Study On Community Characteirstics Of Phoebe Zhauum In Enshi, Hnbei Province

Based on large numbers of relevant literatures and samples, further investigation of the Zhennan existing resources of Enshi in Hubei, a survey of the species composition, analysis of plantage, community structure and physiognomy, species diversity, population structure, population regeneration and endangered causes of Zhennan community in Enshi was conducted through survey sampling. The results show as follows:1. The Zhennan community is the largest area (has the largest distribution) in Enshi. Its vegetation is protected very well. Results show that there are103families,229genera,332species of vascular plants. The prevailing is dicotyledon, and the gymnosperm is poor. The main dominant families(species number>10) include Rosaceae, Gramineae, Fabaceae, Compositae, Lauraceae and Vitaceae, with60genera and95species, accounting for10.68%,38.43%and41.57%of total sum of the families, genera and species respectively. The community contains more genera of fewer and single species, respectively, of total genera and species of98.69%and92.88%.2. The community floristic elements are complex. From the families and genera of seeds plants of the areal-types distribution, the temperate components of families and genera occupies fairly low percentage. The results of floristic characteristics indicate that the tropical elements are more than temperate elements, so the area is an intersection of tropical and temperate, which show that there are some transitional features in the area. It is consistent with the region’s climate zone and location.3. The Zhennan community is located in the subtropical evergreen broad-leaved forest. Zhennan as the dominant species has evergreen of the community appearance all the year round. The phanerophytes occupies the dominant position in Zhennan community in Enshi, which reflects a muggy growing season and a longer winter of community habitat. Compared with life-forms of other communities, the result reveals that Zhennan community has transitional characteristic of tropical to temperate.The community could be divided into three layers including arbors, shrubs and herbs.4. After analysis of the species diversity of Zhennan community, it unveils the diversity pattern from high to low diversity index is shrub, herb and arbor. Compared the species diversities to other communities, it shows that the community of Zhennan bears relatively high species diversity.5. Based on the analysis of the size-class structure and height structure of main tree species in the Zhennan community, the results show that the size-class structure of main species showed nearly growing or stable community, and gradually becoming stable, and the Zhennan as dominant species in the community in a fairly long period will not be replaced by other types.6. The studies on ability of natural regeneration and endangered causes show that although there are a great many Zhennan seedlings under forest, most of them disappear before they grow up. So intraspecific competition, light conditions and living space are the main restrictive factors for the seedlings under forest of Zhennan. In addition, over-exploitation and utilization by human in history, severe destruction of the habitats, the spread limitation of Zhennan’s seeds, tropism of the warm and humid environment and so on. All above lead the Zhennan to become an endangered species. Therefore, there is of necessity to put forward protection measures of Zhennan.