沙坡头国家级自然保护区荒漠植被关键群落的最小面积与物种多样性

The Minimun Sampling Area and Species Diversity for the Key Desert Plant Communities in Shapotou National Nature Reserve

以处于腾格里沙漠东南缘的沙坡头国家级自然保护区干旱荒漠生态系统的植被关键群落为研究对象,采用"种-面积曲线"的方法确定关键群落最小面积,并在此基础上使用α多样性指数表征物种多样性。共选取4种饱和曲线模型进行拟合,研究结果表明对荒漠植被群落而言,S=c/(1+ae-b A)和S=c-ae-b A模型具有更好的拟合优度和更高的准确性。当比例因子ρ取0.6、0.7、0.8时,群落最小面积分别为18 m2、24 m2、32 m2,可满足包括总群落的60%、70%、80%的植物种类的中等精度要求;当比例因子ρ取0.9时,群落最小面积为45 m2,可满足包括总群落的90%的植物种类的高等精度要求。该区域物种多样性并不十分复杂,灌木层的生态学地位极其显著,发挥着不可替代的作用,群落的稳定性和生态功能也主要由灌木层中的优势种决定。

With the key vegetation communities in arid desert ecosystems of Shapotou National Nature Reserve as the study object,which is located in the southeast edge of Tengery Desert.A method of ＂species-area curve＂ was used to identify key community smallest area and characterization usingαdiversity index on the basis of species diversity.This study uses four kinds of saturation curve model to determine the minimum sampling area of the key vegetation communities.The results show that for the key desert plant communities,the species-area curve obtained via the equations saturation curve model S =c/（1 ＋ ae-bA） and S =c-ae-bA have a better goodness of fit and greater accuracy than the others obtained via other two equations.when the proportional factor （ρ） is set at 0.6,0.7,0.8 respectively,the minimum area communities are 14 m2,23 m2,40 m2,which can meet the medium accuracy requirements of including 60％,70％,80％ of the total plant community species ; when the proportional factor （ρ） is set at 0.9,the minimum area communities is 45 m2,which can meet the high accuracy requirements of including 90％ of the total plant community species.Species diversity of the region is not very complicated.Ecology status shrub layer is extremely significant and plays an irreplaceable role in community stability and ecological functions which are mainly determined by the dominant species in the shrub layer.