Spatio-temporal changes in the normalized difference vegetation index of vegetation in the western Sichuan Plateau during 2001—2021 and their driving factors

The western Sichuan Plateau, with a fragile and sensitive ecological environment, acts as a critical ecological barrier between the Qinghai-Xizang Plateau and the Sichuan Basin. Research on the dynamic changes in the normalized difference vegetation index (NDVI) and their driving factors holds practical significance for monitoring the ecological environment quality of the western Sichuan Plateau. Based on 2001—2021 MODIS NDVI data, as well as meteorological data, surface factor data, and human activity data, this study analyzed the NDVI distribution of vegetation in the western Sichuan Plateau on a spatio-temporal scale using trend analysis, Hurst index, and geographical detector. Furthermore, this study determined the principal driving factors in NDVI changes. The results are as follows: During 2001—2021, the NDVI of 67.19% of regional vegetation in the western Sichuan Plateau showed a fluctuating upward trend. Elevation is the most critical factor influencing NDVIs, with an explanatory power of 0.529. The elevation is followed by accumulated temperature ≥0 ℃ and air temperature. The driving factors in interactions among NDVI exhibited nonlinear or double-factor enhancement, with q values between relative humidity and elevation being highest (0.623). 84% of factor combinations showed significantly different effects on the spatial NDVI distribution in the western Sichuan Plateau. The results of this study facilitate the research on the driving mechanism of vegetation growth, providing a reference for vegetation protection in the western Sichuan Plateau.