宁夏盐池四儿滩湿地–干草原植被群落稳定性研究

Vegetation stability of the Siertan wetland-dry grassland in Yanchi, Ningxia

以宁夏盐池县四儿滩湿地-干草原为研究对象,根据四儿滩湿地植被特征,将其由湿地中心向外依次划分为湿生带、交错带、旱生带。通过2012年7—9月份的野外调查,利用改进的M.Godron稳定性测定方法,研究其植被群落的稳定性。结果表明:(1)3条样地带的植被群落稳定性交点坐标分别为(18.39,81.61)、(24.75,75.25)、(22.85,77.15),即湿生带植被群落稳定性最高(欧氏平方距离为5.180 2),旱生带次之(欧氏平方距离为16.267 7),可见水分对植被群落稳定性有着正相关作用;而由于交错带位于湿生带和旱生带之间,同时湿地面积不断缩减,因而交错带处于不断演替的阶段,其植被群落稳定性最低。(2)3条样带的植被种类数量表现为,交错带数量最多(23种),旱生带次之(21种),湿生带的种类最少(12种),主要与旱生带土壤含水量低,湿生带土壤盐碱化严重的现象密切相关,而交错带由于处于旱生带和湿生带之间,同时具备了土壤含水量适中,土壤盐碱化较弱的优点,故植被种类最多。整体上,四儿滩湿地植被群落趋于稳定,且植被种类较多。这与近年来盐池县实施的草场封育措施密切相关,大大降低了放牧对湿地植被的破坏,利于植被生长和恢复。此外,今年雨水较往年多,很大程度地提高了干旱半干旱区植被的覆盖率和多样性,提高其稳定性。

Take the Siertan （marsh） wetland-dry grassland in Ningxia as the study area and according to the vegetation feature, Siertan wetland-dry grassland was divided into three different communities from the centre to the edge, called ＂Three zones＂（wet zone, ecotone, dry zone）. The vegetation stability of the Siertan was measured by the improved M.Godron＇s method for studying community stability. The results showed that, the intersection coordinates of the three zones were （18.39, 81.61）, （24.75, 75.25）, （22.85, 77.15）. The vegetation stability of wet zone turned out to be the best（5.180 2）, followed by the dry zone（16.267 7）. It could be concluded that, soil water content played a positive effect on vegetation stability. While the ecotone locates between the wet zone and the dry zone, as well as the shrinking wetland area, the ecotone in a continuous succession of stages, which made ecotone to be the weakest in vegetation stability. But as a whole, the intersection coordinates of the three zones were all very close to （20, 80）. What＇s more, ecotone possessed the richest vegetation variety（23）, while the wet zone was exposed to be at the bottom （12）among the three zones, which mainly owing to the soil moisture content and soil salinization. The dry zone possessed the lowest soil moisatre content and mild soil salinization. While the wet zone turned to be in the contrast. With regard to the vegetation variety, the ecotone was obviously the best, owing the advantages of appropriate soil water content and weak soil salinization. The vegetation stability and vegetation variety of Siertan was pretty well on the whole, which closely related to the closed pasture management in recent years and the heavy rainfall in the year.