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.
1992
Forfattere
Halvor Solheim Kåre Olav VennSammendrag
Det er ikke registrert sammendrag
Forfattere
Halvor SolheimSammendrag
Healthy Norway spruce trees infested by the bark beetle Ips typographus were investigated weekly for 10 weeks to examine the early stages in fungal invasion. The study was performed in southeastern Norway during an epidemic period. The fungal association consisted of Ophiostoma species and an undescribed Graphium species, which invaded the sapwood in an obvious succession. The pathogenic species Ophiostoma polonicum was the first invader of both phloem and sapwood and was always in the leading edge of fungal penetration into sapwood. Ophiostoma bicolor followed O. polonicum in the sapwood invasion. These species were successively replaced by Graphium sp. 1 , Ophiostoma pennicillatum and Ophiostoma ainoae. Ophiostoma pellicillatum seems to be more adapted to colonizing the phloem than the sapwood. The earliest invaders were the species most frequently carried by the beetles.
Sammendrag
Stadige tilførsler av langtransporterte luftforurensninger vil kunne føre til en svekkelse av skogen og derigjennom økt omfang av vanlige skader og sykdommer. Arbeidet med diagnostisering av skogskader er derfor styrket gjennom det såkalte brannkorpset, for å kartlegge omfanget av skader og så langt som råd er å finne en årsakssammenheng. Denne rapporten gir hovedresultatene av dette arbeidet i 1991. Det har vært mange tilfeller av gulfarget barmasse, først og fremst på gran. Symptomene har variert, og årsakene er ikke fullstendig klarlagt. Næringsmangel er påvist i flere tilfeller. Klimapåkjenninger, særlig tørke, kan i mange tilfeller ha vært utløsende årsak til disse symptomene. Enkelte steder over hele landet var det klimaskader pga. unormalt høy og vekslende temperatur gjennom vinteren og våren 1990-91. Flere steder var det såkalte frostbelter.Skader ble observert på flere treslag, og på lyng. Almesjuke fikk et betydelig omfang i 1991, noe som trolig har sammenheng med mangelfullt saneringsarbeid. Luftforurensninger kan ha vært predisponerende for noen av skogskadene, men det er ikke mulig å si hvor stor betydning dette kan ha hatt.
1991
Forfattere
Dan AamlidSammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Paal KrokeneSammendrag
Det er ikke registrert sammendrag
Forfattere
Guro BrodalSammendrag
Det er ikke registrert sammendrag
Forfattere
Halvor SolheimSammendrag
Det er ikke registrert sammendrag
Forfattere
Halvor Solheim Bo LångströmSammendrag
test av sammendrag
Forfattere
Halvor SolheimSammendrag
During an outbreak in the 1970\"s, millions of Norway spruce trees were killed by the spruce bark beetle Ips typographus. At that time, little was known about the associated fungi and their role in the tree-killing process. Studies were started to elucidate ecological aspects of fungi associated with I. typographus, with special emphasis on the fungal invasion process.I. typographus has no mycangium and caries a variety of fungal spores, externally in pits on the pronota and elytra and internally within the digestive tract. Spores are also transmitted by phoretic mites. Most species belong to Ophiostomataceae and confusions within some important species have been put right. The fungal flora aseetle, but with some variations. Four species proved to be common in Norway, but Ophiostoma polonicum was more frequent in epidemic areas man in endemic areas . The frequency of this species is thus suspected to increase during epidemics. Studies during epidemic conditions revealed that the fungi invaded the sapwood of infested Norway spruce trees in an obvious succession, with O. polonicum in the leading edge of fungal penetration until heartwood was reached. The species found to be most commonly transmitted by I. typographus were shown to be first in the succession.The temperature is important for the rate of fungal invasion and the development of visible blue-stain, which occurred close to the leading edge of fungal penetration. The fungal colonization of sapwood leads to a gradual decrease in the moisture content, followed by desiccation symptoms in the foliage of infested trees. The tree trunks soon reached a moisture level not favourable for decaying Hymenomycetes, except near the base of the trees.The primary invader O. polonicum appeared to be pathogenic to Norway spruce trees when mass inoculated, while the secondary invaders were not at the given load of infection doses. However, the inoculation doses are of importance for the success of inoculated fungi. Judging from the large reaction zones in the phloem made by same secondary invaders, they may play an important role in the tree killing process in areas with low frequencies of O. polonicum. O. polonicum can kill other species of spruce used in European forestry and Douglas fir, so the fact that conifers other than Norway spruce rather rarely are attacked by I. typographus seems not to depend on the absence of a pathogenic fungus to overwhelm the trees.The fungi associated with I. typographus are sensitive to the lesion resin produced by Norway spruce trees in response to the fungal invasion. The potential of O. polonicum to be a primary invader seems to be linked to its rapid growth rate and ability to grow for a prolonged period under oxygen-deficient conditions. In conclusion, it seems that the interrelationship between Norway spruce, I. typographus and associated fungi is similar to other interrelationships. One of the associated fungi, O. polonicum, appeared lo play a key role in overwhelming infested trees due its abilily to grow for a prolonged period in wood with low oxygen pressure.