东亚－北美木本植物间断分布的研究

A STUDY OF DISJUNCT DISTRIBUTION OF WOODY PLANTS IN EAST ASIA NORTH AMERICA

东亚－北美间断分布区的木本植物种类，初步统计共有３４科４９属９７５种，其中东亚地区７３０种，占总数的７５％，北美地区２４５种，占２５％，说明东亚种数远多于北美，估计本间断分布区中属的总数为全世界诸多洲际间断分布中极为丰富的类群。东亚－北美间断分布区有如此众多属存在的原因有三，一是地质变迁，二是气候变化，三是地史悠久。东亚－北美间断分布区中约有１８个属的现代分布中心在东亚，６个属在北美。东亚与北美主要有两个植物气候型，大陆西岸气候型（地中海气候型）的属不多，在东亚引种成功率不大，大陆东岸气候型的较多。

According to my primary statistics,there are 34 families 49 genera and 975 species appearing in disjunct distribution type both in East Asia and North America, of which 730 species are in East Asia area,making up 75% of the total,245 in North America area,making up 25%,The fact shows that the species in East Asia far outnumber those in North America.It′s estimated that the genera number in this disjunct distribution area is the greatest among the continents in the world.Forming such a considerable genera number may be supposed to have three reasons:the geological change,the change of climate and the long historical geology,There are quite a great number of present woody plants centered in East Asia and North Amercia.of them 18 genera are centered in the former,and 6 genera in the latter.The disjunct distribution area is influenced by two main plant climatic types:the climatic types of western coast of the continent(mediterranean climatic type)and eastern coast of the continent.It can be concluded from numerous practical experiments that the introduction ratio from western coast of North America is not so high as that from eastern coast of North America into East Asia.