黄河源头地区植物的区系特征

THE FLORISTIC CHARACTERISTICS IN THE SOURCE AREA OF THE YELLOW RIVER IN CHINA

黄河源头地区位于青藏高原东北部，属于昆仑山东部范围之内，约占东经９６°００＇，－９９°２０＇，北纬３３°５０＇一３５°４０＇，海拔大都在４３００－４８００ｍ之间。气候具有高原大陆性气候的特点。本区共有种子植物４１科、１４２属、４６２种，分别占青藏高原植物亚区唐古特地区总科数的４５．１％，总属数的２９．４％，总种数的２８．１％，是唐古特地区中植物种类最贫乏的地区。植物的区系特点如下：１．种类贫乏；２．本区系的北温带成分占有绝对优势的地位，并且旧世界温带成分和其它温带成分也较丰富，因而本区系表现出明显的北温带性质；３．本区系的植物在种类上缺乏古老的、原始的类型，并且许多单型属和少型属是由它们广布的近缘属衍化而来，表明本区系是一个年青的、衍生的区系；４．本区系的高山特化和寒旱化适应现象特别突出，在区系成分上较多中国一喜马拉雅成分和北极高山成分，所以本区系具有明显的高原高山植物区系的特色；５．本区系的植物在生活型方面以多年生草本为主而缺少木本种类。以上各点表明，黄河源头地区植物区系是整个唐古特地区经过了高山特化和寒旱化适应的高原高山分布的草本类型的代表。这些特点的形成，除了历史的原因外，更多的和更重要的还是生态因素?

The source area of the Yellow River is situated at the northeastern Qinghai一Xizang(Tibet)Plateau in China. It belongs to the area of eastern Kunlun Mt.,between 33°50'north latitude and35°40'north latitude,and 96°00'east longituole and 99°20'east longitude ,the area with altitudesranging from 4300 rn to 4800 m.The features of climate is the type with the alpine and conti-nent. There are 462 species of seed plants, which belong to 41 families and 142 genera , and re-spectively has a percentage of 45.1%of total families,and 29.4%of total genera,and 28.1%oftotal species of Tanggute area from the Qinghai一Xizang Plateau subdivision.The flora is thepoormost of species in Tanggute area. The floristic characteristics in the area are as follows:(1)species are poorer,and is the poormost area in Tanggute area.(2)The north temperate zone is su-perior to numbers of species in this area,and rich in the Old World Temperate elements and oth-ers,so this flora shows the clear nature of the north temperate zone,(3)This flora is short of theancient type and primitive species, and a lot of genera which contain only 1 specie or severalspecies are developed from its relational genera that is wildly distributed, shows the flora is ayoung and derivative flora. (4) It’s specially glaring alpine specializaton and appearance to adaptcoldize and droughtize in the flora, and the elements of Sino一Himalayan and Arctalpine,so theflora with distinctive plateau and alpine features is obvious.(5)On the life form of plants of theflora,it is primary pernnial grasses,and deficient species of trees and bushes. Summarizing afore-said characteristics, the flora of the source area of the Yellow River in China is the representativeof herbaceous type that is a alpine一specializationed and adapted cold and drough,and distributedin plateau and alpine area. Ecological factor played a most important role in forming aforesaidcharacteristics besides historical factor.