Floristic characteristics of seed plants in Beichuanhe basin of upper reach of Yellow river
HU Jian-Zhong-；Zheng-Jia-Li
Soil and Water Conservation College of Beijing Forestry University; Key Laboratory of Soil and Water Conservation and Desertification Combating of the Ministry of Education, 100083, Beijing, China
Abstract：Located in the upper reaches of the Yellow river, the Beichuanhe basin occupies a very important ecological position. There are 74 families, 357 genera and 1006 species of seed plants in the basin. The floris-tic elements are so plentiful, complex and changeable that there are 12 areal types and subtypes of genus of seed plants in the basin, accounting for 80 % and 45.2 % respectively, compared with that in the whole China. The number and ratio of genus of Temperate have the dominant weights of all the types, and the floris-tic elements of North Temperate, which has 117 genera, accounts for 32.8% of the total genus in the basin and 54.9% in the whole country. The basic characteristics in the basin should be determined by North Temperate . The regionalization of flora in the basin should be classified as Tangut region, Qinghai-Tibet subking-dom, Holarctic kingdom. The study of floristic element has supplied sufficient basis for developing, utilizing and preventing the local plant resources, as well as developing plant introduction from other basin or areas.
2005, Vol. 3 
