Phytogeographical Affinities of Forest Floras between China and Japan

The flora of eastern China is the main part of Sino-Japanese floristic region. It shows by the analysis and comparison that the floristic relations of Eastern China with Japan are closer than that of northeast China with Korea. The similarity indices of genera and species of seed plants in the two regions are very high, being 72.6% and 43.3% respectively. The structure and species composition of broad-leaved evergreen forests in the two regions are also similar, in which there exist the corresponding communities, such as the forests ofCastanopsis carlesii, C. Sieboldii.. Many plants in Easter China are nonspecific with those in Japan, e.g.,Cercidiphyllum japonicum, Magolia sieboldii, Nandina domestica etc.. Though the generaGinkgo, Liriodendron, Sassafras etc. existing now in China are extinct from Japan, their fossils have been discovered from the Tertiary Strata in Japan. It seems to indicate that the phytogeographical affinities between Japan and E. China was closer in ancient time than it is now; and both of the forest floras originated from one same flora. The flora in Japan did not evolve independently until it separated from Chinese continent and drifted to northeast in the late period of the Tertiary.