研究了鲜为人知的滇南勐宋地区的原始山地雨林植被, 根据分布生境、群落结构和种类组成特征，可将该山地雨林区分为沟谷和山坡两个类型, 分别定义为八蕊单室茱萸(Mastixia euonymoides)-大萼楠(Phoebe megacalyx)林和云南拟单性木兰(Parachmeria yunnanensis)-云南裸花(Gymnanthes remota)林。该山地雨林的外貌仍以单叶、革质、全缘、中叶为主的常绿中、小高位芽植物组成为特征，层间木质藤本植物仍较丰富，草本高位芽植物和附生植物丰富，但板根和茎花现象少见，属于热带山地垂直带上低山雨林或山地雨林植被类型。与该地区的典型热带季节雨林和赤道热带雨林相比, 勐宋的山地雨林群落中的大、中高位芽植物和藤本高位芽植物比例相对减少， 小、矮高位芽植物和草本高位芽植物比例相对增加，单叶、革质、非全缘叶和小叶比例相对增加，板根现象少见。与中国热带北缘-南亚热带地区（季风）常绿阔叶林比较, 勐宋的山地雨林有较多的附生植物和草本高位芽植物，相对较少的小高位芽植物和矮高位芽植物，小叶比例亦较少，非全缘叶和革质叶比例相对较低。故勐宋山地雨林是滇南热带北缘山地的一种较湿润生境的植被类型, 与所谓的季风常绿阔叶林不同。在物种多样性上，勐宋热带山地雨林在单位面积植物种数上并不比该地区的热带季节雨林低, 物种多样性指数与低丘季节雨林相当，比沟谷季节雨林低， 明显高于季风常绿阔叶林。
The species composition, plant diversity, and the ecological and physiognomic characteristics of a tropical montane rain forest in Mengsong, southern Yunnan, were studied. Two main forest community types were recognized based on their habitat, species composition and forest profiles: a Mastixia euonymoides-Phoebe megacalyx community and a Parachmeria yunnanensis-Gymnanthes remota community. The montane rain forest is characterized by evergreen mesophanerophytes and microphanerophytes with simple, leathery and entire mesophyllous leaves, a relatively high abundance of woody lianas and epiphytes, abundant herbaceous phanerophytes, few buttressed trees and little or no cauliflory. Compared to the seasonal rain forests of the region and equatorial lowland rain forests, the montane rain forest has a lower abundance of mega- and mesophanerophytes and big woody lianas but a higher abundance of microphanerophytes, nanophanerophytes and herbaceous phanerophytes, and more plants with simple, leathery and non-entire leaves and microphyllous leaves. Compared with the dominant monsoon evergreen broad-leaved forests common in southern China, epiphytes and herbaceous phanerophytes are more abundant in the montane rain forest but have fewer plants with non-entire and microphyllous leaves. The montane rain forest in Mengsong can be classified as a wet tropical montane forest similar to the lower montane rain forest from tropical Asia. The montane rain forest in Mengsong has similar species diversity to the seasonal rain forest but higher species diversity than the monsoon evergreen broad-leaved forest of the region.