Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2004
Sammendrag
Tall oil is a by-product in pulping of resinous wood by the sulphate process. Tall oil contains a complex mixture of wood extractives. Some of these extractives act as natural protection against wood decaying fungi while other serve as nutrition for the fungi. This report describes a screening of the efficacy of four refined tall oils with different chemical composition on wood decaying fungi.Testing was performed as filter paper assay and mini-block assay. In the filter paper assay growth rates of the white rot fungus Coriolus versicolor and the brown rot fungus Poria placenta were inhibited by the tall oils. None of the oils caused total inhibition of the fungi but there was a clear pattern towards increased efficacy with increased portion of resin acids in the oils.Impregnated mini-blocks with approximately 200 kg/m3 retention of tall oil after leaching showed an evident effect against Coniophora puteana and Poria placenta compared to untreated control samples. However, using the criteria from EN 113 requiring less than 3% mass loss, tall oil failed.The results indicate that decay resistance of tall oil impregnated Scots pine sapwood to the retention level used in this study is comparable with the decay resistance of Scots pine heartwood. It was expected that the efficacy of the tall oils was related to chemical composition of the oils. This was confirmed for the filter paper assay where the efficacy increased with increasing amount of resin acids. However, this pattern was not found for the mini-block assay.The protective effect of the tall oils in wood seems therefore to be more related to their hydrophobic properties than to their fungicidal properties.
Forfattere
Line Hoem Erlend Ystrøm HaartveitSammendrag
Det er ikke registrert sammendrag
Forfattere
Per Holm Nygaard Heleen A. de WitSammendrag
Aluminium (Al), mobilized by acidic deposition, has been claimed to be a major threat to forest vitality. Fine root mortality, decreased root growth and reduced nutrient uptake have been observed in controlled laboratory experiments where roots of tree seedlings were exposed to elevated concentrations of Al. Yet, evidence for Al-induced root damage from forest stands is scarcely reported. Nevertheless, Al dissolved in soil water has received a key role in the critical load concept for forests. Here, we present effects of artificially elevated concentrations of Al in the soil solution on fine roots in a middle-aged stand of Norway spruce (Picea abies (L.) Karst.). Although the inorganic Al concentrations about 200 M and Ca:Al ratio about 0.7 that were established in the soil solution within this experiment have been associated with reduction of root growth and root mortality for spruce seedlings in hydroponic studies, no acute damage on fine roots was observed. Three years of treatment did not cause visual root damage, nor were effects on fine root necromass observed. Fine root necromass made up about 10 % of fine root biomass for all treatments. However, significantly lower molar Ca:Al and Mg:Al ratios in living and dead fine roots were found in the plots where Al concentrations were highest and ratios of Ca to Al in the soil solution were lowest. The lack of response on fine root biomass suggests that forest stands tolerate higher Al levels than results from laboratory experiments indicate. We conclude that effect studies in the laboratory have limited value for field conditions. The key role of Al toxicity, expressed as the Ca/Al ratio, in critical load calculations for forests may have to be reconsidered.
Sammendrag
Ecosystems as objects of natural sciences are often difficult to understand, as an object of traditional management they are sometimes easy to utilize. Computer-based modeling offers new tools to study this apparent paradox.We propose an interactive framework from which the traditional approach based on dynamic system theory can be challenged for living systems: Models derived on the basis of the state concept have not (yet?) allowed predictions that derive novel management competence relevant for the altered boundary conditions of ecosystems. Here a concept of interaction as currently used in information sciences serves as starting point for deriving models more appropriate for ecosystems.An application and test of this concept consists in a search for signatures of interaction in environmental and ecological time series. Confronted with the notorious lack of detailed process understanding, it is plausible to rely on time series analysis techniques. The intricate nature of typical multivariate data sets from ecosystems immediately suggests a preference for nonlinear techniques, and among them temporally local methods, able to detect even subtle changes in the underlying dynamics.We shortly introduce a couple of these methods, which have been demonstrated to be appropriate for time series exceeding minimal length requirements. This is exemplified by recurrence quantification analysis. In addition we present methods to quantify the memory content (Hurst analysis) and complexity of data sets (defined in an informationtheoretic context).Time series analysis of extended environmental and ecological data sets can give detailed structural insights, monitors subtle changes undetectable otherwise, forms the basis for further inferences and provides rigorous model testing on all scales. The success of dynamic system theory when applied to non-living environmental data is strikingly contrasted by the difficulties of the same method when dealing with ecological data We conjecture that this difference reflects the extent to which interaction has been disregarded for ecosystems.
