内蒙古高原针茅摹群落β多样性研究

用比较样地法调查了内蒙古高原４类地带性针茅（Ｓｔｉｐａ）草原群落的β多样性特征。结果表明，Ｗｈｉｔｔａｃｋｅｒ指数βＷＳ与尺度有关，随取样面积的增加，βＷＳ逐渐降低，取样面积相同时，４类群落的βＷＳ比较接近，各群落 的Ｃｏｄｙ指数最初也随样方面积的扩大而增大，当样方面积扩大到一定尺度时，贝加尔针茅群落和大针茅群落为〉０．５ｍ＾２，克氏针茅群落和小针茅群落为〉２ｍ＾２，Ｃｏｄｙ指数趋于稳定。同一尺度

Beta-diversity of Stipa communities in Inner Mongolia Plateau]

The beta-diversity characteristics of four Stipa communities (S. baicalensis, S. grandis, S. krylovii and S. klemenzii) were studied using comparable plots methods. As a measurement of species turnover within communities, Whittacker's index(beta ws) was size-dependent, and reduced gradually with the increasing quadrat size. Under the same scale, beta ws indices of the communities were similar. Cody's index (beta c) was also affected by sampling size. beta c increased initially as quadrat size enlarged, then stabilized over the size of 0.5 m2 for S. baicalensis and S. grandis communities, and 2 m2 for S. krylovii and S. klemenzii communities. S. baicalensis community had the highest Cody index, while S. klemenzii community had the lowest one. In most cases, the within-community distance interval had a relatively high effect on Cody index; From S. baicalensis to S. klemenzii community, the functional group diversities of forbs, perennial bunch and rhizome grasses decreased greatly, the diversity of intermediate xerads reduced significantly, and the diversity of xerads increased firstly, and then declined for S. klemenzii community. The changes in species composition of four Stipa communities could give a reflection to the degrees of community replacement along ecological gradients, and Cody indices between the communities reduced gradually. The Morisita-Horn similarity coefficient between S. baicalensis and S. grandis community was significantly higher (0.72) than those between S. grandis and S. krylovii communities (0.55), and between S. krylovii and S. klemenzii communities(0.42).