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.
2011
Authors
Holger LangeAbstract
Spatial dependencies among environmental variables are often quantified by spatial autocorrelation functions. The latter basically assume linearity and isotropy, requirements usually not satisfied for measured data. Typical symptoms of violated assumptions are biased parameter estimations. Relaxing the assumptions of linear dependencies and isotropy, we present a conceptual generalization of spatial analysis where locally varying anisotropies in the geographical space are uncovered by investigating nonlinear dependencies among observations. The framework is illustrated by generalizing two examples: distance decay relations and spatial filtering. The proposed alternative is based on geodesic ecological and anisotropic spatial distances.
Authors
Frank MillerAbstract
No abstract has been registered
Academic – Analysis of three-dimensional grain angle variation in Norway spruce stems
Peder Gjerdrum
Authors
Peder GjerdrumAbstract
Grain angle was observed on 178 discs equally spaced along each of 24 mostly quite large spruce stems, and a general model estimated for grain angle variation along the radial distance from pith. Due to the three-dimensional approach and the large-size stems, new variability was identified, as compared to traditional two-dimensional approach applied on moderate-sized stem discs. The model standard error was 2.3º; half of this variation can be attributed to combined stem and disc effects, and half to purely random variation. Standard error for the model estimated for individual discs was 1.6 º. Observed against the stem centroid, pith angle varies randomly with average close to zero and standard deviation 2.2º. The results should be applicable for wood quality modelling and for commercial sawn timber production.
Authors
Mette Vaarst Christoph Winckler Stephen Roderick Gidi Smolders Silvia Ivemeyer Jan Brinkman Cecilie Marie Mejdell Lindsay k Whistance Pip Nicholas Michael Walkenhorst Christine Leeb Solveig March Britt IF Henriksen Elisabeth Stöger Elisabeth Gratzer Berit Hansen Johann HuberAbstract
No abstract has been registered
Authors
Matthias Zielke Arne Hermansen John Beck JensenAbstract
No abstract has been registered
Authors
May Sæthre I. Godonou Trond Hofsvang Ghislain Tchoromi Tepa-Yotto B. JamesAbstract
No abstract has been registered
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No abstract has been registered
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No abstract has been registered
Abstract
Dieback of European ash (Fraxinus excelsior), caused by the ascomycete Hymenoscyphus pseudoalbidus (anamorph Chalara fraxinea), started around 1992 in Poland and has since then spread over large geographical areas. By November 2010, the disease had been recorded in 22 European countries. The gradual expansion and high intensity of the ash dieback epidemic in Europe may suggest that H. pseudoalbidus is an invasive alien organism. In Norway, ash dieback was first reported in spring 2008, and a survey in early summer of the same year revealed that the disease had spread over large parts of the southern and eastern regions of the country. The distance from the southernmost to the northernmost infected stands was, at that time, about 400 km. Some old necrotic lesions were also observed, indicating that the ash dieback pathogen is likely to have been present in Norway since at least 2006. In 2009, a spore sampler was installed in a diseased ash stand at Ås, South-Eastern Norway. Sampling started in late July and continued until late September. Large numbers of ascospores resembling those of H. pseudoalbidus were observed, with the maximum number of spores occurring from the end of July to mid-August. The deposition of ascospores occurred mainly between 6 and 8 a.m. Ascospores are most likely to be the primary source initiating host infections and responsible for the rapid recent spread of H. pseudoalbidus in Europe.
Abstract
A high through-put Abbreviated liquid Chromatography Mass Spectrometric (ACMS) method was used to assess the relative influence of genotype and temperature on polyphenol composition in cloudberries. Principal component analysis (PCA) plots of the collated ACMS data showed a separation between crosses based on their female parents (Nyby or Fjellgull). Crosses with Nyby as female parent had higher relative levels of masses assignable to certain ellagitannin derivatives. Crosses with Fjellgull had higher levels of distinctive masses assignable to quercetin derivatives (including a hydroxy-3-methylglutaroyl hexose derivative not previously identified in cloudberry) and anthocyanin-derivatives. There was also a separation between samples grown at lower and higher temperatures, which was driven by m/z signals associated with ellagitannins and notably a major component, Sanguiin H-6. Therefore, abbreviated MS techniques can discern genetic and/or environmental influences in polyphenol composition and can quickly assess quality in breeding programmes or in response to environmental changes.