THE SOUTH BIRCH FOREST,WEST BIRCH FOREST IN GUANGXI AND THEIR SUCCESSIONAL TREND

South Birch forest and West Birch forest are a seral stage of evergreen broadleaf forest sere,mainly occuring in red and yellow soil mountain of subtropics in Guangxi.Three plant associations are described as follows: Betula austro-sinensis Rhododendron cavaleriei-Indocalamus barbatus Phyllagathis microplectra Association; Betula alnoides-Myrica esculenta-Glochidion eriocarpum-Dicranopteris dichotoma Association; Betula alnoides-Ardisia quinqueqona-Indosasa hispida-Osmunda vachellii Association.Their successional trend of recovering evergreen broadleaf forest can be fully proved through information analysis of species compositions change of community.