Analyses Of Plant Community Structure And Species Diversity In The Baishanzu Natural Reserve

This thesis focused on the structure and species diversity patterns of plant communities in the Baishanzu Natural Reserve, Zhejiang province. Based on the investigations of66plots, I analyzed species composition, spatial structure, alpha diversity, beta diversity, as well as size distribution of dominant species in these communities. The results showed that:1. There were14pteridophytes species (12genus,9familaies),9gymnospermous species (7genus,3familaies),341angiospermous species (177genus,69families) in the plots. Within angiospery, there were302dicotyledon species (152genus,63families) and39monocotyledonous species (25genus,6families). Meanwhile, Rosaceae, Theaceae, Fagaceae and Lauraceae were families with high species richness.2. There were seven vegetation types (coniferous forest, coniferous broad-leaved mixed forest, broad-leaved forest, bamboo, shrub, herb and meadow),23formation groups and40formations in the Baishanzu Nature Reserve.3. Important value analyses showed that dominant species were Pinus taiwanensis, Cryptomeria fortunei, Cunninghamia lanceolata and Pinus massoniana in the coniferous forests. Beside the dominant coniferous trees, Schima superba and Fagus lucida were constructive species in the coniferous broad-leaved mixed forests. Species in Castanopsis, Cyclobalanopsis and Lithocarpus were dominant in broad-leaved forests. Population sizes of dominant species in each vegetation type were nearly reverse "J" shape or followed biased normal distribution. Most indi vials of these populations were seedlings and saplings.4. In general, the highest species richness of the tree layer appeared in the evergreen broad-leaved forests. The highest species richness of the shrub layer was in the coniferous and broad-leaved mixed forests. The species richness of the herb layer was highest in the bamboo communities, and lowest in the evergreen and deciduous broad-leaved mixed forests. The Shannon-Wiener diversity index and Simpson diversity index of tree layer were highest in the evergreen broad-leaved forest, followed by the evergreen and deciduous broad-leaved mixed forests, the coniferous and broad-leaved mixed forests, coniferous forests and bamboo forest. The Shannon-Wiener diversity index of shrub layer was highest in the coniferous and broad-leaved mixed forests. Differences of Simpson diversity index and Pielou’s evenness index were small among shrub layers of various forest community types. Herb layer of the bamboo community had the highest values of the three diversity indexes, and had significantly higher Shannon-Wiener index than the coniferous forests, the coniferous and broad-leaved mixed forests, the mixed evergreen and deciduous broadleaf forests and evergreen borad leaved forest, and also had significantly higher Simpson index and Pielou’s evenness index than the coniferous forests and evergreen borad leaved forest.5. The beta diversity pattern was described by Chao’s Jaccard index based on45randomly distributed standard vegetation plots (20m×20m) in this area. Results from Mantel test, Distance-based Redundancy analysis and ANOVA showed that beta diversity was increased with spatial distance and habitat difference among plots, but only36%of its variance can be explained by the joint effect of spatial distance and habitat difference. Specifically, only coverage of tree layer and elevation of the local community had significant effect on beta diversity at Baishanzu Nature Reserve. The impact of tree layer (explained20%variance in the beta diversity) on the beta diversity was also larger than the effect of elevation (only18%), while spatial distance had the smallest explanation (9%).