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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.

2011

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Abstract

Some of the most common Norwegian wood species were tested in a Double layer test in South East Norway. After eight years of exposure the highest decay rating (≥3) was found in Scots pine sapwood, Norway spruce, alder, birch and aspen. Two wood types had decay rate ≤1: Scots pine heartwood and cedar. Wood moisture was logged and compared with precipitation during a two month period the second year of exposure. Scots pine sapwood had higher wood moisture content than Norway spruce, and a good correlation was found between precipitation and wood moisture content. When comparing similar materials exposed at three different geographical locations in Southern Norway, the samples exposed in Bergen had higher decay rating than samples exposed at Ås and Oslo.

Abstract

Moisture is often recognised as a key factor regarding the long time performance of wooden products, and one of the main challenges for timber products is to predict accurate service life in use class 3 (not covered above ground) and use class 4 (in soil or fresh water contact). A range of durability classification studies have been performed both in field and laboratory. But for several wood species information regarding the durability in use class 3 is lacking. Also, there is still a lack of studies comparing replicate wood products in different field exposure situations. This study evaluates the natural durability of different North European wood species in two different climates and in two different use classes. The wood species were compared with imported species and two preservative treatments. The overall picture shows a higher decay rating for wood species tested in ground contact compared with the results from the above ground “Double layer tests”. Moreover, the woods tested in Western Norway are more decayed than those tested in Eastern Norway. These findings can be explained by higher decay risk in use class 4 than in use class 3, and higher decay risk in a humid climate (Western Norway) than in a dry climate (Eastern Norway). The results indicate similar ranking of the durability of the wood species regardless of the environment they have been exposed to. The results from a linear regression show that MOE-loss of the mini-stakes after three years describes 70 % of the variation in decay rating of the “Double layer” stakes after six years exposure in Western Norway. This result strongly indicates that MOE-loss can be a prospective tool for rapid field testing of natural durability of wood.

Abstract

Fungi are the main degraders of organic matter and are associated symbiotically with over 80% of terrestrial plants (Smith and Read 1997). Thus, the extent of the mycelial network is an indicator of the decomposing or symbiotic activity. Although the importance of fungi in soil is undisputable, the determination of the extent of hyphal mats and the hyphal biomass is difficult to assess. Methods for estimating hyphae in soil are mostly based on the gridline intersect method originally developed to determine the root length or recently by measuring of the ergosterol content, fungal sterol found in the cell membranes....