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Commissioned Reports - Modelling


Date: 2007
Title: Modelling spiral angle in Sitka spruce
Authors: Mavrou Ioanna
Full Report: University of York, Masters Thesis

Summary
The aim of this study was to develop a model which would predict accurately enough the degree of spirality of Sitka spruce plantations without the necessity of them being felled. The model constructed included as variables the grain angle and the annual rings taking into account variability between trees and height in trees.


Date: 2007
Title: Linking batten performance to silvicultural models (232396)
Authors: Report commissioned from BRE
Full Report: PDF

Summary
This project facilitates collaboration between BRE and Forest Research on the development of combined batten performance and silvicultural models, and to apply and validate recent research findings by both organisations in particular from the EU compression wood project and DTI PII project on timber scanning.

BRE and Forest Research share a common knowledge base for Sitka spruce that has the potential to be applied to both silviculture and industrial sorting.  Recent project work at BRE has built on data gathered during the EU compression wood project.  The main bulk of the practical work has comprised the testing and assessment of 500 Sitka spruce battens obtained from four forest stands.  In collaboration with Forest Research, ninety logs were characterised with variables such as top and bottom diameter, whorl spacing and under-bark slope of grain being recorded.  The logs were scanned by a 3D laser scanner prior to being converted.  Log shape variables such as sweep, ovality and taper were obtained from the scanner data. Pith eccentricity and ovality was manually measured from log disc images produced by FR.  The battens were machine stress graded and then conditioned to in-service levels of moisture content. Measurements were taken of distortion, knot size and position, knot area ratio, compression wood content, rate of growth, density, position relative to pith and slope of grain. Other work involved testing of small clear samples spruce, together precise measurement of radial, tangential, and longitudinal shrinkage during drying.  A database of around 100 machine grader rejects was also compiled, with the battens being re-graded to obtain detailed machine stiffness values.

Future need for both better industrial sorting and silvicultural practice is clear:  harmonisation of European structural timber codes and standards will increase competition, at the same time a greater supply of Sitka spruce of varying quality will be available for harvest.  Through understanding of the interrelationships of the timber variables and batten performance characteristics, based on the BRE/FR combined datasets and models, timber sorting and silvicultural practices can be evaluated and the knowledge applied to make best use of this material.


Date: 2006
Title: Predicting the Branching Properties of Sitka Spruce Grown in Great Britain
Authors: Alexis Achim
Full Report: PDF


Date: 2006
Title: Wood density determination in Picea sitchensis using computerised tomography
Authors: Aaron James Taylor
Full Report: PDF


Date: 2004
Title: Models for the timber quality assessment of the actual forest resource: Methodology for Sitka Spruce
Authors: Dr Jean-Michel Leban
Full Report: PDF


Date: 2002
Title: Refinement of the CESTRA wood modelling system for correlating wood and tree growth characteristics (PPD51, CV6580)
Authors: Report commissioned from BRE
Full Report: Awaiting electronic version

Summary
This report concerns work for the Forestry Commission under FC Contract FPD22 and follows on from the work carried out on Sitka spruce (BRE report number 80323) to establish the effects of specific methods of measuring the Modulus of Elasticity (MoE) on results for Scots pine. This research was chosen to widen the investigation of Global-E on Sitka spruce and Scots pine as the two species have differing growth habits and characteristics. In particular the distribution of growth characteristics such as knots may have a bearing on the measured stiffness using either of the methods.

It was discovered that there was some disparity in results between the Sitka spruce and Scots pine in relation to the most critical relationship, converting Global – E values into E-Cen values. There was some comparability over the mid-range of stiffness values, but towards both extremes of the range comparability was poor.

This suggests that a single equation to convert Global –E to E-Cen values for all timber species used for structural use within the European Union is unreliable as it may lead to inappropriate MoE values being attributed to certain species of timber.


Date: 1998
Title: Modelling Wood Characterstics
Authors: Report commissioned from BRE
Full Report: Awaiting electronic version



Date:
Unknown
Title: Towards a timber quality model for sitka spruce in Britain
Authors: Barry Gardiner et al
Full Report: PDF