EFFECT OF STEM BENDING ON HYDRAULIC CONDUCTIVITY AND WOOD STRENGTH OF LOBLOLLY-PINE
EFFECT OF STEM BENDING ON HYDRAULIC CONDUCTIVITY AND WOOD STRENGTH OF LOBLOLLY-PINE
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DOI：
10.1139/x94-060
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发表时间：
1994-03-01
影响因子：
2.2
通讯作者：
WILLIAMS, SA
中科院分区：
文献类型：
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作者：
FREDERICKSEN, TS;HEDDEN, RL;WILLIAMS, SA
以30年生火炬松（Pinus taeda L.）用绞盘弯曲树木，以确定弯曲的影响，这可能会发生严重的风应力，对导水率和木材强度的树干。股骨柄弯曲至股骨柄即将失效的程度，然后释放。释放后，股骨柄从其原始垂直位置平均倾斜6.25度。边材渗透性和可行的传导面积的测量进行了弯曲的树木切干切片，并与未受应力（对照）的树木采取的部分进行了比较。使用染料来确定功能性导电元件的百分比。弯曲处理导致导电边材面积平均损失约30%。功能传导面积的损失沿弯曲轴沿着大于垂直于弯曲方向的股骨柄侧面。股骨柄压缩侧的损坏最严重。尽管有这种损伤，但由于处理，边材渗透性没有观察到差异。与对照股骨柄相比，弯曲股骨柄压缩侧的弹性模量和断裂模量分别降低了19%和34%。火炬松似乎是能够维持显着损害其水传导系统，而不损害其水力传导性。然而，由于弯曲而导致的木材强度降低可能会导致对风折的敏感性增加和（或）商业价值降低。
Stems of 30-year-old loblolly pine (Pinus taeda L.) trees were bent with a winch to determine the effect of bending, which might occur from severe wind stress, on the hydraulic conductivity and wood strength of tree stems. Stems were bent to a point of imminent stem failure and then released. After release, stems leaned an average of 6.25-degrees from their original vertical position. Measurements of sapwood permeability and viable conducting area were made on stem sections cut from bent trees and were compared with sections taken from unstressed (control) trees. Dye was used to determine the percentage of functional conducting elements. An average loss of approximately 30% in conducting sapwood area was attributed to the bending treatment. Loss of functional conducting area was greater along the axis of bending than on the lateral sides of the stem perpendicular to the direction of bending. Damage was greatest on the compression side of the stem. Despite this damage, no difference was observed in sapwood permeability due to treatment. Modulus of elasticity and modulus of rupture were reduced by 19% and 34%, respectively, on the compression side of bent stems compared with control stems. Loblolly pine appears to be capable of sustaining significant damage to its water conducting system without compromising its hydraulic conductivity. However, reduced wood strength due to bending may result in increased susceptibility to wind breakage and (or) decreased commercial value.