Introduction
Water resources and soil resources is the most important nature resources, which severe influence the high-quality sustainable development of economy and society (Guo 2020,2021). Water and soil losses are one of the most severe environmental problems worldwide (Wen et al 2019). Among the various practices in water and soil conservation, forest restoration has usually been regarded as critical and effective (Yetemen et al., 2010). High-quality sustainable management of forest vegetation ecosystems had been proven necessary for the protection of regional ecological environments and for the improvement of sustainable development in the society and economy. It is important to consider the balance between resources consumption and resources supply in the course of forest vegetation restoration (Guo 2021a and b).
Once with the soil water loss regions population increasing such as on Loess Plateau, China, the human activities of reclamation, forest denudation, overgrazing and civil wars became frequent, which caused the decline in the density of natural plant populations (Metcalfe and Kunin 2006), the disappearance of indigenous vegetation was leading to the quick decrease of vegetation cover (Guo 2000a and b) and forest area rate (Guo 1996), and the ability of forest vegetation to keep ecological balance. This in turn has resulted in serious soil and water loss. In order to improve the ecological environment and promote healthy development of regional economy, large-scale afforestation has been carried out. However, for the sake of high yield and high return, tree species with deep roots and fast growth have been selected and planted at initially high planting densities such as on the Loess Plateau, plant take up water from considerable soil depths. Because most of Loess Plateau belongs to water-limited regions and the water supply was limited, these issues such as lower survival rate of afforestation, lower preserving rate, lower yield, lower ecologic and economic benefit were caused in the process of vegetation restoration (Jiang 1997; Yang & Shao 2000; Li 2001; Yang 1996; Hou et al 1999).Moreover, soil deterioration occurred on the Loess Plateau in the form of soil desiccation under both perennial grasses and forests (Li 2001; Yang 1996; Hou et al.1999; Li et al.1990; Wang et al. 2000; Chen et al. 2005). Such soil deterioration directly affected the stability of plant community and reduced the soil and water benefits of forest vegetation. So we should manage soil and water conservation vegetation in the way of high quality sustainable to get maximal soil and water conservation beneficial and match the People’s yearning for a better life and the need for soil and water conservation(Guo 2021b)