黄河兰州段湿地种子植物区系研究

以黄河兰州段湿地作为一个独立的植物区系单元，对其种子植物分别从科，属和种3个层次进行了统计分析，同时，对科，属和种的分布区类型进行了划分，在此基础上分析了该区种子植物的地理成分。结果表明：黄河兰州段湿地种子植物区系含种子植物31科、84属、115种，分别占中国种子植物科、属、种数的11．00％，2．89％和0．48％，相对于该区较小的面积尺度，其种子植物种类较丰富，物种多样性较高；该区系以被子植物占绝对优势，其中，以禾本科（21属，25种）和菊科（13属，22种）为优势科，这两个科共含有34属、47种，分别占该区系总属数和总种数的39．53％和40．17％，表明他们对该区系的构成起较大作用；黄河兰州段种子植物区系中科、属、种的地理分布类型都以温带成分占绝对优势，该区系中有世界广布属25个，占该区总属数的29．4％，各热带分布型共11属，占本区总属数的12．95％，各温带分布型共49属，占该区总属数的57．65％，其中，北温带分布有20属，占总属数的23．53％，世界温带分布有9属，占总属数的10．59％，种的分布型也以北温带分布型占优势，此分布型共计55种，占总种数的47％，其次是温带亚洲分布型，有17种，占总种数的14．53％；热带分布型的种较少，仅占总种数的19．65％，表明该区系的温带成分明显多于热带成分，温带性质十分明显。

Investigation on the seed plant flora of the wetland along the Yellow River in Lanzhou City

The seed plants from the wetland along the Yellow River in Lanzhou City,as an independent floristic unit,were investigated by typical sampling method and analyzed at family,genus and species levels,respectively.Meanwhile,on the basis of the modern geographic distribution patterns of all species,genera and families,the geographic distribution types of seed plants in this region were identified and analyzed.The results showed as follows:The seed plant flora of the wetland along the Yellow River in Lanzhou City was consisted of 115 species,belonging to 31 families and 84 genera,this showed a high species diversity.In this flora,the angiosperm occupied a dominant position,and Gramineae and Compositae were the dominant families,these two families had 34 genera and 47 species,which were 39.53% and 40.17% of total genera and species in this flora,respectively,and they made the most proportion to the flora constitution.The temperare properties of the flora were obvious and the geographic elements were complicated.The temperate elements occupied absoloutely dominant position,geographic distribution types of families,genera and species were all temperate distribution types.