Distribution pattern of tree species richness along an altitudinal gradient in Kanas of Xinjiang

By using direct gradient analysis,semivariogram analysis and fractal analysis,the distribution pattern of tree species richness in three transects along an altitudinal gradient in Kanas tourism district of Xinjiang was studied by transect method,and the variation characteristics of the tree species richness were described.The results indicated that the percentages of different tree species along the gradient had different change trends with altitude,and the tree species richness displayed a distinct decreasing trend along the gradient across all scales.Semivariogram analysis showed that the spatial heterogeneity of trees species richness was mainly caused by spatial autocorrelation at small or middle scale.Fractal analysis suggested that the fractal dimension of tree species richness was larger,and there was not inflexion at small or middle scale,reflecting that tree species richness had distinct spatial heterogeneity along altitudinal gradient in the same scale ranges because of the effects of random ecological processes.