Soil water carrying capacity of vegetation and soil desiccation in artificial forestry and grassland in semi-arid regions of the Loess Plateau
半干旱区人工林草地土壤旱化与土壤水分植被承载力

Recently, soil deterioration appeared on the Loess Plateau in the form of excessive soil drying under perennial grasses and forests. Excessively dry soil influences the growth and development, stabilization, economic and ecological benefits of plant communities, which is one of the most important problems of vegetation rehabilitation. In this paper, the authors analyzed the relationship between soil desiccation and drying of the root zone soil layer, developed an approach to determine the limit of root zone drying, and considered that the main measure to control soil desiccation is to control the density and productivity of a vegetation community which is related to the theory of the land's carrying capacity of vegetation. Plant water uptake and utilization mainly depends on soil water, and the soil water is related to the precipitation. Soil water is the most important factor influencing plant growth and development in most of the Loess Plateau. The land's carrying capacity of vegetation in this region is mostly affected by soil water. The term soil water carrying capacity of vegetation was developed and defined as the ability of soil water to carry vegetation. The limit is the largest density of the vegetation community when soil water consumption is equal to or lower than soil water supply in the root zone soil layers from which plant roots can take and utilize water on an annual basis under modern management conditions. The authors provide preliminary discussion of the method and the factors influencing soil water carrying capacity of vegetation, and considered that all of the factors which influence the soil water consumption and soil water supply, plant community growth and development and the water utilization coefficient of plant including geography, topography, climate, vegetation type and plant development stage, will influence the level of soil water carrying capacity of vegetation. It is important to conduct further research on soil water carrying capacity of vegetation for forest and grassland management.