Structural Characteristics and Diversity of the Tree Species in the mid-montane Humid Ever-green Broad-leaved Forest in the Gaoligong Mountains,Yunnan

Structural characteristics and diversity of the tree species in the mid-montane humid ever-green broadleaved forest in the Gaoligong Mountains in Yunnan Province were studied. The results showed that the forest is characterized by evergreen mesophanerophytes with simple and leathery and entire mesophylls,having a few deciduous trees in the canopy layer and an unconspicuous seasonal aspect. In the plot,the species richness and the abundance are most among trees with height 5 m or with 1 cm≤DBH 5 cm,and decreased with the increase of the height or DBH class,respectively,which can be fitted very well with linear function or negative exponential function. The basal area are largest among trees with 11 m≤H 14 m or with 20 cm≤DBH 25 cm. In the plot,there were 10 546 individuals in 95 species,and ite Shannon-Weiner indes is 1. 716,its Simpson index is 0. 014,and its evenness index is 0. 867,indicating a higher level of species diversity in the whole. The species richness,the abundance and the Shannon-Weiner index were decreased gradually with the increase of the height and DBH class,but the Simpson index and the evenness index showed the opposite trend. Compared with other domestic plots,the species richness,density,basal area per ha of Gaoligongshan plot were at the middle level,but the maximum importance value was the lowest,and the proportion of the rare species was only higher than one plot,showing a higher diversity among these plots.