关于异龄林大小等级划分标准的探讨

在森林资源调查中，对异龄林用平均年龄和龄组进行归类，会缩小不同林分之间的结构差异，并造成林分年龄的偏低估计。利用海南省热带天然林样地资料。在对异龄林结构进行分析的基础上，提出用占总株数20％的大径级林木来计算异龄林的平均直径、平均树高等林分特征因子，并根据平均直径大小按“径组”（或粗度级）将异龄林分为5级，基本与同龄林的5个龄组相对应。便于对森林资源的统计和汇总分析。提出的径组划分标准可为异龄林的调查和统计提供参考，也为开展这方面的进一步研究提供借鉴。

Discussion on Classification Criterion of Size Class for Uneven-Aged Forest Stands

Classification for uneven-aged forest stands by mean age and age group in forest inventory may reduce the difference of structure of various stands and underestimate the age of stands. Based on the analysis of uneven-aged forest stands by using the sample plot data of tropical natural forests in Hainan Province, it was presented that such stand-level characteristics of uneven-aged forest stands as mean diameter and mean height can be measured by the 20 % larger trees, and uneven-aged forest stands can be classified into 5 classes by diameter group （or stand size class）, just like even-aged stands being classified into 5 classes by age group. The classification criterion of diameter group presented in this paper will provide reference for the inventory and statistic of uneven-aged forest stands and for the relevant studies in the future.