桂西南岩溶植被演替过程中的植物多样性

Species Diversity in the Process of Succession of Karst Vegetation in Southwest Guangxi

2001年10月至2002年8月,以“空间代替时间”方法对(?)岗自然保护区及其周边区域的岩溶植被进行调查,采用物种丰富度(S)、Shannon-Wiener指数(H)、Simpson指数(D)、Margalef’s指数(E)分别从乔木层、灌木层、草本层以及整个群落分析桂西南岩溶植被各演替阶段的物种多样性特征。结果表明:随着演替进行、草本层由种类较少的阳性草种发展到种类丰富的耐荫草种,物种多样性随着演替的进行而增加,在灌草丛阶段存在一个较小的峰值。灌木层物种多样性在藤刺灌丛阶段达到最大,随后到先锋阶段明显下降,至亚顶极、顶极阶段灌木层的物种多样性又略有回升,但不及藤刺灌丛阶段,亚顶极阶段与顶极阶段的灌木层物种多样性差异不大。乔木层由于亚顶极阶段既存活有阳性树种,又存活有阴性树种,物种多样性基本上是先锋群落阶段〈亚顶极群落阶段、亚顶极群落阶段〉顶极群落阶段。桂西南岩溶植物群落物种多样性并非随着演替发展而增大,而是在亚顶极阶段达到最大值;不同群落演替阶段各层次物种多样性表现为灌木层〉草本层、灌小层〉乔木层的规律。

The vegetation was investigated by the method 'space substitute time' in and around Longgang Natural Reserve,southwest Guangxi from Oct. 2001 to Aug. 2002. The species diversity of Karst plants at different phases of succession in the survey area were analyzed with species richness,Shannon-Wiener index,Simpson index,Margalef's index in the layers of tree,shrub,herb and community. The results are as follows. With the development of succession, the rare light species are substituted by the abundant shade-tolerant species in herb layer. The species diversity of herb layer increases with progress of succession, but there is a small peak value in phase of shrub-herb. The species diversity in shrub layer reaches maximum in phase of vine-shrub,then apparently declines in the pioneer of phase;but rises again to some extent in sub-climax and climax phase,and the species diversities of herb layer in sub-climax and climax phase have no much different. Since coexistence of light trees and shade trees in sub-climax phase, the species diversity in tree layer follows the laws of pioneer phase < sub-climax phase and sub-climax phase > climax phase. The species diversity of community in the survey area doesn't increase with progress of succession,but reaches maximum in sub-climax phase. The shrub layer doesn't only grows shrub,but also grows young trees and seedlings in sub-climax phase. The species diversity of plant community at different phases of succession follows the laws of shrub layer>herb layer and shrub layer>tree layer.