Breeding objective for plantation eucalypts grown for production of kraft pulp

Abstract

A long-term production function for unbleached eucalypt kraft pulp, incorporating all growing, harvesting, transport, and pulping costs, and variable capital and operating costs, was used to determine the economic importance of standing volume, basic density, pulp yield, and stem form. The value of each trait to breeding was defined as the relative improvement toward the objective (of minimizing total pulp cost) for a given selection intensity when selecting for each trait individually. For genetic parameters typical of eucalypts, and with the aid of simulated first-geneneration eucalypt populations, density and standing volume were the most important traits, providing the greatest savings in total pulp cost. Combined selection using density and volume provided 95% of the gains possible from an index involving all traits (density, volume, pulp yield, and form). Selection for pulp yield alone provided only 53% of the savings possible from selection for density, and improvement in stem form had negligible effect on total pulp cost.