Analysis on species diversity and its disturbance of Salix shrub community in east Qilian mountain

The species diversity of Salix shrub community ,in alpine area of east Qilian mountain,was analysed .The results show that:(1)The diversity indices based on cover value and important value are more accordant than that based on abundance.(2)For the diversity of Salix shrub community, species richness,Simpson’s index and Shannon-Wiener’s index of herb layer were more than but Alatalo’s evenness degree was less than those of shrub layer.The maximum value emerged at 3150-3250m in the shrub layer and at 3100 meter height in the herb layer.(3)Both Whittaker’s index and Routledge’s index showed that β diversity degree of the shrub layer was higher than that of the herb layer but Cody’s index did not.In the shrub layer, β diversity declined as altitude increasing. In the herb layer,the rate of species replacement was the highest from 3150m to 3200m,but the rate declined as altitude increasing above this altitude.(4)The disturbance could improve the level of species diversity.The species richness,Simpson’s index and Shannon-Wiener’s index had increased after Salix shrubs were cut down.