© 1979 by Institute of Chartered Foresters
The Relationship Between Quality and Quantity in Spruce Timber Production Report of a Meeting of the Border Group of the Institute Held at Ayr, 8–9 December 1977
Forestry Commission, Dumfries
In northern England and southern Scotland 240,000 hectares or two-thirds of the productive woodland area are spruce, mainly Sitka spruce.
A continuing theme for the Border Group has been the relation between quality and quantity of timber production in spruce, particularly Sitka spruce. It is generally accepted that the aim for Sitka spruce should be to produce a good general purpose timber.
The most recent meeting discussed the results of a sawmill conversion of logs from Sitka spruce stands grown under different silvicultural regimes. Sitka spruce is intrinsically one of the lighter and weaker timbers and, to ensure that at least 80 per cent of the sawn timber is suitable for structural grades, crops should be grown within current standard silvicultural regimes with particular attention paid to the moulding of the first 6 to 8 metres of the stem which provides more than half the sawn timber.
The trees should be light-branched and have the highest possible timber density. Attention must be given from planting to the thicket stage and through to final felling to the production of crops grown uniformly within their yield classes. In the higher yield classes pruning up to 5 metres may be necessary on final crop trees to maintain the strength and grade of timber rather than to provide ‘clears’.
More information is required on the log sizes required for maximum sawmill recovery of chosen end products. A regional sales grading system of sawlogs should be introduced.