Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2012
Sammendrag
Wood for outdoor decking has a high market share in the Nordic and Baltic countries among private house owners. Important issues for the consumer are maintenance intervals and aesthetic appearance as well as decay resistance. Knowledge and consumer information about these aspects are required to ensure that wood can compete with alternative decking materials. In this paper an accelerated testing of decking, “stapelbädds metoden”, was evaluated after ten years of exposure at Ås, Norway. The test method covers different hazard situations within use class 3. Different preservatives and wood modification treatments were used in addition to untreated Scots pine (sapwood and heartwood) and larch (heartwood). The samples were treated with two different surface treatments. In addition there was one set without any surface treatment. Fungal discoloration and decay was evaluated. This provided new information about performance both on and above ground for a range of different combinations of preservative/modified systems and surface treatments of wood in decking for outdoor use. Generally, there were no significant differences in performance between the surface treatments, both with regard to surface discolouring fungi and decay fungi. For all surface treatments, the samples with rating 3 (heavy attack) in bottom layer in one or several stacks was: Tanalith M, Tanalith M (c), Gori Pres 10, Scanimp, styren, furfurylation, thermal modification, Ultrawood, larch heartwood, pine heartwood and pine sapwood. For all surface treatments, the samples with mean rating ≤ 2 (evident attack) in top and middle layer in one or several stacks was: ACQ 1900, Wolmanit CX 8, Tanalith E7, Gori SC 100, Royal, Royal with pigment, Scanimp, styrene and larch heartwood
Sammendrag
Genomic sequencing gives us a tool to systematically and rapidly discover novel genes, how their products function in the cell, and explore their interactions. When the DNA sequences are known, primers can be designed to detect transcripts of genes with gene products related to basic cellular processes and hyphal growth. The characteristic gene products induced in different fungi by different wood protection systems during decay can be identified. This knowledge will give us a better understanding of the fungal degradation of wood and we can optimize wood protection systems. Hence, no single technique will give us the answer to all questions about the decay of wood we need to gather small pieces of the puzzle using different approaches. The aim of the present study was to investigate the effects of acetylation level on the growth of Postia placenta with regard to amount of total DNA and gene expression targeting six different genes. This paper presents preliminary results after 36 weeks of incubation. We found no mass loss in the acetylated samples treated to a high treatment level after 36 weeks of incubation in a modified monoculture soil-block test. The presence of P. placenta DNA and the absence of mass loss could indicate on an inability of the mycelia to establish a wood exploitation phase. The results also showed that P. placenta increased the expression of AlO (involved in production of H2O2), cytochrome P450 (related to breakdown of toxic compounds), and QRD (involved in generating biodegradative hydroxyl radicals via redox cycling) along the incubation time, growing on acetylated wood treated to a high treatment level.
Sammendrag
From the range of information published, acetylation appears well suited to provide adequate protection against biological attack for materials derived from typically non-durable wood species. Acetylated wood is now commercially available both in Europe and in the USA. But still there are a lot of unanswered questions related to fungal decay mechanisms in acetylated wood.The paper summarize existing knowledge and highlight future research opportunities related to fungal deterioration of acetic anhydride modified wood. In addition statistical analyses based on previously published data were performed to quantify what factors contribute most to the performance (calculated as test sample/control).The results showed that WPG can explain approximately 50 % of the performance, measured as test sample/control (T/C), for acetic anhydride treated wood. Other of the applied variables, like wood species or type of fungus can reduce the variance in T/C by additional 15 %.
Sammendrag
A proposal for a web-based platform for scientific exchange of test data in the field of wood durability and wood protection has been made. The overall aim of the durability data base is to improve the usability of existing test data and to create an added value for durability research and service life prediction. The database allows for test results from standardized and non-standardized laboratory and field tests. Natural durable timber, preservative and water-repellent treated timber, chemically and thermally modified timber as well as composites have been considered. Finally all types of decay organisms and other degrading agents are regarded.
Sammendrag
During the last decade wood modification has become a recognized method for delivery of enhanced timber. Hence, a range of studies have been performed to evaluate the decay resistance of modified wood. High resistance of modified wood against fungal decay is assumed to be due to changes in the wood properties rather than a toxic effect on fungal physiology. This is an advantage due to the concern from the European Union, national movements and society in general about the environmental impact of wood protection is increasing. In this paper we aimed to quantitatively summarise the performance of the different types of modified wood. However, this turned out only to be possible for acetylation. This was due to the format of the published data, variation in treatment processes and wood species used for the other treatments. For acetylated wood statistical analyses based on previously published data were performed to quantify what factors contribute most to the performance (calculated as test sample/control). The results showed that WPG can explain approximately 50 % of the performance, measured as test sample/control (T/C), for acetic anhydride treated wood. Other of the applied variables, like wood species or type of fungus can reduce the variance in T/C by additional 15 %. In addition, the paper highlight future research opportunities related to fungal deterioration of modified wood.
