西双版纳青梅林的群落学研究

A PHYTOCOENOLOGICAL STUDY ON VATICA FOREST IN XISHUANGBANNA

本文对分布在西双版纳勐腊县南部以龙脑香科植物版纳青梅为标志树种的热带森林作了群落学分析,认为它具有热带雨林的结构和基本特征,在性质上属于热带季节雨林。由于分布海拔偏高和生境特殊,它的上层乔木几乎常绿,在外貌上与望天树林和本地区典型的季节雨林有一定差异,在区系组成上向山地雨林过渡,它表现为一种季节雨林向山地雨林过渡的类型,同时也是一种热带北缘地区季节雨林的海拔极限类型。

The tropical forest characterized by species V atica guangxiensis of Dipterocarpaceae, existing in Mengla nature reserve of Xishuangbanna of Southern Yunnan, is a forest type of the dipterocarp forest from the northern margin of the tropical zone of SE Asia. A phytocoenological analysis on the forest has been presented in the paper. This forest, which has the vertical profile of three tree layers and other general eco-physiognomical features of tropical rain forest, is undoubtedly a true tropical rain forest. It could be considered as a community type of tropical seasonal rain forest which belongs to a formation of lowland rain forest. Occured at a relatively higher elevation (800—1100m above sea level) and deep valley habitats, the forest community, which has few deciduous trees in its tree layers, is a little different from the typical seasonal rain forest from the same region in which, deciduous tree species take up 1/4 or 1/3 of total species of the uppermost trees. Furthermore, it is seen in the forest community that there are a decline of typical tree species of tropical lowland and an appearance of some representative tree species of tropical montane. Evidently this forest is the type of lowland rain forest at altitudinal limit in the northern margin of tropical zone and has appeared to be transitional toward montane rain forest.