Ecological studies on the plant community succession on the abandonedf cropland in taibaishan, qinling mountains II. The community #alpha# diversity feature of the successional series

The community diversity at different secondary successional stages on the abandoned cropland in Taibaishan,the peak of Qinling Mountains,was measured and studied using the methods of species abundance,Shannon-Wienner index,Pielou's evenness index and Alatalo evenness index.The results show that the diversity indices arose steadily when the succession developed from the annual herbosa to the mixed broad leaved deciduous forest,After the stage of the mixed broad leaved deciduous forest,the indices decreased more or less except species abundance.According to the surrounding communities,the climax community would be Quercus aliena var. acuteserrata forest.At the climax,diversities of shrub and herb layers (living forms) arose again though that of tree layer continued to decrease.The characterisitics of the three living form diversities in different successional stages are as follows:in the primary stages,indices of herb living from>those of shrub one>those of tree one.In the middle stage (the stage of mixed broad-leaved deciduous forest) there are difference among the indices of the three living forms. But in the climax stage, indices of shrub living form>those of herb one>those of tree one. In order to measure the community diversity as a whole, the average of the relative thickness of the leaf layer and the relative coverage of each living from were used as weighting parameter here for the first time, and the dynamics of the general diversity indices proved that the weighting method is reasonable.