Loblolly pine is a major fibre source for the pulp and paper industry. Here we developed the first nonlinear models to predict the within-tree and regional variation of tracheid length and width for planted loblolly pine. Data were obtained from macerated tracheids and near-infrared spectroscopy calibration models from trees sampled in 109 stands across the southeastern United States. The fixed effects for the final tracheid length model, which included cambial age, height of disk within tree, and physiographic region, explained 71 percent of the variation with root mean square error (RMSE) of 0.28 mm, while the fixed effects for the final tracheid width model explained 57 percent of the variation with RMSE of 1.4 μm. There was significant variation in tracheid properties across the growing regions. Tree maps showing within-tree variability in tracheid properties were produced. Five simulated scenarios were compared using the models developed, with mean tracheid dimensions calculated on a whole-tree basis at a first and second thinnings, and at final harvest. Also from the final harvest, the tops of trees, and outerwood chips produced during lumber manufacturing were also simulated. For the whole tree scenarios, both mean tracheid length and width increased with age, increasing from 2.24 mm and 40.5 μm (age 12), to 2.51 mm and 41.3 μm (age 18), and to 2.73 and 41.8 μm at age 25, respectively. The tops of the trees at age 25 had a mean tracheid length of 2.46 mm and a mean width of 41.0 μm, while the chips had a mean tracheid length of 3.13 mm and a mean width of 42.5 μm. Due to the models representing samples collected from across the southeastern United States, and their relatively high precision, they are suitable for incorporation into growth and yield systems allowing for prediction of tracheid properties.

中文翻译：

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人工火炬松气管长度和宽度的树内和区域变化预测模型

火炬松是制浆和造纸工业的主要纤维来源。在这里，我们开发了第一个非线性模型来预测种植的火炬松的气管长度和宽度在树内和区域内的变化。数据是从美国东南部109个林分采样的树木中浸软的气管和近红外光谱校准模型获得的。最终气管长度模型的固定效应（包括冈比亚年龄，树内圆盘高度和地貌区域）解释了71％的变化，均方根误差（RMSE）为0.28 mm，而最终的固定效应管胞宽度模型解释了57％的变化，RMSE为1.4μm。在整个生长地区，气管特性有显着差异。生成显示树内气管特性变化的树图。使用开发的模型对五个模拟情景进行了比较，在第一次和第二次间伐以及最终收获时，以整棵树为基础计算了平均气管尺寸。同样从最终收获开始，还模拟了树木的顶部和木材制造过程中产生的外木屑。对于整棵树，平均气管长度和宽度均随年龄增长而增加，分别从2.24 mm和40.5μm（12岁）增加到2.51 mm和41.3μm（18岁），以及25岁时的2.73和41.8μm。 。25岁时树木的树顶平均气管长度为2.46毫米，平均宽度为41.0μm，而木片的平均气管长度为3.13毫米，平均宽度为42.5μm。