鼎湖山季风常绿阔叶林物种多样性指数空间分布特征

Spatial distribution of species diversity indices in a monsoon evergreen broadleaved forest at Dinghushan Mountain

生态学模式和生态学过程都具有尺度效应,研究取样尺度与物种多样性之间的关系,探索物种多样性空间分布的内在机制有助于更好地理解植物群落结构及其组织方式。作者研究了鼎湖山季风常绿阔叶林20ha样地中Simpson指数、Shannon-Weiner指数和Pielou均匀度指数在空间上的分布特征及其与取样尺度的关系,并采用方差和变异系数描述它们的空间变异特征。结果表明,这3种指数均表现出较强的区域性分布特征,且这种区域性特征与取样尺度有关。它们的方差随尺度的增加都表现出单峰分布的特征,在80m×100m尺度上达到最大值;而变异系数则随尺度的增加而减小,其中Shannon-Weiner指数和Pielou均匀度指数在<20m×25m尺度上,其变异系数急剧减小,之后则较为平缓。本研究结果表明在分析鼎湖山季风常绿阔叶林20ha样地物种多样性时应考虑尺度效应和取样区域。

Sampling scale is important in exploring the structure and dynamics of plant communities. Spatial patterns and formation mechanisms of species diversity are fundamental issues in community ecology. The effect of scale on species diversity patterns and their interpretation has attracted particular attention. In this paper, we studied spatial distribution patterns of Simpson, Sharmon-Weiner, and Pielou＇s evenness indices within a 20-ha plot as well as relationships of these indices with sampling size in a monsoon evergreen broadleaved forest at Dinghushan Mountain, Guangdong Province. The three indices all strongly depended on region of the study area, and such a regional pattern was scale dependent. Spatial distribution patterns also differed depending on which of two measures of diversity variation, viz. variance and coefficient of variation, we used. Variance of the three indices was unimodal with increasing scale, and was maximum at the 80 m× 100 m scale, while the coefficient of variation decreased with increasing scale. For the Shannon-Weiner and Pielou＇s evenness indices, coefficient of variation dramatically reduced when the scale size was less than 20 m × 25 m, and then followed by a more gentle change. Our results showed that sampling scale and region should be taken into account when studying species diversity in this 20 ha monsoon evergreen broadleaved forest.