Sammendrag
The use of wood in outdoor constructions has long traditions in Norway. In the last decade, the environmentally demands for wood protective systems has become stricter. At the same time, new design solutions are arising that will challenge the decay protection in outdoor constructions. In this article, the potential for antioxidants as a wood protective agent was tested. Both natural and synthetic antioxidants have been used. All samples achieved a sufficient uptake of impregnation agent, and all the tested products showed a reduction in wood decay rate compared to the control. The protections by the antioxidants are more effective against brown rot fungi, than white rot fungi. The synthetic antioxidants stop the fungal degradation of the brown rot fungi, and should be considered as an additive in future and existing wood protective systems.
Forfattere
Andreas TreuSammendrag
Improving wood preservation techniques can contribute substantially to reducing waste and avoiding negative environmental impacts. Dr Andreas Treu outlines a promising technique to dramatically reduce or even stop wood degradation altogether by using electro-osmosis. International Innovation is the leading global dissemination resource for the wider scientific, technology and research communities, dedicated to disseminating the latest science, research and technological innovations on a global level. More information and a complimentary subscription offer to the publication can be found at: www.researchmedia.eu
Forfattere
Janka DibdiakovaSammendrag
An increasing demand for forest biomass to energy is leading to a more intensive harvesting of timber, also including an exploitation of the crown biomass. This sets new demands for forest inventory systems to generate more detailed information about the forest biomass fractions. Norway has unutilized forest resources, which can be used for bioenergy. These also include Norway spruce (Picea abies (L.) Karst.). The material was sampled from three different locations in Southern Norway from west to east. Each location was represented with tree different site indices. Vertical profiles of branch weight, length and diameter were studied. The effect of different tree and site characteristics were used to predict the profiles. Significant differences were found between the geographical locations studied after adjusting for tree height and diameter in breast height. Branches from the western site were longer and had a greater mass compared to branches from the other two locations. The branch diameter distribution indicated that the east location had larger branch size, while branches in middle and west site had smaller sizes. This study highlights the range of branch variability within locations, but indicates that Norway spruce branch biomass in Norway may be considered as a valuable raw material.
Sammendrag
The extractives responsible for the natural durability of western redcedar (WRC) are not well understood. Recent work by the Norwegian Institute of Wood Technology and the Norwegian Forest and Landscape Institute has evaluated the natural durability of Norwegian wood species and reference species, including Norwegian-grown WRC and North American-grown WRC, in a series of decay tests. The availability of retained samples from these tests presented an excellent opportunity to compare the extractives contents of North American and Norwegian grown-WRC, and to correlate field test decay data and extractives content. The North American-grown WRC contained much greater concentrations of extractives than the Norwegian-grown WRC evaluated in this test. However, despite these differences, performance in the EN 252 stake test in Sørkedalen was only marginally better for North American-grown WRC. Both sets of samples were comparatively low in an as yet uncharacterized compound previously associated with decay resistance. However, there were not enough data to thoroughly examine the correlations between extractives and durability data in this material.
Forfattere
Christian Brischke Linda Meyer Gry Alfredsen Miha Humar Lesley Francis Per Otto Flæte Pia Larsson-BrelidSammendrag
The material-inherent resistance of wood is one of the most important qualities influencing the durability of timber. Hence, it has also a major effect on the service life to be expected from a timber construction. In addition, design details and the respective climatic conditions determine durability and make it impossible to treat wood durability as an absolute value. Moreover, the reference magnitude varies between locations because of climatic differences. Durability classification is therefore based on comparing a certain performance indicator between the timber in question and a reference timber. Finally, the relative values (= resistance factors) are grouped and related to durability classes, which can refer to a high range of service lives for a certain location. The insufficient comparability of such durability records turned out to be a key problem for the service life prediction of timber structures, even when the climatic conditions are clearly defined. This study aimed therefore on an inventory of literature data, directly based on service life measures, not masked by a durability classification schedule. It focused on natural durability of timber tested in the field under above-ground conditions. In total 395 durability recordings from 31 different test sites worldwide and based on ten different test methods have been considered for the calculation of resistance factors: 190 for hardwoods and 205 for softwoods. Nevertheless, the considered datasets were heterogeneous in quality and quantity; the resulting resistance factors suffered from high variation. In many cases information was presented too condensed and incompletely, which is inescapable for instance in journal articles. To increase the amount of available, comparable, and directly service-life related data a reliable platform is needed. A proposal for a corresponding data base is provided in part 2 of this paper.