## 4 Discussion
### Buffer Analysis of a Typical Mine Sites  
As shown in Figure 16 the ecological impacts of coal mining and urban development were assessed in the Sihe Mine Area in Qingshui County, Jincheng City, and the Fenghuangshan Mine Area in the urban area. By analyzing Landsat imagery from 1990 and 2002,  
Figure 15: LISA clustering of the RCEI in Jincheng City from 1990 to 2022.  
buffer analysis was used to explore changes in the mean RCEI value per 0.5 km within a range of 0 to 8 km. Figure 16: Areas producing a million tons of coal and their mean RCEI values with distance. (**a**) Location of Jincheng City’s Sihe Mine Area and Fenghuangshan Mine Area; (**b,c**) Raster plots showing the mean RCEI values of the Sihe Mine Area and Fenghuangshan Mine Area with distance; (**d,e**) Line plots depicting the mean RCEI values of the Fenghuangshan Mine Area and Sihe Mine Area with buffer zones from 1990 to 2022. The results revealed significant negative impacts of coal mining activities on the ecosystem. In the Sihe mine, a notable decrease in the mean RCEI within 0.5 to 1.5 km of the mine center was observed, dropping from 0.5791 in 1990 to 0.3476 in 2002. This decline is attributed to construction and mining activities, which increased coal dust pollution, expanded built-up areas, hardened land surfaces, reduced vegetation cover, and deteriorated vegetation health. Since its inception in 1996, the Sihe mine has produced 15 million tons of coal annually. The surrounding small-scale villages had relatively little ecological impact, making it easier to visualize the effects of mining activities on the surrounding environment. Although the Sihe mine had not yet been mined in 1990, the area's ecological environment was already moderately low due to neglect and local farming activities. The average RCEI value fluctuated within the 0.5 to 8 km range. Since 2002, as the mine entered the production phase, the mean RCEI value in the center dropped sharply. However, beyond 2 km, the mean RCEI value increased due to the government's 1999 policy of returning farmland to forest. In the Fenghuangshan Mine Area, the mean RCEI values within 0.5 to 1 km were relatively low but still higher than those in the Sihe Mine Area by more than 0.1 percentage points. This difference is due to the lower production at the Fenghuangshan mine (about 4 million tons) compared to the Sihe mine (15 million tons), reflecting the differential ecological impacts of coal production levels. The change in mean RCEI values for the Fenghuangshan mine buffer zone indicated significant ecological quality changes from 1990 to 2022. This change was directly linked to the cessation of mining in 2018 and the mine's closure between 2019 and 2020. With the cessation of production and closure, population activity decreased significantly, and urban sprawl was curbed. Government-supported ecological restoration efforts significantly improved the mine site's ecological quality, as evidenced by the increased average RCEI value. Beyond 1.5 km, the mean RCEI value showed a rapidly increasing trend, attributed to the improved ecological environment of the Baima Temple forest wetland on the west side of the mine area. However, extending the distance to 3 to 7 km into the urban area, the destructive impacts of urban activities on the ecological environment caused the mean RCEI value to decline stepwise until it reached its lowest point at the center of the 8 km urban area. Within the 7 to 8 km range, the mean RCEI value increased slightly as some areas entered the forested zone. The results of the buffer zone analyses of the two typical mines in the study area showed that the mining cycle of coal mines had different impacts on the surrounding ecosystem. These impacts varied with the distance from the buffer zone. Exploring the impacts of mines on the surrounding ecological environment at different ranges and with different mining cycles can provide guidance and a theoretical basis for coal mine siting, coal mining, and environmental protection in resource-based cities in the future.