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.
2006
Abstract
No abstract has been registered
Abstract
The effect of plant age and cold hardening on resistance to pink snow mould caused by Microdochium nivale was studied in perennial ryegrass. Resistance to M. nivale was estimated as relative regrowth after inoculation and incubation under artificial snow cover at 2 degrees C. Resistance increased with increasing plant age. Cold hardened and unhardened plants of the same age displayed identical resistance. Preliminary studies indicate that expression of genes coding for the PR proteins chitinase and PR-1a increased during incubation of inoculated perennial ryegrass, but no clear difference in expression of these genes was found between plants of different ages, or in hardened versus unhardened plants.
Abstract
The paper analyses and discusses possible impacts on Norwegian agriculture of an EU membership based on the regionalized agricultural sector model CAPRI. Norwegian agriculture is characterized by a small-scale farming structure and high levels of support. Previous analyses have shown that Norwegian agriculture is expected to undergo dramatic changes because of EU membership in terms of farm income, production and structural change. Our study indicates that a substantial share of the agricultural production can be maintained at the national level. Milk and crop production may remain largely unaffected, while meat production decreases in the range of 10–20% compared to a reference run without membership. However, a reduction in total farm income by about 40% indicates that structural adjustments will follow EU accession. The results are discussed in view of the pattern of adjustments observed in Finland and Austria after EU accession in 1995. The need for the dairy industry to take advantage of the improved market access is stressed. Attention is also called to some strengths and limitations of the CAPRI model to analyse large-scale policy changes and to identify model improvements as an area of future research.
Authors
Frode VeggelandAbstract
No abstract has been registered
Authors
Kjersti Holt HanssenAbstract
An increasing interest for uneven-aged forestry requires more knowledge concerning the impact of selective cuttings on the physical environment, and the effect of an uneven-aged forest structure on establishment and growth of the regeneration. Our objectives were to correlate pre-harvest growth and vitality of advance seedlings and saplings with light levels in the stands, and to measure the change in light availability following selective cuttings. We performed a selective cutting with two levels of removal (40 and 60 % of standing volume) in three uneven-aged stands in eastern Norway, two Norway spruce (Picea abies) stands and one Scots pine (Pinus sylvestris) stand. The standing volumes in the spruce stands were approximately 300 m3 ha-1, in the pine stand 180 m3 ha-1. The selective cutting was aimed at removing the economically ripe trees, resulting in the removal of large as well as damaged and diseased trees. Light levels were measured with hemispherical photography before and after cutting, and sapling growth and vitality was registered. Spruce sapling vitality and growth before cutting varied with light conditions. Saplings with good vitality on average received 26 % of full daylight. Few pine saplings had good vitality even though the average light level in the pine stand was 35 %, illustrating the difference in shade tolerance between the two species. The relationship between light levels and sapling growth might be caused by the availability of both light and soil resources, as a large gap will offer a better supply of nutrients and water as well as light. The selective cutting increased average light levels with 10-30 percent points. In the spruce forests, the frequency distribution curve of measured light values was rather narrow and peaked before harvesting but wide and low afterwards (Fig. 1), indicating that the selective cutting created a broad range of site conditions below the canopy. For the pine forest, the light distribution curve kept a rather narrow, unimodal shape also after cutting.
Authors
Per Otto Flæte Erlend Ystrøm Haartveit Kjell VadlaAbstract
Considerable areas in the northern parts of Norway are afforested with Picea abies (L.) H.Karst. (Norway spruce), Picea × lutzii Little (Lutz spruce), and Picea sitchensis (Bong.) Carrière (Sitka spruce). The species have different machining and wood properties but are similar in visual appearance. We evaluated whether near infrared (NIR) spectroscopy combined with multivariate statistical modelling could be used to identify wood from these three species. In all, 83 wood specimens were available for analyses, 36 of which were used as a test set for model validation. NIR spectra were obtained on the cross-sectional surfaces. An initial principal component analysis showed that little information from the first and second components could be used for discrimination, but in score-plots of the third and fourth components the samples from the tree species formed clusters. This showed that the NIR spectra did contain information relevant for tree species identification, and that only a small fraction of the total variance could be used for that purpose. For classification of the wood specimens, partial least squares discriminant analyses were applied. All 47 specimens in the training set were fitted into the correct group. The test set validated results showed that except for two wood specimens, all specimens were correctly classified. The two misclassified samples were Sitka spruce. This study showed that development of well-performing rediction models for differentiation of wood from Norway spruce, Lutz spruce, and Sitka spruce is possible.
