HERITABILITIES AND ADDITIVE GENETIC COEFFICIENTS OF VARIATION IN FOREST TREES

Estimates of individual-tree narrow-sense heritability and additive ge netic coefficient of variation of seven traits of forest trees were co mpiled from 67 published papers. Distributions of the values for each trait were characterized and compared by calculating medians and runni ng Kolmogorov-Smirnov and Wilcoxon signed-rank tests. Generalizations are possible about at least some of the traits examined. Heritability of wood specific gravity was almost always above 0.3 (median 0.48). He ritabilities for other traits tended to be low: medians ranged from 0. 185 to 0.26, and individual values generally ranged from 0.1 to 0.4. E vidence that heritabilities of form traits tend to be higher than thos e of growth traits was weak. The analysis of additive genetic coeffici ents of variation suggested that specific gravity tends to have lower values than other traits (median 5.1%), while height and diameter (med ians 8.5 and 8.6%, respectively) had lower values than straightness (m edian 11.65%). Individual-tree volume showed the highest levels of add itive genetic coefficient of variation (median 20.3%). The levels of a dditive genetic variation and heritabilities suggest that reasonable l evels of genetic gain can be achieved by screening relatively low numb ers of trees.