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    王涛, 董利虎, 李凤日. 基于混合效应的杂种落叶松人工幼龄林单木枯损模型[J]. 北京林业大学学报, 2018, 40(10): 1-10. DOI: 10.13332/j.1000-1522.20170437
    引用本文: 王涛, 董利虎, 李凤日. 基于混合效应的杂种落叶松人工幼龄林单木枯损模型[J]. 北京林业大学学报, 2018, 40(10): 1-10. DOI: 10.13332/j.1000-1522.20170437
    Wang Tao, Dong Lihu, Li Fengri. Individual tree mortality model for hybrid larch young plantations based on mixed effects[J]. Journal of Beijing Forestry University, 2018, 40(10): 1-10. DOI: 10.13332/j.1000-1522.20170437
    Citation: Wang Tao, Dong Lihu, Li Fengri. Individual tree mortality model for hybrid larch young plantations based on mixed effects[J]. Journal of Beijing Forestry University, 2018, 40(10): 1-10. DOI: 10.13332/j.1000-1522.20170437

    基于混合效应的杂种落叶松人工幼龄林单木枯损模型

    Individual tree mortality model for hybrid larch young plantations based on mixed effects

    • 摘要:
      目的利用固定间隔期复测数据,运用不同方法建立杂种落叶松人工幼龄林单木枯损模型,为确定杂种落叶松合理的经营措施和推广应用提供依据。
      方法基于2003—2015年黑龙江省江山娇实验林场48块样地的复测数据,通过Logistic模型,利用全子集法和最大似然估计构建杂种落叶松单木枯损模型。使用列联表分析和分类率-阈值散点图,确定枯损模型预估时的最佳阈值。引入随机参数,构建样地水平广义线性混合模型。模型估计方法为自适应积分最大似然估计,模型筛选指标为Akaike信息标准(AIC)、贝叶斯信息标准(BIC)以及-2倍对数似然值。通过计算绝对平均偏差(Bias),绘制ROC曲线以及模型预估枯损率与实际枯损率直方图对两种模型的预测结果进行评价比较。
      结果包含单木(林木胸径,DBH;胸径平方,DBH2)、林分(林分断面积,BA)、竞争(大于对象木树木断面积之和变形,BALD)3个水平变量组合的单木枯损模型拟合效果最佳。杂种落叶松枯损主要发生在小径阶且相对竞争较大时。单木枯损概率随DBH增加逐渐减小,随BALD、BA增加而逐渐增加。最佳阈值有效提高了模型预估效果,方差-协方差结构为无结构矩阵(UN)时,四参数混合模型的拟合结果最佳,其预估的林分枯损率更接近实际林分枯损率。
      结论混合模型能够更有效地描述和预估杂种落叶松的单木枯损。阈值分析是提高二分类模型预测准确性的有效方法。杂种落叶松作为速生树种,幼龄时期应适时进行抚育间伐以减少枯损发生的概率。

       

      Abstract:
      ObjectiveTo study the individual tree mortality of hybrid larch young plantations, using fixed intervals re-measured data and different methods to establish hybrid larch (Larix kaempferi × Larix olgensis) individual tree mortality model, this paper aims to provide the basis for the determination of sustainable management and promotion of hybrid larch.
      MethodBased on the re-measured data of the 48 permanent sample plots from 2003 to 2015 in Jiangshanjiao Experimental Forest Farm in Heilongjiang Province of northeastern China, the Logistic model was used to predict the probability of individual tree mortality by the method of all sub-set and maximum likelihood estimation. Contingency table analysis, scatter plot of classification rate and threshold were used to determine the best threshold when the model estimated. Adding random parameter at plot level aims to make the mixed model with maximum likelihood estimation based on adaptive quadrature. Selected criteria of models were Akaike information criterion (AIC), Bayesian information criterion (BIC) and negative double of logarithmic likelihood ratio. The model test criteria was the absolute average deviation (Bias). The ROC curve and histogram was used for prediction of mortality rate of the models and actual mortality rate was drawn to examine the performance of model.
      ResultThe results showed that the best fitting result appeared when the model contained the combination of individual level (DBH, DBH2), stand level (stand basal area, BA) and competition level (deformation of basal area of the trees greater than the subject tree, BALD). The mortality of the hybrid larch occurred when the DBH class was small, and competition was more intensive. The probability of individual mortality decreased with the increase of DBH, and increased with the increase of BALD and BA.The optimal threshold improved the prediction effect of the model. When the unstructured matrix was the variance-covariance structure, four random parameters of the mixed model had the best fitting result. The prediction of mortality rate of mixed model was closer to the actual mortality rate.
      ConclusionMixed model is more effective to describe individual tree mortality for hybrid larch. Threshold analysis is an effective method to improve the prediction accuracy of the dichotomous model. Hybrid larch is fast-growing species and thinning treatment should be appropriately implemented to reduce the probability of tree mortality in young forests.

       

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