关键词: 沙坡头地区, 固沙植被, 土壤水分动态

Abstract: The artificial sand-fixing vegetation under no-irrigation condition was established in 1956, which is a successful model of protective system for railway communication in China. In this paper, based on observation data during about 40 yea rs, the characteristics of soil water changes in time and in spatial and its effects on vegetation in different sand-fixing areas were analyzed. The results showed that soil water obviously decreased after 9~10 years since vegetation was planted. Especially, the soil water in deeper soil layer remarkably reduced. There is a good corrective relationship between precipitation and soil water in 0~40 cm layer, but we failed to find the relationship between precipitation and soil water in deeper layer (from 40 to 300 cm). The soil moisture in deeper layer further worsened resulted from plants with deep roots system absorbing water around roots, which restrained the plant growth and existing and affected directly on the composition and stability of sand-fixing vegetation. After 40 years, the shrubby coverage in sand-fixing vegetation decreased from maximum 47.6% to 6%~9% presently. The soil moisture content will keep a constant value (1%~1.5%) when shrubby coverage reduced to 6%~9%.

Key words: Shapotou area, sand-fixing vegetation, soil water dynamics