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.
2013
Forfattere
Arne SteffenremSammendrag
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Sammendrag
North European epiphytic lichens are often genetically impoverished compared with their North American counterparts. This has been hypothesized to impede sexual reproduction due to reduced chances of finding compatible mating type partners. We compared genetic variation and reproductive mode in two threatened Scandinavian lichens, Evernia divaricata and Usnea longissima, with more viable populations in North America to see (i) if these species also show genetical depletion in northern Europe and (ii) if the occurrence of sexual propagules (ascospores in apothecia) is more prevalent in genetically diverse populations. Genetic variation of the fungal component was assessed by sequencing two nuclear rDNA gene regions (ITS and IGS) in 1005 and 1477 thalli, collected from 92 and 160 localities of E. divaricata and U. longissima, respectively. Scandinavian populations of both species were almost devoid of genetic variation compared with much higher genetic diversity in North America.We found no support for the proposed relationship between genetic diversity and fertility. Fertile thalli were found in several genetically invariable populations. Fertility increased with population size and regional abundance in E. divaricata, but not in U. longissima. In Scandinavia, E. divaricata was more fertile than previously recorded, whereas all sampled populations of U. longissima were sterile and possibly clonal.
Forfattere
Jørund RolstadSammendrag
Environmentalists tell us that we’re loosing species at an increasing rate, and if we are to stop the cascading extinctions by 2020 (which we have agreed upon in international conventions) we need to take immediate action. Making sure we’re not loosing any ’native’ species may seem a daunting task, especially if we look at insects, spiders, fungi, and other tiny creatures that live in dead wood. For thousands of these saproxylic species the wood and timber that we are harvesting make up the bread and butter of their everyday life. The competition is fierce, and it doesn’t get any better when we remove most of the wood that otherwise would have become their future homes. What shall we do?
Forfattere
Christian Brischke Linda Meyer Gry Alfredsen Per Otto Flæte Lesley Francis Mattias Hansson Pia Larsson-Brelid Jöran Jermer Christian Welzbacher Andreas Otto Rapp Karin Brandt Eckhard MelcherSammendrag
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Sammendrag
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Sammendrag
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Sammendrag
Acetylation appears suited to provide adequate protection against biological attack for materials derived from non-durable wood species. But still there are unanswered questions related to resistance against fungal decay. The paper summarises existing knowledge related to fungal deterioration of acetic anhydride modified wood and also highlights future research opportunities. In addition, statistical analyses based on previously published decay fungi studies were performed to quantify what factors contribute most to the performance (calculated as test sample/control). The results showed that weight per cent gain can explain approximately 50% of the performance for acetic anhydride treated wood. Others of the applied variables, like wood species or type of fungus, can reduce the variance in performance by additional 15%. Based on the surveyed literature the degree of cell wall bulking in combination with lowering of the equilibrium moisture content seems to be the primary mode of action.
Forfattere
Christian Brischke Christian Welzbacher Antje Gellerich Susanne Bollmus Miha Humar Katharina Plaschkies Wolfram Scheiding Gry Alfredsen Joris Van Acker Imke De WidtSammendrag
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Sammendrag
Even if it is well established that acetylation of wood by the use of acetic anhydride is able to impart a significant degree of decay resistance, more evidence is needed to understand the mechanisms by which acetylated wood is protected from fungal decay. The aim of this paper was to study if a standardised leaching procedure with water (EN 84) vs. no leaching affected the Postia placenta decay of acetylated samples. Three different acetylation levels (low, medium and high) were tested in addition to untreated Southern yellow pine as control. The samples were harvested at two different stages of fungal incubation; 4 and 28 weeks. We compared changes in mass loss, wood moisture content, fungal biomass measured indirectly as fungal DNA, plus a small gene expression screening including five different genes. Generally there were not any striking differences between the leached and the non-leached samples. For the acetylated samples a statistically significant difference in mass loss between leached and non-leached samples were found at low and medium acetylation level after 28 weeks. Wood moisture content differed significantly between leached and non-leached acetylated samples for low acetylation level after 4 weeks and for at low and medium levels after 28 weeks. The gene expression levels were generally significantly lower after 4 weeks compared to 28 weeks of incubation. After 28 weeks no significant difference was found between leached and non-leached acetylated samples for any of the measured genes.
Sammendrag
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