Abstract: The midmontane humid evergreen broadleaved forest is one of typical vegetation types in the subtropicalmontane vertical zone of Mt.Xiaobaicaoling,and this vegetation type is one of largest area,integrated and valuable in the Baicaoling Nature Reserve too.The evergreen broadleaved forest is dominated by Lithocarpus variolosa.Based on the community structure and component of floristic element analysis of 116 frequent and dominant species in this vegetation type,it can be shown that only those species with the arealtype endemic to China and SinoHimalayan arealtype can occur in all the layers of community,and the Tropical Asiatic elements,SinoHimalayan elements and elements endemic to China are floristically dominant in the forest.Those two points indicate that the flora of Mt.Xiaobaicaoling is belonging to Yunnan Plateau Subregion,Yunnan Plateau Region,SinoHimalayan Forest Subkindom,East Aisa Kingdom (IIIE13a).Floristically,the elements endemic to China are those species distributed mainly in the region of Mt.Xiaobaicaoling and the adjacent regions (including NW Yunnan,Sichuan,Guizhou and Tibet),and the socalled adjacent regions are mainly belong to the Hengduan Region in regionalization of China.So it can be shown that the floristics of Mt.Xiaobaicaoling is relatively in nature close to that of Hengduan Region.On the basis of the comparison of the same vegetation type from Mt.Xiaobaicaoling and adjacent regions,it can be shown that this vegetation type od Mt.Xiaobaicaoling is with higher altitude and drier habitat than others due to the more northern location of Mt.Xiaobaicaoling in Yunnan Plateau and reflects the effect of the microclimate in the Valley of Jinshajiang (the upper Yangtze River).

Key words: Mt.Xiaobaicaoling