Investigating the Regulation Effects of Vegetation Restoration on Precipitation Patterns Over the Loess Plateau, China

The large-scale vegetation restoration program implemented across China's Loess Plateau altered regional precipitation regimes by modifying biophysical processes in surface-atmosphere interactions. This study integrated multi-decadal satellite records (1982–2018) with WRF model simulations to reveal the biophysical mechanisms underlying vegetation-mediated precipitation modulation. The results indicated that: (1) The response of precipitation to vegetation restoration on the Loess Plateau was not obvious between 1982 and 1999. However, precipitation began to trend upward after 2000, with arid regions experiencing higher multi-year average precipitation compared to semi-arid and semi-humid regions. Nonetheless, the positive effect of vegetation restoration on regional precipitation started to diminish after 2015. (2) Vegetation restoration increased evapotranspiration, altering atmospheric humidity and air movement via changes in surface hydrothermal dynamics and energy conversion, thus boosting regional precipitation. Vegetation restoration contributed 3.68 mm/a to regional PRE between 2000 and 2018, accounting for about 31.32% of the PRE growth rate. (3) Vegetation restoration could compensate for the soil moisture consumption from increased evapotranspiration by increasing precipitation; however, after 2015, the beneficial effects of vegetation restoration on precipitation and soil moisture started to wane. These results indicated that vegetation restoration initiated a positive feedback loop, enhancing both soil moisture and regional precipitation. However, an excessive increase in vegetation might exacerbate regional water scarcity and pose a significant threat to the local ecology if precipitation and soil moisture did not increase proportionally. This finding held crucial implications for guiding vegetation restoration efforts on the Loess Plateau, optimising water resource management and promoting ecological sustainability.