Timber Improvement: I. A Study of the Variation in Wood Characteristics in Young Sitka spruce

As part of a programme aimed at improving Sitka spruce timber(Picea sitchensis (Bong.) Carr.), a study has been made of thevariation in some wood characteristics of significance in affectingtechnological behaviour, and the effect on these characteristicswhen trees of outstanding form and vigour are selected. It wasfound that:

1. There is a similar pattern of within-tree variationin density,tracheid length, and grain inclination for bothselected andaverage, final crop trees.
2. There is a very appreciablevariation in these timber characteristicsbetween trees at comparableages, indicating the potential forimprovement by selection.
3. There is a reduction in density and some increase in graininclinationbut no difference in tracheid length in vigorouscompared withaverage-growth trees at comparable ages.
4. Thereis no evidence that selection for above average densityhasan adverse effect on tracheid length; it tends to favourtreeshaving a high minimum early wood density and, to a limitedextent,wood with narrow cells.