中文摘要：

以长白山金沟岭林场杨桦次生林为研究对象，分析了杨桦次生林直径分布特征，通过Weibull分布函数和负指数分布函数2种直径分布模型的模拟和检验，表明两者都适宜于异龄次生林的直径分布模拟；计算了次生异龄林中连续2个径阶中的株数之比（常数q值），分布范围为1．26～1．49。

英文摘要：

Permanent plots in the polar-birch secondary forests in Changbai Mountain, northeastern China, were established, and Weibull function and Negative exponential diameter distribution function, based on observation data of these plots, were developed to model diameter frequency distributions. Results showed that Weibull function and negative exponential function were suitable models for modeling uneven-aged secondary forests. And the study calculates the diameter q value, which was between 1.26-1.49.