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.

1993

Abstract

Seedlings of mountain birch and lowland birch were grown for two seasons in fertilized peat at two different elevations in south-western Norway at 60 N (50 and 450 meter). Seedlings from a local mountain birch population from western Norway were most successful at the high elevation site in terms of annual production, and had the highest C/N ratio, while the lowland population and the lowland birch seedlings showed the highest growth rates at the low-elevation site. The C/N ratios in these plants, however, were very low. It is concluded that the survival strategy is different at the two sites. At low-elevation sites the competition factor seemed to be the main selective force, and the most fast-growing plants were most successful, while at high elevations abiotic factors came into account, and a high source strength rather than high growth rates seemed to be the most important factor for plant survival. Chemical analysis of annual stemt tissue showed that all birch populations increased their concentrations of soluble sugars, soluble proteins and organic phosphorus in winter as a response to frowt hardening, the highest concentrations usually found in subarctic and subalpine populations.

Abstract

In a field experiment in central Sweden, the vigour of 25-yr-old Scots pines was manipulated by pruning, prior to inoculation with Leptographium wingfieldii and Ophiostoma minus, two blue-stain fungi associated with Tomicus piniperda. Our main purpose was to correlate fungus invasion and host defence reactions with host vigour. Both fungi invaded the inner bark and the sapwood at the points of inoculation. L. wingfieldii caused larger lesions in the bark, but O. minus tended to grow faster in the sapwood. The flow of primary resin was related to tree vigour, whereas carbohydrates present in needles and stem phloem were not. Lesion formation and the content or composition of resin acids in lesions did not differ between fungi or pruning treatments.