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
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
Peder Gjerdrum I. AkerfeldsAbstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
One of our main interests is to learn about the molecular basis of host defense responses, using the coniferous host Norway spruce infected with the pathogen Heterobasidion parviporum as the experimental system. This basidiomycete and the closely related pathogen H. annosum are the major root rot causing pathogens in conifers.To screen host material for differential resistance towards H. parviporum, it is a necessity to quantify the fungal colonization of the host tissues. Therefore, we aimed to develop and compare the sensitivity of a real-time PCR to an ergosterol based method for determining the rate of colonization. We developed a quantitative multiplex real-time PCR procedure that reliably detecting down to 1pg H. parviporum DNA and 1ng host DNA.There was a very high correlation between the fungal-biomass/total-biomass and fungal-DNA/total-DNA rankings obtained with ergosterol and real-time PCR, strengthening the credibility of both methods. The results indicate that this real-time procedure can be a useful method to screen different spruce material for their relative resistance to the pathogen H. parviporum.
Authors
C. Futsæther Nina Elisabeth Nagy L. Eikenes Anders Lönneborg A. Johnsson T. Singstad A. VollsnesAbstract
No abstract has been registered
Abstract
Determining the level of pathogenic fungi and other microorganisms during colonization of the host is central in phytopathological studies. A direct way is to monitor fungal hyphae by microscopic examination, but indirect chitin and ergosterol-based assays have been among the most applied methods in determining fungal biomass within host tissues. Recently real-time technology is increasingly receiving attention as a way to follow infection agents in host tissues.We study the molecular basis of host defense responses, using the coniferous host Norway spruce (Picea abies) infected with the basidomycete Heterobasidion annosum as the experimental system. This basidiomycete is the major root rot causing pathogens in conifers of all age classes.In order to screen host material for differential resistance towards H.annosum for both scientific and commercial reasons, it is a necessity to reliably quantify the fungal colonization of the host tissues. Therefore, the aim of this study was to develop and compare the sensitivity of a real-time PCR assay to an ergosterol based method for determining the rate of colonization by H.annosum in inoculated spruce material. We also applied the methods to rank the infection level of the pathogen on the spruce tissue culture clones.We were able to develop a quantitative multiplex real-time PCR procedure that reliably detecting down to 1pg H.annosum DNA and 1ng host DNA in DNA extracted from infected tissues. There was a very high correlation between the fungal-biomass/total-biomass and fungal DNA-total DNA rankings obtained with ergosterol and real-time PCR respectively, strengthening the credibility of both methods.Based on both ergosterol and real-time PCR, it was clear that some spruce clones were faster and more heavily infected than others. These results indicate that both ergosterol and this real-time procedure can be useful methods to screen different spruce material for their relative resistance to the pathogen H.annosum.
Authors
Vincent R. Franceschi Trygve Krekling Erik ChristiansenAbstract
Application of 100 mM methyl jasmonate (MJ) to the intact bark of 30-yr-old Norway spruce induced anatomical reactions related to defense. Within 30 d, a single MJ treatment induced swelling of existing polyphenolic parenchyma cells (PP cells) and an increase in their phenolic contents and the formation of additional PP cells and of traumatic resin ducts (TDs) at the cambial zone. These changes occurred up to 7 cm away from the application zone.Treatment enhanced resin flow and increased resistance to the blue-stain fungus, Ceratocystis polonica. Methyl jasmonate application to the oldest internode of 2-yr-old saplings also induced TD formation and, more surprisingly, TDs were formed in the untreated internode. Traumatic ducts were not formed in branches, ruling out an effect of volatile MJ on the upper internode. Methyl jasmonate application never gave rise to a hypersensitive response, cell death, tissue necrosis, or wound periderm, indicating the amount of MJ transported across the periderm was very low relative to the application concentration.This is the first report of a single compound giving rise to major cellular features related to acquired resistance and previously shown to be induced by wounding, fungal infection, and bark beetles in Norway spruce.
Authors
G. van TolAbstract
No abstract has been registered
Authors
H. Mäkinen P. Nöjd H.P. Kahle U. Neumann Bjørn Tveite K. Mielikäinen H. Röhle H. SpieckerAbstract
Regional and temporal growth variation of Norway spruce (Picea abies (L.) Karst.) and its dependence on air temperature and precipitation were compared in stands across latitudinal and altitudinal transects in southwestern and eastern Germany, Norway, and Finland.The temporal variation of radial growth was divided into two components: medium- and high-frequency variation, i.e. decadal and year-to-year variation, respectively. The medium-frequency component was rather different between regions, especially the southern and northern ones. However, within each region the medium-frequency growth variation was relatively similar, irrespective of altitudinal and latitudinal differences of the sample sites.A part of the high-frequency variation was common to all four regions, which suggests that some factors synchronising tree growth are common for the entire study area. The high-frequency component of growth was more strongly related to monthly air temperature and precipitation than was the medium-frequency variation. The limiting effect of low temperatures was more significant at northern as well as high-altitude sites, while the importance of precipitation increased in the south and at low altitudes.
Abstract
Concentrations and fluxes of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON), together with pools of carbon and nitrogen in the soil and biomass, were determined along north-south and east-west transects across Norway, Sweden and Finland. The data were analysed statistically and modelled using the mechanistic model DyDOC.Concentrations of DOC and DON were greatest in the O horizon and decreased downwards in the soil. The highest production of dissolved organic matter appears to take place in the O horizon and any contribution from thoroughfall is probably small. A pronounced seasonal effect with peak DOC concentrations in late summer/early autumn may be due to a seasonal (largely temperature) effect on DOC production.The effect of acidic precipitation upon DOC concentrations and fluxes was unclear. DOC in the O horizon was mostly of recent origin, while DOC in the B horizon appeared to include some older material, possibly desorbed from the soil. A positive correlation was found with electrical conductivity and a negative correlation with pH in DOC concentrations from the O horizon.A lack of correlation between DOC concentrations and temperature is probably due to a time lag between peak temperatures and peak DOC concentrations. Modelling of DOC concentrations and fluxes using DyDOC gave rasonable results, suggesting that it might be possible to use DyDOC as a general tool for modelling and forecasting DOC concentrations and fluxes in Nordic forest ecosytems.Scenario analysis using DyDOC suggested that increased temperature without increased litter input might result in increased production of CO2 rather than DOC. An increase in both temperature and litter input would lead to increased DOC concentrations, with possible implications for drinking water quality. Increased precipitation will lead to increased fluxes of DOC.