河西走廊盐化草甸土壤水盐对植物群落数量特征的影响

The Effect of Soil Moisture and salt on the Quantitative Attributes of Plant Community in the Saline Meadow of Hexi Corridor,China

采用通径及逐步回归方法分析了从河西走廊盐化草甸４３个样点收集的植物与土壤水盐资料。土壤水盐因子（包括土壤水分、盐分及与之显著相关的有机质、ｐＨ及地下水位）对群落及其优势种（芦苇与＊草）的数量特征均有显著影响，群落盖度主要取决于土壤盐分与有机质；芦苇与赖草盖度分别取决于土壤盐分与有机质，高度分别取决于地下水位及土壤水分；赖草频度及生物量与土壤ｐＨ有关。盖度与高度是受土壤水盐因子影响较大的两个群落特征，可作为群落优势度的构成要素。芦苇与赖草的群落特征受制于不同的土壤水盐生态因子，显示了二种土壤水盐生态位的分异，这可能是二种长期共存的生态学机制。

The path and ptogressive regression methods were used to analyze the data in vegetatipn,soil moistureand salt collected from the salinized meadow of Hexi Corridor.The factors such as soil moisture,saltcontent,organic matter, pH value and water table have significant influences on the quantitative attributesof plant community and predominant species.The comm unity coverage mainy depends on the salt andorganic matter content in the soil,likewise the coverages of Phragmites communis and Leymus dasystachys arealso sign ificantly influenced by the soil salt and organic matter contents.The heights of bot h species aredetermitled by the water table and soil moisture.The frequency and above-ground biomass of L.dasystachyare related to the soil pH.The coverages and height are the major community attributes,which are significantly influenced by thesoil moisture and salt content,and therefore they could be used as the indicators of communitydominance.The community features of Phragmites communis and Leymus are subject to the different soilmoisture and salt factors,and the mechanism of coexistence of both species is therefore attributed to theirdifferent niches in soil moisture and salt content.