青海柳属植物地理分布及其区系特点

通过野外调查和查阅大量标本及文献资料,对青海省柳属(SalixL.)植物地理分布和区系特征进行了研究。青海产柳属植物多达45种(含种以下5变种、1变型),隶属15个组(Sect.),分别占青藏高原组、种的100%、40.9%和我国组、种的40.5%、17.5%,居我国第4位。青海柳属植物主要分布于青海东部,包括祁连山系东段和青南高原东南部,垂直分布集中于海拔2000～4000m,是世界柳属植物海拔分布最高的地区之一。青海柳属植物区系特征表现在:(1)种类丰富;(2)多型性突出;(3)地理成分较复杂,以欧亚大陆温带分布成分和青藏高原分布成分为主,中国特有分布占有一定的地位;(4)特有现象不明显,仅占青海种数的8.9%;(5)两雄蕊或单雄蕊的进化类群占绝对优势,占青海种数的93.3%。青海柳属植物与邻近的东部(甘肃东部、陕西)和东南部(四川西部、西藏东部)地区联系密切。由于第三纪以来喜马拉雅和青藏高原不断抬升,形成了适应高寒和干旱环境的青海柳属植物的分布与区系特征。

Geographical Distribution and Floristic Characters of Salix (Salicaceae) in Qinghai Province

The geographical distribution and floristic characters of Salix species in Qinghai are studied by means of field survey,examining herbarium specimens and literatures.The result indicates that there are 45 species(including 5 varieties and 1 form)in Qinghai,they belong to 15 sections,accounting for 100% and 40.9% of species and sections in Qinghai-Tibet plateau,40.5% and 17.5% of species and sections in China,and take the fourth place in China.They mainly distribute in the Eastern of Qinghai,including the Eastern of Qiliansan Mountain series and the southeastern part of Southern Qinghai plateau,and their vertical distribution concentrates on the altitude 2 000-4 000 m,it is one of the highest altitude areas of the world that Salix species distribute on.The floristic characters of Salix species in Qinghai Province are as following:1)Rich species;2)High intra specific differentiation;3)Complex geographical components.They are mainly of Eurasia temperate and Qinghai-xizang Plateau distribution,but the component endemic to China plays an important role;4)Endemism is not obvious,only accounting for 8.9% of Salix species in Qinghai;5)Absolute domination with groups of diandrous stamens and monadelphous stamens,accounting for 93.3% of species in Qinghai province.The Salix species in Qinghai Province are closely related to the Eastern(East of Gansu and Shaanxi)and the southeastern(West of Sichuan,East of Xizang).Because of the continuous lifting of Himalayas and Qinghai-Xizang Plateau since Tertiary,the distribution and floristic characters of Salix in Qinghai,adapting the freezing cold and dried environment,are formed.