Show simple item record

dc.contributor.authorKrajnc, Luka
dc.contributor.authorFarrelly, Niall
dc.contributor.authorHarte, Annette M.
dc.identifier.citationKrajnc, Luka, Farrelly, Niall, & Harte, Annette M. (2019). The influence of crown and stem characteristics on timber quality in softwoods. Forest Ecology and Management, 435, 8-17. doi:
dc.description.abstractThe relationships between several crown and tree properties and timber quality were examined on three softwood species: Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), Norway spruce (Picea abies (L.) H. Karst) and Sitka spruce (Picea sitchensis (Bong.) Carr). Crown and stem characteristics were collected on 487 standing trees, and their acoustic velocity measured using a stress-wave device. Of the trees measured, 60 were chosen for further testing, stratified by crown social class and cut into structural sized boards (N =1342). Each board was assessed with regard to knots using a grading X-ray machine, after which all boards were destructively tested in four-point bending and their mechanical properties (elastic modulus, bending strength and density) evaluated. To exclude the effect of branchiness across the crown social classes, mechanical properties were also examined on small clear samples cut from the undamaged section of the tested boards, a total of 1303 specimens were tested destructively in bending. Multi-level models based on Bayesian data analysis were used to evaluate the relationships between recorded characteristics, acoustic velocities and mechanical properties. Considerable differences in acoustic velocities were found between crown social classes, with suppressed trees having the highest velocities. This trend was also confirmed in mechanical properties of structural-sized boards and small clear specimens, suggesting that branchiness is not the primary cause of differences. Results indicate that slenderness affects both tree stiffness and the properties of sawn timber differently across the crown social classes. The relationship is negative in suppressed trees (increasing slenderness leads to a decrease in velocity or mechanical properties) and positive in dominant and co-dominant trees. The effect of crown projection area on either tree acoustic velocity or mechanical properties differs between social classes. In general, it was found to be positive, therefore an increase in crown projection area leads to an increase in either tree acoustic velocity or wood properties of timber. This trend is more evident in sawn timber than in acoustic velocities. The effects appear to be species dependant. No evidence was found of the effect of crown ratio, crown eccentricity or crown roundness on either the examined wood properties or acoustic velocities. Results confirm that there is a link between crown/stem development and timber quality. They indicate that in order to increase the overall quality of timber produced, the proportions of crown social classes in final stand composition should be adjusted with thinning.en_IE
dc.description.sponsorshipThe first author would like to gratefully acknowledge the support from a Teagasc Walsh Fellowship in the conduct of this work. The authors would like to thank Coillte and the Irish Forestry Unit Trust for enabling access to the forests and providing the testing material. The use of GoldenEye-702 machine was kindly provided by the Murray Timber Group while Martin Bacher from MiCROTEC helped with the scanning of the boards.en_IE
dc.relation.ispartofForest Ecology And Managementen
dc.subjectWood qualityen_IE
dc.subjectCrown propertiesen_IE
dc.titleThe influence of crown and stem characteristics on timber quality in softwoodsen_IE
dc.contributor.funderTeagasc Walsh Fellowshipen_IE
dc.contributor.funderIrish Forestry Unit Trusten_IE
dc.local.contactAnnette M. Harte, Dept. Of Civil Engineering, Civil Engineering Building, Nui Galway. 2732 Email:

Files in this item

Attribution-NonCommercial-NoDerivs 3.0 Ireland
This item is available under the Attribution-NonCommercial-NoDerivs 3.0 Ireland. No item may be reproduced for commercial purposes. Please refer to the publisher's URL where this is made available, or to notes contained in the item itself. Other terms may apply.

The following license files are associated with this item:


This item appears in the following Collection(s)

Show simple item record