Norway spruce, as a commercial forest tree, faces many problems these days, whether it is large-scale bark beetle outbreak, long-lasting drought, or often-mentioned climate change. Foresters are therefore trying to find an alternative species that would be able to replace spruce in terms of production, but also with the properties of the wood. Promising candidates include domestic species, for example European silver fir, but also introduced trees. A team of scientists from our Faculty also focused on one of the non-native species, specifically grand fir.
Grand fir is a North American conifer. The area of natural distribution is in the northwest of the USA and the west of Canada. It is a fast-growing tree with wide annual rings. For this reason, its wood is generally considered to be of lower quality. With the exception of these wide annual rings, the wood of grand fir is similar in colour to the wood of our native silver fir; structurally, it is also very similar to spruce. It is relatively light, similar to our native species, and it is also not very resistant to the action of biotic agents. Therefore, its wood is generally used for construction purposes and pulp and paper production.
In order to find out how similar the quality of the wood is to local species, scientists from the Faculty of Forestry and Wood Sciences of the Czech University of Life Sciences in Prague subjected wood samples to many tests focused on selected material properties. The series of tests were focused on mechanical properties, mainly bending strength, compressive strength, toughness, and flexural modulus. Important physical properties such as wood density, wood swelling, and surface properties were also evaluated. These tests were further applied to investigate the properties of wood modified by heat at 180 °C and 200 °C. The above-mentioned tests proved that the wood of grand fir is similar in quality to silver fir and Norway spruce. Therefore, it is a potential substitute for native species and its wood can be used for similar purposes. Thermal modification resulted in improved compressive strength, and reduced moisture content and wood swelling. However, it negatively affected other mechanical properties of wood, namely its bending strength and toughness, and there was also a decrease in density.
Edited by: Oldřich Vojtěch
Zeidler A, Borůvka V, Remeš J, Pulkrab K. Heat-Treated Wood from Grand Fir Provides the Same Quality Compared to Silver Fir. Forests. 2022; 13(10):1542. https://doi.org/10.3390/f13101542