小叶杨胸径和树高生长进程的连续性和阶段性定量研究

应用logistic模型和有序样品聚类法对小叶杨胸径和树高生长进程的连续性和阶段性进行定量研究,将胸径和树高2个表观生长过程科学地划分为前慢期、速生期和后慢期3个阶段,实现了胸径和树高二维有序样品的聚类,不仅反映出小叶杨生长进程的综合节奏性,更为龄组划分提供了依据。对小叶杨而言,所获如下结论值得重视:(1)径生长开始进入速生期时,完成了幼龄林阶段;(2)高生长速生期结束时完成了中龄林阶段,此时恰好是径生长速率最大的时期;(3)径生长速生期结束时,基本完成了近熟林阶段。除小叶杨外,文中提供的方法尚可供其他树种生长进程的连续性和阶段性定量研究中参考。另外,还以logistic模型为基础,以时间因子为媒介,推导出一个能准确地描述小叶杨关系的新模型——logistic衍生模型。

A quantitative research on DBH(diameter breast height) and height growth process of Populus simonii Carr

The DBH and the height growth process of Populus simonii Carr.can be divided into three phases named early-slow growth,rapid growth and post-slow growth stages to attain the two-dimensional ordered sample clustering by using Logistic model and ordered sample clustering method.This not only reflected the comprehensive rhythm of Populus simonii Carr.growth process but also provided the basis for age group division.Several conclusions have been drawn from the study.The DBH growth going into the rapid growth stage indicated that the young forest stage has been past.The middle-aged forest stage was over after the rapid height growth finished,and meanwhile,the DBH growth rate has reached the maximum.,the nearly mature forest stage was going to ends after the DBH rapid growth finished. The research method in this paper can be applied to the study of other tree species.In addition,a new Logistic model precisely describing the relationship between the DBH and the height growth process of Populus simonii Carr.was put forward.