关键词: 松嫩平原, 羊草草地, 草甸, 盐碱化, 盐碱化草地, 干扰裸露, 土壤水分动态, 古尔班通古特沙漠, 固定沙丘, 随机模拟, 概率密度函数

Abstract: Field survey and site study were conducted to approach the process and causes of salinization-alkalization of Leymus chinensis grassland in Songnen Plain, and to examine the hypothesis of soil disturbance-bareness. In the grassland, surface soil (0-30 cm) had a lower salt content, while deeper soil (>30 cm) was in adverse. Thereby, the grassland was defined as soil-salted grassland. There was an increasing salt content in surface soil. This process was called as soil salinization-alkalization, and the grassland under the salinization-alkalization was named as alkali-salinized grassland. The leading reason for the surface soil salinization-alkalization was that the surface soil originally with low salt content was disturbed and lost away, subsurface soil rich in salt emerged as new surface soil, and the salt in deeper soil layers accumulated in the new surface soil and other soil layers. Secondary halophyte communities formed on the surface-soil-disturbed new bare land, but the communities had no succession sequence. The degradation process of the grassland was soil degradation first, followed by vegetation degradation, halophyte invasion, and successive evolution from nearly primitive condition.

Key words: Songnen Plain, Leymus chinensis grassland, meadow, salinization-alkalization, alkali-salinized grassland, disturbed-bareness, soil moisture dynamic, probability density function, stochastic simulation, Gurbantunggut Desert., fixed dune