Study on the Value of Ecosystem Services and Land Use Change in the Area North of the Tianshan Mountains from 2000 to 2020

The northern Tianshans region in the arid zone of northwestern China plays a key role in promoting high-quality development of the ecological environment. In recent years, ecological environmental protection in this region has encountered major challenges due to the dual impacts of human activities and natural changes. In order to accurately assess the current status of the ecological environment in the northern Tianshans, this study analyzed the spatial and temporal changes in land use and ecological and environmental effects using land use data from 2000 to 2020 and explored the current status of land use, land use dynamic process, and ecosystem service value (ESV) in the region. Two-factor spatial autocorrelation analysis revealed the spatio-temporal characteristics of the value changes over the 20-year period as well as their spatial heterogeneity. The results show that: (1) land use changes are dominated by increases in cultivated land, forest land, watershed, and wetland, and decreases in grassland, glacier snow, and bare land. Of these changes, the expansion of cultivated land area is the most significant, showing a total increase of 1136.13 x 103 hm2. (2) The ESV increased and then decreased, reaching the highest value in 2005 and the lowest in 2020. The value of individual ecosystem services is dominated by regulating services, accounting for about 67% of the total value. (3) The overall regional balance of ecological environment quality and the contribution rate of the conversion from bare land to other land types is as high as 82.7986%, constituting the main factor in regional ecological environment improvement. The spatial distribution pattern exhibits the characteristic of "high in the northeast and low in the southwest". (4) There is a positive correlation between the ESV, the Normalized Difference Vegetation Index (NDVI), and the Anthropogenic Impact Composite Index, with the NDVI being the main cause of spatial heterogeneity in the ESV. The research results provide a scientific basis for ecological protection, land management, and policy formulation in the northern foothills of the Tianshan Mountains and are of great significance for promoting regional sustainable development.