*3.3. Spatial-Temporal Transformation Characteristics of Land Use Types in Territorial Space in Qinghai*

During 1980–1990, the area transformed from GES was the largest (453.49 km2), accounting for 39.62% of the total area transformed (Figure 4a), among which 42.32% was converted into APS, 38.39% into OES, and 19.12% into other spaces. The total area of all the types of spaces converted to GES was only 72.03 km2, and thus the total area of GES decreased.

From 1990 to 2000, the number of GES areas transferred to other spaces was the largest (which was 897.11 km2), accounting for 49.46% of the total converted area (Figure 4b), among which 40.46% was converted to OES, 31.85% to APS, and 27.68% to other spaces. However, the area of various spaces converted to GES was only 463.08 km2, and thus, the total area of GES continued to decline.

From 2000 to 2010, the area of OES converted to other spaces was the largest (28,669.66 km2), accounting for 79.09% of the total amount (Figure 4c), among which 90.57% was converted into GES, 8.14% into WES, and 1.29% into other spaces. The area of all the types of space converted to OES was only 5441.88 km2. Notably, compared with the previous 20 years, the total area of the OES decreased, whereas that of GES increased.

During 2010–2015, the area of OES converted to other spaces was 1585.31 km2, accounting for 43.20% of the total amount (Figure 4d), among which 44.28% of OES was converted to WES, 38.37% to GES, and 16.85% to other spaces. The area of all types of space was converted to 1085.79 km2, and the total area of OES continued to decrease.

From 2015 to 2020, the area of OES converted to other spaces was 3407.57 km2, accounting for 41.19% of the total amount (Figure 4e), of which 62.58% was converted to WES, 31.28% to GES, and 6.15% to other spaces. The total area converted to OES was only 1866.97 km2; notably, the total area of OES continued to decrease during this period.

**Figure 4.** Spatial distribution of territorial space changes in Qinghai Province from 1980 to 2020.

#### *3.4. Comprehensive Quality of the Ecological Environment*

3.4.1. Spatial-Temporal Evolution Characteristics of Ecological Environment Comprehensive Quality

The overall eco-environmental quality index of Qinghai province for 1980, 1990, 2000, 2010, 2015, and 2020 was 0.2557, 0.2562, 0.2561, 0.2653, 0.2655, and 0.2667, respectively. Except for a slight decrease in 2000, the overall ecological environment portrayed a significant improvement. Additionally, there were significant differences in the ecological and environmental quality grades (Figure 5). The area of high-quality regions continued to increase, whereas that of medium high-quality regions portrayed an initial decrease followed by an increase. The area of high-quality regions was the smallest in each period, accounting for less than 20% of the total area of the study area. Notably, the changes in the medium-quality and low-quality areas portrayed a wave-state potential. The area of medium low-quality regions portrayed an initial increase followed by a decrease, and the area of medium–low- and low-quality regions exceeded 55% of the total area, constituting the main body of eco-environmental quality (Table 5). As shown in Figure 5, the high-quality and the medium–high-quality areas were mainly distributed in the east and northwest of Qinghai. The medium-quality regions were distributed in the south and east of Qinghai and gradually expanded to the north; the low and medium–low-quality areas were distributed in most parts of the north and central Qinghai, but portrayed a decreasing trend.

**Figure 5.** Distribution of eco-environmental quality levels in Qinghai Province from 1980 to 2020.


**Table 5.** Distribution of ecological environment quality grades of Qinghai (km2/%).

3.4.2. Main Land Use Conversion Affecting Eco-Environmental Quality

We observed two types of ecological quality trends, namely, improvement and deterioration, which offset each other, ensuring stability. From 1980 to 2020, the trend of ecological environment improvement in Qinghai Province was much higher than that of ecological environment deterioration; notably, the degree of ecological environment improvement continued to increase. As shown in Table 6, the conversion of OES into GES and WES and that of GES into WES and FES were the main factors for environment improvement. The conversion of GES into OES, APS, and IPS, and that of WES into OES and GES, were the main factors for environmental deterioration. The land function types that led to the improvement of the ecological environment were relatively concentrated, and the first seven land function transformations that contributed to the improvement/deterioration of ecological quality accounted for 99.34% and 97.56%, respectively.


**Table 6.** Major land use transformations influencing ecological environment quality and contribution rates.

#### *3.5. Driving Force Analysis of Eco-Environmental Quality*

The results indicated that the eco-environmental quality of Qinghai province was jointly affected by multiple factors, and different influencing factors had varied effects on the eco-environmental quality of the region (Figure 6). All factors passed the significance test at the 0.05 level, and the factor contribution rate q value was used to measure the impact degree of each factor on the spatial differentiation of the eco-environmental quality of the region (q ≥ 0.100 was the factor, with a great impact on the eco-environmental quality of the study area). From 1980 to 2020, X5 (0.294), X4 (0.074) and X1 (0.061) contributed more to the natural factors, and X9 (0.223), X10 (0.199), and X8 (0.195) contributed more to the socio-economic factors. In general, socio-economic factors had a greater impact on the quality of the ecological environment.

**Figure 6.** Contribution rates of driving factors for spatial differentiation of eco-environmental quality in Qinghai from 1980 to 2020.

#### 3.5.1. Analysis of Natural Factors

From the perspective of factor interpretation, we analyzed the trends for the following factors: X1 (altitude), X2 (slope direction), X3 (relief amplitude), X4 (annual average temperature) and X5 (annual average precipitation). X1, X2, and X3 had little influence on the eco-environmental quality, and the changes were relatively stable. However, the q values of X1 and X3 in 1980 decreased slightly compared with those in 2020, indicating that the influence of X1 and X3 on the eco-environmental quality of the study area weakened. Compared with 1980, the advantage of q value of X2 in 2020 increased, indicating that the influence of X2 on the eco-environmental quality of the study area gradually enhanced, but its overall influence was less, compared to that of other factors. The influence of the q value of X4 on the ecological and environmental quality fluctuated in different years, but it had a greater impact on the ecological and environmental quality in 2020 (up to 0.1), indicating that the influence on ecological and environmental quality in 2020 strengthened. Finally, X5 had a great impact on the ecological and environmental quality. Although we observed a trend of fluctuation, the q value in each year was greater than 0.25, which indicated that X5 was the main driving force of the ecological and environmental quality. The q value increased from 0.31 to 0.34 from 1980 to 2020, indicating that the influence of X5 on the ecological and environmental quality of the study area increased significantly.
