基于地基激光数据的杨树干形分析

Analysis of poplar stem form based on terrestrial laser scan

利用地基激光扫描技术采集泗洪陈圩林场36块样地1927株杨树的点云数据,通过软件RiSCANPro对数据进行预处理。用K均值聚类对点云数据进行林木定位分割,并提取了树木胸径、树高等测树因子,通过公式计算出4种干形参数(胸高形数、形率、高径比和形高),用SPSS软件基于4种不同造林密度由高到低(株行距配置3m×8m、5m×5m、4.5m×8m、6m×6m)对4种干形参数进行差异分析,还对干形参数进行了模型研建,主要研究结果如下:1)不同造林密度对胸高形数、形率、高径比、形高有显著影响。胸高形数、形率和高径比随密度的增大而增大,形高则随密度增大而减小,即高密度林分的树干干形更为饱满,低密度树干干形尖削。2)指数方程是胸高形数与形率关系的最优模型,适用性检验精度高,达到99.12%,模型表达式为:f1.3=0.223*exp(1.025*q2),可应用于胸高形数的预测,为分析杨树干形参数提供参考。

In this study, the point cloud data of 1 927 poplars in 36 plots of Chenwei forest farm in Sihong were collected by using Terrestrial Laser Scan(TSL), the data is pre-processed by software RiSCAN Pro. K-means clustering method was used for extracting tree trunk through point cloud data, we also extracted the diameter and height parameters of the tree, 4 kinds of stem form parameters (form factor, form quotient, height-diameter ratio and form height) are calculated by formula. Using SPSS software to analyze the variance on 4 kinds of stem form paraments based on four different planting densities from high to low (plant row spacing 3m*8m,5m*5m, 4.5m*8 m, 6 m*6 m), the models of stem form parament was also built, The main results are as follows: 1) different planting densities have asignificant impact on the form factor, form quotient, height-diameter ratio and form height. As the density increases, the form factor, form quotient and height-diameter ratio increases while the form height decreases. In a word, the stem form for high-density is straighter and low-density is relative taper;2) the exponential equation is the optimal model of the relationship between form factor and form quotient, it has a high accuracy of applicability test which achieves 99.12%,the model expression is f1.3=0.223*exp(1.025*q2) which could be applied to predict form factor and provide a reference for analyzing the parameters of Poplar stem form.