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.
2002
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Authors
Peder GjerdrumAbstract
This dissertation addresses questions of timber quality in the interface between the forestry and the sawmill. The labour was carried out in an industrial environment for the benefit of the sawmill industry and - in a wider scope - for the entire wood chain. Specimens from a total of more than three thousand five hundred softwood sawlogs and trees were investigated for heartwood, spiral grain or log geometry. Applying analytic and statistical tools, several models for wood properties were built. For pine heartwood the samples spanned most growth conditions and forested areas in the Scandinavian Peninsula. Age was found to be the predominant factor in heartwood formation. A global model termed the Heartwood Age Law could be recognised: Heartwood age, at arbitrary height in the tree, equals the square root of cambial age less three, to the second power. This finding might be used for heartwood modelling. Based on temperature gradients between the sap- and heartwood, an algorithm for calculating the heartwood diameter fraction in an IR image was established. Used in conjunction with a scanner, the following model was established: Top end heartwood diameter might be calculated by multiplying top end diameter observed in a shadow scanner with heartwood diameter fraction estimated from an IR image of arbitrary end of the log. The observed temperature gradient between heart- and sapwood indicated the accuracy of the method. In the industry, IR heartwood detection might be applied in sorting sawlogs to produce timber of distinct properties. Further, correlation to properties like ring width and knots, and to time since harvest, was suggested. A constant change rate in grain angle was found for the mature part of spruce sawlogs. Albeit great variability in intercept and inclination, a linear pattern in grain angle to radial distance from the pith prevailed for specimens from both of the two separated Nordic samples. A combined model including the juvenile zone around the pith was suggested. Two parameters are sufficient to model the grain angle for the entire radial range from the pith to the mantle in any spruce specimen. The main impact of the finding might be for use in modelling and simulation. Derived from observations in a 3D scanner, four parameters describing the centroid of sawlogs were calculated. Based on these parameters several distinct crook types could be classified in an automated routine: First, straight logs were separated from crooked ones; then smooth and simple sweep (that might be accepted in sawlogs) were separated from abrupt crook. Even more specific crook classes could be identified. In an industrial application, this model might increase the speed and reliability of sawlog classification. Observing the log diameter on or under bark and the cross-sectional shape of a sawlog both have an impact on the yield. Optimal yield was only obtained after accurate observing the diameter under bark, integrated in the conversion process. Based on actually observed crosscut shapes, simulation indicated that this strategy might produce up to one tenth more main yield as compared to diameter observation in one direction before barking. Other methods were intermediate. Further investigations analysing the variation in crosscut shape along the stem and the accuracy of observation were recommended.
Authors
Hans Haavardsholm Blom M. LüthAbstract
Schistidium spinosum Blom Lth is described. It grows on siliceous rocks in hill and mountain areas in the western parts of continental Europe. It is placed in the confertum group, whereas the very similar S. liliputanum (C. Mll.) Deguchi has its closest relatives among species of the apocarpum group. Schistidium liliputanum is reported as new to North America where it is widespread in the eastern part of the continent.
Abstract
Several strong westerly storms hit Western Norway during the winter of 1986-87. We studied the uptake, loss and visible effects of sea salt aerosols in Scots pine and Norway spruce. Foliage of was sampled at distances 0-100 km from the coastline between 59¢ª and 65¢ª N, and analysed for chloride, sodium and other elements. The range of chloride and sodium concentrations in needles was 0.5-5.0, and 0.1-3.0 mg g-1, respectively. The local variation was very large close to the coast. The relation to distance from the sea was improved by using distance from the nearest fjord rather than from the outer coastline. Other elements were less variable and not related to distance from the sea, or to sea salt concentrations. Only 1-10% of the needles sea salt content could be removed by 2 minutes washing in distilled water, and still much less of other elements. The amount of sea salt removed by washing was less related to distance from the sea than was the total content. Visible damage to the foliage occurred at chloride concentrations above 1 mg g-1 in the needles. Our conclusions are that analysis of the needles chloride or sodium content is a robust method for confirming damage to tree foliage by sea salt aerosols. Fjords as well as the ocean are significant sources of sea salt aerosols. Large local variation in salt deposition and damage will occur at a rugged coast. Nutrients and other elements are not significantly affected by the sea salt deposition. The use of chloride or sodium as a tracer for dry deposition should take into account not only the enrichment of these elements in canopy throughfall, but also the accumulation in the needles.
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No abstract has been registered
Authors
Halvor TorgersenAbstract
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Authors
Kjell Esser Tor Gunnar Vågen Yibabe Tilahun Mitiku HaileAbstract
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Authors
Peder Gjerdrum H. Säll H.M. StorøAbstract
Any evident grain deviation will reduce strength and increase warp in sawn timber. To describe the magnitude and variance of grain angle in Norway spruce, specimens from 1046 Norwegian sawlogs and 380 logs from Sweden and Finland were examined. For individual specimens, grain angle outside the innermost zone closest to the pith might be expressed by a simple linear function of radial distance from the pith. The intercept and inclination of this function are close to bivariate normally distributed with mean values (SD) of 2.7 deg. (1.9) and -0.039 deg/mm(0.037), respectively. Inclination is less negative for wider annual rings (r = 0.3), and intercept and inclination are negatively correlated (r = -0.4). The constant rate of change indicates inherited property rather than influence of any dynamic, external stimulus. No predictor for grain angle pattern was found. The linear model leads to simplifications both when observing the grain angle in the forestry, and in calculations of strength properties and distortion in the timber industry.
Authors
Lars Sandved Dalen Carl Gunnar Fossdal R. Bhalerao John Beck Jensen Teemu H. TeeriAbstract
Trees cover over one-third of the world\"s land area and carry out about two-thirds of global photosynthesis. Coniferous forests cover 1.2 billion hectares of Alaska, Canada, Scandinavia, and Russia, and comprise one-fourth of the world\"s boreal and temperate forests. More than 50% of Scandinavia\"s land area consists of forests, mostly coniferous. Information about the molecular responses in trees to biotic and abiotic factors is therefore of great importance - both scientifically and practically. Generation of expressed sequence tags (ESTs) is an important part of genome research. Randomly selected cDNA clones are partially sequenced, and the ESTs reflect the level and complexity of gene expression in the sampled tissue. In order to find interesting gene products and to study gene expression in the most common and economically important conifer in the Nordic countries, we have started an EST-project on Norway spruce. So far we have sequenced ~3500 cDNA clones based on mRNA isolated from needles and cell cultures. Here, we present the frequency of the different ESTs, their putative function and their functional classification. We aim at sequencing another 20,000-30,000 cDNA-clones from wood-forming tissues and from seedlings treated with drought, low temperatures, pathogen infection, etc. The long-term goal is to develop a non-redundant and annotated collection of Norway spruce clones to be used in combination with microarray analysis