青藏铁路沿线北段植被物种丰富度及盖度的动态变化

SPECIES RICHNESS AND VEGETATION COVERAGE OF TRANSECTS ALONG THE QINGHAI-TIBET RAILWAY IN THE TIBET PLATEAU

通过青藏铁路沿线北段西大滩至唐古拉山北坡范围内植被样带的抽样调查,对植物物种丰富度(S)、植被盖度由北至南的动态变化特征以及两者的相关关系进行了分析。结果表明:(1)在青藏沿线北段高海拔地区,由北至南植物物种丰富度呈逐渐升高的趋势,1m^2样方平均物种数量由沿线北部样带的5或6种,逐渐升高至南部样带的9或10种。多重比较表明,相邻或相近的植被样带间单位面积物种丰富度多差异不显著,而当样带间距加大时,则表现出显著性差异。(2)由北至南各样带1m^2样方平均盖度呈不规则的动态变化,多重分析表明,多数样带间1m^2样方盖度间存在显著差异,说明植被盖度与物种丰富度相比更多地受到地形、土壤理化性质等小环境因素的影响。(3)研究区域北部各样带1m^2样方平均盖度与物种丰富度呈现较显著的正相关关系,且多以乘幂指数方程拟合精度较高。而在研究区域南部,则未表现出显著的相关关系,这是因为这些样带中群落盖度主要受少数优势种盖度所控制,而与群落物种数量相关性不大。最后,提出今后需要加强青藏铁路沿线高寒地区植被分布格局及其环境解释的相关研究,以便深入分析区域植被分布的格局和成因。

Ten vegetation transects were surveyed along the Qinghai-Tibet Railway between Xidatan and northern slopes of Tanggula Range on Tibet Plateau. The trends of species richness and vegetation coverage along the latitude were analyzed. Besides, the relationship between the species richness and coverage was analyzed. In the high altitude region of Tibet Plateau,just as other low altitude region,the species richness gradually rose from the northern latitude to southern latitude of the study area. The coverage of plots rose in the same condition. The species number was 5 or 6 in the northern transects,but it was 9 or 10 in the southern transects. The altitude of the study area was 4 400-4 900 m,so high altitude and the altitude difference between transects did not influence the change rule of species richness. Transects were arranged beside the railway, so the topography was gentle, belong to piedmont, plain or valley. All transects located on the gentle topography reduced the influence of altitude and topography on species richness. So it was propitious to sum up the influence of latitude on the species richness. The vegetation coverage gradually rose as the latitude shifting from northern to the southern part. The relationship between the species rich- ness and coverage was positive correlation in three northern transects,but the correlation between the spe- cies richness and coverage was low in the southern transects. The reason may be that few species dominated the community in the southern transects. At last,the vegetation ecology study foreground of Tibet Plateau was described in the paper. The distribution pattern of species richness and the environmental cause may be an important study direction in the future.