This study focused on wood distortion of boards sawn from Norway spruce (Picea abies (L.) Karst.) trees grown in uneven-aged stands. The stands were multi-aged with tree ages up to 170 years. In total, 60 trees were harvested from six stands that had been managed by single-tree selection for decades. A butt log and a top log were sawn from each tree, both 2.5 m long. Wood deformations were measured from boards dried to an average moisture content of 7–10% from the 2.5 m long boards. A linear mixed model was constructed to describe the variation in twist deformations in the boards after drying. According to the model analysis, twist increased with greater grain angle, greater average annual ring width and relative ring width difference, greater knot size and count, and the interaction of grain angle with the vertical log position along the stem. Greater distance of the board from the pith was associated with lesser twist. Contrary to expectations, proportion of compression wood and tree position in the stand diameter distribution were not correlated with twist. Pin knots, although their occurrence and size was minimal, had a high degree of correlation with twist. The occurrence and severity of twist remained approximately at the same level as in even-aged Norway spruce as observed in other studies.

中文翻译：

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年龄不一的挪威云杉架的木板变形

这项研究的重点是用挪威云杉（Picea abies）锯切的木板的木材变形（L.）喀斯特地区。看台是多年龄的，树龄长达170年。几十年来，通过六个树木的选育，总共收获了60棵树木。从每棵树上锯出一个对接原木和一个顶原木，它们的长度均为2.5 m。从2.5 m长的木板干燥至平均水分含量为7–10％的木板上测量木材变形。构建了一个线性混合模型来描述干燥后板中扭曲变形的变化。根据模型分析，捻度随着籽粒角的增大，年轮平均宽度和相对环宽度差的增大，结节尺寸和数量的增大以及籽粒角与沿茎杆的垂直测井位置的相互作用而增大。木板与髓之间的距离越大，扭曲越小。与预期相反，林分直径分布中压缩木材的比例和树木的位置与扭曲无关。针结的出现和大小虽然很小，但与扭曲的相关性很高。如其他研究中所观察到的，扭曲的发生和严重程度与挪威云杉的平均水平大致保持相同水平。