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    火炬松人工林胸高断面积差分模型的拟合与筛选

    Model selection and fit of algebraic difference models for basal area of loblolly pine plantations.

    • 摘要: 以148个样地的逐年观测数据为基础,建立了集约经营的火炬松人工林胸高断面积的Schumacher差分生长模型。与传统建模方法不同,本文首先拟合了胸高断面积的Schumacher收获模型,然后用代数差分法导出了相对应的差分生长模型。对随林分变化的参数的识别是以模型拟合结果为标准进行的,并得到了新的代数差分模型。方差结构模型和期望模型的拟合与筛选分别采用了约束型极大似然估计(REML)和极大似然估计(ML)。模型选择的拟合统计量为AIC、BIC和极大似然比检验(LRT)。结果表明,不同的经营措施对胸高断面积的影响不仅表现在回归模型的系数不同上,而且表现在回归模型的结构上。

       

      Abstract: On the basis of annual observations from 148 sample plots, we built Schumacher algebraic difference models for basal areas of loblolly pine (Pinus taeda) plantations under intensive management. Using a different modeling approach from the conventional, we first fitted basal area yield models, and then used the algebraic difference approach (ADA) to derive corresponding algebraic difference models. The method for identifying the standdependent coefficient is modelfitting based, and leads to new ADA basal area models. The restricted maximum likelihood estimation (REML) was used to estimate variance structure models, and the maximum likelihood to fit expectation models. AIC, BIC(Schwarz’s Bayesian Information Criterion), and log likelihood ratio test (LRT) are the model selection criteria/test. The results showed that basal areas under different management scenarios presented significantly different growth trajectories with respect to both model coefficients and model structures.

       

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