Water use strategies of sparse vegetation in the desertification area determine the future trends of afforestation

Water use strategies of sparse vegetation are significant for understanding carbon water cycle processes in the desertification area. Afforestation is controversial in terms of the vegetation growth and water consumption trade-offs. Here we explored the acquisition of sparse vegetation, water use efficiency and its drivers, and water use strategies by combining multi-source data. The results show that sparse vegetation mainly uses soil moisture in northern China. Afforestation is sustainable that the vegetation changes are obviously driven by natural factors such as the precipitation, temperature and evapotranspiration. Otherwise, it is unsustainable that the vegetation changes are driven by many complicated factors. By further analysis, the vegetation height and topography can also affect the water use strategies. The sparse vegetation in the desertification is mainly dominated by the low shrubs and shrub-like trees (an average height of 5–10 m). As the trees grow, the proportion of groundwater utilization has increased. Once the tree height is above 20 m, groundwater is the dominant water use source. Once the altitude is above 3500 m, groundwater is the dominant water use source. So it is significant to choose the right tree for the right place. The result of this study can provide theoretical references for afforestation mode and subsequent management.