Modeling of radial variations of wood properties in naturally regenerated trees of Betula platyphylla grown in Selenge, Mongolia

Journal of Wood Science

Official Journal of the Japan Wood Research Society

Table 5 Estimations of wood properties of the core wood and outer wood using the best model for comparison between core wood and outer wood

Property	Core wood		Outer wood		t value (p value)
Property	Mean	SD	Mean	SD	t value (p value)
WFL (mm)	0.89	0.07	1.17	0.07	− 0.281 (< 0.001)
VEL (mm)	0.54	0.01	0.69	0.01	− 0.146 (< 0.001)
BD (g/cm³)	0.50	0.03	0.59	0.03	− 0.089 (< 0.001)
AD (g/cm³)	0.59	0.00	0.67	0.00	− 0.085 (< 0.001)
DMOE (GPa)	8.52	1.08	13.02	1.09	− 4.499 (< 0.001)
MOE (GPa)	5.65	1.35	9.70	2.51	− 4.049 (< 0.001)
MOR (MPa)	60.0	6.5	102.8	6.8	− 42.731 (< 0.001)
U (kJ/m²)	40.5	3.5	113.9	5.2	− 73.349 (< 0.001)
CS (MPa)	35.8	0.7	49.0	0.7	− 13.260 (< 0.001)
SS (MPa)	6.8	1.1	11.4	1.0	− 4.550 (< 0.001)

Number of trees = 10. WFL, wood fiber length; VEL, vessel element length; BD, basic density; AD, air-dry density after drying at around 22 °C and 65% relative humidity for 2 weeks (11.3 ± 0.5% of moisture content); DMOE, dynamic Young’s modulus; MOE, modulus of elasticity; MOR, modulus of rupture; U, absorbed energy in impact bending; CS, compressive strength parallel to grain; SS, shearing strength of small clear specimens. Wood properties were estimated from the first to 70th annual ring in each tree using the best developed model for the radial pattern (Model II, Tables 2 and 5). The means and standard deviations (SDs) of the core wood and outer wood were calculated from the first ring to boundary age (listed in Table 6) and from the boundary age to 70th annual ring, respectively. Significant differences between the core and outer wood were detected using a paired t test