Spatial and Temporal Variation Characteristics of Vegetation Cover in the Tarim River Basin, China, and Analysis of the Driving Factors

The Tarim River Basin (TRB) in Northwest China has an extremely fragile ecological environment that is highly sensitive to climate change. Understanding the long-term change dynamics of vegetation coverage in this arid zone is critically important for predicting future trends as well as for improving regional ecological protection and soil and water conservation measures. Based on NDVI data from 2000 to 2022, a temporal and spatial analysis of vegetation coverage in the TRB is carried out using the pixel dichotomy model, Sen trend analysis, the MK test, the Hurst index, and correlation analysis. The results reveal the following: (1) from 2000 to 2022, the vegetation coverage shows a fluctuating increasing trend, with decreases in extremely low and low coverage areas and increases in high and medium coverage areas. Extremely low vegetation coverage accounts for 46.89% of the study area. (2) Throughout the 23-year period, the change trend of vegetation cover essentially remains stable. The proportion of the improved area is greater than that of the degraded area, accounting for 66.49% and 27.93%, respectively, and there is significant fluctuation variation, accounting for 29.99%. Further, there is high variation in vegetation cover as well as high ecological environment vulnerability. The future area of continuous improvement accounts for 31.64%, which is larger than that of continuous degradation (27.17%), and the area of uncertainty accounts for 41.18%, which is strongly random. (3) The distance between land use and the closest river is the main limiting factor of vegetation cover change in the five studied sub-regions of the TRB. The highest explanatory power of the combined factor of land use and precipitation is 0.723. With a correlation Q value above 0.6, the interaction between land use type and natural factors (e.g., temperature, precipitation, evapotranspiration, distance from the river, etc.) is significant. This study is helpful to predict the trend of vegetation change in the TRB, and provides a scientific basis for regional ecological protection, soil and water conservation, and land use planning.