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.
2008
Abstract
Tree-killing bark beetles conquer healthy trees by means of pheromone mediated mass-attacks. The initial attackers select trees through a process of random landing and processing of tactile and short-range chemical stimuli. Inside acceptable hosts they produce aggregation pheromones that attract additional attackers. In a recent field experiment we induced defense responses in 60-year-old Norway spruce trees and monitored colonization by the spruce bark beetle Ips typographus. Induced stem sections had significantly less beetle colonization than control sections, with shorter parental galleries and fewer eggs deposited. In addition, fewer beetles were attracted to beetles tunnelling in induced bark. This reduced ability to attract conspecifics suggests that induced host defenses interfere with beetle pheromone production or emission. The mechanisms responsible for this are unknown, but may involve emission of volatile terpenes such as (E)-b-farnesene and linalool, which have been shown to increase up to 100-fold in induced Norway spruce trees. These compounds have been reported to attract natural enemies of herbivores or repel herbivores directly in other conifer-insect interactions.
Abstract
Seed production in Norway spruce (Picea abies) seed orchards may be severely reduced by insects attacking cones and seeds. Insects in several orders and genera are responsible for the damage, and at present there are no effective and environmentally acceptable control options. Studies in Sweden have shown promising results with spraying Bt (Bacillus thuringiensis var. kurstaki x aizawai) against species of Lepidoptera, but for other pests other control methods must be developed....
Authors
Christian Guido BrucknerAbstract
No abstract has been registered
Authors
Christian Guido Bruckner Peter, G. KrothAbstract
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Abstract
Whereas lichen growth rates have received considerable attention, comparatively few detailed studies of growth patterns have been carried out. Generally, most lichens seem to grow apically, with pseudomeristomatic tissue confined to lobe margins and branch tips. However, some species appear to retain the capacity to expand throughout the thallus. Such intercalary growth processes have proved difficult to confirm in the field for two- and three-dimensionally growing folious and fruticose forms. Using transplants of the conspicuous, one-dimensionally growing Usnea longissima Ach., we document that intercalary growth actually does occur, with thalli expanding geometrically in length with a doubling time of less than a year under favorable conditions.
Authors
Anders Lunnan Inge Stupak Antti Asikainen Karsten Raulund-RasmussenAbstract
Forest bioenergy is utilisation is closely related to issues of pronounced political importance such as energy policies and international processes for sustainable management, especially climate change and sustainable forest management. The book chapter discusses both aspects and end up by summing up the contributions of the WOOD-EN-MAN project.
Authors
Berit Nordskog David M. Gadoury May Bente Brurberg Tor Håkon Sivertsen R. Kennedy Arne HermansenAbstract
No abstract has been registered
Authors
Toril Drabløs EldhusetAbstract
Oxalate exuded constitutively by Picea abies / Laccaria bicolor may lead to rhizosphere oxalate concentrations relevant for Al resistance.