Quality of Douglas fir wood

Background and Objective

The expected climate change defintely affects silvicultural management systems. In this context, Douglas fir is regarded as a tree species with high future potential, especially because of its higher drought resistance as compared with spruce. However, wood quality parameters of about 50 years old Douglas fir trees grown in the south of Germany have to be related to different growth conditions (narrow/broad tree rings) for a future optimization of silvicultural aspects.

Approach

Douglas fir trees of same age but with varying stem diameters (fast or slow growing trees) will be analyzed by various microscopic techniques. Additionally technological analyses are performed to determine their properties.

Data and Methods

Macroscopic and microscopic analyses, durability tests, and technological analyses.

Results

Growth speed, branch development, and proportions of juvenile and adult wood are the most important factors affecting the wood quality parameters of Douglas-fir. Young-growth wood of Douglas-fir from the south of Germany displays only slightly lower quality as compared to old-growth wood from North America. In comparison to other European softwoods, Douglas-fir grown in Europe produces high-grade timber which at minimum equals but mostly exceeds the values of timber from e.g. Norway spruce. Furthermore, the project revealed a slightly reduced natural durability of young-growth Douglas-fir wood from Europe. These findings appear not to be caused by differing environmental growth conditions but seem to rest mostly with the notably younger age of trees harvested in Europe and the silvicultural regimes applied to affect the trees’ growth speed.