## 4 Discussion
### Influence of Human Activities on Temporal and Spatial Changes of RSEI in Shendong Mining Area  
The results indicate that, despite the influence of long-term anthropogenic activities (coal mining and land-use type conversion) and climate change, the ecological environment of the Shendong Mining Area has not experienced large-scale significant degradation. In fact, some areas have even shown further restoration and improvement, suggesting a gradual enhancement in the ecological environmental quality of the mining area. This aligns with previous research findings on the ecological environmental quality changes in the Shendong Mining Area [2; 19]. Meanwhile, existing research conducted in South Africa [29], Australia [30], and Canada [31] has also demonstrated that targeted ecological interventions can effectively mitigate the environmental degradation caused by mining activities. The average \(RSEI\) time series value in the second period (2011-2023) significantly increased compared to the first period (1990-2010); the fluctuation of the \(RSEI\) time series was also more pronounced in the first period. Prior to 2011, activities such as open-pit mining, underground mining, and industrial and mining land use led to vegetation damage, resulting in larger differences in \(NDVI\) values between different regions. \(NDVI\), representing the greenness index, is an important component in \(RSEI\) calculation; this, in turn, led to greater fluctuations in \(RSEI\) across the entire study area. In the context of large-scale coal mining, more than 76.1% of the regional ecological environment quality still shows an improving trend. In areas, such as the Daliuta and Halagou mining districts, ecological environment improvement is particularly significant, indicating a strong correlation with the ecological restoration efforts undertaken by the Shen Dong Coal Group. Data show that, since 2011, the Shen Dong Coal Group has invested heavily in environmental greening funds to address issues, such as subsidence and fissures, caused by coal mining. The total area treated for ecological governance has reached 330 km\({}^{2}\), which is 1.4 times the area developed [32]. This has led to a considerable improvement in regional ecological quality, reinforcing the gradual restoration trend. The ecological restoration rate is above the national average; sufficient funding has ensured the effective implementation of ecological restoration. Third, continuous improvement in mining technology also contributes to the protection of the regional ecological environment. On the one hand, the Shendong Coal Group has adopted technologies, such as longwall comprehensive mechanization, large-panel mining, and backfilling mining, to minimize the damage to surface vegetation, soil, and groundwater caused by underground coal mining. This reduces the area of fissure damage and enhances the self-restoring ability and stability of ecologically fragile areas in the mining region. On the other hand, the exploration of microbial redamation technology has effectively addressed the issues of soil depletion, water scarcity, and root damage in subsidence areas, accelerating the recovery of the damaged ecological environment [33]. Fourthly, under the influence of large-scale coal mining, most of the vegetation in the Shendong mining area will remain stable, and some areas are even showing signs of improvement. This demonstrates the gradually emerging effectiveness of the Shen Dong ecological restoration policy. The Shendong mining area, with Baoertai and other mining districts as the main focus, has established a comprehensive ecological governance framework called \"Three-Phase Three-Ring.\" This framework integrates engineering and biological measures, with biological fixation as the primary method and engineering protection as a supplement, to implement conservation and management.