辽宁老秃顶子北坡乔木层物种多样性垂直分布格局

利用乔木层样方的物种重要值矩阵信息，运用TWINSPAN分类方法，科学地划分出辽宁老秃顶子北坡的主要森林群落类型，并采用物种丰富度、α多样性和β多样性等指标，进一步研究了老秃顶子北坡森林植被乔木层物种多样性随海拔梯度的变化趋势．结果表明，老秃顶子北坡森林植被可划分为6个群落类型；乔木层物种多样性随海拔梯度的变化趋势为：随着海拔的升高，物种丰富度基本呈现出先上升后下降的分布格局；α多样性中Shannon—Wiener指数呈波浪式缓慢下降，而Pietou均匀度指数没有明显的变化；β多样性（Cody指数）则随着海拔的升高先上升而后下降．

Elevational Patterns of Plant Species Diversity in Tree Layer on the Northern Slope of Mt.laotudingzi,Liaoning province

In this paper, we analysed the composition and structure of communities on the northern slope of Mt. laotudingzi based on TWINSPAN classification; the patterns of plant diversity along altitudinal gradient were described by indices of species richness, α diversity and β diversity. Six community groups characterized by different dominants were distinguished; with increasing altitude, the species abundance rised firstly and subsequently decreased; Shannon-Wiener index decreased slowly, and Pielou evenness index showed no significant change; β diversity which indicated by the Cody index rised and then declined in the tree layer.