Study On The Floristic Characteristics And Plants Diversity In The Evergreen Broad-leaved Forest Communities Of Dagangshan Moutain In Jiangxi

Plant community diversity means the diversity of composition, structure, function and dynamics of communities. Understanding species composition is important to understanding community diversity. The work reported in this thesis focused on community diversity and its gradient pattern through studying the species composition using systematic field sampling and survey.The study area is located on the northern slope of Dagangshan Mountain where there is not only a high diversity on vegetation and species, but also high variation of diversity pattern along the elevation gradient. It is a perfect transect for the research of biodiversity and gradient patterns.The spatial variation of species diversity in a subtropical ever-green broad-leaved forest was studied comprehensively in terms of flora characteristics, quantitative characteristics, species diversity, niche and spatial pattern. The results are follows:Species richness, species evenness and species diversity were studied, also with their spatial distribution trends. The richness and abundance of trees are various in each quadrate. The small-scale difference of species diversity among quadrat groups along the altitude from valley to hilltop gradually reduced. There is a small fluctuation in a certainty scope on horizontal grads.The composition, structure, and life forms of dominant species changed from diverse and complex to simple with the increase of elevations. Variation of regeneration property, distribution frequency, and important value of dominant species showed obvious replacement of species along the elevation gradient.The results of a diversity measurement indicated that, no matter what different success ional layers of trees, or shrub and herb layers, the richness and diversity decreased nonlinearly with the increase of elevation. The peak values of richness of trees and herbs along elevation gradient were no other than the ecotones between different types of vegetation.Communities at different elevation could be ordinated not only by using important values of all plant species, but also by that of trees and shrubs. The ordination results based on important values of herbs were not as good as using of trees or shrubs.Spatial structure of evergreen broad-leaved forests in Subtropics, South China is quite complicated and is typical of heterogeneity, irregularity and non-homogeneous. Research on spatial pattern of species diversity of plant community only combined with analysis of flora characteristics, quantitative characteristics, species diversity, niche and spatial pattern can improve the better understanding of overall regional Plant community diversity.