Fagaceae is one of the most important families in temperate and subtropical regions. There are 7 gena and about 352 species and variants in China. The distributions of species richness and species Endemic Index and their relationships with climatic and geographic characters of Chinese Fagaceae were studied. The Endemic Index is firstly defined in this paper to describe the speciality of species components in some flora. If there are N species in some flora, and the i-th species has been found in another Ki—1 flora,then the species Endemic Index(EI) is defined as follow:
Through comparison and stepwize regression analysis,we found out that species richness center of Fagaceae was mostly at Yunnan,Guangxi and Guizhou provinces, but its endemic center was usually in Yunnan,Tibet and Hainan provinces. The results show that geographic isolations, such as gulf, large mountains, were important factors limiting the distribution of Fagaceae, and that the Endemic Index(EI)was more sensitive to these factors than species richness.