Increasing Vegetation Cover Enhances Ecosystem Services in the Rare Earth Mining Area of China: Threshold Effects and Implications

Overexploitation of rare earth mining areas in southern Jiangxi Province has caused severe vegetation degradation. However, the impact of vegetation restoration on Ecosystem Services (ESs) and their interactions in rare earth mining areas remains underexplored. This study uses vegetation coverage (FVC) as an indicator to assess vegetation changes in rare earth mining areas from 1986 to 2020. The Integrated Assessment of ESs and Trade-Offs (InVEST) and the Carnegie-Arms-Stanford Method (CASA) model were applied to assess soil conservation, carbon storage, water retention, and purification services in the study area from 1990 to 2020, while analyzing the spatiotemporal evolution of ecosystem services. Finally, the eXtreme Gradient Boosting (XGBoost) model was used to construct the Regional Total Ecosystem Services (RTES) index, analyzing the threshold effect between ESs and FVC. The results reveal that: (1) From 1986 to 2020, vegetation coverage in rare earth mining areas exhibited a fluctuating upward trend, with significant increases occurring in 40.14% of the study area; (2) ESs declined significantly overall; (3) Increased vegetation coverage improved the regional ecological environment to some extent, though this improvement was constrained by a threshold effect. To optimize RTES, vegetation coverage in the Gannan rare earth mining areas should range between 0.6 and 0.7. This study offers a theoretical foundation for large-scale ecological management and moderate restoration of rare earth mining areas, supporting regional sustainable development. It also underscores the need for the public and managers to recognize the impact of vegetation restoration on ecosystem functions in rare earth mining areas.