天然云冷杉针阔混交林的年龄变动及估测精度分析

本文采用长白山地区天然云冷杉针阔混交林的14个皆伐样地数据，分析6个主要树种的径阶年龄变异系数，根据其计算不同精度下外业捕样调查估测林分年龄所需的样本量；采用平均_小法估测林分年龄，分析其他测精度随着株数的变化。结果表明，6个树种的年龄变异系数随着径阶的增加，呈现波动性变化。石杉、冷杉和红松3种譬f叶树的年龄变异系数随...

Variation of tree age for natural spruce-fir-broadleaved forests and estimation precision.

In this study, using 14 clear-cutting plots data of natural spruce-fir mixed forests with coniferous and broad-leaved trees in Changbai mountains, the age coefficients of variation across diameter classes for six major tree species were analyzed, with which the sample sizes needed for the estimation of stand age with different precision in field work survey were calculated. Using the mean tree method, we also estimated stand age and analyzed the variation of estimation precision with the number of mean trees. The results showed that with the increasing diameter class, the age coefficients of variation for all six tree species had a fluctuation change. The age coefficients of variation of three coniferous trees, such as spruce (Picea jezoensis), fir (Abies nephrolepis) and pine (Pinus koraiensis) had no significant difference with the values mainly between 20% and 35%; those of three broad-leaved trees, such as linden (Tilia amurensis), birch (Betula costata) and maple (Acer mono) were between 15% and 35%. The precision of stand age estimation with 1 to 3 mean trees was low, ranging between 30% and 60%. With the increasing number of mean trees, the estimation precision improved gradually, then increased slowly (above 90%) after certain number, and then fluctuated around the maximum values.