Dominant associations of precipitation and soil water with global vegetation reversals under climate change

Satellite observations have revealed significant changes in global terrestrial vegetation over the past four decades. However, the neglect of interactions among influencing factors has sparked intense debates regarding vegetation dynamics at regional and global scales. This study systematically evaluated the spatiotemporal evolution of global vegetation dynamics (1982–2020) and their complex underlying mechanisms by integrating five remote sensing-derived vegetation products with climate and socio-economic data. The results showed that approximately 51.98% of the global terrestrial vegetation area experienced change reversals between 1995 and 2005, with vegetation “greenness” predominantly transitioning from increasing to decreasing. This percentage differs between different climate zones, ranging from 46.41% in the cold zone to 54.99% in the tropical zone. This phenomenon is associated with a weakening of the interaction explanatory power (i.e. the explained spatial variance quantified by the q-statistic) of the interactive coupling among total precipitation (TP), soil water (SW), and other factors (e.g. temperature and vapor pressure deficit, VPD), decreasing from 70% ± 4% to 64% ± 4%, rather than with an independent dominance of VPD changes, as emphasized in previous studies. These findings underscore the importance of explicitly accounting for interactions among water-related factors when interpreting regional and global vegetation dynamics under a warming climate.