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
Bjørn ØklandAbstract
Several studies conclude that sun-exposed habitats with sufficient supply of dead wood are essential for many saproxylic and mycetophagous beetle species in forests. This has induced Scandinavian foresters to leave artificial tall stumps on clear-cuts in spruce forests.In the present study of Norway spruce forest, habitat preferences during flight were studied for saproxylic and mycetophagous beetles recorded as sporocarp-visitors of Fomitopsis pinicola and Fomes fomentarius, using 690 randomly placed window traps in 69 sites covering three forest types: clear-cuts, young and oldgrowth stands.Many of the sporocarp-visitors showed a strong preference for oldgrowth forest, avoiding clear-cuts and young replantations. By stepwise linear multiple regression, presence of canopy cover appeared as a major factor while variables associated with sporocarps and dead wood were most often secondary in importance. The results indicate that sufficient canopy cover is important for many sporocarp-visiting beetles in Norway spruce forests
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
In this article, we present an empirical account of how the Codex Alimentarius Commission (CAC), as an intergovernmental body, has changed after being referred to in the SPS Agreement of the WTO as the reference point for the elaboration of international food standards. We explore key issues that have recently been discussed in the Codex and which may have a significant impact on international food trade. Further, we develop a theoretical framework based on two alternative versions of institutional theory. We then analyze the observed changes of the role and functioning of Codex from these frameworks. Our conclusion is that a logic of consequences prevails over a logic of appropriateness in explaining nation-state behavior in an international context. Finally, our study of the Codex recognizes the importance of identifying the core interests of states, their strategic use of arguments based on these interests, as well as the institutional framework that affects them.
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.
Authors
Harald Kvaalen Ola Gram DæhlenAbstract
No abstract has been registered
Abstract
A quantitative multiplex real-time PCR procedure was developed to monitor the dynamics in Norway spruce (Heterobasidion annosum) pathosystem. The assay reliably detected down to 1 pg of H. annosum DNA and 1 ng of host DNA in multiplex conditions. As a comparative method for quantifying fungal colonization,we applied the ergosterol assay. There was a very high correlation between the results obtained with the two methods, this strengthening the credibility of both assays. The advantages and disadvantages of these assays are discussed.
Abstract
Determining the level of pathogenic fungi and other microorganisms during colonization of the host is central in phytopathological studies. A direct way to monitor fungal hyphae within the host is microscopic examination, but chitin and ergosterol-levels are commonly used to indirectly measure the amount of fungus present. Recently real-time PCR technology is being used to follow infection agents in host tissues. We study 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, and applied the methods to rank the infection level of the pathogen on the spruce clones 053 and 589. 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. Based on both ergosterol and real-time PCR, it was clear that the clone 053 was hosting more fungal biomass than clone 589. 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.
Abstract
No abstract has been registered
Abstract
This study shows that it is questionable if critical load modelling can contribute in the search for harmful effects of acid deposition on forest health at present. Critical loads for S and N deposition were calculated using the MAGIC and PROFILE models for more than 100 monitoring plots in Norway spruce forest in south-east Norway. The two models gave different results, likely due to differences in the models, including differences in the time spans applied. The PROFILE model gave considerably more plots with exceedance than the MAGIC model. At plots where the CL was exceeded, calcium/aluminium (Ca/Al) ratios in the soil solutions were low. However, very few of these plots had possible harmful values of the Ca/Al-ratio. More than 50 yr seems in most cases to be needed to bring Ca/Al ratios below 1.0. Present deposition was better correlated with measured forest condition variables such as crown condition and needle chemistry, than with modelled exceedance according to any of the two methods. The deposition of S and N was weakly, negatively correlated to foliar concentrations of P and Ca, and positively to foliar N concentrations and crown density.