西双版纳热带山地雨林群落学特征分析

Coenological Characteristics of Tropical Montane Rain Forest in Xishuangbanna

根据4块样地的调查资料,分析了西双版纳热带山地雨林的群落学特征.结果表明:在2 500 m2的样地中,共计有维管束植物105～178种,分属于46～61科、80～130属.区系成分可分为11个类型,4 块样地均以热带区系成分为主(约90%),其中又以热带亚洲(印度-马来西亚)分布(23.40%～32.88%)和泛热带分布(25.20%～36.67%)的成分占优势.群落以高位芽植物为主,其中又以中(约50%)、小高位芽植物(21.30%～27.78%)占优势;在叶片特征上,群落以中叶(72.66%～82.54%)、单叶(75%～86.96%)、纸质(58.73%～62.22%)、全缘(76.67%～83.33%)、非尾尖(约90%)为主.低海拔带上山地雨林的热带区系成分以及藤本植物、中叶和全缘叶植物所占的比例高于高海拔带上的山地雨林,而小高位芽植物比例则低于后者,体现出较强的热带雨林性质.西双版纳的山地雨林与本地区的沟谷雨林、低丘雨林相比表现为热带区系成分、藤本植物、大高位芽植物以及巨叶、大叶植物较少,而温带成分、小高位芽植物、小叶植物较为丰富,体现出向常绿阔叶林的过渡特征.

Tropical montane rain forest （TMRF）,one of the primary forest vegetation types in Xishuangbanna,occurs at lower altitude in the north （TMRF Ⅰ ） and higher altitude in the south （TMRF Ⅱ ）. In order to understand the community characteristics of tropical montane rain forest in different zones,four permanent plots （50m× 50 m） of tropical montane rain forest communities at different sites in Xishuangbanna were established,two of which were for TMRF Ⅰ and two for TMRFⅡ. The grid method （10m×10 m） was used to record all individuals with DBH greater than 2.0 cm in each plot. Shrub and herb species were investigated in nine 5 m×5 m and 2 m ×2 m sub-quadrates respectively. Plant species composition,physiognomic characteristics of those communities were analyzed. The results showed that,in the 2 500m^2 plot,total number of plant species in the communities of TMRF is 105-178,representing 80-130 genera and 46-61 families. The floral composition of those communities can be divided into 11 areal types and the tropical distribution composition accounts for about 90%. Among those floral areal types, Pantropic and Trop. Asia （Indo-Malesia） distributions are dominant,accounting for 23.4%--32. 88% and 25.2%-36.67%, respectively. Concerning about the life form spectrum, phaenerophytes are dominant in the communities, among which the proportion of meso and micro-phaenerophytes are very high,accounting for about 50% and 21.30%-27.78% ,respectively. Concerning about the leaf characteristics, the communities was composed mainly of leaves whose characteristics are mesophylls （72.66 % - 82.54 % ）, single （75 % - 86.33 % ）, papery （ 58.73 % - 62. 22 % ）, entire（76.67%-83.33%） and no-caud. （about 90%）. Compared with the communities of TMRF Ⅱ ,the communities of TMRF Ⅰ has more tropical distributional plants,more lianas,mesophylls and entire leaves,but has less micro-phaenerophytes. This indicates that the communities of TMRF Ⅰ are more close to the typical seasonal rain forest in Xishuangbanna. Compared with the communities of ravine and lower hill seasonal rain forests in Xishuanbanna,the communities of TMRF have less tropical distributional plants,mega-phaenerophytes and lianas,as well as less mega and macrophylls, but have more temperate distributional plants, micro-phaenerophytes and microphylls. This indicates that the communities of TMRF have obvious transitional characteristics from seasonal rain forest to evergreen broad-leaved forest.