油松幼龄材材性兼论速生材改良与利用

CHARACTERISTICS OF JUVENILE WOOD IN STEMS OF CHINESE PINE AND WOOD QUALITY IMPROVEMENT AND USE OF FAST GROWN TREES

用山西中条山油松为试材,测定结果表明,株内幼龄材与成熟材的材性差异是,前者管胞长度短、胞壁薄,微纤丝角度大,年轮较宽,径弦向干缩系数小,树干基部基本密度稍大,浸提物含量高,但其力学性能差,顺纹抗压、顺纹抗拉、抗弯强度、抗弯弹性模分别比后者低13.7×10^(-2)、47.7×10^(-2)、11.4×10^(-2)和26.2×10^(-2),不易作承重弯曲构件。根据上述试验结果,讨论了通过林木育种、营林措施和确定合适的轮伐期等途径可以减少幼龄材的比例,改善其材质,以及改进传统的加工工艺,以合理利用速生材。

In this paper, the difference of properties between juvenile wood and mature wood at a given level (0.3, 1.3, 3.3, ..., 9.3m height) in stems of trees were comparatively studied. Shorter tracheid length, smaller tracheid diameter, thinner tracheid wall, wider growth ring, higher extractive content, flatter fibril angle of the S_2 layer in tracheid walls, and smaller coefficients of radial and tangential shrinkage are the characterics of the juvenile wood in pinus tabulaeformis. Compressive strength parallel to the grain, bending strength, modulus of elasticity in static bending and endwise tensile strength of juvenile wood are respectively lower (13.7×10^(-2), 14.2×10^(-2), 26.2×10^(-2), 47.7×10^(-2)) than those of mature wood in the stems of chinese pine.There are singnificant difference (0.05 level) between the properties of juvenile wood and those of mature wood. A problem needing attention about comparison between different fast grown trees and the properties of their products is the effect of the ring age. There is a large percentage of juvenile wood in fast grown merchantable trees. Its wood quality is improved by the ways of tree breeding, silvicultural practices, and proper, age of rotation. Another way of complete utilization of its wood is moditying traditional manufactring technigues.