Fast-growing hybrid aspens (Populus tremula L. x P. tremuloides Michx.) are currently of great interest in Sweden since they can produce biomass at high rates and, at the same time, can be used to produce higher value wood products. This study focuses on the effects of pruning hybrid aspen to improve its wood quality. About 50% of the trees in the experimental stand were pruned by removing twigs, at heights up to 4?m, when they were 7–8 years old. Ten years later, 20 pruned and 20 unpruned trees, representing four clones, were randomly selected. Ten knots or twig/stem junctions, respectively, per tree were exposed for inspection using a chain saw and examined. The results revealed that pruned trees cicatrised the knots within about three years and thereafter produced substantial amounts of faultless wood. In contrast, unpruned trees (which had retained almost 80% of their twigs, often as dry twigs with bark pockets) had produced small uneven amounts of quality wood. Removal of twigs with acute angles and/or large diameters resulted in greater colour defects and rot in annual rings outside the pruning position, but the time of cicatrisation was not significantly affected. The results show that pruning can be used to enhance the wood quality of hybrid aspen over a short time period, and that pruning should be performed early during the rotation period when branches are small, in order to minimize discolouration and rot in the new annual rings.
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机译：快速生长的杂交白杨（Populus tremula L. x P. tremuloides Michx。）目前在瑞典备受关注，因为它们可以高生产率生产生物质，同时可以用于生产更高价值的木制品。这项研究的重点是修剪混合白杨木以改善其木材质量的效果。在实验林中，当树龄为7-8岁时，通过摘除树枝，修剪树枝，修剪树枝的高度不超过4？m，可修剪约50％的树木。十年后，随机选择了代表四个克隆的20棵修剪过的树木和20棵未修剪的树木。每棵树分别暴露十个结或树枝/茎干，以使用链锯进行检查并进行检查。结果表明，修剪后的树木在约三年内结疤，然后产生了大量的无瑕疵木材。相反，未修剪的树木（保留了近80％的树枝，通常是带有树皮口袋的干燥树枝）产生了少量不均匀的优质木材。去除具有锐角和/或大直径的树枝会导致更大的颜色缺陷，并在修剪位置以外的年轮中腐烂，但结ica时间不会受到明显影响。结果表明，修剪可用于在短时间内提高杂交白杨的木材质量，并且应在轮枝较小的轮换期间尽早进行修剪，以最大程度地减少新的年轮的变色和腐烂。 。
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