Forfattere
J.W. Hudgins Erik Christiansen Vincent R. FranceschiSammendrag
Conifers have evolved constitutive and inducible defense mechanisms to help in both wound healing and defense against attack by bark beetles and other organisms. These defenses include oleoresin, phenolics, and static structures in secondary phloem, such as lignified cells and calcium oxalate crystals, that create physical barriers. We used a phylogenetic approach to investigate the defense anatomy of conifer stems of 13 species from five families following treatment with methyl jasmonate (MJ), a compound that induces defense responses in stems of several Pinaceae species.Methyl jasmonate induced a response similar to wounding except that the response was not accompanied by lesion formation, necrosis or a hypersensitive response. In the Pinaceae species studied, MJ induced polyphenolic parenchyma (PP) cell activation and xylem traumatic resin duct (TD) formation. Members of the Taxodiaceae, which are not known to produce large quantities of resin, showed massive xylem TD formation and surface resinosis following MJ treatment.Treatment with MJ caused members of the Araucariaceae and Cupressaceae to form axial phloem resin ducts but not xylem ducts, whereas Podocarpaceae species showed no induction of resin-producing structures. All species treated with MJ showed phenolic deposition in PP cells, and early lignification of phloem fibers was observed in most of the non-Pinaceae species.We conclude that, although evolution of resin-producing structures occurred independently in conifer lineages, MJ seems to induce resin production regardless of tissue location, as well as inducing deposition of phenolic compounds. Co-evolution of conifer defensive strategies and bark beetle pests is discussed.
Forfattere
Anders Lunnan M. Nylinder M. KärkkäinenSammendrag
Det er ikke registrert sammendrag
Forfattere
Bernt-Håvard ØyenSammendrag
Historien om kulturskogene i Hordaland er beskrevet.
Forfattere
Lars Sandved Dalen Øystein JohnsenSammendrag
Plant growth and adaptation to cold and freezing temperatures in a CO2-enriched atmosphere have received little attention despite the predicted effects of elevated CO2 on plant distribution and productivity. Norway spruce (Picea abies (L.) Karst.) seedlings from latitudinally distinct seed sources (66N and 60N) were grown for one simulated growth season under controlled conditions in an atmosphere enriched in CO2 (70Pa) and at ambient CO2 (40Pa), combined factorially with low (3.6mM) or high (15.7mM) concentrations of nitrogen fertilization.There was a clear difference between the two provenances in height growth, in the timing of bud set, and in freezing tolerance. Nitrogen fertilization increased height growth in both provenances, while CO2-enrichment stimulated height growth only in the southern provenance. We found no significant effects of elevated CO2 or nitrogen fertilization on the timing of bud set.During cold acclimation, freezing tolerance increased from -10C to -35C, and there was a marked increase in all soluble sugars except inositol. Elevated CO2 in combination with high nitrogen led to a slight increased freezing tolerance in both provenances during the early stages of cold acclimation. However, towards the end of cold acclimation, elevated CO2 and high nitrogen led to reduced freezing tolerance in the southern provenance, while elevated CO2 and low nitrogen reduced freezing tolerance in the northern provenance. These results suggest that CO2-enrichment influences the development of freezing tolerance, and that these responses differ with available nitrogen and between provenances.
Forfattere
Per Otto Flæte Erlend Ystrøm HaartveitSammendrag
In Scandinavia Scots pine (Pinus sylvestris L.) is an important commercial tree species. Its heartwood has traditionally been used in constructions exposed to risk of decay. In a laboratory experiment Scots pine wood specimens sampled from inner heartwood, outer heartwood and sapwood were exposed to the brown rot fungus Poria placenta.In general outer heartwood was more resistant than inner heartwood, but there were variations even within the same wood zone. NIR spectra obtained on solid wood prior to decay testing were used in multivariate calibrations to predict decay resistance of heartwood.Results from segmented cross validated partial least squares (PLS1) regression modelling showed that resistance to decay in Scots pine heartwood could be predicted with satisfying precision using NIR spectroscopy. As NIR spectra were collected on solid wood, development of the method for industrial use is potentially possible.
Forfattere
Jørn Kristian Lileng Erlend Ystrøm HaartveitSammendrag
Forest roads ensure access to standing timber and their standards may restrict the opportunity set for efficient logistical solutions. Traditionally, the objective of road investments has been maximisation of returns for the landowner.Investments in forest roads in Norway are subsidised by the Norwegian government. These subsidies should preferably be allocated to projects creating the best premises for efficient log supply. The total cost approach evaluates costs using a holistic perspective. In this paper we use this approach to evaluate the profitability of investments in forest roads so that the total costs for log supply to the industry are minimised.The distribution of standing timber in the catchment area of the forest road is also taken into account. The results show that the sum of costs for road construction, harvesting and forwarding account for more than 99% of the total costs, compared to less than 1% for the sum of log hauling costs. Differentiation of forest road standards is more appropriate in situations where the volume of standing timber decreases in remote areas of the forest road network.