基于电子经纬仪立木无损精测技术的干形指数研究

Study on Stem Form Index Based on Non-destructive Precision Measurement through Electronic Theodolite

针对传统干形指数研究中上部直径获取困难、树干分段界限难以精准确定等问题,提出了一种基于电子经纬仪立木无损精测技术研究干形指数的方法。选取内蒙古自治区旺业甸实验林场198棵落叶松样本为研究对象,将每株样木10等分,计算相对分段干形指数;使用方差分析法可知各相对分段之间有不同程度的差异;利用聚类分析法可将树干聚合为2-10段;为了获取最优分段数,利用相对干形指数分别计算不同分段情况的材积,并用电子经纬仪观测的材积进行对比。结果表明：树干高度H分为3段时即可达到理想效果,各段平均相对干形指数（对应高度）分别为：4.295（H0.0-H0.1）、1.524（H0.1-H0.4）、1.670（H0.4-H1.0）。此参数的研究可定量描述树干干形分界线,在材积测量中只需测量对应分段处的3个直径即可精准测定材积,有效减少外业工作量。

Upper diameter data is difficult to obtain and the trunk segment boundaries are difficult to determine accurately by using traditional stem form index research method. To solve the above problems, a method based on stumpage non-destructive accurate measurement technique by using the electronic theodolite was proposed. 198 lgrches were selected as samples and each one was divided into ten equal segments. Relative stem shape index of all segments were calculated. Firstly, significant differences between those relative segments were found by using variance analysis method. Subsequently, a tree could be aggregated with 2 - 10 trunk segments by using cluster analysis. In order to acquire the optimal quantity of segments for volume calculation, all statistical combination was tested by comparison of relative stem form index and volumes observed using electronic theodolites. The results showed that the optimal quantity of segment was obtained when the stem was divided into three segments, average relative stem form indexes for each segment （ corresponding to height） were ： 4. 295 （ H0. 0 - H0.1 ）, 1. 524 （ H0. 1- H0.4 ） , 1. 670（ H0.4 - H1.0 ） ,where H is the total height of a tree. Those parameters could be quantitatively described as trunk-shaped boundary. Thus a tree volume could be accurately measured by just measuring diameters at the corresponding height, which could effectively reduce the labor consumption on field survey and related researches.