长白落叶松人工林心材变化规律

依据黑龙江省孟家岗林场49株人工落叶松1179个圆盘和轮盘数据,分析了心材半径的纵向变化规律.结果表明: 心材半径随树高增高而逐渐减小,与树干外形基本一致,其中去皮半径(XR)、胸径(DBH)及形成层年龄(CA)与心材半径之间关系较显著,利用逐步回归分析建立落叶松心材半径(HR)和面积(HA)模型:HR=b₁+b₂XR²+b₃CA+b₄XR, HA=b₁+b₂DBH·XR+b₃CA+b₄DBH·XR².应用AIC、BIC、对数似然值以及似然比检验等模型评价指标,对利用样地、样木效应拟合的心材半径和面积模型进行比较.当考虑样木效应拟合心材半径和面积模型时,将b₁、b₂、b₃作为混合参数得出的模型最好.混合模型的预测精度高于基本模型.在应用上,总体心材半径和面积可以通过混合模型来预测.采用Beta回归模型模拟了心材比例,模型中各参数均显著,决定系数较高,模型模拟效果较好.

Change pattern of heartwood of Larix olgensis plantation.

Based on the data of 1179 discs and whorls of 49 trees from larch (Larix olgensis) plantations located in Mengjiagang forest farm in Heilongjiang Province, China, we analyzed the longitudinal variation pattern of heartwood radius. The results showed that the heartwood radius decreased with the increases of tree height, which was basically the same as the trunk shape. The relationship between the xylem radius (XR), diameter at breast height (DBH) and cambial age (CA) with the heartwood radius was significant. The stepwise regression analysis was used to develop heartwood radius (HR) and heartwood area (HA) models: HR=b₁+b₂XR²+b₃CA+b₄XR, HA=b₁+b₂DBH·XR+b₃CA+b₄DBH·XR². We used the evaluation statistics such as AIC, BIC, Log Likelihood and Likelihood ratio test to compare the heartwood radius and heartwood area models which fitted with the plot effect and tree effect. The heartwood radius and heartwood area models with parameters b₁, b₂, b₃ as mixed effects performed best when the tree effect was considered. The prediction accuracy of the mixed model was better than that of the basic model. In the application, the total heartwood radius and area could be predicted by the mixed model. Beta regression model was used to simulate the heartwood proportion. In this model, all parameters were significant, and the coefficients of determination were relatively high, with a good simulation effect.