根据6块样地的调查资料，分析了西双版纳热带山地雨林植物多样性特征。结果表明：在2 500 m2的样地上，西双版纳热带山地雨林群落共有植物物种99～181种。其中乔木层的物种丰富度（S）为54～113，Shannon-Wiener指数（H′）为1.648 7～4.049 1，Simpson指数（λ）为0.503 5～0.969 5，Pielou 均匀度指数（Jsw）为0.413 3～0.854 9。灌木层的S为35～89，H′为2.413 2～3.716 2，λ为0.762 7～0.958 2，Jsw为0.678 8～0.859 3。草本层的各指数值：S为31～65，H′ 为2.792 1～3.499 2，λ为0.902 0～0.938 2，Jsw为0.729 3～0.838 2。低海拔带上的山地雨林（Ⅰ号、Ⅱ号样地）的各指数值（H′、λ、Jsw）在群落不同层次中均表现为草本层 > 灌木层 > 乔木层，而物种丰富度在不同层次中无一定变化规律；高海拔带上山地雨林（Ⅲ号、Ⅳ号、Ⅴ号、Ⅵ号样地）的物种丰富度和多样性指数（H′、λ）表现为乔木层 > 灌木层 > 草本层，而均匀度指数（Jsw）在不同层次中则无一定变化趋势。高海拔带上的山地雨林乔木层和灌木层的物种丰富度、多样性和均匀度指数均明显高于低海拔带上的山地雨林，这是由于前者所处生境较为优越。沿着海拔梯度，群落乔木层的物种丰富度、多样性和均匀度指数均在中等海拔高度地带（约1 200～1 220 m）达到最高值，这是由于中等海拔高度的山地雨林位于生境条件最为优越的沟谷地带，而且与低地季节雨林毗邻，热带雨林植物成分丰富。
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 plant diversity characteristics of tropical montane rain forests in different zones, six permanent plots (50 m×50 m) of tropical montane rain forest communities at different sites in Xishuangbanna were established, two of which were in the TMRF I and four in the TMRF II. The grid method (10 m×10 m) was used to record all individuals with a 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-quadrats, respectively. Plant diversity indices of trees, shrubs, herbs, and three sub-tree layers, and changes in plant diversity indices of communities along the altitudinal gradient were analyzed. The results showed that the total number of plant species in the TMRF communities were 99-181, tree species richness (S) was 54-113, Shannon-Wiener diversity (H′) was 1.648 7-4.049 1, Simpson index (λ) was 0.503 5-0.969 5 and Pielou‘s evenness index (Jsw) was 0.413 3-0.854 9. For shrubs, S was 35-89, H′ was 2.413 2-3.716 2, λ was 0.762 7-0.958 2, and Jsw was 0.678 8-0.859 3. For the herbs, S was 31-65, H′ was 2.792 1-3.499 2, λ was 0.902 0-0.938 2, and Jsw was 0.729 3-0.838 2. The diversity indices, H′, λ, and Jsw, were greatest in the herb layer followed by shrubs and then trees, whereas species richness showed no obvious differences in the TMRF I. For TMRF II, the species richness and diversity indices, H′ and λ, were greatest in the tree layer followed by the shrub layer and then the herb layer, but the evenness index (Jsw) was not different among the three layers. The species richness, diversity indices and evenness index of the tree layer and shrub layer in TMRF II communities were higher than those in TMRF I communities, most likely due to the superior habitat of the TMRF II communities. Along the altitudinal gradient, all indices (S, H′, λ, Jsw) were greatest at the mid-altitudinal zone (about 1 200-1 220 m) for trees. This can be attributed to the fact that TMRF communities in the mid-altitudinal zone are situated in a ravine area and have the most favorable growing conditions among the six plots. Furthermore, these communities are very near to the seasonal rain forest at lower altitudes, and thus the tropical rain forest plants are very abundant at these altitudes.