通过野外调查和现有文献资料的分析,研究了西藏米拉山东坡不同海拔带内植物资源的构成特征。结果表明:米拉山区有维管植物86科324属765种,其中蕨类植物15科20属37种,裸子植物有3科7属12种。种类组成趋向于集中在少数科内,区系优势现象明显,反映出米拉山自然环境的特殊性和区系的过渡性。米拉山的植物物种多样性和地理成分多样性都有随海拔升高而减小的变化趋势。海拔3100～4100m是本山区中植物分布相对集中的高度带。海拔3500～3700m是物种资源最为丰富的地段。海拔3700m以下地段和海拔5100m以上地段的植物物种资源构成与其他各海拔带的相似性较低。

Based on the literatures and investigations of plant resources, specific richness and species composition at different altitudes, as well as vertical differentiation of vegetation in the east slope of the Mila Mountains in Tibet, which is divided into different altitudinal belts by every 200 meters, have been systemically analyzed.The results show that there are 86 families,324 genera and 765 species in Tracheophyta flora of Mila Mountains, among them there are 15 families, 20 genera, 37 species of Pteridophyta and 3 families, 7 genera and 12 species of Gymnospermae. The composition of species tending to centralize in few families and obvious advantage of region reflect the environmment  particularity and floral region transition in Mila Mountains. With the altitude ascending, the species richness index and the geographical element diversity index of the flora descend. Maximum of the species richness index is found in the belts 3 100- 4 100 m inelevation. The Srensen similarity indexes of specific composition, between the belts of basal zone (below 3 700 m altitude), as well as those of alpine zone(above 5 100 m altitude), and others, are relatively low.