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.
2010
Abstract
The anamorph genus Leptographium Lagerberg and Melin includes species that are typically bark beetleassociated fungi, with teleomorphs in Grosmannia. During a survey of ophiostomatoid fungi in Norway, two unusual species, that fit the broader morphological description of Leptographium, were isolated directly from the rootfeeding beetles, Dryocetes authographus and Hylastes cunicularius, as well as from roots infested by these insects. The first of these could be distinguished from other described species based on a sparse sporulation, black spore drops and chlamydospores in older cultures. This species also produces a Hyalorhinocladiella synanamorph. The second species was characterised by distinctly curved conidia. Based on these unusual morphological characteristics and distinct DNA sequences, these fungi were recognised as new taxa for which the names Leptographium chlamydatum sp. nov. and L. curvisporum sp. nov. are provided.
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Scots pine (Pinus sylvestris) sapwood was investigated for variation in treatability using the wood modifying agent, furfuryl alcohol (FA) in water. The variation in treatability within trees, between trees and between different stands of Scots pine was studied. Investigated variables that reduced the residual variance significantly were: site location, latitude of site, height of trees, annual ring width, vertical and horizontal position in the tree and method of drying. Linear mixed model statistics were used and tree number was handled as a random variable. The best model reduced the treatability residual variance by 67%. Location was the single factor affecting treatability most. Differences in latitude between locations may be the reason for that. Latitude correlated negatively with the treatability. Within the trees, the treatability of sapwood increased with distance from ground and with distance from heartwood border. A small, but significantly better treatability was found for kiln dried wood (60A degrees C) compared to air dried wood (20A degrees C).
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Abstract
Scots pine (Pinus sylvestris) sapwood is per definition (EN-350-2) easy to treat. Combination with its good availability on the European markets, it is a construction and building material in demand. However, partially large differences in penetration are reported from industry and research. To keep a reliable product quality, impregnation processes aligned to the material most difficult to treat. Hence, it is crucial to know about the factors inhibiting the fluid flow into the material. Scots pine samples from a wide geographic distribution, 25 different sites in 6 different countries, have been collected and impregnated with an aqueous monomer furfuryl alcohol solution. From each of the respective sites logs of 1.3 meter in length were collected from nine trees belonging to three different breast height diameter classes. Three trees from each dominance class were chosen randomly. The log was drawn from the felled stem in a height of 1.2 meters with exact marked north/south exposition. Sapwood slabs orientated in the heaven directions, underwent a drying procedure at 40°C for 48 h and small clear samples of 20 x 20 x 50 mm were prepared. A large variation of the ratio of filling was found for the material tested. Diameter as well as sample origin seem to influence the materials permeability.
Authors
Vegar Bakkestuen Per Arild Aarrestad Odd E. Stabbetorp Lars Erikstad Odd EilertsenAbstract
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Authors
Paal KrokeneAbstract
The interaction between conifers, ophiostomatoid fungi and bark beetles is a key factor in conifer ecosystems worldwide, since combined beetle-fungus attacks may cause massive tree mortality, huge economical losses and landscape-level ecological changes. For more than a century researchers have been arguing about who is responsible for tree mortality in bark beetle attacked trees - the beetles themselves or their associated fungi. As in many such polarized debates the best answer probably lies somewhere in between the extremes. The beetles are obviously central in tree killing, as they are actively selecting suitable host trees, short-circuiting tree defenses by boring straight into the relatively defenseless cambial area, and causing mechanical damage to the phloem. However, ophiostomatoid fungi are equally obvious contributors to tree death since nearly all tree-killing bark beetles are associated with such fungi, these fungi are able to colonize and kill healthy phloem and sapwood far beyond the beetle tunnels, and many fungi can kill healthy trees in experimental mass-inoculations. Thus, the trees are facing a beetle-fungus complex that probably acts synergistically to overwhelm tree defenses. The beetles’ mass-attack strategy is central to the success of the beetle-fungus complex, since multiple attacks deplete tree defenses and speed up tree-killing.