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Compression wood in Scots pine and Norway spruce

distribution in relation to external geometry and the impact on dimensional stability in sawn wood

Warensjö, Mats (2003). Compression wood in Scots pine and Norway spruce. Diss. (sammanfattning/summary) Umeå : Sveriges lantbruksuniv., Acta Universitatis agriculturae Sueciae. Silvestria, 1401-6230 ; 298
ISBN 91-576-6532-X
[Doctoral thesis]

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Abstract

This thesis gives a summary and discussion of results from five studies concerned with: the distribution of compression wood in relation to external stem and log geometry and the impact of the compression wood distribution on deformations of sawn timber. Moreover the straightening process of trees is discussed. In order to study the distribution of compression wood in stems and logs, 63 trees of Norway spruce and Scots pine representing different age and curvature categories were sliced into 621 discs. In order to study the impact of compression wood on deformations of sawn timber, 146 logs of Scots pine and Norway spruce were processed into studs and battens. Before crosscutting, the external geometry of stems and logs were assessed. A 3D-logscanner was used for the assessment of logs. Deformations such as bow, spring and twist were measured on studs and battens at green condition, at 18% moisture content and at 12% moisture content. Compression wood content in thin cross sections of discs, studs and battens were analysed using transmitted light and image analysis. The analyses showed that a majority of all discs and cross sections contained compression wood. In all studies, the pith eccentricity was significantly correlated to the discs´ compression wood content. For the 6-year-old Scots pine trees, the compression wood content was significantly correlated to the size of basal sweep but not to out-of-roundness. For the 22-year-old Scots pine trees, the compression wood content was not correlated to either bow height or size of basal sweep. For the 60-year-old Norway spruce trees, the compression wood content was significantly correlated to compression wood content in log ends, pith eccentricity and bow height. For sawn timber, the compression wood content and its position was significantly correlated to bow and spring but not twist. Twist was significantly correlated to grain angle measured on tangential faces of studs and spiral grain angle measured under bark on the surface of logs. Results indicate that eccentric growth and compression wood formation play major roles in the development of stem straightness. Moreover, young trees with basal sweep will be straighter over time. Consequently, the straightness of a log is not a reliable measure of the compression wood content within the stem. By combining data describing external geometry with information regarding compression wood content and pith eccentricity obtained from log ends it is possible to detect logs that are prone to contain compression wood. The results also indicate that the distribution of compression wood in sawn timber influences the direction and size of bow and spring.

Authors/Creators:Warensjö, Mats
Title:Compression wood in Scots pine and Norway spruce
Subtitle:distribution in relation to external geometry and the impact on dimensional stability in sawn wood
Year of publishing :December 2003
Volume:298
Number of Pages:36
Papers/manuscripts:
NumberReferences
ALLI. Rune, G. & Warensjö, M. 2002. Basal sweep and compression wood in young Scots pine trees. Scandinavian Journal of Forest Research 17: 529-537. II. Warensjö, M. & Rune, G. Stem straightness and compression wood in a 22-year-old plantation of container-grown Scots pine. Accepted for publication in Silva Fennica. III. Warensjö, M., Nylinder, M. & Walter, F. 2002. Modelling compression wood in Norway spruce using data from a 3D-laser scanner. Conference article presented at the 4th IUFRO WP S5.01.04 Workshop, Harrison Hot Springs Resort, British Columbia, Canada, September 8-15. Submitted manuscript. IV. Warensjö, M. & Rune, G. The impact of compression wood and grain angle on deformations of studs from 22-year-old Scots pine trees. Submitted manuscript. V. Warensjö, M. The impact of compression wood on deformations of battens from Norway spruce sawlogs. Manuscript.
Place of Publication:Umeå
ISBN for printed version:91-576-6532-X
ISSN:1401-6230
Language:English
Publication Type:Doctoral thesis
Full Text Status:Public
Agris subject categories.:K Forestry > K50 Processing of forest products
Subjects:Not in use, please see Agris categories
Agrovoc terms:pinus sylvestris, picea abies, stems, reaction wood, sawnwood, wood production, wood defects, image analyasis
Keywords:Pinus sylvestris L., Picea abies (L.) Karst., stem form, reaction wood, sawn wood, deformations, instability, basal sweep
URN:NBN:urn:nbn:se:slu:epsilon-e-3520
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-3520
ID Code:415
Deposited By: Mats Warensjö
Deposited On:01 Dec 2003 00:00
Metadata Last Modified:22 Jun 2016 06:28

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