扎龙湿地沿植被退化序列的土壤特征及盐渍化机理

Edaphic characterization and mechanism of soil salinization along vegetation second succession sequence in Zhalong saline marsh

基于野外调查和室内分析,研究了扎龙湿地沿着植被演替序列的土壤特征及对局地尺度土壤盐渍化发展的影响.结果表明,湿地退化是多种因素综合作用下的结果.扎龙湿地在小尺度内表现为盐沼土、碱化草甸土以及碱土相间分布的格局.质地粘重且粉沙含量高的特征利于土壤表层富集盐分.芦苇沼泽的地表枯落物干质量含量达2 655 g/m2,使得其持水量达2.05 m3/m3,这促进了湿地保持水分效应和沼泽化.地表植被被人为破坏后导致其表层持水性能几乎完全消失,在干旱的条件下湿地表层迅速积盐.人为扰动改变了湿地土壤的持水性能,也促进湿地退化.

Based on in-situ observation and laboratory analysis,edaphic characterization and mechanism of soil salinization along vegetation second succession sequence in Zhalong saline marsh were examined. Results show that wetland rapid degradation was the comprehensive effect of various driving factors.Soil system at the local scale of Zhalong wetland presented as the pattern of saline marsh,alkaline meadow soil and alkaline soil. Properties of large rate of silt content with clay texture along soil profile would help to salt concentration in surface horizon.The content of litter in reed marsh was as high as 2655 g/m^2,which bring maximal water retention volume of 2.05 m^3/m^3.High content of litter in reed marsh promote the water retention effect and marsh formation.In contrast,the retention function in surface horizon would almost completely diminish,given the covers were destroyed by human activities,thereafter,induced to rapid salt accumulation stressed by drought condition.Human activities changed the water retention function of the wetland,promote wetland degradation as well.