不同草原群系植物种多样性的比较研究

A Comparative Study on Plant Species Diversity in Different Steppe Formation

本文对小针茅（Ｓｔｉｐａｋｌｅｍｅｎｚｉｉ）、克氏针茅（Ｓ．ｋｒｙｌｏｒｉｉ）、大针茅（Ｓ．ｇｒａｎｄｉｓ）、羊草（Ｌｅｙｍｕｓｃｈｉｎｅｎｓｉｓ）群系，以及各群系内部不同退化状态的植物种多样性作了比较研究，分别以种的丰富度、干重值、重要值指标作了种的多度分布统计，又计算了不同群系及各群系内不同状态的Ｓｈａｎｎｏｎ信息多样性指数，结果表明：１）植物种多样性有随小针茅→克氏针茅→大针茅→羊草群系逐步增长的趋势，这与群系的水分生态状况是一致的；２）群系内随不同退化状态，种多度分布呈现出有规律的变化；３）三种指标所表达的信息多样性指数呈现出明显的变化规律，这种规律可用“中度干扰假设”（ＩｎｔｅｒｍｅｄｉａｔｅＤｉｓｔｕｒａｎｃｅＨｙｐｏｔｈｅｓｉｓ）来解释，由于多样性是干扰梯度的峰形函数，所以中度干扰导致最大的多样性．由此可以根据多样性变化的峰形函数确定放牧保护的临界等级（阈值）．

uther compare the specise diversity of the different formations. such as Stipa klemenzii,S.krylovii,S.grandis and Leymus chinensis formation ,and the different degrative stage in each for-mation. It also calculates the diversity indices of Shannon information according to the richness,the date of dry weight and the importante valne of species. The results were as follows :1)Alongwith the formation chang of Stipa klemenzii→S.grandis → Leymus chinensis , thechang of the specise diversity have a trend gradually increas. This is indentical with the water eco-logical of the formtions;2)Along with the different gradient stage in the formation,the changes ofthe species abundance distribution was ragular; 3)The diversity indices of information quantitiedby three index hed obvious changes law. It can be explained by “Intermediate Disturance Hypoth-esis”. Because diversity is the kurtosis function of disturance grandiant , the intermediate distu-rance resulted in maximum of diversity. The threshold value of grazing protection can be deter-mined by kurtosis function of diversity changes.