The rebound effects of recent vegetation restoration projects in Mu Us Sandy land of China

The sustainability of vegetation restoration projects implemented in China and their effect on water storage in arid and semi-arid regions has been a contentious topic of discussion in China. In this study, the combination of land use-land cover changes (LULCC) and the normalized difference vegetation index (NDVI) was used to understand the processes responsible for changing vegetation patterns over time, particularly in the Mu Us Sandy Land. The effect of vegetation change on the region's water storage was further analyzed using the Global Land Data Assimilation System (GLDAS) and the Gravity Recovery and Climate Experiment (GRACE) remote-sensing products. The results showed remarkable restoration of the Mu Us Sandy Land from 2000 to 2018, with regions in which the NDVI showed a significant increase (P < 0.05) and decrease accounting for 67.73% and 0.23% of the study area, respectively. Most increases in NDVI were evident in areas with no transformation between land categories. The effects of vegetation restoration on surface and ground water remain contentious. While a high density of plants is recognized to retain surface soil moisture, there are also indications that it leads to reduced groundwater storage in the Mu Us Sandy Land. Considering the outcomes of this study, we recommend that the water balance should be considered in future ecological restoration projects in China and globally to ensure environmental sustainability.