A Study on Community Structure and Species Diversity of Subalpine Forests in Western Sichuan

Based on data from 6 types of forest community within 45 plots,species richness index,evenness index and species diversity index of sub-alpine forest communities in the Jiajinshan mountain were determined and analyzed.The results showed that the species diversity and evenness of the communities embody a sequential change as Evergreen Broadleaved ForestDeciduous Broadleaved ForestMixed Picea asperata and Pruhus serrulata ForestMixed Picea asperata and Betula platyphylla ForestMixed Abies fabric and Betula ultilis ForestPure Abies fabric Forest.In the sub-apline area,species diversity and evenness decrease gradually as the elevation ascends.The species richness within the herb layer and the shrub layer are similar in that they are significantly higher than that within the tree layer.As for the evenness,shrub layer is similar to the herb layer and both are in a small variation among communities.The evenness of the tree layer varies significantly among different communities.Species diversity index within different layer shows a trend of:herb layershrub layertree layer.Furthermore,the structure of artificial forests is simpler than that of the natural forests,but their herb species diversity is higher.The number of Phaneropytes in artificial forests is smaller than that of natural forests,but the number of Geophytes and Therophytes is significantly larger.And Phaneropytes dominate natural forests.Accordingly,a suggested management strategy is to maintain proper species diversity in forests so as to optimize the forest structure and to ensure its ecological service.