Intracultivar variations in wood properties of Japanese cedar (Cryptomeria japonica) planted on sloping ground

Wood property variations were examined in sixty trees of a sugi cultivar (Obiaka cultivar) which were planted on two slopes, each of which was divided into two areas (A1, A2, B1 and B2). Tree growth in the upper area (131) with a steep slope was less than in other areas, i.e., tree heights were lower and stem diameters were smaller. Additionally, B1 area trees had lower heartwood percentages and greater dynamic moduli of elasticity of the logs, but there was no difference in sap-wood and heartwood moisture content, microfibril angle and tracheid length. It was assumed that logs from trees in the B1 area had larger dynamic moduli of elasticity because the curewood in the first eight rings from the pith had higher basic density resulting from high earlywood density and high latewood percentage. Since smaller diameter earlywood tracheids and rounded latewood tracheids were formed in the corewood of B1 area trees, it was assumed that xylem characteristic of compression wood was formed by leaning stems being restored to their original position. Tree growth and wood properties of B1 area trees were different from trees in other areas in the corewood within the first eight rings, but not in the outer part of the stem.