提出一种人工测量胸径和地径数据后，采用电子经纬仪按照解析木近似分段方法，对活立木上部直径和相应高度进行测量，按照圆台累加法模拟解析木平均断面区分材积法求积的立木材积测算方法。为了验证这种技术方法的可靠性，在北京地区选取了87棵伐倒样木，首先使用电子经纬仪对样木从相互垂直的两个方向分别进行观测，计算结果求平均值。然后伐倒样木，采用传统的平均断面材积法进行树高、材积测定并作为真值，最后将电子经纬仪观测结果同伐倒木测定树高、材积进行比对分析。试验结果表明：电子经纬仪立木测算树高相对于解析木测定树高的平均相对误差为-0.11%，相对误差平均值绝对值为1.70%，决定系数 R2为0.994，相对误差的频数基本符合正态分布；材积的平均相对误差为0.18%，相对误差平均值绝对值为1.75%，决定系数 R2为0.999，相对误差的频数呈正态分布。说明电子经纬仪活立木测算结果与传统伐倒解析木测算得出的树高和材积具有一致性，可以替代伐倒木区分求积法，达到林业调查的规范要求。%A new standing tree volume measurement method was put forward that firstly, the diameter at breast height and ground diameter data were measured by manual measuring method, then by adopting analytic tree approximately-segmentation method and using electronic theodolite, the standing tree upper part diameter and corresponding height were measured, last by using method of conical frustum summation, the analytic trees’ average cross-section distinguishing process for calculating the standing tree volume was simulated. In order to verify the reliability of this method, eighty seven felled sample trees were chosen from Beijing area. From two mutually perpendicular directions, the sample trees were respectively observed by electronic theodolite, hence the average value of the observed values were obtained; the sample trees were cut down, whose tree height and timber volume were measured through conventional average cross-sectional volume method, and their measurement data are regarded as truth values; in the end, a comparative analysis of tree height and timber volume between the observed values and the calculated values was conducted. The test results show that the average relative error of measuring the tree height by electronic theodolite standing timber volume compared with analytic cut trees was -0.11%, the absolute value of relative error was 1.70%, the determination coefficient R2 was 0.994, and the frequency of relative error was in line with the normal distribution. As to the volume of timber, the average relative error was 0.18% while the average value of relative error was 1.75%, the determination coefficient R2 was 0.999, and the frequency of relative error also conformed to normal distribution. The findings show that the tree height and timber volume calculated by electronic theodolite standing timber volume accord with traditional analytic cut trees. Therefore, the electronic theodolite standing timber volume could replace analytic cut trees to meet the accuracy requirement of forestry investigation.
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