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.