Abstract: By a field experiment, we studied the effects of different densities(low density and high density) on community structure(species composition and important value, diameter class and height class) and species diversity(The richness index S, Shannon-wienner index H, Simpson index H′, and Pielou index J_sw of Camptotheca acuminata plantation in Baiyun Mountain, Mianzhu District, Sichuan Province). Diameter class and height class had the same response to different density. Partial peak attribution was demonstrated in stand with big density, and peak attribution was demonstrated in stand with small density. In the tree layer of C.acuminata plantation, each species diversity indexes were low in both high and low density. Underground plants showed different responses to stand density, and there were higher species diversity of the herb layer under shrub layer in high and low density, respectively.

Key words: stand density, Camptotheca acuminate plantation, community structure, species diversity