Inner Mongolia through an in-depth developed ecological restoration technology system. This system, which includes landform reshaping, soil and water conservation, soil enhancement, vegetation restoration, and monitoring of restoration effects, was applied, and its impacts on soil erosion control, vegetation coverage, and water conservation capacity of the ecological project area and impact area were tracked and evaluated between 2017 and 2023. The quantitative assessments demonstrate significant reductions in soil erosion, increases in vegetation coverage and enhancements in the water conservation capacity. The contribution rate from the ecological project area to the impact area was 36.39 %, 32.87 %, and 27.36 %, respectively, attributable to ecological restoration efforts. These results underscore that integrated ecological restoration improves environmental conditions and fosters sustainable, high-quality regional development. The study aims to offer a localized, systematic, and scalable ecological restoration approach for typical open-pit mines and waste dump areas in alpine grasslands.