Elevational patterns of plant species diversity on northern slope of Mt. Laotudingzi of Liaoning Eastern Mountains

Based on the data of open plots,the species richness,α diversity and β diversity as measure target,this paper analyzed the pattern of plant species diversity along altitudinal gradient on the northern slope of Mt.Laotudingzi,which was mid-size mountain and the relative height was 867 m in Liaoning Eastern Mountains.The results indicated that:(1)The pattern of plant species richness along elevational gradient was complicated.However,it represented that the valley and peak of species richness appeared continuously at the mid-altitudinal zone,namely the most lowest value of species richness appeared at 1 067 m in the dark coniferous forests which dominated by Abies nephrolepis and Picea jezoensis,and peaked at 1 167 m in the mixed coniferous and broad-leaved forests dominated by Betula costata and Abies nephrolepis,the value was 18 and 54.(2)The Shannon-Wiener showed wavy fluctuation with increasing elevation between 667 to 1 267 m in forests and its value was 1.37~2.07;It raised substantially along 1 267 to 1 347 m in shrubs and herbs,reaching maximum value 3.95 at 1 347 m on the northern slope of Mt.Laotudingzi.The Simpson index ranged from 0.98 to 0.99 along altitudinal gradient from 667 to 1 267 m,which means no obvious change;at 1 267~1 347 m,with increasing elevation the value was significantly reduced to 0.85 which was the minimum at 1 347 m.The pattern of α diversity along elevational gradient was more complex in tree layers,shrub and herb layers of the northern slope of Mt.Laotudingzi.(3)The three valleys of Jaccard index appearing at 767~867,1 067~1 167,and 1 317~1 347 m,correspond to transitional zones of the fallen broad-leaved forests to mixed coniferous and broad-leaved forests,dark coniferous forests to mixed coniferous and broad-leaved forests,shrubs to herbs,respectively.The Cody index peaked at 1 167~1 267 m which indicated the transitional of mixed coniferous and broad-leaved forests dominated by Betula costata to fallen broad-leaved forests dominated by Betula ermanii,and peaked at 1 317~1 347 m,which illustrated the transition from shrubs to herbs.