青藏铁路唐古拉山南段沿线植被多样性及盖度特征分析

An analysis of vegetation cover and species diversity of roadside vegetation in southern section of Tanggula Mountains along the Qinghai-Tibet Railway.

通过以铁路线为样带中心点,对青藏铁路唐古拉山南段沿线垂直于铁路两侧系统设置植被调查样带、样地、样方,重点调查铁路沿线原生植被物种组成、高度、盖度、株丛数等,着重分析了不同样带植被物种丰富度、植被盖度、物种共有度沿纬度方向的空间变化特征,为铁路生态安全体系建设和植被生态修复提供重要参考。结果表明：①1 m×1 m样方平均物种数多在9～12种之间,丰富度相对较低;20 m×20 m样地平均物种17～26种。各样带总的物种丰富度在47～59种之间;植被物种丰富度纬度方向距离差异不明显;样方、样地、样带小尺度的变化对物种丰富度会产生很大影响。②青藏铁路南段总体植被覆盖度高,植被覆盖率80%以上的占1/2强;因受局部环境条件的影响,其植被覆盖度也存在一定差异。③应用Jaccard指数对沿线各植被样带物种共有度进行分析,结果表明,随着样带纬度方向间距的增大,物种共有度指数值呈逐渐减小的趋势,相邻样带的物种共有度最大,物种纬度方向逐渐替代的规律明显。

In order to guide the ecological security construction and vegetation restoration work along the Qinghai-Tibet Railway（QTR）,a field survey was conducted to study the characteristics of the roadside plant communities.The spatial variations of species richness,vegetation cover,and similarity of species following the latitude direction were analyzed based on the field data.The results show： 1） The average species richnesses in 1 m×1 m sample plots were between 9 and 12.The average species richnesses in 20 m×20 m sample plots were between 17 and 26.The average species richnesses in 11 transects were between 47 and 59.In summary,the variation of species richness along the south-to-north direction was not significant.Furthermore,the species richness was varied significantly with the size of sample plots.This shows that the species richness of vegetation along the QTR in southern section of Tanggula Mountains is mainly decided by the local environment conditions.2） The vegetation cover in study region is good,and there are above half of the research sections that have an average vegetation cover over 80%.However,due to the variation of local environment factors,some differences in vegetation cover exist among different regions.3） The similarity of species was studied by using Jaccard Index（JC）.The result reveals that the value of JC decreases as the increase of the distance between two transects.In conclusion,the gradual succession of species along the latitude direction is very obvious.