Two American tree species have been identified as being suitable for the production of cross-laminated timber
Deforestation is one of the largest contributing factors to global climate change, and a huge emphasis has been placed on the importance of sustainable timber production. Only a small proportion of known tree species are considered to be of value for large-scale lumber production, and the intensive harvesting of these species (in combination with land clearance for agriculture) is driving a large net decrease in global forest area. Many trees species that are valued for their wood are slow-growing in nature, and the demand for timber far outweighs the speed with which they can reproduce.
Identifying other species that are of potential value for timber production therefore has the potential to reduce the pressure on trees that are normally targeted for their wood. Additionally, many modern construction materials such as concrete have high carbon footprints, and more sustainable alternatives are in high demand.
A recent paper published in the Journal of Materials in Civil Engineering by researchers from the University of Massachusetts has identified two species of tree grown in the north-eastern US as being suitable for the production of cross-laminated timber, which is a panel product made from composite layers of wood. The trees – eastern hemlock and eastern white pine – were harvested and used to create 17 panels, which were then subjected to extensive strength testing and analysis to assess whether they satisfied the baseline structural performance requirements of the industry standards.
The researchers found that the panels produced using both species met building standards, although eastern hemlock was recorded to outperform eastern white pine. Eastern hemlock is typically considered to be a ‘low value’ tree, as it is under widespread attack throughout its native range by the hemlock woolly adelgid and is susceptible to a wood defect known as ring shake. Salvaging wood from these trees is therefore a key forest management priority, as the adelgid infestation causes it to die and eventually fall, increasing the risk of forest fires.
These trees therefore present an opportunity to produce large amounts of sustainable, industry-standard construction materials with a reduced carbon footprint that can be used for walls, roofs and flooring. The researchers explain that these trees could support local cross-laminated timber manufacturers, boosting economies and creating jobs as well as directly influencing forestry management.
The article is available on the ASCE Library website: Kaboli, H., Clouston, P. & Lawrence, S. (2020) Feasibility of Two Northeastern Species in Three-Layer ANSI-Approved Cross-Laminated Timber. Journal of Materials in Civil Engineering, Vol. 32 Issue. 3. DOI: https://ascelibrary.org/doi/abs/10.1061/%28ASCE%29MT.1943-5533.0003058
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