Effect of ecological restoration on evapotranspiration and water yield in the agro-pastoral ecotone in northern China during 2000–2018

Evapotranspiration (ET) and water yield (WY) play a crucial role in sustaining available water resources, and are greatly affected by climate and anthropogenic activities. The agro-pastoral ecotone in northern China (APENC) has been undergoing ecological restoration projects since 2000 to rehabilitate ecosystem services such as food production and water availability. Previous studies have primarily accessed the combined effect of vegetation greening and climate change on ET. However, the independent influences of these factors, particularly land use/cover change (LUCC) and vegetation greening on both ET and WY remain poorly understood. In this study, we systematically investigated the effect of LUCC, vegetation greening, and climate change scenarios on regional ET and WY variations from 2000 to 2018 in the APENC using a coupled carbon and water model. Results showed a significant increase in the mean annual ET, with a trend of 5.8 mm/y while the WY had a statistically insignificant trend of −0.6 mm/y from 2000 to 2018. Areas with significant increases in ET and decreases in WY mainly occurred in the southeastern part of the APENC. Vegetation greening induced by ecological restoration had a more pronounced impact on ET variation than climate change, while LUCC resulted in relatively minor changes in ET in the APENC. The variations in WY were primarily influenced by changes in precipitation, the increase in precipitation effectively offset the decrease in WY caused by vegetation greening. These findings provide valuable information to policy/decision markers for sustainable management of large-scale ecological restoration programs in dry regions.