Spatiotemporal Dynamics of Land Degradation Induced by Open‐Pit Mining: A National‐Scale Assessment of Forest Biomass Loss in China

Open‐pit mining is a significant anthropogenic driver of land degradation. Large‐scale topsoil removal during mining operations inevitably destroys surface vegetation, resulting in substantial forest aboveground biomass loss and degradation of ecosystem carbon storage capacity. Existing studies remain largely confined to individual mining sites or short‐term monitoring periods, lacking quantitative assessment and spatiotemporal analysis of forest biomass loss in open‐pit mines at a national scale over extended time series. We integrated open‐pit mine boundary data, annual tree cover datasets, and forest aboveground biomass datasets to systematically quantify spatiotemporal evolution patterns of forest biomass loss in Chinese open‐pit mines over 34 years. A sliding window algorithm was employed to identify the onset of mining disturbance and reclamation timing, and a quantification model was established for biomass loss assessment, supplemented by the Mann–Kendall test, Sen's slope estimator, and Pettitt test to statistically infer degradation trends and structural change points. Results revealed that: (1) Open‐pit mining in China caused severe forest biomass loss with distinct temporal phases. A highly significant national upward trend was confirmed, with 2002 identified as a critical structural break year. (2) Biomass loss exhibited high spatial heterogeneity, with hotspots concentrated in ecologically vulnerable regions of North China, Northeast China, and Southwest China. (3) Forest areas accounted for 99.1% of total biomass loss, indicating that mine expansion occurred predominantly at the expense of forest carbon sinks and land productivity.