Abstract:Based on the results of density experiments involving Populus canadnesis, P. euramericana Guinie cv-214 and Zhongbao 14 which were carried out from 1988 to 1991, the effects of initial density of a stand and competition among individual trees are analyzed in this paper. The reasonable density, buffering effect, range of reasonable density and line of reasonable density of upper limit are also presented. Meanwhile, we find that the distribution of reasonable density of upper limit on the figure of double logarithm abides by logistic distribution model (lnw=K/1+e(0.732·lnN-2.429) This distribution curve shows a reversed‘S’shape. This curve can be divided into upper, middle and lower regions, all of which are roughly the same as ln(w)--ln(N) line. In the middle of the curve, its slope is about -1.5; and this is taken as the reasonable density line of upper limit. Finally, the dynamics of density and growth of a stand are summarized and discussed.