Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2022
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Abstract
The genus Pinus represents more than a hundred different tree species, most of them forming stems that can be commercially utilised for both timber and wood pulp industry. Pines are native to most of the Northern Hemisphere, while introduced and often naturalized in the Southern Hemisphere. The sapwood of pines is considered ‘not durable’ but generally easy to impregnate. On the contrary, the coloured heartwood of pines is difficult to impregnate and considered ‘less to moderately durable’ against decay fungi, but due to varying content and composition of extractives, both moisture performance and inherent durability vary within and between species. This study reviewed the literature to quantify the extent of variability of pine wood and its potential causes. Literature data from durability tests performed under laboratory and field conditions made it possible to compile reference factors for 26 pine species. The inter-species variation of biological durability is more prominent in above-ground exposure (0.7–14.9 times higher compared to the non-durable pine sapwood) compared to soil contact scenarios (1.0–2.4). The latter might be explained by fungicidal and hydrophobic extractives of pines, which play a more dominant role in above-ground exposure compared to soil exposure with permanent wetting.
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Authors
Gry AlfredsenAbstract
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Given the right climatic and environmental conditions, a range of microorganisms can deteriorate wood. Decay by basidiomycete fungi accounts for significant volumes of wood in service that need to be replaced. In this study, a short-wave infrared hyperspectral camera was used to explore the possibilities of using spectral imaging technology for the fast and non-destructive detection of fungal decay. The study encompassed different degradation stages of Scots pine sapwood (Pinus sylvestris L.) specimens inoculated with monocultures of either a brown rot fungus (Rhodonia placenta Fr.) or a white rot fungus (Trametes versicolor L.). The research questions were if the hyperspectral camera can profile fungal wood decay and whether it also can differentiate between decay mechanisms of brown rot and white rot decay. The data analysis employed Partial Least Squares (PLS) regression with the mass loss percentage as the response variable. For all models, the mass loss could be predicted from the wavelength range 1460–1600 nm, confirming the reduction in cellulose. A single PLS component could describe the mass loss to a high degree (90%). The distinction between decay by brown or white rot fungi was made based on spectral peaks around 1680 and 2240 nm, related to lignin.
Authors
Gry Alfredsen Christian Brischke Richard Acquah Tolgay Akkurt Per Otto Flæte Eva Frühwald Hansson Geir Wæhler Gustavsen Hasan Hosseini Targo Kalamees Jaan Kers Villu Kukk Roja Modaresi Jonas Niklewski Anna Sandak Sandak Jakub Philip van NiekerkAbstract
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Authors
Nina Elisabeth Nagy Hans Ragnar Norli Monica Fongen Runa Berg Østby Inger Heldal Jahn Davik Ari HietalaAbstract
Tree defense against xylem pathogens involves both constitutive and induced phenylpropanoids and terpenoids. The induced defenses include compartmentalization of compromised wood with a reaction zone (RZ) characterized by polyphenol deposition, whereas the role of terpenoids has remained poorly understood. To further elucidate the tree–pathogen interaction, we profiled spatial patterns in lignan (low-molecular-weight polyphenols) and terpenoid content in Norway spruce (Picea abies) trees showing heartwood colonization by the pathogenic white-rot fungus Heterobasidion parviporum. There was pronounced variation in the amount and composition of lignans between different xylem tissue zones of diseased and healthy trees. Intact RZ at basal stem regions, where colonization is the oldest, showed the highest level and diversity of these compounds. The antioxidant properties of lignans obviously hinder oxidative degradation of wood: RZ with lignans removed by extraction showed significantly higher mass loss than unextracted RZ when subjected to Fenton degradation. The reduced diversity and amount of lignans in pathogen-compromised RZ and decaying heartwood in comparison to intact RZ and healthy heartwood suggest that α-conindendrin isomer is an intermediate metabolite in lignan decomposition by H. parviporum. Diterpenes and diterpene alcohols constituted above 90% of the terpenes detected in sapwood of healthy and diseased trees. A significant finding was that traumatic resin canals, predominated by monoterpenes, were commonly associated with RZ. The findings clarify the roles and fate of lignan during wood decay and raise questions about the potential roles of terpenoids in signal transduction, synthesis, and translocation of defense compounds upon wood compartmentalization against decay fungi.
Abstract
No abstract has been registered