Influence of Norway Spruce and European Larch Heartwood Ring-Width on Extractive Content and Durability

Miha Humar

doi:10.5552/drind.2013.1244

Abstract

Norway spruce and European larch wood are among the most important species for construction applications in central Europe. In order to assess the infl uence of the ring-widths and presence of the extractives on the performance of these wood species against wood decays fungi, Soxlet extracted and non-extracted spruce and larch wood specimens with different ring-widths were exposed to three brown rot fungi according to the EN 113 procedure. In parallel spruce and larch wood specimens were exposed in fi eld test sites in use class 3 conditions according to the double layer procedure. The results showed that ring-widths do not infl uence the performance of the spruce and larch heartwood against brown rot fungi in laboratory conditions, but on the other hand have infl uence on the performance of spruce wood in fi eld test setup. Additionally, extraction does not have an infl uence on the durability of spruce wood, but has an infl uence on the durability of larch wood.

Highlights

In order to assess the influence of the ring-widths and presence of the extractives on the performance of these wood species against wood decays fungi, Soxlet extracted and non-extracted spruce and larch wood specimens with different ring-widths were exposed to three brown rot fungi according to the EN 113 procedure
The results showed that ring-widths do not influence the performance of the spruce and larch heartwood against brown rot fungi in laboratory conditions, but on the other hand have influence on the performance of spruce wood in field test setup
Laboratory tests were performed on larch and spruce wood specimens, while field tests were only performed on selected spruce and larch wood specimens

Summary

Introduction

Norway spruce and Larch are among the most important central European wood species and they are frequently used for construction applications. Larch, especially European larch, has traditionally held a good reputation in the Alps as a source of building material. This reputation is based upon its excellent mechanical properties combined with its good natural durability out of soil contact (Collardet and Besset, 1988; Flæte et al, 2011). The apparent natural durability and longevity qualities of larch wood do not seem to be expressed in the same way outside its distribution within the Alps (Curnel et al, 2008). Some of the authors reported, that durable larch wood can be found even in the lowland plantations in Eastern Europe (Curnel et al, 2008)

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