雅鲁藏布江中游地区植被与环境的关系

 在调查雅鲁藏布江中游的拉萨河流域海拔3 500～4 500m范围内的植被种类及其分布的基础上,选取5个具有代表性的样方,从中发现植物物种38个,最多的是草本18种,其次是灌木13种;按科分,最多的是禾本科7种,其次是菊科6种。对样方的分析结果表明:该地区水分是植被分布的控制性因素,随着海拔高度的增加,降水增加,气温降低,植被覆盖度及平均厚度增加;特别地,河心沙洲由于河水的补给,供水充分,植被不受水分胁迫,植被覆盖度及平均厚度均远高于同海拔高度的其他地区;该地区风沙地貌十分发育,可以通过水土保持增加植物可利用水量,从而提高植被覆盖度,实现固沙。

Relationship between vegetation and environmental factors in the middle reaches of the Yalutsangbu River

A quadratic sampling method was used to investigate plant species and their distribution within an elevation range of 3.5-4.5 km in the middle reaches of the Yalutsangbu River.And 5 typical samples were sampled to reveal the relationship between vegetation and environmental factors.Therefore,38 plant species were discovered in the 5 samples.And herbs as well as shrubs have the most species,with the precise numbers being 18 and 13 individuals.Regarding to families,Gramineae,with the largest number of any family has 7 species;composite which has 6 species.Furthermore,the analysis on the samples shows that the water availability is the dominate factor affecting vegetation distribution in this region.Specifically,while the elevation increasing,precipitation increases and temperature decreases,moreover,the vegetation coverage and mean thickness increase.In particular,vegetation coverage and mean thickness in the sand bar of river are much larger than those in other places with the same elevation,only because there is no water stress due to water supply from river.In addition,aeolian sand landform distributes widely in this region.It is feasible to increase water availability by conserving soil and water,which helps to promote vegetation coverage and stabilize sand.