Characteristics of Evergreen Broad-Leaved Forest in Xiaoxi National Natural Reserve,Hunan Province and Its Ecological Significance

Xiaoxi National Natural Reserve of Hunan Province,located at the middle of Wulingshan Mountains in Central China,extending from 110°06'50″～110°21'35″ E and,28°42'15″～28°53'15″N,with an area 3 520 ha,is the one of well-protected typical evergreen broad-leaved forest in China.The preliminary results show that the evergreen broad-leaved forest of Xiaoxi,which mainly consists of Castanopsis tibetana forest,Cyclobalanopsis xiangxiensisi forest,Manglietia patungensis forest,Machilus lichuanensis forest,Castanopsis eyrei forest,Castanopsis fargesii,Schima superba forest and Lithocarpus xiangxiensisi forest,is a typical lower evergreen broad-leaved forest,because it possesses not only the general subtropical evergreen broad-leaved forest characteristics,but also the high hot-wet and tropical-temperate characteristics.It is favorable for biodiversity conservation and ecology-environmental maintenance.Xiaoxi evergreen broad-leaved forest is rich of species diversity,as well as the rare and endangered species,and the special ecological habitatenvironment of valleys,in which the species are bred and conserved.It is of important value and significance to study the subtropical evergreen broad-leaved forest in China or even in the whole world,expounding the mechanism of vegetation formation and evolution,specially the mechanism of species speciation,diversity and maintenance in valleys.