Mengxin Sun ^* Xin Shen Hailiang Xu Ai Shajiang

• 中国科学院, 北京市, China

Understanding the spatial and temporal variations in the values of ecosystem services and the factors influencing them is crucial for effective ecosystem service management and decision-making. This study focuses on four major headwater streams and the mainstream of the Tarim River Basin from 2000, 2005, 2010, 2015 and 2020, we applied the comparable coefficient approach to assess changes in ecosystem service values and their spatial distribution resulting from land use and land cover changes. Additionally, we employed geospatial analysis to investigate the drivers of ecosystem service values and their interactions. The results indicate that (1) The overall land use pattern in the study area has remained relatively stable, but it has undergone multi-phase fluctuations driven by government policies and climate change. Farmland maintained a growth rate of over 10% from 2000 to 2015, but its expansion slowed between 2015 and 2020 under the influence of the "Grain for Green" policy, which promoted reforestation and grassland restoration. Built-up land saw significant growth between 2005 and 2010, followed by a reduction from 2015 to 2020 due to stricter urban planning and regulatory measures. Among natural land types, glaciers have shown a significant reduction in area. Although glacier meltwater has contributed to the increase in water bodies and wetlands, long-term reliance on glacier melt poses substantial risks. (2) The overall Ecosystem Service Value (ESV) has increased by 99.34 billion, with grasslands and water bodies contributing the most to regional ecosystem services (60% and 10%, respectively), while farmland and built-up areas contributed relatively less. In 2015, the expansion of wetlands and water bodies facilitated vegetation growth, causing the ESV to peak. However, the subsequent reduction in wetlands and water bodies, along with glacier retreat, led to a decline in ESV. (3) In terms of influencing factors, vegetation health (NDVI), proximity to water bodies, and precipitation have consistently been key natural drivers of ESV across different periods. Meanwhile, socioeconomic factors such as GDP have become increasingly influential on ESV in recent years. The interaction between climatic factors and socioeconomic development has further complicated the dynamics of land use and ESV.