Radiata : an economic breeding objective : the definition of an economic breeding objective for plantation radiata pine grown to produce timber flitch and newsprint and an investigation of some aspects related to short-rotation breeding in general using plantation eucalypts as an example

An economic breeding objective was defined for unpruned radiata pine grown to produce structural grade timber flitch and high brightness newsprint from thermomechanical pulp (TMP) in Australia. A production enterprise model was developed including all sources of income (sale of flitch and newsprint) and costs (including growing, harvesting, transporting and mill processing components). The enterprise, as modelled, was shown to be profitable (Profitability Index 19.9%, assuming a discount rate of 5%). The majority of wood volume was assumed to be utilised to produce high brightness newsprint (77% by volume), with only 23% used to produce rough green flitch. The effect of future changes in growth, bark volume, stem sweep, stem taper, branch quality, timber strength, basic density, tracheid length, tracheid coarseness and wood brightness (breeding objective traits) on the profitability of this production enterprise was modelled by defining profit functions relating each of these traits to the economics of each stage of production. Sensitivity analysis was employed throughout this process to examine which assumptions were driving profitability, and identify any that may need verification. For each trait an economic weight was estimated as the incremental Profitability Index associated with a unit increa, se in each trait. Basic density, mean tracheid length and wood brightness were demonstrated as having a major effect on the production of high brightness newsprint from TMP. Growth, as expected, had a large impact on the cost of growing a plantation, however was predicted to be only of moderate to low importance in increasing enterprise profitbability overall. Branch index was shown to have a major impact on the profitability of the flitch production line of the enterprise. Bark volume, stem sweep, stem taper and tracheid coarseness appeared to have a very low impact on production system profitability. However, the importance of stem sweep and stem taper as well as branch index and timber strength are likely to become more important if the enterprise increases its production ratio of flitch to newsprint. An investigation into multi-trait selection strategies clearly demonstrated the dominance of basic density as a selection trait on enterprise profitability. The assessment of wood and tracheid properties is much more costly than assessment of growth and form traits. However it was demonstrated that the gains predicted from individual-tree selections compared with selection based on family-means for basic density and tracheid length are significant and well worth the additional associated cost.