Properties of South West Timber
This research assessed the distribution and variation in structural quality of Douglas-fir stands within the South West of England. Assessing the quality of timber is complex as it is a subjective means for describing a resource. The project adopted a multi-disciplinary approach by examining the anatomical properties of wood, the influences that site and silvicultural practices employed by foresters have on these and how the two factors combined influence strength and stiffness, properties deemed important when utilising timber in an engineering context.
The PhD was completed in Spring 2012. In summary, it was found that the structural grades assigned by the British Standards for visual grading of Douglas Fir may be underestimating the mechanical properties of defect-free South West grown Douglas-fir which were found to be comparable to Douglas fir from eg Australia, New Zealand and the US. Across all samples the timber was found to be suitable for use in a wide range of structural applications (average C20 grade). It was further established that the age of timber was of far greater significance than rate of growth in determining mechanical properties such that mature wood greater than 40 years old had properties in excess of C24 structural grade. Whilst this study focussed on defect-free samples and the structural properties in individual trees, results suggested that further consideration needs to be given to structural sized sections containing defects, and to which silvicultural management practices are best suited to the production of timber with the fewest defects.
A summary of the PhD thesis can be found here: PhD summary