Methods for preventing fungal decay of wood in wet conditions
Coordinator: Lisbeth Garbrecht Thygesen, UCPH, lgt(a)ign.ku.dk
There is a need for better utilisation of wood from Nordic forests to allow forested areas to be set aside for biodiversity, conservation, carbon sequestration and other purposes. One way to utilise wood better is to make it last longer. This challenge is addressed in a new research project financed primarily by FORMAS and SNS.
Impregnation with biocides efficiently prolongs the service life of wood but this method is being phased out due to the environmental biohazards implied. Chemical wood modification is an alternative impregnation method, which makes wood more durable without the biocidal component. Instead, unharmful molecules are added to the wood cell walls, which nevertheless prevents or delays fungal degradation of the wood cell wall biopolymers. It is unknown exactly which mechanisms are behind this, but exclusion of moisture is known to play an important role.
Currently known wood modification methods become less efficient under continuous exposure to very wet conditions such as outdoors in direct contact with wet soil. How fungi can degrade modified wood in such environments is unknown. Understanding this better will help us design more durable modifications, as these extreme conditions highlight the mechanisms at play, such as the access routes of the fungi into the wood cell walls.
Our overall hypothesis is that blocking transport between the wood cell wall and the fungal hyphae are key to preventing decay, and that this transport becomes possible also in modified wood when enough moisture is present. We will test this hypothesis by designing specific wood modifications that block different parts of the transport route, and studying how the decay progresses at the micrometre level when the modified wood is very wet, i.e. at conditions close to water saturation.
Lund University has years of experience with exposing wood to accurately controlled wet conditions, and with input from the Norwegian Institute for Bioecenomy Research, a unique setup is being developed for the project for investigating how fungal degradation of modified wood occurs in such environments. Wood samples for these experiments are chemically modified in a collaboration between Lund University and the University of Copenhagen. The latter is also in charge of characterising the modified wood by use of micro-spectroscopy both before and after degradation. Naturally durable heartwood is studied for comparison.
Participants
• Lund University (LU)
• Norwegian Institute for Bioecenomy Research (NIBIO)
• University of Copenhagen (UCPH)