Authors
Gilbert Kamgan Nkuekam Jolanda Roux Halvor Solheim Michael J. WingfieldAbstract
No abstract has been registered
Abstract
A method for quantitative determination of extractives from heartwood of Scots pine (Pinus sylvestris L.) using gas chromatography (GC) with flame ionization detection (FID) was developed. The limit of detection (LOD) was 0.03mg/g wood and the linear range (r=0.9994) was up to 10mg/g with accuracy within ±10% and precision of 18% relative standard deviation. The identification of the extractives was performed using gas chromatography combined with mass spectrometry (GC–MS). The yields of extraction by Soxhlet were tested for solid wood, small particles and fine powder. Small particles were chosen for further analysis. This treatment gave good yields of the most important extractives: pinosylvin, pinosylvin monomethyl ether, resin acids and free fatty acids. The method is used to demonstrate the variation of these extractives across stems and differences in north–south direction.
Abstract
In Norway exterior wood structures have traditionally nearly exclusively been made of treated and untreated Norway spruce (Picea abies (L.) Karst) and Scots pine (Pinus sylvestris L.). In recent years there has been a tendency that other tree species, like various domestic hardwoods and imported species have been used in exterior above ground applications, often unfinished. For several wood species, especially hardwoods, information regarding the durability in use class 3 is lacking. The test procedures prescribed in the European standards, both laboratory and field tests, have some weaknesses regarding to natural durability testing. Hence, some new methods for accelerated above ground testing have been put forward. The main objectives of this project are to evaluate natural durability of Norwegian wood species for above ground applications, and to study various methods for assessing decay in wood. This paper presents the material and methods used in the project, and report the results from double layer tests after one year of exposure. No decay was detected, but almost all wood species were considerably discoloured. Thuja (Norw.), Thuja (Am.), Intsia and Tectona had the least amount of discolouration. The Norwegian softwood species had generally less discolouration than the Norwegian hardwood species. CCA and Cu preservative impregnated and FA modified Pinus sylvestris sapwood had more cracks than most of the untreated wood species. Moreover, some of the Picea abies qualities and Pinus sylvestris sapwood samples had substantial amounts of cracks.
Authors
Ingjerd Solfjeld Øystein JohnsenAbstract
We have examined shoot and root growth and the concentration of carbohydrates in seedlings of a northern (67oN) and a southern (61oN) ecotype of Betula pendula Roth. cultivated at root-zone temperatures of 2, 6, 12 and 17oC. Three hydroponic experiments were conducted in controlled environments. We used three different pretreatments before seedlings were subjected to the experimental temperature treatments. Actively growing seedlings that were acclimated to the hydroponic solution for 3 weeks at a root temperature of 17oC, continued to grow at all the experimental temperatures, with an expected increase in growth from 2 to 17oC. However, if we started with ecodormant cold stored plants or used seedlings grown actively in perlite, no growth was observed at 2oC and only minor growth was found at 6oC. The highest root temperature always produced the best growth. The concentration of nonstructural carbohydrates was higher in seedlings grown at 2oC than at 17oC, and this is probably due to extensive incorporation of carbohydrates into cell walls and otherstructural elements at 17oC. We found no evidence for differences between the two ecotypes in root growth, in timing of bud burst, but shoot growth terminated in the northern ecotype in the first experiment because the natural photoperiod was below the critical value. Our study highlights the importance of post-transplantation stress (planting check) related to root growth, and that root threshold temperatures may change according to the way plants are pretreated.