The Phytoeoenological Features of Mixed Evergreen and Deciduous Broadleaf Forest on Yellow-brown Soil Mountain in Guangxi THE STUDY OF CLASSIFICATION AND SUCCESSION OF ALNIPHYLLUM FORTUNEI FOREST IN GUANGXI Sampling method for rapid measurement of leaf area index by leaf litter collection in deciduous forests Content and Ratio of Carbon and Nitrogen of Three Types of Warm Temperate Deciduous Broadleaf Forests in Dongling Mountain THE STUDY OF CLASSIFICATION AND SUCCESSION OF ALNIPHYLLUM FORTUNEI FOREST IN GUANGXI THE SOUTH BIRCH FOREST,WEST BIRCH FOREST IN GUANGXI AND THEIR SUCCESSIONAL TREND