LAUSR

There is increasing pressure to raise yields from intensively managed forests in order to improve profitability and to provide for future expected demand for wood products. Deployment of genetically improved tree stocks and control of tree spacing are two means by which forest managers can manipulate total yield, log properties and the economic value of forest stands. In this paper, we present the results from the end-of-rotation assessment of two long-term trials that were established in New Zealand to examine the performance of radiata pine (Pinus radiata D. Don) seedlots with different levels of genetic improvement when grown at a range of stand densities. We found that there were significant differences in total recoverable volume, total monetary value of the logs produced, stem form, branch size, wood density and acoustic velocity (a proxy for wood stiffness) among both seedlots and stand densities. Significant interactions between seedlot and stand density were not observed for any of the attributes of interest. Significant positive relationships were observed between Total Value ($ ha⁻¹) and a seedlot's trait ratings for diameter growth, stem straightness and branch cluster frequency. Together, these trait ratings along with stand density were able to explain 82 per cent of the variation in Total Value. Results indicate that large gains in volume production and total realized value appear possible in radiata pine stands through the appropriate combination of stand density and genetically improved tree stocks. Increases in value do not solely come from increases in volume production, but also from improvements in stem form and branch size which result in a higher proportion of more valuable log grades.