松嫩平原羊草草地盐碱化过程

Salinization-alkalization of Leymus chinensis grassland in Songnen Plain of Northeast China

通过野外调查及定位研究,探讨了松嫩平原羊草草地盐碱化发生原因和过程,论证了羊草草地盐碱化过程的土壤＂干扰-裸露＂假说.松嫩平原羊草草地表层土壤（0~30 cm）盐分含量低,表层以下土壤层盐分含量高,定义此为土壤盐渍化草地;土壤表层盐分含量增多的过程称为羊草草地盐碱化过程,盐碱化后形成的草地为盐碱化草地或盐生植物群落.羊草草地表层土壤盐分增多的主导原因是原初含盐量低的土壤表层被干扰消失,表层以下富含盐分的土层直接裸露成新地表,深层盐分在新的表层积累,这种积累也表现在其他各层.次生盐生植物群落形成于羊草草地土壤表层被干扰后的裸地上,各盐生植物群落间没有演替序列关系.松嫩平原羊草草地的退化进程为土壤退化在先、植被退化在后,盐生植物侵入并形成群落及后续的演变近于始自原生状态.

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.