Comparison on the Physical and Mechanical Properties Between Clone and Seedling from Cunninghamia lanceolata

In order to reveal the differences in the physical and mechanical properties of wood from Cunninghamia lanceolata clones and seedling plantations, the main physical and mechanical properties of wood from 26-year-old C. lanceolata clones and seedling plantations at different circumferential orientations(north-south orientation) and different height positions were measured, and the wood strength and quality coefficients were investigated to comprehensively evaluate the material grades of wood from C. lanceolata clones and seedling plantations. The results showed that in addition to impact toughness, the density, shrinkage, difference shrinkage, swelling rate(all dry−air dry), hardness, flexural strength, flexural modulus of elasticity, compressive strength parallel to grain, and transverse compressive strength of C. lanceolata clones were higher than those of seedlings; the influence of circumferential orientation on the physical and mechanical strength of C. lanceolata clones and seedlings was not significant; tree height had a significant impact on the air dry density and water absorption of C. lanceolata clones wood, the basic density, air dry density, water absorption, transverse compressive strength, and hardness of seedling wood, while it had a significant impact on the basic density, total dry density, and volume moisture expansion of clone wood, the total dry density, and volume moisture expansion of seedling wood, and had no significant impact on other physical and mechanical strength of the 2 types of wood; the air dried density, end hardness, transverse compressive strength, and longitudinal compressive strength of the 2 types of wood showed a trend of first decreasing and then increasing with the increase of tree height; in addition to the shrinkage, the physical and mechanical properties of the 2 types of wood were in the low-grade of domestic wood; the comprehensive quality coefficient of the 2 types of C. lanceolata wood was relatively high, and they were both high-grade wood.