Study On The Population Ecological Of Pseudotaxus Chienii In Fengyangshan National Natural Reserve

Pseudotaxus chienii (Cheng) Cheng, an endemic plant in China, is one of the secondary state protection wild plants, and distributes in Fengyangshan Nature Reserve as one of its concentrative dwelling places. Community survey was carried out on 10 conmunities, which were dominated by P. chienii in the region. The community characteristics, size structure, spatial distribution pattern, species richness, interspecific associations and the niche features were analyzed in the article. The results showed as the followings:The populations of P. chienii could grow in the communities as dominated by Rhododendron simiarum, Fokienia hodginsii -R. simiarum and evergreen broad-leaved forests. When analysing flora and species diversity. There were 59 families, 104 genera and 160 species, including 5 families, 6 genera and 8 species of peridophyte, 4 families, 7 genera and 8 species of gymnosperme, 49 families, 88 genera and 160 species of angiospermae. The floristicelements were complex, and the total of tropical distribution type amounted to 46.84 %.In the R. simiarum communities, the size structure, the survival curve and the overwhelming community distribution pattern of P. chienii showed a sustaining development. In the communities dominated by F. hodginsii—R. simiarum, albeit the size structure was declining, the survival curve was Deevy-III type. Plenty of seedlings were still existed, and the population could keep steady. This two types were considered to be the most suitable ones for the P. chienii population. The important value of it reached 5-10%. While in the evergreen broad-leaved forests, the population of P. chienii showed to be a declining type, and the survival curve was Deevy-II type. The distribution pattern was random, which indicated that the P. chienii population would not fit for survive in this kind of communities. It was concluded that P. chienii might associate to the habit that the canopydensities of the communities were about 0.6-0.8.As the species richness, the index showed that the evergreen broad-leaved forests were much larger than broad-leaved and coniferous mixed forests and dwarf forests, while as the Simpson index and Shannon index, the indexes were evergreen broad-leaved forests > broad-leaved and coniferous mixed forests > dwarf forests. In the vertical structure of community, each index showed that shrub layer) tree layer>herb layer.Based on percentage of co-occurrence (PC) and association coefficient (AC), the interspecific associations of main tree and shrub populations in P. chienii communities were analyzed. The result showed that the interspecific association was not obviously correlative in most of the species-pair. In the tree stratum, P. chienii had some positive association with Schima superba, Ilexwilsonii , Rhododendron latoucheae and soon. In the shrub stratum, P. chienii had some positive association with Fokienia hodginsii , Mirsine stolonifera , Symplocos setchuensis , Eleutherococcus evodiaefolius, while obviously negative association with Cyclobalanopsis multinervis , Ilex editicostata , Schima superba.Finally we used niche breadth (Shannon-Winner coefficient) and niche overlap (Pianka coefficient), niche features of dominant species in P. chienii communities were reported in this paper. The result showed that there were much difference between the niche breadth in the three types of the communities. The niche breadth of Cyclobalanopsis stewardiana, Schima superba, Rhododendron simiarum were large, while the niche of breadth Viburnum sympodiale, Acanihopanax evodiaefolius, Pieris japonica were much small. P. chienii occupied the niche breadth about 7to 12 in the communities. The niche overlap between P. chienii and other populations was not large at all. Some populations which had relatively larger niche overlap with P. chienii always located in the substrate of the arbor, and mainly of them were shrub and little arbor.From the results that have been above-mentioned, the population of P. chieniimust be able to sustain and develop, unless the existing habitat in Fengyangshan would be protected effectively. The protection of P. chienii requires more basic work in order to establish efficient measure to protect the habitat of the population.