基于地面激光扫描数据的马褂木材积建模与出材率研究

Volume modeling and yield for Liriodendron tulipifera based on terrestrial laser scan data

[目的]马褂木是优良的用材树种,研究其材积模型并分析多种密度种植下的径级材种造材出材率,旨在为马褂木人工林高效培育提供重要的指导。[方法]在马褂木多密度人工林试验区获取全样地地面激光雷达数据。通过点云提取单木结构参数,对4种造林密度(株行距配置:2m×2m、3m×3m、4m×4m、5m×5 m)马褂木试验林测树因子(胸径DBH,树高H,材积V)进行分析,建立一元材积方程、削度方程模型,并应用削度方程计算各密度林分材种出材率。[结果]研究得到的一元二次式V=0.0003D_(2)+0.0065D-0.0369为研究区马褂木最优一元材积式,该模型的决定系数(R^(2))为0.884,经过剩余标准差(S_(EE))、系统误差(T_(RE))、平均相对误差(M_(SE))、预估精度(ρ)等评价指标检验,无明显系统偏差,可用于研究区马褂木材积估计。研究选定改进的舒马赫方程式作为不同密度马褂木的削度方程,该模型R^(2)为0.924,经检验方程均方根误差为1.454,平均相对误差为0.050,预估精度达到0.910。进一步采用削度方程为多密度马褂木试验林进行多径级材造材,得到疏林地4m×4m密度种植下的大径材出材率最大(39.582%),密林地2m×2m密度种植下的小径材出材率最大(81.250%),而综合出材率最大的是4m×4m密度(98.650%)。[结论]马褂木多密度经营下,疏林地大径材出材率最大,密林则以小径材为主要径级材种。基于地面激光点云获取的单木参数可以直观地进行森林经理研究,对提升人工林的生产经营水平以及提高林业工作者的工作效率均有积极影响。

[Objective]Liriodendron tulipifera is an excellent timber species.It is of great significance to study the volume model of L.tulipifera wood and analyze the yield of merchantable timber under different densities for the efficient cultivation of L.tulipifera plantation.[Method]In this study,the terrestrial laser scan(TLS)data was obtained in the multi-density L.tulipifera plantation area in Jiangsu Province of eastern China.The single tree parameters(DBH,tree height H,volume V)were extracted for the various densities(2 m×2 m,3 m×3 m,4 m×4 m,5 m×5 m)of the L.tulipifera sample stand.The single entry volume model was conducted and the taper equation model was established.The timber yield of each density stand was calculated by the taper equation.[Result]The quadratic formula with one variable:was obtained as the single entry volume model for L.tulipifera wood in the study area.The model’s coefficient of determination(R^(2))was 0.884.After the test of residual standard deviation(S_(EE)),systematic error(T_(RE)),mean relative error(M_(SE)),precision estimation(ρ)and other indicators,there was no obvious systematic deviation,so the model can be used to estimate the volume of L.tulipifera in the study area.This study selected the improved Schumacher’s equations as taper equation for different afforestation densities,the model’s R^(2) was 0.924,root mean square error(RMSE)was 1.454,and MSE was 0.050,ρwas 0.910,etc.Furtherly,the taper equation was used to make multi-diameter grade wood in the multi-density afforestation forest sample plots.It was found that the output rate of large-diameter timber was the highest(39.582%)under 4 m×4 m density planting forest,the output rate of small-diameter timber was the highest(81.250%)under 2 m×2 m density planting forest,and the maximum composite yield was 4 m×4 m density planting forest(98.650%).[Conclusion]For L.tulipifera plantation under the multi-density management,the yield of large-diameter timber in the open forest is the largest,while the small-diameter wood is the main diameter class in the dense forest.The single tree parameters obtained based on the ground laser point cloud could be intuitively studied for the forest manager,which has a positive impact on the improvement of the production and management level of the plantation and the improvement of the work efficiency of the forestry workers.