Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
1997
Forfattere
T. Vrålstad T. SchumacherSammendrag
Det er ikke registrert sammendrag
Forfattere
Rune Halvorsen Økland Eiliv Steinnes Tonje ØklandSammendrag
Det er ikke registrert sammendrag
Forfattere
Karin HansenSammendrag
Det er ikke registrert sammendrag
Forfattere
Naomi M. Saville Wenche E. Dramstad Gary L.A. Fry Sarah A. CorbetSammendrag
This paper presents the results of a bumblebee mark-reobservation study conducted in a fragmented agricultural landscape, where bumblebee resources (forage, and probably also nest sites) exist mainly on scattered remnants of semi-natural habitat. The results show that reobservations of bumblebees marked while foraging were numerous and in general at short distances (less than 50 m) from where they were marked. In contrast, when bumblebees were marked at the nest, the numbers of reobservations were very low, even though monitoring of nest traffic showed the nest to be very active during reobservation walks. The results indicate that bumblebees do not necessarily forage close to their nest, and that caution is needed if foraging area and nest location are based solely on the observation of foragers
Forfattere
Sören WulffSammendrag
Det er ikke registrert sammendrag
Forfattere
Dan AamlidSammendrag
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Forfattere
Bernt-Håvard ØyenSammendrag
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Forfattere
Halvor Solheim Les SafranyikSammendrag
The pathogenicity of the blue-stain fungi Ceratocystis rufipenni Wingfield, Harrington & Solheim and Leptographium abietinum (Peck) Wingf., associated with the spruce beetle (Dendroctonus rufipennis (Kirby)), was evaluated after inoculation of 35 Sitka spruce (Picea sitchensis (Bong.) Carrière) trees at densities of 200, 400, and 800 inoculation points/m2 in a 60-cm band at breast height. Trees were felled 5 months after inoculation to assess fungal infection and pathogenicity. Ten trees inoculated with C. rufipenni at the two highest densities were rated as dead at the time of harvesting whereas all trees inoculated with L. abietinum were rated as surviving or survival uncertain. Inoculation with C. rufipenni produced significantly longer lesions in the phloem and killed significantly more phloem than did L. abietinum. For both fungi, the percentage of dead phloem increased with increasing inoculation density. The percentage of occluded sapwood increased with increasing inoculation density of C. rufipenni, and all sapwood was occluded at 800 inoculations/m2. Inoculation with L. abietinum resulted in approximately 25% occluded sapwood and the occlusion was not affected by inoculation density. Ceratocystis rufipenni may contribute considerably to overwhelm spruce trees infested by D. rufipennis.
Forfattere
Darrell W. Ross Halvor SolheimSammendrag
Pole-size Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) were inoculated with two fungi (Ophiostoma pseudotsugae (Rumb.) von Arx and Leptographium abietinum (Peck) Wingf.) associated with the Douglas-fir beetle (Dendroctonus pseudotsugae Hopkins) to evaluate their pathogenicity. Pruning the lowermost 30% of the live crown had no effect on host tree defenses. Inoculation with O. pseudotsugae produced significantly longer lesions in the phloem and resulted in a significantly greater percentage of necrotic phloem than inoculation with L. abietinum. The percentage of occluded sapwood was also greater following O. pseudotsugae inoculations, but the difference was not statistically significant. Individual lesion lengths declined significantly with increasing inoculation density, but the total percentage of necrotic phloem increased significantly. Both fungi appeared to be better adapted to grow in sapwood than in phloem. None of the inoculated trees were dead after 5 months, but some were chlorotic with less than 30% functional sapwood within the inoculation band. The results suggest that these fungi may assist the Douglas-fir beetle in overcoming the defenses of live trees.
Sammendrag
Det er ikke registrert sammendrag