Variation of wood properties in stems of Picea abies (L.) Karst

摘要

Norway spruce(picea abies) is used both for general construction and for joinery industry in Nordic countries. When used for indoor purposes, the wood is usually dried to a very low moisture content (< 6—8%). However, this may cause considerable shrinkage and it may result in warping, splitting and checking of boards. There should be avoided in uses where stability is important. In order to produce high quality spruce timber it is important to know the relationship between wood properties (e. g. density; reaction wood and knot size) and dimensional changes.rnLongitudinal shrinkage of wood is generally quite small. Average values for green to ovendry shrinkage are between 0.1 and 0.2 percent for most wood species. However, compression wood and juvenile wood tend to shrink excessively along the grain. Juvenile wood of Picea abies has shown a large longitudinal shrinkage and it increased with increasing height in stem(Saranpaa 1994).rnThe aim of this study was to investigate the variation of growth ring width, basic density, moisture content of sapwood and heartwood and the longitudinal shrinkage of Norway spruce grown in different stands and forest sites in Finland. In addition, thepurpose was to study how these properties change from pith to bark and with increasing height in the stem.rnA large range of stands were selected to study how silvicultural praxtise may effect the wood quality.