Response of Vegetation NDVI to Climate Change and Human Activities in Eastern Gansu

[Objective] The eastern Gansu Province is an important ecological transition zone and a fragile area on the Loess Plateau, and understanding the dynamic variation mechanisms of vegetation NDVI (Normalized Difference Vegetation Index) provides a crucial basis for regional ecological restoration. [Methods] This study investigated the response of vegetation NDVI to climate change and human activities in the eastern Gansu based on MODIS NDVI, climate, and land use data from 2000 to 2024, using methods including Theil-Sen trend analysis and the Hurst exponent. [Results] (1) Vegetation NDVI in the eastern Gansu exhibited a spatial pattern of “high in the southeast and low in the northwest”, and areas with significant improvement accounted for 54.74%. However, the Hurst exponent (0.35-0.65) indicated that the future improvement trend had weak persistence. (2) Human activities were the dominant driver, with a contribution rate exceeding 80% in 57.53% of the area, mainly influenced by the Grain for Green program (2 248 km2 of cropland converted to grassland) and urbanization (an increase of 35.14% in the urbanization rate). The contribution rate of climate change was mainly in the 0%-20% range (45.04% of the area), and improved hydrothermal conditions (precipitation increased by 180.95 mm) provided essential support for vegetation growth. (3) A total of 86.68% of the area was jointly driven by climate and human activities, forming a distribution pattern characterized by “human activities as the primary driver and climate as the supporting factor”. [Conclusion] From 2000 to 2024, vegetation NDVI in the eastern Gansu showed a significant improving trend, but with obvious spatial differentiation. The improvement is mainly attributed to the strong driving effect of human activities. However, its rapid intervention leads to weak future sustainability of the ecosystem, posing a significant risk of “degradation after greening”.