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.
1999
Sammendrag
No abstract has been registered
Forfattere
Jan Erik SundbySammendrag
No abstract has been registered
Forfattere
D. LindgrenSammendrag
No abstract has been registered
Sammendrag
A field experiment was carried out to test the hypothesis that treatment of Norway spruce trees with the Ips typographus-transmitted blue-stain fungus Ceratocystis polonica enhances tree resistance to later mass attack by this bark beetle. Twenty-five mature trees were pre-treated by inoculating a non-lethal dose of the fungus into the bark, while 18 trees served as untreated controls. Three and a half weeks after treatment a bark beetle attack was initiated by attaching dispensers with I. typographus pheromone to the tree trunks. A significantly larger proportion (67%) of the control trees than of the pre-treated trees (36%) were killed by the beetle attack. The result is discussed in relation to recent results regarding defence mechanisms in Norway spruce trees.
Forfattere
Gro HylenSammendrag
Age trends of phenotypic, environmental, and additive genetic variance and heritability were estimated for overall density and its components earlywood and latewood densities and latewood proportion. The objective was to acquire information for both individual and cumulated rings from ring number 3 to 12 counted from the pith. Age-age correlations were calculated for cumulated density traits only. The wood density data were obtained with X-ray analysis of increment cores from 47 open-pollinated families of Norway spruce (Picea abies (L.) Karst.). The families had earlywood and latewood with significant differences in density for individual and cumulated rings and consequently for overall density. The latewood proportion had significant family variation for cumulated rings but not for all individual rings. Large fluctuations in environmental variance caused fluctuations in heritability estimates for successive rings. A strong decrease in environmental variance for all cumulated traits, especially from ring 3 to 5, resulted in a steady increase in heritability estimates. The latewood density had the highest heritability estimates and latewood proportion the lowest for both individual and cumulated rings. Overall density and the cumulated components at cambial age 12 showed strong genetic correlations with their respective traits at all younger ages.
Forfattere
Per Gerhard Ihlen B.J. CoppinsSammendrag
Arthothelillm lirellans and A. orbilliferum are reported new to Scandinavia. Both species were found in Hordaland, western Norway. Their ecology and European distribution are discussed, and distribution maps presented.
Forfattere
Ulrik Bräuner NielsenSammendrag
No abstract has been registered
Forfattere
Peder GjerdrumSammendrag
In pine, heart- and sapwood can in some respect be considered two different timber species, with divergent wood properties. The knowledge of their occurrence has thus been a task for wood scientists ever since the fundamental work of Pilz (1907) a century ago. Close to 1800 observations from all over Scandinavia are analysed. Conclusion is that the physiological conversion from sap- to heartwood in the living tree is under the sole control of time, i.e. years past since activity in the apical. Other factors (height in tree, tree or stand characteristics) seem to be without influence The prediction of heartwood amount in individual trees in a stand of known age is thus attainable. Accordingly, the estimation of age in a log cross-cut, and thus of mean annual ring width, is also feasible, once diameter and heartwood ratio is known. Experiments using IR photography indicate the potential of using such equipment in heartwood detection.
Forfattere
Svein SolbergSammendrag
No abstract has been registered
Forfattere
P.K. Egeberg Morten Eikenes E.T. GjessingSammendrag
In Norwegian lakes, organic nitrogen typically constitutes about 60% of the total dissolved pool of nitrogen. However, evaluation of its effect on aquatic ecosystems and its role as promoter of heterotrophic growth in water distribution systems is difficult because of restricted knowledge about the various forms of organically-bound nitrogen in water. On line standard wet chemical analysis of total nitrogen was combined with high-performance size exclusion chromatographic (HPSEC) separation of natural organic matter (NOM) for investigation of the distribution of nitrogen between size classes of NOM. It was found that the high molecular weight (HMW) size fractions (humic acids) are enriched in nitrogen relative to the low molecular weight (LMW) size fractions (fulvic acids, nominal molecular weights of about 1000 Daltons) by a factor of up to 10. The low molecular weight size fractions (a few hundred Daltons) are interpreted to be of autocthonous origin based on their low C/N ratios, and correlation with the eutrophic status of the source waters. It was observed that NOM from water sources surrounded by large catchments contains relatively more nitrogen in HMW size fractions than NOM from small catchments, except that bog-derived NOM is particularly enriched in HMW nitrogen.