Investigating impacts of large-scale vegetation restoration on water recycling processes in the agro-pastoral ecotone of Northern China

From 1998 until now, the Chinese government has implemented numerous policies and programs, such as the Grain for Green Program, the Three-North Shelter Forest Program, and the Beijing-Tianjin Sand Control Program, to restore ecosystems and to improve environmental protection in the agro-pastoral ecotone of Northern China (APENC). However, it remains unclear how the large-scale vegetation restoration modulates the regional moisture cycle in the APENC. To fill this gap, we investigated the variations of observed precipitation and estimated evapotranspiration from 1995 to 2015. The evapotranspiration is estimated by the Priestley-Taylor Jet Propulsion Laboratory model with dynamic vegetation (DV). The precipitation recycling ratio calculated by the Dynamic Recycling Model is used to analyze the impacts of vegetation restoration on regional moisture recycling. Our results show that the precipitation and ET under the DV were significantly increased during the period of 1995-2015, with the increasing rate of 4.42 mm yr^-1 and 2.13 mm yr^-1, respectively. The precipitation recycling ratio was also significantly increased during the study period, showing positive feedback of vegetation restoration on precipitation. The atmospheric water budget analysis shows that vegetation restoration noticeably modifies the annual mean values of water transport terms in the regional water cycle, indicating an indirect effect on local precipitation. Our findings help better understand the impacts of land cover change on local water resources, which in turn supports local water resource management and decision making.