摘要
基于黑龙江省林口林业局林场和东京城林业局林场29块标准地中49株人工红松1207个节子数据,使用图片处理软件Digimizer对节子纵剖面图片数据进行提取,将节子形状用一个二维散点图表示。根据节子二维形状散点图,把人工红松节子分为3种类型:活节(整个节子为健全节)、未包藏死节(节子由健全节和疏松节组成)和包藏死节(节子的健全节和疏松节部分被树干包藏)。3个类型节子的健全节体积通过对健全节形状参数方程求积得到;疏松节体积利用圆柱体的体积计算得到;节子总体积等于健全节体积与疏松节体积之和。最后,基于节子变量(节子直径、节子相对高、节子总长度)和树木变量(胸径),采用样地和树木水平的线性混合模型建立了红松人工林健全节体积、疏松节体积和节子总体积的预测模型。与基础模型相比,考虑样地和树木水平的混合效应所建立的健全节体积、疏松节体积和节子总体积预测模型,其参数估计更精准,残差分布更均匀,拟合精度明显提高。检验结果表明,基础模型预估精度均在90%以上,引入样地和树木效应的混合模型的预估精度均在93%以上,说明所建模型可以很好地预测红松人工林节子体积大小。
Based on 1207 knots from 49 sample trees of 29 standard plots of Korean pine plantations in Linkou and Dongjingcheng Forest Bureau of Heilongjiang Province,China,we extracted longitudinal sections of knots using the image processing software Digimizer and represented the shape of knots using two-dimensional scatter plots.According to the two-dimensional scatter plots,knots of Korean pine plantation were divided into three types:1)alive knots(whole knot contained only sound knot portion);2)non-occluded dead knots(whole knot contained both sound and loose knot portions);3)occluded dead knots(the sound and loose portion of the knot were partially occluded by the bark).For all the three types of knots,the volume of sound knot was calculated by mathematical integral of the sound knot shape equation.The volume of loose knot was calculated using the volume equation of a cylinder.The total volume of knots was calculated as the sum of sound and loose knot volume.Finally,based on knot variables(diameter,relative height and total length of knots)and tree variable(diameter at breast height),we established the prediction models for sound knot volume,loose knot volume,and total volume of knot using the linear mixed model at plot level and tree level.Compared with fixed-effects model,the mixed effects models of the volume of sound knot,loose knot,and total knots provided more accurate parameter estimation,more uniform residual distribution,and higher model fitting precision.The validation results showed that prediction precision of each fixed-effect model was higher than 90%,while that of the mixed models with plot and tree effect was above 93%,indicating that the established model could well predict the volume of knot for Korean pine plantation.
作者
贾炜玮
洪燕虎
李凤日
JIA Wei-wei;HONG Yan-hu;LI Feng-ri(School of Forestry,Northeast Forestry University/Key Laboratory of Sustainable Forest Ecosystem Management of the Ministry of Education,Harbin 150040,China)
出处
《应用生态学报》
CAS
CSCD
北大核心
2020年第9期2943-2954,共12页
Chinese Journal of Applied Ecology
基金
国家自然科学基金项目(31870622)
中央高校基本科研业务费专项资金项目(2572019CP08)资助。
关键词
红松
健全节体积
疏松节体积
节子总体积
线性混合模型
Korean pine
sound knot volume
loose knot volume
knot total volume
linear mixed model
