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.
2001
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In 1996, 7000 ha of pine forests were defoliated by the pine looper Bupalus piniaria in south-western Sweden.The susceptibility of trees of different defoliation classes (0, 30, 60, 90 and 100% defoliation) to beetle-vectored blue-stain fungi was tested in inoculation experiments.Forty and 120-year-old Scots pine trees were inoculated with `single\", i.e. a few inoculations of Leptographium wingfieldii and Ophiostoma minus, two blue-stain fungi associated with the pine shoot beetle Tomicus piniperda. The young trees were also \"mass\" inoculated with L. wingfieldii at a density of 400 inoculation points per m2 over a 60 cm stem belt.Host tree symptoms indicated that only trees with 90100% defoliation were susceptible to the mass inoculation.Single inoculations did not result in any consistent differences in fungal performance between trees of different defoliation classes, regardless of inoculated species or tree age class.Leptographium wingfieldii produced larger reaction zones than O. minus, and both species produced larger lesions in old than in young trees.As beetle-induced tree mortality in the study area occurred only in totally defoliated stands, mass inoculations seem to mimic beetle-attacks fairly well, and thus seem to be a useful tool for assessing host resistance.As even severely defoliated pine trees were quite resistant, host defence reactions in Scots pine seem to be less dependent on carbon allocation than predicted by carbon-based defence hypotheses.
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Air pollution induced changes in pine needle chemistry were observed at sample sites in the surroundings of the Pechenganikel smelter. Close to the smelter, elevated concentrations of Ni, Cu and S were found (Ni: 0.7-1 mmol/kg, CU: 0.4-0.5, and S 40-60 mmol/kg) Close to the pollution source needles were enriched in Ni and Cu by needle age. Correlation and principal component analyses show that changes in the element composition of pine needles depended on air pollution and on natural factors as well. The contribution from air pollution increased with needle age. Besides direct input of pollutants from atmosphere, soil contamination and nutritional disturbance contributed significantly to the observed changes.
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Epiphytic lichen vegetation on birch stems was studied in the border areas between Norway and Russia. The area is heavily influenced by sulphur dioxide pollution emitted from Russian nickel smelters.Hypogymnia physodes and Melanelia olivacea were the two most abundant lichen species on birch stems in the investigated area. However, the coverage of H. physodes and M. olivacea was clearly reduced in parts of the investigated area. The lichen vegetation increased with increasing distance from the pollution source, i.e. from a lichen desert to normal background levels. A different pattern of occurrence of the two lichen species was observed.
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No abstract has been registered