Species Composition and Diversity in the Process of Natural Succession of Karst Vegetation in Central Guizhou:Case Study of Puding Country in Guizhou

The process of natural succession of vegetation in Karst rocky desertification area in central Guizhou was divided into the herbosa stage,the stage of herbosa-shrub,the stage of vine-shrub,the stage of subaltern tree forest and the stage of evergreen broad-leaved forest according to the characteristic of plant community.The species diversities in the layers of herb,shrub,tree and community at different successional stages were measured by the methods of species abundance,Simpson index,Shannon-Wiener index and Pielou’s evenness index.The results showed that the diversity indices in herb layer rose steadily after the succession developed from the herbosa stage,and reached the maximum in the stage of vine-shrub,then decreased gradually.The diversity indices in shrub layer,tree layer and community reached the maximum in the stage of subaltern tree forest.The diversity indices of herb layer were higher than those of shrub layer in the herbosa stage and the stage of herbosa-shrub.There were difference among the indices of the herb and shrub layers in the stage of vine-shrub,and the indices of tree layer were the lowest.While in the stage of subaltern tree forest and climax stage,diversity indices of shrub layer were higher than those of herb layer,which was greater than those of tree layer.In the case of litter artificial disturbing effect,the advantage of herbage declined while that of shrub and arbor rose steadily in the natural succession of vegetation in Karst rocky desertification area in central Guizhou.And the Karst forest formed finally.