金沙江流域干热河谷上中下游草地植物群落结构与相似性

选择金沙江干流及支流小江干热河谷典型草地,采用标准样地调查法,对其上游、中游、下游以及支流干热河谷草地植物分布特征、群落结构、种群习性等开展研究,结果表明：（1）金沙江干热河谷草地植物群落结构自上游至下游,多年生草本植物种类的比例逐渐增加,灌木和一年生草本植物种类比例逐渐减少;金沙江干热河谷草地植物群落是以多年生草本为主灌木为辅的群落结构类型;支流小江干热河谷群落中,多年生草本和灌木植物种类比例相同,一年生草本植物种类比例较低。（2）金沙江流域干热河谷草地群落中,扭黄茅（Heteropogon contortus）为优势种群,次优种群随地理环境的改变而不同。（3）金沙江干热河谷存在种群扩散通道作用,但种群扩散通道作用受扩散距离的影响。（4）金沙江干热河谷草地植物种群的扩散、定居受到经向、纬向的影响。

The structure and similarity characteristic of the grassland community in hot-dry valley upper middle and lower of Jinsha River

This study was conducted to investigate the vegetation distribution patterns, community structure and population characteristics of typical grassland community in the hot-dry valley along Jinsha River and Xiaojiang River, a tributary of Jinsha River. The results show that, （1） while the proportion of perennial grass species increase from upper to lower Jinsha River, the proportion of shrub species and annual grass species decrease. The plant community in the hot-dry valley of Jinsha River is determined by peren-nial grass species accompanied with some shrub species. For plant community in the hot-dry valley of Xiao River, the proportion of annual grass species is lower than those of perennial grass species and shrub species. The proportion of perennial grass species is almost equally with shrub species. （2） Heteropogon contortus （Poaceae） is the dominant species of grassland community in the dry-hot valley of Jinsha River. By contrast, the sub-dominant species appear to be variable dependent on the characteristics of environmental and climatic conditions of habitats. （3） Population dispersal corridors are likely to exist in the plant community in the dry-hot valley of Jinsha River, the effects of which was influenced by dispersal distance. （4） Overall, spatial factors （latitude and longitude） are of importance for the dispersals and establishments of grassland species in the dry-hot valleys of Jinsha River.