## 3 Results and Analysis
### Analysis of the Average RSEI in the Study Area
#### 3.2.2 Spatial Characteristics Analysis of Ecological Environment Quality in the Study Area  
The spatial distribution of the ecological environment quality grades in the study area is illustrated in Figures 6 and 7. The areas of moderate or lower quality were primarily located at altitudes below 1200 m and on slopes less than 10\({}^{\circ}\), which also fell within the general ecological protected area. The areas of good and excellent quality were primarily situated at altitudes above 1600 m, within key and core protected areas. Over the 30 years, the regions where the ecological environment quality grade degraded were concentrated in the built-up and mining areas of Ankang City, Hanzhong City, Shangluo City, and Weinan City. In the general protected area, the improvement in ecological grades was mainly evident in the shift from moderate to good. In the key and core protected area, the trend of change from good to moderate ecological quality was not significant before 2005. After 2005, there was a noticeable decline in the proportion of areas with good and moderate ecological quality, largely reflecting a transition from good to excellent. When considering elevation and slope, regions with elevations under 1600 m primarily showed an ecological upgrade from fair and moderate to good, while regions with elevations over 1600 m mainly saw an upgrade from good to excellent in ecological quality. For areas with slopes less than 20\({}^{\circ}\), ecological grades were mostly fair, poor, and moderate. In areas with slopes greater than 20\({}^{\circ}\), the ecological grades were predominantly good, with the proportion of excellent  
Figure 6: Stacked chart of ecological environment quality grades in different regions from 1990 to 2020. Figure 7: Spatial distribution of ecological environment quality grade changes from 1990 to 2020.  
ecological quality significantly increasing after 2005, with a peak proportion of 30.68% and an average of 15.57%. Analysis of Driving Factors for Spatial Heterogeneity in Ecological Environment Quality in the Study Area  
In order to analyze the driving factors behind the spatiotemporal changes in ecological environment quality within the study area, the factor detector from the geodetector was utilized to explore the explanatory strength of natural geographic, policy protection, and socioeconomic factors for the spatial heterogeneity in ecological environment quality at different times. The results showed that all factors passed the significance test (\(p<0.05\)), indicating that each factor had a certain explanatory strength for the spatial differentiation in ecological environmental quality (Table 4). The factor detection results for different periods all pointed out that NDVI, temperature, land use, and DEM were the main factors affecting the spatial differentiation in ecological environmental quality. Among them, from 1990 to 2000, NDVI and temperature were the two most important factors causing spatial differentiation in ecological environmental quality; from 2000 to 2010, NDVI and land use became the two most significant impacting factors. After 2010, the explanatory strength of NDVI, temperature, and land use decreased, while the explanatory strength of DEM increased. In addition, the soil type of the study area, the setting of the ecological function area, and protected area boundaries also impacted the spatial differentiation in ecological environmental quality to a certain extent. Notably, the q value for the range of protected ecological areas averaged 0.12 before 2010, but from 2010 to 2020, its explanatory strength rapidly increased to 0.24, indicating that the implementation of ecological protection policies in the study area gradually influenced the spatial differentiation in ecological environmental quality.