Dynamic modulus of elasticity and bending properties of large beams of Taiwan-grown Japanese cedar from different plantation spacing sites

The effect of plantation spacings (types A-E) on the bending strength and d ynamic modulus of elasticity of 41-year-old Taiwan-grown cedar (Cryptomeria japonica D. Don) was investigated. The results indicate that the highest v alues for the static bending modulus of elasticity (MOE. modulus of rupture (MOR), and dynamic modulus of elasticity (E-D/ E-Dt) occurred in trees obt ained from those most densely planted (type A); there was a significant dif ference between type A and the other four spacing types (B, C, D, and E), b ut there were no significant differences among those four types. Interrelat ions among MOEI MOR, E-D/, and E-Dt could be represented by positive linear regression formulas, which revealed highly significant differences. The re lations among the square value of stress-wave transmission velocity (V-/(2) and V-t(2)) and MOE, MOR, E-D/ and E-Dt, respectively, could be represente d by positive linear regression formulas. The differences were highly signi ficant.