The ring characteristics of 95 year old Japanese cedar plantation trees grown in Taiwan were explored. Significant differences in the average ring width (RW), earlywood width, latewood width, ring density (RD), earlywood density, latewood density, highest density, lowest density, and latewood percentage were observed among three tree diameter classes and three radial stages of ring numbers. The RW parameters in the radial direction increased from the pith outward to the fifth ring number, and then decreased between about the 20th to 30th ring number. Finally, it was almost constantly sustained toward the bark side. The RD in the radial direction slowly decreased from the pith outward to the bark side. Wider tree rings and higher density are associated with juvenile wood close to the pith and narrower tree rings and lower density are typical for mature wood outward to the bark side. The RD in the intermediate tree was higher than in the dominant and overtopped trees; however, the RW in the intermediate tree was not narrower than in the dominant and overtopped trees. The RW did not correlate with the RD.
Key words: Japanese cedar (Cryptomeria japonica), plantation trees, ring characteristics.