雅鲁藏布江中游沙地植物区系与阿拉善荒漠植物区系的比较

A COMPARISON OF FLORAS IN THE SANDY LAND OF MIDDLE YARLUNG ZANGBO BASIN AND IN ALXA DESERT

从区系地理成分来看，雅鲁藏布江中游沙地植物区系以东亚成分（中国—喜马拉雅成分）占绝对优势，而阿拉善荒漠则以亚洲中部荒漠成分（即戈壁成分）占主导地位。另外，两个地区的地方特有成分的优势都十分明显，但雅鲁藏布江中游沙地中的特有种大都是在青藏高原隆起以后由于特殊的生境（高寒、干旱）而分化出来的新种，而阿拉善荒漠中的特有种大都是些古老的单种属和寡种属。雅鲁藏布江中游沙地植物区系和阿拉善荒漠植物区系都具有古老的热带起源，然而前者是在古老的第三纪热带植物区系的基础上，在高原隆升过程中经过山区特化和气候特化形成的新的年轻的区系。

The floras of the sandy land in the Middle Yarlung Zangbo Basin and the Alxa Desert were compared. From the floristic components it can be seen that the flora of the sandy land in the Middle Yarlung Zangbo Basin is predominated by Eastasian elements, and the flora of the Alxa Desert by the central desert elements of Asia. Moreover, the superiority of the endemic species in the two floras are quite clear. But the most endemic species in the flora of this sandy land have been differentiated in the high altitude, cold and drought habitat during the lift of the Qinghai—Xizang Plateau, and the endemic species in the flora of the Alxa Desert are mostly the relict ones. The floras both in the sandy land and in Alxa Desert are all with palaeo tropical origins, but the former is an new and young one formed in the Period of the Plateau rising based on the Tertiary tropical flora, and the latter retains the ancient features of the tropical origin, especially the Mediterranean sea origin.