Annual Fluctuation of Stress Wave Velocity and Young's Modulus of Standing Trees from 2 to 10 Years after Planting Clone Seedlings of Japanese Cedar (Cryptomeria japonica)

Regarding Japanese cedar plus tree mating family from Shizuoka prefecture

Abstract

Cuttings from Japanese cedar (Cryptomeria japonica D. Don) mating families, which were presumed to have high Young's modulus, were clonally propagated and planted. The stress wave propagation velocity (standing tree V_p) and annual fluctuations in growth characteristics were measured from 2 to 10 years after planting. In addition, the applicability of the evaluation method with V_p in early age was verified by comparing them with the Young's modulus of logs cut in the 6th to 10th years. The V_p of standing trees showed a difference among the lines due to the annual fluctuation from 2 to 10 years after planting the seedlings. The coefficient of determination was high even in the regression equation for each measurement year, and the difference among the lines continued to appear. Differences among the lines were also observed in the dynamic modulus of elasticity (E_fr) of logs cut down 6 to 10 years after planting the seedlings, and the coefficient of determination of linear regression between the standing tree V_p and the log E_fr of each line was also high. Therefore, V_p measurement was considered to be an effective method for non-destructively estimating Young's modulus. Furthermore, the regression equations of E_fr from the pith to the 5-year ring and from the 6-year ring to the outermost ring showed a high coefficient of determination. This suggested that clones with a high Young's modulus in the early stages would continue to form materials of similar qualities.