Located in Huitong County, Hunan Province (26°45´N and 109°30´E), Huitong National Research Station of Forest Ecosystem is affiliated to the Institute of Applied Ecology of Chinese Academy of Sciences. This region marks a transition from Yun-Gui Plateau to the hills along the southern bank of Yangtze River and belongs to the up reach of Yuan River, a tributary of the Yangtze. The altitude ranges from 300 m to 1100 m above the sea level. The densely grouped hills and valleys feature the topography in this region, which determining forestry to be the major method of land use in this County. The mother rock mainly consists of grayish green slate, metamorphic rock and sandy shale. With relatively deeper layer, red earth or reddish yellow earth are generally distributed from 300m to 600m above sea level, and mountainous yellow earth above 600m. This region has a typical climate of Central Subtropical Zone, with average annual temperature of 16.5℃. The annual rainfall and annual evaporation range from 1200 to 1400mm and from 1100 to 1300mm, respectively, with average relative humidity of 83% and 300 days of frost-free period. The zonal vegetation is evergreen broad-leaved forest typical of subtropics, with the major species component of Castanopsis spp.and Lithocarpus spp.