Feedbacks between large-scale vegetation restoration and regional precipitation over the Chinese Loess Plateau

Abstract

Large-scale anthropogenic revegetation has considerable climate, carbon, and ecosystem benefits by affecting ecohydrological and hydrometeorological processes. Previous studies have pointed out that large-scale vegetation restoration in non-humid areas significantly increases evapotranspiration (ET), resulting in the reduction of soil moisture and streamflow. However, the impact of vegetation-climate feedback on water balance was ignored in these studies. The Loess Plateau (LP) in China has the largest vegetation restoration area in the world since 1999. Here, we combined in-situ hydro-meteorological observation and coupled land-atmosphere model to analyze how vegetation reconstruction affects the water resource budget of the LP. Two simulation experiments were designed to achieve a quantitative evaluation, including a real scenario that reflects the actual vegetation restoration, and a hypothetical scenario without vegetation restoration. The net impact of vegetation restoration on local precipitation can be analyzed by comparing the two scenarios. We quantified the feedback effect of vegetation restoration on local precipitation and the underlying mechanisms. The observation results show that precipitation increased on the LP after the restoration, and the surface water production in most areas on the LP (82.3%) shows a strong robust growth trend (2.76 mm yr-2), although the ET has increased at the same time. Our simulations show that the annual average precipitation under the vegetation restoration scenario on the Loess Plateau is 12.4% higher than the non-vegetation restoration scenario. We found the enhancement of land-atmosphere interaction is a main reason for the rapid growth of precipitation. Such an enhancement is caused by vegetation restoration that greatly accelerates the local water cycle. The contribution of large-scale vegetation restoration to precipitation increase is about 37.4%. Our research emphasizes the importance of considering vegetation-climate feedback when assessing the impact of large-scale vegetation restoration and will provide guidance and theoretical support for ecological protection and sustainable vegetation restoration in water-scarce regions.