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.
1995
Authors
Wenche E. Dramstad Gary L.A. FryAbstract
Increasing interest in combining agricultural and nature conservation goals has focused on the potential beneficial role of remnant biotopes on farmland. This study examines the role of field boundaries and a small habitat island within cereal fields in providing a source of forage for bumblebees (Bombus Latr.), throughout one season. Transect techniques were used to assess bumblebee use of common types of boundary vegetation between crops and semi-natural habitats, and along a footpath within a small woodlot, in southeastern Norway. There were seven species of bumblebee in these habitats, which used only a small fraction of the total number of flowering plant species available to any extent; only nine out of a total of 78 flowering plant species received more than five visits. All bumblebee species had a preference for perennial herbs as forage resources. The quantity of floral resources, their spatial pattern and temporal constancy varied among sites with the least disturbed and open habitats being of greatest value to bumblebees. Length of field boundary and single date surveys are poor indices of the value of field boundaries to bumblebees.
Authors
Tore SkrøppaAbstract
No abstract has been registered
Authors
Gudmund Vollbrecht Pelle Gemmel Björn ElfvingAbstract
No abstract has been registered
Authors
Dan AamlidAbstract
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Authors
Susanne HardingAbstract
No abstract has been registered
Authors
Guro BrodalAbstract
No abstract has been registered
Authors
Tore SkrøppaAbstract
No abstract has been registered
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No abstract has been registered
Authors
Dan AamlidAbstract
No abstract has been registered
Authors
Franck Brignolas B. Lacroix François Lieutier Daniel Sauvard A. Drouet A.C. Claudot A. Yart Alan A. Berryman Erik ChristiansenAbstract
Two Norway spruce (Picea abies Karst.) clones, one resistant and the other susceptible to mass inoculation with Ophiostoma polonicum Siem., were compared with regard to their phenolic compositions and chalcone synthase (CHS) and stilbene synthase activities of their phloem before and at 6 and 12 d after artificial inoculation with sterile malt agar or O. polonicum. In unwounded phloem, the resistant clone differed from the susceptible clone by the presence of taxifolin glycoside, lower concentrations of stilbene glycosides, and higher CHS activity. After inoculation, ()-catechin concentration and CHS activity dramatically increased around the wound, particularly in the resistant clone. Stilbene synthase activity also increased, but more slowly and to a lower level, whereas the concentrations of stilbenes remained stable. Tanning ability decreased in the susceptible done, whereas it remained stable in the resistant one. It is proposed that the induced phenolic response of Norway spruce phloem consists of an activation of the phenolic pathway, finally leading to tannins and insoluble polymers. It is suggested that resistance to O. polonicum depends on the ability of the tree to easily activate the flavonoid pathway.