Timber properties of species with potential for wider planting in Great Britain

Diversifying the range of tree species planted in Great Britain is an important goal in adapting to climate change and increasing the resilience of British forests. The wood properties and utilisation potential of less widely planted species are important considerations for forest managers but, for many species, there is limited relevant information available on their properties, especially for construction timber. This study examined the main physical and mechanical properties of eight species: European silver fir, Pacific silver fir, grand fir, Caucasian fir, Serbian spruce, Japanese red cedar, sycamore and silver birch. Sample material was obtained from a mixture of experimental trials, demonstration plots and normal forest stands in the age range 40–60 years. Measurements of wood density, bending stiffness and bending strength were made on structural-sized samples and indicative EN 338 strength classes were estimated. Theresults suggested that European silver fir, Pacific silver fir and Serbian spruce could all potentially be graded into the C16 strength class with a near 100% yield, while grand fir would be limited to the C14 strength class. Japanese red cedar fell below C14, limited by strength, density and stiffness. Caucasian fir was limited by strength to about C14. When silver birch and sycamore were graded against the softwood ‘C’ strength classes, they met the requirements of C40 and C20 respectively. Neither species, however, graded well in the hardwood ‘D’ strength classes. More testing is required for formal grading assignment, as these preliminary indications are based on sampling that is not fully representative of future scaled up commercial production.