Huang Y S, Chen S S, Lin T P, Chen Y S
Division of Forest Utilization, Taiwan Forestry Research Institute, Taipei.
Tree Physiol. 2001 Mar;21(4):261-6. doi: 10.1093/treephys/21.4.261.
The distribution of growth stresses in leaning trunks of Cryptomeria japonica (L.f.) D. Don was determined by measuring the stresses released by the kerf method with strain gauges glued at specified positions along the trunks. Effects of both tree height and peripheral positions on the surface of leaning trunks on surface growth stress were determined. The inner residual growth strains in leaning trunks were also measured. We found high compression stresses in the lower side of leaning trunks that differed greatly from the tensile stresses in normal erect trunks. However, transverse compression stress was found around the tree trunk in both normal and compression wood. In leaning trees, the distribution of internal stresses in the bent trunk portion differed from that in the erect trunk portion, being compressive on the outside and tensile on the inside. The resistant moment introduced by compression stress generated in compression wood is released by the bending of the leaning trunk. The bending stresses are then superimposed on the original internal growth stress. We demonstrated that Poisson's effect of longitudinal stresses should be considered when evaluating transverse surface growth stresses. The existence and intensity of compression wood development can be assessed by growth stress measurements. We conclude that the compressing force of compression wood functions physiologically to give an upward righting response in a leaning trunk.
通过使用粘贴在树干特定位置的应变片测量切口法释放的应力，确定了日本柳杉倾斜树干中生长应力的分布。研究了树高和倾斜树干表面周边位置对表面生长应力的影响。还测量了倾斜树干内部的残余生长应变。我们发现倾斜树干下部存在高压缩应力，这与正常直立树干中的拉应力有很大差异。然而，在正常木材和压缩木材中，树干周围均发现了横向压缩应力。在倾斜树木中，弯曲树干部分的内应力分布与直立树干部分不同，外侧为压缩应力，内侧为拉应力。压缩木材中产生的压缩应力所引入的抵抗力矩通过倾斜树干的弯曲而释放。然后，弯曲应力叠加在原始的内部生长应力上。我们证明，在评估横向表面生长应力时，应考虑纵向应力的泊松效应。通过生长应力测量可以评估压缩木材发育的存在和强度。我们得出结论，压缩木材的压缩力在生理上起作用，使倾斜树干产生向上的扶正反应。
