Response of grassland cover to climate and future trend prediction in Hexi region

Located in inland Northwest China, the Hexi region has a typical arid and semi-arid climate and serves as a vital node in the Belt and Road Initiative. In recent years, global changes and human activities had impacted the sustainable development of both the regional ecosystem and the socio-economy. Grasslands play an important role in sustaining socio-economic development and ecological balance in arid and semi-arid zones, which are essential for providing critical ecosystem services such as water and soil conservation, windbreak and sand fixation, and biodiversity conservation. Grassland coverage serves as a key indicator of regional ecological health. Investigating the spatiotemporal patterns and response mechanisms of grassland coverage in the Hexi region holds significant importance for maintaining ecological balance and regulating regional climate. This study utilized MODIS NDVI time-series data and meteorological records from 2001 to 2022 to conduct multi-scale spatiotemporal analyses of grassland coverage dynamics and their climatic responses. An XGBoost model integrated with CMIP6 dataset was further employed to simulate grassland coverage trends from 2023 to 2050 under different scenarios in the Hexi region. The results showed that: (1) Grassland coverage in the study area showed an overall increasing trend with stable fluctuations. The spatial distribution of grassland coverage exhibited distinct spatial heterogeneity, presenting a pattern of "higher in the southeast and lower in the northwest". Approximately 57.22% of grasslands demonstrated significant improvement, though the sustainability of this trend remains uncertain. (2) Grassland coverage responded differentially to climatic factors, with precipitation showing the highest correlation coefficient. Grasslands in the northwest part of the region were notably influenced by soil moisture. Climate change (CC) and human activities (HA) contributed 27.88% and 72.12% to coverage changes, respectively, indicating HA as the dominant driver. (3) By 2050, annual average grassland coverage is projected to increase under SSP2-4.5 and SSP5-8.5 scenarios but decrease under SSP1-1.9. The SSP2-4.5 scenario is deemed more conducive to grassland development in the Hexi region. These findings provide a scientific basis for ecological restoration and sustainable development in this region. Future research should integrate high-resolution land use data with long-term ecological monitoring to explore the complex response of grassland ecosystems to climate change and human activities. Furthermore, comprehensive assessments of grassland ecosystem services and values should be strengthened. Coupled with long-term field surveys and monitoring in vegetation-sparse and degraded areas, this work will provide critical decision-making support for ecological management and the sustainable use of resources in the Hexi region. The results also help us to scientifically understand the response and feedback between vegetation changes and global change in various natural and human environments.