A NON-DESTRUCTIVE FIELD MEASUREMENT OF STEM MOE FOR EVALUATING WOOD QUALITY IN STANDING TIMBER

本文介绍了一种能测定立木树干弯曲弹性系数的野外仪器及其在日本落叶松人工林中的应用。弯矩是通过施加在连接到杆上的杠杆臂上的重物来产生的。结果表明：1.落叶松木材弹性模量在10年生至20年生期间显著增加，此后逐渐趋于稳定。2.树干的弹性模量与实验室对样木原木的测试结果吻合较好。3.13个落叶松林分136株树干的MOE值在60~150t/cm~2之间。4.林内生长速度对MOE值的影响不大。各林分MOE的变异系数约为12%。5.同一地区落叶松林分的平均MOE存在差异，这可能是由于当地的环境条件，如坡度暴露所致。6.在52株优树无性系林分上进行的试验表明，落叶松无性系在木材质量上没有明显的优势，而无性系间的差异较小。本研究提出的方法可用于活木木材质量的评价、间伐间伐树种的选择和/或从木材质量的角度选择优树。

This invesigation deals with a field instrument capable of determining the bending modulus of elasticity (MOE) in the stem of standing trees and the application of the instrument to some plantation grown Japanese larch stands.The MOE calculation is based upon the deflection of the stem. The bending moment is generated by a weight applied on a lever-arm attached to the stem. The deflection is detected by the middle-ordinate gage placed on the convex side of the bent stem.Results are summarized as: 1. The increase of MOE in larch trees was remarkable from 10 to 20 years of age, and thereafter it gradually became stable. 2.The MOE of the stems agreed well with laborarory tests on logs obtained from sample trees. 3. The MOE values of 136 stems at 13 larch stands were in the range of 60-150 t/cm^2. 4. The effect on MOE values by growth rate was little within a stand. The coefficient of variation for MOE in each stand was about 12%. 5. Differences of average MOEs between larch stands in the same area were found, which may have been due to local environmental condition such as slope exposure. 6. A test in a larch clone stand derived from 52 plus-trees did not show any superiority in MOE to the above mentioned larch stands, while the inter-clone deviation was little.The method proposed in this study may be utilized for the assessment of wood quality in live trees, the selection of trees for thinning cut and/or the selection of plus-trees from the wood quality viewpoint.