Abstract
An optimum allocation of selection weight on the traits that were related to carbon storage in the stem of sugi was investigated to establish criteria for choosing plus tree clones suitable for carbon storage. The traits examined in this study were tree height, diameter at breast height (DBH), basic density, and carbon content per unit weight. In the case of single trait selection, the selection for tree height would bring about a good amount of gain in both tree height and DBH due to strong genetic correlation. Relative gain in carbon content, though the heritability was high, was negligibly small due to its very low coefficient of variation. Selection for basic density would bring about comparable genetic gain, while it resulted in negative responses in growth traits. An optimum allocation of selection weight for tree height and basic density in selection index was examined by changing their economic weight step by step so as to maximize the expected carbon storage potential of the selected population under the standard selection intensity: selection for the top 38% clones. The carbon storage potential was found to be maximized when the index was I=2.8×(Tree height)+18.87×(Basic density) where the increase in the selected population was 21.4% greater than the population mean. Clones with high index value tended to put more weight on tree height than on basic density.
