【目的】比较修枝和不修枝对杉木木材物理力学性质的影响,为杉木大径级无节柱材的培育提供科学依据。【方法】以 17 年生杉木人工林为研究对象,采用随机区组设计,设置修枝和不修枝试验处理,在修枝 20 年后采用平均标准木法选择修枝和不修枝杉木进行不同木材物理力学指标测定。【结果】17 年生中龄林杉木修枝 20 年后显著提高了木材的干形形率,修枝对杉木木材尖削度、高径比、全干密度、气干密度、体积干缩系数、干缩率、湿胀率等指标的影响不显著。修枝显著降低了杉木木材弦面硬度、径面硬度、抗压强度和抗拉强度,修枝杉木木材弦面硬度、径面硬度分别比不修枝降低 14.52%和 16.43%,杉木不同方向木材节子的硬度大小排序为端面硬度>弦面硬度>径面硬度,但修枝对杉木木材端面硬度、弹性模量等力学性能的影响不显著。【结论】修枝 20 年后对杉木人工林干形形率和木材力学性质有显著影响,但对尖削度和高径比的影响不显著。修枝显著降低杉木木材的弦面硬度、径面硬度、抗压强度和抗拉强度,但对杉木木材端面硬度、弹性模量等力学指标的影响不显著。修枝与不修枝杉木木材的各项物理力学性质指标均属甚小级至小级,修枝杉木木材的强度综合品质系数略低于不修枝杉木,但修枝并没有降低杉木木材的等级,修枝与不修枝杉木木材均属于低强度等级木材。

【Objective】This research aims to compare the effects of pruning and non-pruning on the physical and mechanical properties of Chinese fir (Cunninghamia lanceolata) wood and to provide a scientific basis for the cultivation of large-diameter, knot-free timber.【Method】A 17-year-old Chinese fir plantation was selected as the study site. A randomized block design was implemented with two treatments: pruning and non-pruning. Twenty years after pruning, the mean sample tree method was employed to select representative pruned and non-pruned trees for the measurement of various physical and mechanical properties of the wood.【Result】After 20 years of pruning in a 17-year-old mid-rotation stand, the form factor of Chinese fir wood was significantly increased. Pruning had no significant effect on stem taper, height-to-diameter ratio, oven-dry density, air-dry density, volumetric shrinkage coefficient, shrinkage rate, or swelling rate. However, pruning significantly reduced tangential hardness, radial hardness, compressive strength, and tensile strength. Specifically, the tangential and radial hardness of pruned wood were 14.52% and 16.43% lower, respectively, than those of non-pruned wood. The order of hardness across grain directions was: endwise > tangential > radial. No significant differences were observed in endwise hardness or modulus of elasticity between pruned and non-pruned wood.【Conclusion】After 20 years, pruning significantly influenced the form factor and certain mechanical properties of Chinese fir wood but did not significantly affect stem taper or height-to-diameter ratio. While tangential and radial hardness, compressive strength, and tensile strength were significantly reduced, endwise hardness and modulus of elasticity remained unaffected. Both pruned and non-pruned Chinese fir wood exhibited physical and mechanical properties within the “very low to low” range. The comprehensive strength quality coefficient of pruned wood was slightly lower than that of non-pruned wood; however, pruning did not alter its overall classification. Both types of wood were classified as low-strength timber.