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.
2000
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Authors
Arild Andersen Ragnar EltunAbstract
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Bjørn ØklandAbstract
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Authors
Bjørn ØklandAbstract
Insect species in 20 families of Diptera were collected by an equal number of interception traps in spruce forests of different management practice:young regrowth 5-10 years after logging and replantingmanaged old-growth forestgap opening of old-growth forest with plenty of even-aged dead wooda shady remnant biotope of uncultivated old-growth forest with plenty of dead wood in various levels of decay. Forest cultivation seems to favour saprophagous generalists on behalf of the specialised fungal fauna. The species in mycorrhizal fungi were clearly reduced in young regrowth, while species in wood-inhabiting fungi were most diverse in the remnant biotope with a heterogeneous composition of dead wood.The abundance of saprophagous generalists was significantly increased in the managed forest variants (young regrowth and managed old-growth forest). More studies are necessary to evaluate how the shift in decomposer fauna influence nutrient cycling and other ecosystem processes in forests.
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Abstract
Nitrogen is among the most important plant nutrients, and the effects on forest trees of changes in the concentrations and fluxes of both inorganic and organic nitrogen need to be known. In Norway, much of the nitrogen present in natural waters is organic (Mulder et al., 2000), therefore this fraction can not be neglected. Work using glycine has shown that forest plants can take up some forms of organic nitrogen directly, without preliminary mineralisation (Nsholm et al., 1998).Amino acids and amino sugars appear to be the most important organic sources of nitrogen for plants, including Norway spruce (Picea abies (L.) Karst.) (Johnsson et al., 1999). Organic nitrogen occurs in different forms. In soils, the most important are heterocyclic compounds and amino acids (35 % and 40 % respectively, Schulten and Schnitzer, 1998). In soil waters, amino sugars may also be important (Michalzik and Matzner, 1999).At present, organic nitrogen is normally determined as the difference between total nitrogen and the sum of nitrogen in nitrate and ammonium. This is not entirely satisfactory, as there will be a certain amount of uncertainty in each of the three determinations required. The total uncertainty involved in the determination of organic nitrogen may then be quite large compared to the actual concentration, especially when most nitrogen is present as inorganic nitrogen.A method for the direct determination of organic nitrogen is therefore desirable. Because organic nitrogen generally has a higher molecular weight than inorganic nitrogen, it might be possible to separate organic from inorganic nitrogen using size fractionation methods. In 1998, we worked on the setting up of methods for the determination of amino acids and amino sugars in soil waters, and on the direct determination of organic nitrogen using equilibrium dialysis.
Authors
Tor Arvid Breland Ragnar EltunAbstract
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Authors
Dag Fjeld Leif Egil Hem Tom Roar EikebrokkAbstract
This study examines the role of forest operations strategies in sector development for Norway's fjord region. The paper starts with an examination of forest owner attitudes and perceptions in relation to their harvesting behaviour, use of contractor harvesting and road net extension. The influence of forest owner decisions, contractor mechanisation and road net extension standards on operational efficiency is examined in a simple deterministic model of the regional wood chain. Average wood procurement costs are calculated for increasing sector capacity. Direct and indirect harvesting costs are also followed throughout this development.
Authors
Lars Sandved Dalen Carl Gunnar Fossdal Inger Margrethe Heldal Nina Elisabeth Nagy Praveen Sharma Geir Østreng Anders Lönneborg Øystein JohnsenAbstract
Plants are sessile and have to adjust to the prevailing environmental conditions of their surroundings. This has led to a development of a great plasticity in gene regulation, morphogenesis, and metabolism. Adaptation and defence strategies involve the activation of genes encoding proteins important in the acclimation or defence towards the different stressors.Some of the molecular responses to biotic and abiotic stress factors such as pathogenic fungi or drought are specific, but it has also been shown that similar genes are acitvated by several stressors.At the Norwegian Forest Research Institute we are currently developing a diagnostic tool using the induction pattern of several selected genes from Norway spruce to use as a fingerprint for different types of biotic and abiotic stress. The ultimate goal of this project is to be able to identify unique mRNA expression patterns specific for different stressors such as heat, cold, drought, pathogens etc.In order to study the induction pattern expressed under biotic and abiotic stress, Norway spruce seedlings grown on glass beads in a phytotron we have treated with drought, a root pathogenic fungi (Rhizoctonia sp.), and a combination of drought and the root fungal pathogen.Physiological measurements of height, weight, ion leakage, gas exchange, and chlorophyll fluorescence are taken troughout the experiment. In addition, we have used light and electron microscopy, and immunolocalization to study structural cell and tissue changes. The results so far show great variance in the expression patterns between treatments and over time.