栽培措施对短周期工业材材性影响规律的研究

Regularities of Cultivation Measures Affecting the Properties of Short-cycled Industrial Wood

对4种不同栽培措施的日本落叶松、湿地松、马尾松和杉木等多种短周期工业材309株样木的材性进行了全面测试分析研究，结果表明．立地指数大，木材生长率和纤维宽度大．但纤维长度、纤维长宽比、木材基本密度、顺纹抗压强度和抗弯弹性模量减小；立地指数相差两级，木材的年龄宽度、纤维宽度、长度和微纤线角度的差异达到显著或极显著水平栽植密度小，木材的年轮宽度和干缩比增大但纤维长宽比及体积全干缩率减小；栽植密度增大，杉木和昭林6号杨木材的力学强度提高，但尾叶桉和I－69杨降低；不同栽植密度的木材pH值及酸碱总缓冲容量，都是心材大于边材，但木材的脲醛树脂胶凝速度，则是边材快于心材.与未间伐林分的木材比较，随着间伐强度的增大、年轮宽度增大．但纤维长宽比和微纤丝角度减小；间伐强度增大，针叶树村的力学强度降低，阔叶树树则提高．但将强度间伐材（间代40％）与未间伐材比较，结果完全相反；北京杨木材心材的pH值、酸碱缓冲容量及总容量，均随间伐强度的增大而增大，但边材却减小．施肥措施能够增大纤维直径，但将导致纤维长宽比、木材密度和力学强度的降低施肥可以使树木速生，但会降低木材密度和质量，在培育建筑结构材的林分应慎用．

Wood properties of 309 sample trees from 58 plots were analyzed and determined. The wood species studied in this article are Larix Kaempferi(Lamb. ) Cars., Pinus elliottii Engelm., Pinus massoniana Lamb., Pinus taeda L., Cunninghamia lanceolata (Lamb. ) Hook., Eucalyptus urophylla S. T. Elake, I-69 Poplar, Populus pikinics, Populus chifeng 36, Populus tomentosa Cars. and Populus zhaolin 6. Results show that site indexes exert influences their on growth rate and fiber width and negative on fiber length,the ratio of fiber length to width, basic density of wood, compressive strength parallel to the grain and modulus of elasticity. When the site index difference between plots go beyond two grades, yearly increment width, fiber width,fiber length and fibril angles are remarkably different. Wood buffering capacity to acid and alkali is negatively related to the PH value of forest soil, and the urea-formaldehyde resin gelation time of wood powder is positively related to the PH value of soil and wood; and accordingly it is better to site the forest for plywood industry on a soil with high acidity. As the planting density decreases,width of growth ring and the shrinkage ratio(T/R) increases, but the ratio of fiber length to width and the total volume shrinkage decreases. The effect of planting density on mechanical strength can be positive (as for Cunninghamia lanceolata and Populus Zhaolin 6)or negative (as for Eucalyptus urophylla and 1-69 poplar). In all the studied plots with different planting densities, the PH value and buffering capacity to acid and alkali of heartwoods are always larger than those of sapwoods, and the urea-formaldehyde resin gelation time of sapwood powder is shorter than that of heartwood powder. Thinning intensity influences growth ring width positively, and fibril angles and the ratio of fiber length to width negatively. As to mechanical strength, thinning intensity has a negative influence on coniferous woods (Larix kaempferi and Cunninghamia lanceolata) and a positive influence on hardwoods (Populus pikinica), but the result would go conversely if thinning intensity 'went beyond 40%. In all the plots of Populue pikinica,with an increase of thinning intensity, the PH value and buffering capacity of heartwood will increase, and those of sapwood will decrease, because heartwood of poplar wood usually has a high PH value and a large buffering capacity to acid j poplar plywood tends to have a weak glueline. Fertilization also shows an influence positive on fiber width and negative on wood density, mechanical strength and the ratio of fiber length to width. Fiber diameter has a positive correlation with growth rate, and a negative correlation with wood density. Although fertilization treatment can enhance tree growth, it will make the wood have a low density and a low mechanical strength. Therefore, the forest of pulpwood can be treated with suitable fertilizers to improve fiber production,but to forest of structural timber fertilization treatment should be controlled.