Spatiotemporal patterns and driving factors for vegetation growth status in the upper reaches of the Yellow River

Abstract The impact of climate change on vegetation ecosystems is a prominent focus in global climate change research. The climate change affects vegetation growth and ecosystem stability in the upper reaches of the Yellow River (UYR). However, the spatiotemporal patterns and driving mechanisms of vegetation growth status (VGS) in the region remain poorly understood. Based on the hydrological model PLS, an innovative WEP‐CHC model was developed by integrating regional environmental and vegetation growth characteristics. Furthermore, combined with the PLS‐SEM model and other methods, this study systematically investigated the spatiotemporal patterns and driving mechanisms of VGS in the UYR. The results indicated that: ① VGS exhibited significant spatiotemporal variation trends within the study area. In the study period of 1970–2020, the GPP onset time was significantly advanced ( p < 0.05) while the GPP peak value was significantly increased. Spatial analysis revealed significant spatial complexity in the GPP onset time and peak values across the region. ② Soil freeze‐thaw conditions significantly influenced VGS ( p < 0.05). The complete thawing time of permafrost was closely coincided with the GPP onset time, with a correlation coefficient exceeding 0.84. After controlling soil freeze‐thaw effects using partial correlation analysis, it was found that better initial soil hydrothermal conditions would lead to better VGS; ③ The model constructed with annual hydrothermal conditions (AHC), soil freeze‐thaw period (SFTP), vegetation growth season (VGS), initial soil hydrothermal conditions (ISHC), and annual solar radiation conditions (ASRC), demonstrated good explanatory power for vegetation growth. The R 2 values of PLS‐SEM were above 0.76 in all five subregions. However, their effects on VGS varied significantly across subregions. Overall, AHC and SFTP were the dominant factors in all subregions. Furthermore, the impacts of ISHC and VGC were statistically insignificant, whereas the effects of ASRC exhibited high complexity. This study not only provides new insights into the current state of hydrological‐ecological coupling in the UYR but also offers a new tool for ecological conservation and sustainable water management in other cold regions and similar watersheds worldwide.