Where should we revegetate? Insights from comparing the impacts of natural and artificial vegetation on hydrological processes

Abstract It is widely acknowledged that vegetation change can exert considerable influences on the hydrological processes. Vegetation change can be either natural or artificial. However, the specific effects of natural growth (NG) and artificial restoration (AR) of vegetation on surface hydrology remain unclear. Using a recently developed ecohydrological model, we demonstrate that NG and AR have contrasting spatial impacts on hydrological components across China’s Yellow River Basin, a hotspot with intensive human-driven revegetation over the recent decades. Our analysis identifies a critical annual precipitation threshold of 300 mm, below which both NG and AR have marginal hydrological impact. In regions where precipitation exceeds this threshold, NG significantly reduces evapotranspiration and increases runoff, while AR has the opposite effects. These results suggest that NG is a more sustainable strategy in areas receiving less than 300 mm of annual precipitation, while AR may be appropriate for regions with precipitation higher than this threshold. Our findings offer valuable guidance for policymakers in designing sustainable revegetation strategies tailored to local environmental conditions.