Ecological restoration of historical abandoned mines in karst areas based on the “five-in-one” model

The ecological degradation caused by historical mining sites in the karst region of the Li River Basin poses a severe and persistent threat to regional ecological security. The Pengxin Quarry was targeted for investigation, a typical open-pit karst mine in the basin, with the aim of establishing a systematic ecological restoration technology system to achieve multi-dimensional synergistic rehabilitation of landform, soil, vegetation, hydrology, and maintenance mechanisms. Based on ecosystem succession theory and on-site ecological diagnosis, an innovative integrated restoration model termed “landform reshaping—soil improvement—vegetation restoration—water and soil conservation—long-term maintenance” was proposed and implemented. Engineering practices and long-term monitoring were carried out over a damaged area of 5.17 hm². The restoration project newly added paddy field, dry land, forest land and grassland with total areas of 6 186.67, 16 340.00, 6 553.33 and 4 666.67 m², respectively. Vegetation coverage increased significantly from less than 15% before restoration to over 85%. Soil and water loss was reduced by more than 90%. Concurrently, water conservation capacity and landscape connectivity were markedly improved, and farmland quality was effectively enhanced, achieving synergistic gains in ecological recovery, social benefits, and economic value. The applicability of the “five-in-one” restoration model in karst mining areas is verified, and a closed-loop management pathway of “technology integration—process monitoring—long-term management” is established. It provides a systematic technical reference and a replicable practical paradigm for the ecological restoration of similar mines in karst regions of southern China.