A NEW TECHNIQUE FOR THE DEMARCATION BETWEEN JUVENILE AND MATURE WOOD IN CRYPTOMERIA-JAPONICA

Three average, healthy Cryptomeria trees were felled in fall 1990 from a 40-year-old plantation located in central Taiwan. The plantation wa s established with 1-year-old cuttings at a 2 x 2 m spacing. A 5 cm th ick circular-shaped disk specimen was removed from each sample tree at breast height, then a 2 cm wide wood strip cut along the south-north aspect of each disk specimen. The wood strip was separated further int o individual growth increments in odd-numbered growth rings numbered 1 (near pith) to 33 (near bark) and forty latewood tracheids per growth ring were measured. Their mean lengths were used as items in an analy sis of variance on each of eight sets of data. An analysis of variance was conducted on each of 8 sets of tracheid data generated by varying the number of growth rings from 13 to 5 in the working sample. The ag e of transition from juvenile to mature wood was set at a point where the variance component due to the effect of ring position reached zero percent. We determined the location of the transaction from juvenile wood to mature wood to be at the 23rd growth ring based on latewood tr acheid length.