Assessment of the Ecological Impacts of Coal Mining and Restoration in Alpine Areas: A Case Study of the Muli Coalfield on the Qinghai-Tibet Plateau

Surface mining inevitably impacts the ecological environment, especially in alpine and fragile mining areas. Thus, it is worth discussing the dynamic impact process of mining on regional land use and landscapes. In this study, we took the Muli coalfield, a typical alpine mining area on the Qinghai-Tibet Plateau (QTP), as an example and analyzed the changing characteristics of the eco-environment in 2003–2010 (low-intensity mining), 2010–2014 (large-scale mining), and 2014–2020 (restoration) through a land use transfer matrix, landscape fragmentation index and vegetation cover based on remote sensing data, and discussed the problems and lessons learned. The results show that: (1) the land use transfer process changed from active to basically stable. During the mining phase, the land use transfers were complex and mainly consisted of the transfers of grassland to production land. The land use transfers during the restoration phase were not obvious. (2) Natural landscape types (e.g., river and grassland) were separated by surface mining. In terms of landscape fragmentation, the patch densities showed an increasing trend, while the patch shape fragmentation index showed first decreased and then increased. Additionally, the level of landscape fragmentation during the restoration phase did not change significantly. (3) The changes in average vegetation cover in the gangue fields occurred in four stages: i) gradually decreases from 2003 to 2010, ii) rapid decreases from 2010 to 2014, iii) increases from 2014 to 2017, and iv) further decreases again after 2017. (4) We summarized the lessons learned from the mining and restoration processes and provided a reference for addressing the conflict between mineral exploitation and environmental protection in ecologically fragile alpine mining areas.