Hydrological impacts of vegetation cover change in China through terrestrial moisture recycling.

Terrestrial moisture recycling (TMR), characterized by a continuous process comprising green water flow (i.e., terrestrial evaporation), atmospheric transport, and terrestrial precipitation, functions as a nexus connecting hydrosphere, atmosphere, biosphere, and anthroposphere. During this process, land cover changes that impact green water flow can modify regional and remote precipitation patterns, potentially yielding far-reaching effects on water resources and human livelihoods. However, the comprehensive patterns of moisture recycling and transfer across eco-geographical regions in China, and their connection with various land cover types and vegetation transitions, remain insufficiently evaluated. This study employed an atmospheric moisture tracking model to quantify China's TMR pattern and evaluate the hydrological impacts of vegetation cover changes in China's ecosystems through TMR. The results demonstrate a significant moisture recycling ratio (52.4 %) and a considerable recycled volume (1.9 trillion m/a) over China, characterized by pronounced moisture transfer from south to north and southwest to northeast. Among various land cover types, grasslands, croplands, and forests play pivotal supportive roles in China's TMR, contributing 738.8, 470.0, and 450.0 billion m/a of precipitation in China, respectively. Moreover, the potential transition of vegetation between forest and cropland exerts the most significant and extensive impact on China's hydrological cycle. The conversion from forest to cropland leads to a total decrease of 44.7 billion m/a in precipitation, whereas reforestation from cropland corresponds to a precipitation increase of 74.9 billion m/a. This study provides a quantitative approach to comprehending the TMR pattern and its relationship with ecosystems, substantiating the significance of a comprehensive water management framework that considers the contribution of atmospheric moisture recycling and the impact of vegetation cover change.