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
Authors
Erlend Ystrøm Haartveit Dag FjeldAbstract
Structural changes in the sawmilling industry imply more wood transport as distance between sawmills is increasing. One of the factors that determines the potential for economies of scale is the trade-off between reduced production costs and increased transport costs. The methods used in this study are based on geometric properties of wood procurement areas.The effects of the distribution of forest (area coefficient) and the road net (winding coefficient) upon average transport distance was explored, and considerable regional variation was found.The transport net factor (t) is the product of the area coefficient (a) and the winding coefficient (w) and gives a relative measure of the potential for efficient procurement logistics with respect to the distribution of productive forest area and the road net. The transport net factor is estimated for two wood procurement areas in each of four regions.When studying the sawlogs procurement in regions with different density of sawlogs buyers, average transport distance increases relatively more in areas where several buyers are competing for a limited timber supply than in areas with few competitors.
Abstract
No abstract has been registered
Authors
Bjørn ØklandAbstract
No abstract has been registered
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Authors
Arild Andersen Ragnar EltunAbstract
No abstract has been registered
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No abstract has been registered
Authors
Bjørn ØklandAbstract
No abstract has been registered
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.
Abstract
No abstract has been registered
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.