Soil water carrying capacity for vegetation

Nonnative plantations can effectively conserve soil and water and improve the ecology and environment, but soil desiccation can occur and may become severe in forest and grass lands in water‐limited regions, leading to soil degradation, vegetation decline, and crop failure. Therefore, it is necessary to regulate the changing relationship between plant growth and soil water. However, there is no universally accepted theory to provide guidance in the sustainable use of soil water resources, management of forests, and production of crops in such regions. The regulation of the relationship between plant growth and soil water in water‐limited regions can be expressed by the soil water resources use limit by plant (SWRULP) and soil water carrying capacity for vegetation (SWCCV) indexes. The SWCCV is the population in a plant population or density of indicator plants in a plant community when the soil water supply is equal to soil water consumption in the root zone at a given time, and changes with plant community type, location, and time. For example, the SWRULP in caragana shrubland is 222.8 and the SWCCV is 71 bushes per 100 m 2 in the semiarid region. The degree of coverage, productivity, and benefits of a plant community when the population quantity of an indicator plant equals the SWCCV provides the theoretical basis for ensuring the sustainable use of soil water resources and sustainable development of forest land.