Potential Measures for Use in Developing Selection Procedures for High Timber Density in Juvenile Wood of Picea sitchensis

Abstract

Four clones of Picea sitchensis, each growing on two sites with contrasting growth rates, were examined for the rate at which wood density decreased as growth rate increased during successive years of juvenile wood formation. The clones with the greatest and least rates of change were consistent between contrasting sites. It was determined that the most effective measure of change in wood density was the relative rates of increase in wood volume and wood weight increment in successive annual increments. Wood volume increased more rapidly than wood weight for all clones but there were differences between them. The rankings for these relative rates of change were not (he same as those for mean density nor density of the last annual wood increment. Within a single annually produced sheath of wood, wood density was found to decrease with increasing distance down the main stem. In the outermost sheath, volume increment was at a maximum at least two and more usually three interwhorl positions. Dierences between...