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首页> 外文期刊>Canadian Journal of Forest Research >Changes in root morphology after precommercial thinning in balsam fir stands
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Changes in root morphology after precommercial thinning in balsam fir stands

机译：凤仙花杉木幼林变稀后根系形态的变化。

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Precommercial thinning is often used to control stand density in naturally regenerated balsam fir (Abies balsamea (L.) Mill.) stands. Early stand density control could have beneficial effects on longer term stand stability through a modification of stem shape and root development. To assess the effect of precommercial thinning, two thinned and two unthinned stands were selected. Root sections were collected at 25 cm from the centre of the stem for all major roots (diameter greater than 2 cm). A disk was also cut at breast height level. From these disks, response in radial growth was determined. Detailed root measurements were taken on the sample disks to assess treatment effect on the following variables: asymmetry in root cross-sectional area (CSA) distribution, individual root shape, as well as changes in root shape over time. A quick and pronounced response in root growth occurred. This response was greater than that observed in the trunk. No asymmetry in root CSA distribution was observed at the stand level. Trees allocated more to radial growth above the biological centre of the root both in treated and control stands, but this trend was increased by thinning. Roots also tended to develop T-beam shapes over time, both in control and thinned stands. Most roots initially did not possess an I-beam shape and did not develop one during the course of the study. According to our results, trees respond quickly to the new growing conditions created by thinning by increasing biomass allocation to parts of the roots where mechanical stresses are greater.
机译：在自然再生的苦瓜冷杉（Abies balsamea（L.）Mill。）林分中，通常使用商业前稀疏来控制林分密度。通过改变茎的形状和根系发育，早期的林分密度控制可能会对长期林分稳定性产生有益的影响。为了评估商业稀疏的效果，选择了两个稀疏林和两个未稀疏林分。对于所有主要根（直径大于2 cm），在距茎中心25 cm处收集根切片。在乳房的高度也切了一个圆盘。从这些盘，确定了径向生长的响应。在样品盘上进行了详细的根部测量，以评估处理对以下变量的影响：根部横截面积（CSA）分布不对称，单个根部形状以及根部形状随时间的变化。发生了根部生长的快速而明显的反应。该响应大于在树干中观察到的响应。在林分水平上未观察到根部CSA分布的不对称性。在经处理​​和对照林分中，树木更多地分配给了根生物中心上方的径向生长，但这种趋势由于变薄而增加。在控制林和稀疏林中，根部也倾向于随着时间的推移而形成T型梁形状。最初，大多数根不具有工字梁形状，并且在研究过程中没有发育。根据我们的结果，树木通过增加生物量分配给机械应力较大的根部部分而对稀疏所产生的新生长条件做出快速反应。

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