A study on the community characteristics of evergreen broad-leaved forest in Dagangshan Mountains of Jiangxi Province.

Based on the survey at 25 sample sites with total area of 13.6 hm2,the species composition,physiognomy,species diversity and spatial structure of evergreen broad-leaved forest community in Dagangshan were analyzed.The community is composed of 273 vascular plant species belonging to 89 families and 178 genera.76.4 percent of the genera contain only single species.The geographic composition of it is complex which mainly includes tropical and sub-tropical zones.The phanerophytes including the vines take 86.29 percent of the tota1.The distribution pattern of the 22 major species constituting the community tree layer is gathered.The 4 indexes(richness,diversity and evenness) of species diversity are basically same in the elevation gradient distribution: evergreen broad-leaved forestevergreen and deciduous broad-leaved forestconiferous-broad mixed forestphyllostachys pubescens forest.Four kinds of diversity index with elevation changes is of basic agreement,highest in middle altitude,followed by the low altitude,and lowest in high altidude.Species diversity index changes at latitude gradient accord with the law,that is,increasing from the high latitude to the low-latitude.