黄土丘陵沟壑区退耕地主要自然恢复植物群落的多样性分析

Analyses on Diversity of Primary Natural Restoration Vegetation Communities in Abandoned Croplands in the Hilly-gulled Region of the Loess Plateau

分别采用物种丰富度指数、多样性指数、Pielou均匀度指数J、Sorenson指数(Cs)和Bray-Curtis指数(CN)对黄土丘陵沟壑区退耕地自然恢复群落的多样性进行了初步研究。结果表明:(1)除丰富度指数变化不明显外,其它3个α多样性指数都反映出基本一致的变化趋势,即随着退耕年限的增加,多样性指数和均匀度指数的总趋势都是增加的,但变化比较平缓;(2)相似性系数Sorenson指数(Cs)的测度表明,每一群落类型总是与退耕年限最邻近的群落具有最高的相似度。随着退耕年限的增加,植物群落进一步发育,群落物种组成差异不断增加,群落之间的生态距离逐渐变远。而Bray-Curtis指数(CN)的测度结果与Cs不同。这种差异在一定程度上是对生境破碎化的一种反映。

The richness index（Margalef index）, diversity indices（Simpson index and Shannon-Wiener index）, Pielou evenness index,Sorenson mdex,Bray-Curtis index were used respectively to analyze the diversity of natural restoration vegetation communities in abandoned croplands in the hilly-gullied region of the Loess Plateau. The results showed that： （1） these α-diversity indices expect the richness index revealed a similar pattern. Diversity indices and evenness index increased gradully with the increase of abandoned time, but the change was not so fast; （2） Sorenson＇s similarity index（Cs） indicated that the similarity between every community and its nearest abandoned time was the highest. As abandoned time increased, plant communities developed continuously and the species composition changed while Bray-Curtis index showed the inverse trend. The fluctuation of diversity indices indicates that,to a certain extent,the studied area was fragmented.