杨树苗期合理密度与合理密度线研究

 本文以加杨(Populus Canadensis)，I—214(Populus euramericana(Dode)Guinier CV—214)，中保14等杨树密度试验(1988—1991)为依据，分析了初植密度、竞争对生长的抑制作用，阐述了合理密度、合理密度范围、缓冲作用、上限合理密度线的形成过程。指出在双对数图上，上限合理密度线遵从Logistic分布(1nw=K/1+e(0.732·lnN-2.429)，呈左侧伸展的S型曲线。该曲线可划分为近似于lnw一lnN直线的上中下三部分，其中间部分直线式的斜率为-1.5左右，称作合理密度直线式。对密度与生长的动态作了分析、概述与讨论。

STUDIES ON THE RESONABLE DENSITY AND RESONABLE DENSITY CURVE OF POPLAR SEEDLINGS

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.