Genetic variation of wood density in Luanta fir tested in central Taiwan

Forty-nine wind-pollinated families representing 8 provenances of Luanta fir (Cunninghamia konishii) were sampled from the species' range in Taiwan. The study plantation was established in central Taiwan with 49 ten-tree linear plots in each of 5 blocks in the randomized complete black design. In July 1998 at plantation age 25, a 0.45-cm caliber increment core sample was extracted at breast height in the east cardinal direction from the best tree per plot; altogether 245 cores (1 core/family/plot x 49 families x 5 blocks) were sampled. From each core, only the 6 outermost growth rings (near the bark) were used to determine extracted specific gravity according to the maximum moisture content method. Genetic variations among provenances and among families within provenances were tested following a general linear model. There was no apparent geographic variation pattern, and the main source of specific gravity variation was attributable to differences among families within provenance. Overall specific,gravity was 0.36 and the narrow-sense family heritability was 0.46. Wood specific gravity is strongly controlled by additive genetic variance, suggesting that this trait would respond to selection breeding. The importance of family selection was emphasized in the improvement of this wood property in Taiwan.