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.
1986
Forfattere
Erik Christiansen Anders EricssonSammendrag
Coniferous trees resist invasion of their phloem and xylem by microorganisms through an induced defence reaction; resin-filled reaction zones are formed around the infections to stop the intrusion. The efficacy of the reaction is supposedly dependent on an ample supply of carbohydrates. Two hypotheses were formulated: (i) phloem starch reserves are consumed by the defence reaction; (ii) trees low in phloem starch are vulnerable to infection. To test the hypotheses, stem sections of Picea abies trees were mass inoculated with a pathogenic blue-stain fungus, Ceratoscystis polonica, associated with the spruce bark beetle Ips typographus. Stem starch concentration was manipulated through girdling. Mass inoculation lead to a significant decrease in phloem starch concentration. Starch reserves of single trees were not correlated to their resistance to infection. Translocation capacity of the phloem is suggested critical for the defence reaction.
Forfattere
Lita Greve Fred MidtgaardSammendrag
No abstract has been registered
Forfattere
Stein MagnesenSammendrag
No abstract has been registered
Forfattere
Peter Mulock Erik ChristiansenSammendrag
The spruce bark beetle, Ips typographus, was induced to attack Norway spruce by means of pheromone dispensers. The degree of attack on each tree was recorded and the trees were later categorized as surviving or dying, according to the degree of sapwood blue-staining caused by the attacks. A threshold of successful attack was observed; i.e. above a certain number of attacks the trees were successfully invaded by the beetles and their mutualistic blue-stain fungi. The height of this threshold increased with increasing tree vigour, measured as the relative increment of the sapwood cross-sectional area.
Forfattere
Kåre Olav VennSammendrag
No abstract has been registered
1985
Forfattere
A. KrólSammendrag
No abstract has been registered
Forfattere
Tore SkrøppaSammendrag
No abstract has been registered
Forfattere
John Eilif Hermansen Bendict Faye Tore Corneliussen Johnny Hofsten Hans VenvikSammendrag
The report is a conultancy for NORAD (Norwegian Agency for International Development) and Forest Division of the Tanzania Ministry of Lands, Natural Resources and Tourism. The report gives and overview over catcment forests i Tanzania, the Catchment Forestry Project and recommendation on catchment forest management.
Forfattere
Erik ChristiansenSammendrag
When Norway spruce trees were inoculated with Ceratocystis polonica, a dose-dependent response was recorded. Local resinosis near the inoculation sites decreased with increasing inoculum density; parallelled by an increasing degree of sapwood staining, and tree mortality. Suppressed trees, and trees showing growth decline appeared more susceptible than trees suffering less competition.
Forfattere
Harald Bergseth Alhaji S. JengSammendrag
No abstract has been registered