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.
2008
Sammendrag
This paper reports the results from a study of modulus of elasticity (MOE) and modulus of rupture (MOR) of 42 small clear specimens prepared from 300 year old roundwood floor girders containing high levels of NaCl at Bryggen in Bergen, Norway. NaCl concentration was 6.5 % of the dry matter of the wood. MOE and MOR were 25 % lower than the values obtained from a reference material with equivalent annual ring width and density. The considerable reduction of MOE and MOR should be taken into consideration in conservation of load-bearing wooden structures that have been exposed to NaCl.
Sammendrag
Harmonization was achieved by carrying out joint sampling and assessment exercises at selected sites, inter-laboratory ring tests for the chemical analyses of deposition, plant and soil material, and by drawing up data compilation, data analysis and reporting guidelines and templates for the researchers working in the three countries.
Sammendrag
Insect-induced damages in forests are a major concern for timber production, landscape conservation and ecosystem research. Early detection methods based on remote sensing data can document the severity and spatial extent of ongoing attacks and might aid in designing mitigation measures or even prevention where necessary. In southeastern Norway, a large-scale insect defoliation of pine trees is ongoing. The larvae of the Pine sawfly Neodiprion sertifer reate it with its mass attacks during their feeding on needles in June and July. In the winter before the attack, egg galleries are evident in the needles. This provides a test case for early detection methods and remote sensing techniques for monitoring forest health....
Sammendrag
In Norway exterior wood structures have traditionally nearly exclusively been made of treated and untreated Picea abies and Pinus sylvestris. In recent years there has been a tendency that other tree species, like various domestic hardwoods and imported species have been used in exterior above ground applications, often unfinished. For several wood species, especially hardwoods, information regarding the durability in use class 3 is lacking. The main objective of this paper is to evaluate natural durability of Norwegian wood species for above ground applications comparing two non-standard above ground tests with the European standard tests for soil contact (EN 252) and lab performance against basidiomycetes (EN 113). The European standard tests EN 113 and EN 252 gave quite similar results, and they also corresponded well with the natural durability classification in EN 350-2. The two non-standard above ground tests differed to some extend from EN 113, EN 252 and EN 350-2. The results indicate that natural durability classification for one single wood species can change depending on use class. However, the field trials need a longer period of time before a final classification can be performed. Four species not included in EN 350-2 were classified in this study: Juniperus communis (1), Salix caprea (5), Sorbus aucuparia (5) and Populus tremula (5).
Sammendrag
Wood for outdoor decking has a high marked 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, “stapelbäddsmetoden”, was evaluated after six years of exposure at Ås, Norway, and compared with earlier reported results after three years. Twelve 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. In this method for accelerated testing, discolouration 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. For example, no clear differences were found between the surface treatments and no surface treatment. The wood modifications with styrene and furfurylalcohol performed just as good, or better, than the copper containing treatments.
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
In the last few decades, it has been noted that the epiphytic lichen Usnea longissima appears to be declining in numbers throughout its previous distribution range in Scandinavia. Up until now, clearcutting forestry has been considered the main threat to its persistence. Suspecting that other threats also may be at work, we studied the fate of 20 U. longissima localities in undisturbed forest stands, surveyed in 1994–95 and subsequently in 2003–04, in the Nordmarka region, north of Oslo, Norway. Yearly λ was calculated to be 0.94 (95% CI = 0.91-0.97), both with respect to number of trees bearing the lichen and total number of thalli per locality. This corresponds to a 10-year decline of 46%, or a half-life of 11 years. No new establishments were recorded. Now being listed as Endangered (EN) in the revised Norwegian Redlist of 2006, all known localities will be protected from major forestry operations. However, without knowledge of additional threat sources, its future possibility for survival looks bleak. Possible negative factors are discussed, including air pollution, increasing tree canopy closure, inter-specific competition, and genetic depauperation.
Sammendrag
Whereas lichen growth rates have received considerable attention, comparatively few detailed studies of growth patterns have been carried out. Generally, most lichens seem to grow apically, with pseudomeristomatic tissue confined to lobe margins and branch tips. However, some species appear to retain the capacity to expand throughout the thallus. Such intercalary growth processes have proved difficult to confirm in the field for two- and three-dimensionally growing folious and fruticose forms. Using transplants of the conspicuous, one-dimensionally growing Usnea longissima Ach., we document that intercalary growth actually does occur, with thalli expanding geometrically in length with a doubling time of less than a year under favorable conditions.
Forfattere
Erik LarnøySammendrag
To evaluate the decay resistance of wood, treated or untreated, for hazard classes 3, 4 and 5, the mass loss due to fungal exposure needs to be calculated. The standards for calculating mass loss in wooden test samples (i.e EN 113 and ENV 807) require that the samples used in the test are pre-dried to 0 % moisture content, m0, for determination of the initial dry mass. The standards describe that the samples should be dried at 103±2°C for 18 hours. When drying wood samples to 103 °C the samples are altered. Literature describes that extractives are influenced at temperatures as low as 60 °C, and redistribution and/or evaporation of these, will change the characteristics of the wood samples...
Sammendrag
The treatability of Scots pine (Pinus sylvestris) sapwood is ranked in the European standard EN 350-2 as class 1 (easy to treat), although huge differences in sapwood penetration exist. To obtain full sapwood penetration, process parameters have to be adjusted to the material most difficult to treat. It is therefore of importance to understand the factors that are responsible for penetration differences. Scots pine sapwood was investigated for anatomical differences influencing the ratio of filling (RoF) when treated with the wood modifying agent furfuryl alcohol. The database for the study was samples from two test series including Scots pine from Norway and Denmark. Within these experimental series each sample can be reassigned to its original position in the stem. The RoF for each sample was evaluated, and the variation in treatability within trees, between trees and between different stands was studied...