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.
2005
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Bernt-Håvard ØyenSammendrag
Stand growth and yield models for Sitka spruce plantations in Norway are presented, and new yield tables are constructed.
Sammendrag
The spruce bark beetle is the most serious pest of mature spruce trees in Eurasia. At low population densities it breeds in weakened or newly dead trees, but at high densities it becomes a tree killer. The exact factors triggering outbreaks are not fully understood, but climatic variables are important candidates. Populations in SE Norway have been monitored since 1979. Various time series methods are used to explore the role of climate in outbreaks of the spruce bark beetle in space and time, and to estimate the distribution of bivoltism under different scenarios of climate change. Large windfall events appear to be a major synchronizer of beetle outbreaks in areas subjected to regionalized weather systems, and the northern border of bivoltism may be moved towards north as a function of increasing temperature. Preliminary models of the population dynamics emphasize the frequency of large windfall events and phenological changes due to temperature increase. Final aims are to estimate the regional risks of forest damage under different scenarios of climate change, and to describe practices that may reduce the impact for forest managers.
Forfattere
Peder GjerdrumSammendrag
Ingen kan unngå å legge merke til de dype spor sangen om Kalevala har satt i vår del av verden, i handel, kultur og dagligliv. Artikkelen presenterer det viktigste skogstoffet, som naturfortelling, mytologi og naturfantasi, holdt opp mot våre norske tradisjoner og fortellinger. Kaleva og finner er to sider av samme sak. Pihlström sier: `I den nationalromantiska konsten och litteraturen får den uplöjda vildmarken bli en symbol för fosterländska känslor`. Også finnene som kom til Norge på 1600-tallet opprettholdt en tett tilknytning til skogen, så tett at de gjerne ble kalt `skogfinner`. I 1686 ble det tatt opp et fullstendig finnemanntall. Til tross for at de bodde øde, ofte langt fra bygdene, opplyses det at `de har gjort sin plikt og tjent i kongens klær, de levde skikkelig i menigheten og søkte kirke og ting`.
Forfattere
Bernt-Håvard ØyenSammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
At least three mechanisms are known to cause synchrony among spatially separated insect populations: 1) dispersal among populations, 2) synchronous stochastic effects, often referred to as the Moran effect, and 3) trophic interactions with other species that are either themselves synchronized or mobile.The present study brings in the role of insect taxa for spatial synchrony. The spatial synchrony observed in several North American and Eurasian epidemic bark beetles was compared with patterns of synchrony in outbreaks of defoliating forest Lepidoptera, revealing a marked difference between these two major insect taxa.The bark beetles exhibited a generally lower degree of spatial synchrony than the Lepidoptera, possibly because bark beetles are synchronized by different weather variables that are acting on a smaller scale than those affecting the Lepidoptera, or because inherent differences in their dynamics leads to more cyclic oscillations and hence more synchronous spatial dynamics in the Lepidoptera. Among the epidemic bark beetles tested, spatial synchrony of outbreaks in the Eurasian spruce bark beetle Ips typographus was significantly higher than for the other species.
Sammendrag
Wood samples treated with ammonium copper quat (ACQ 1900 and ACQ 2200), chromated copper arsenate (CCA), Tanalith E 3491 and Wolmanit CX-8 have been studied in accelerated weathering experiments. The weathering experiment was performed by cycles of 2 h UV-light irradiation followed by water spray for 18 min. The changes on the surface of the weathered samples were characterized by roughness and color measurements on the samples with 0, 200, 400 and 600 h of total weathering.The objective of this study was to investigate the changes created by weathering on impregnated wood with several different wood preservatives. This study was performed on the accelerated weathering test cycle, using UVirradiation and water spray in order to simulate natural weathering. Surface roughness and color measurement was used to investigate the changes after several intervals (0200400600 h) in artificial weathering of treated and untreated wood.
Forfattere
Harald Kvaalen Ola Gram Dæhlen Anne Tove Rognstad Borgny Sveen Grønstad Anne Eskild Nilsen Ulrika EgertsdotterSammendrag
Det er ikke registrert sammendrag
Forfattere
Harald Kvaalen Ola Gram Dæhlen Anne Tove Rognstad Borgny Sveen Grønstad Ulrika EgertsdotterSammendrag
Seeds of Abies lasiocarpa (Hook.) Nutt. (subalpine fir) were dissected, and the different parts were analyzed for elemental composition. The data were used to design a novel growth medium for initiation of somatic embryogenesis. Embryogenic cultures were initiated from immature zygotic embryos from six open-pollinated families of A. lasiocarpa on three different media.The frequency of initiation was the highest in early to mid-July when the zygotic embryo explants were ca. 0.8 mm long. Thereafter the response declined rapidly.The culture media did not significantly affect the initiation frequencies, but the subsequent growth and culture survival was dependent on the culture medium. On the Schenk Hildebrandt medium, many cultures ceased to grow and died. Several of the decaying cultures were rescued after transfer to one of the new media. Proliferating cultures could be stimulated to produce mature embryos. Of 2510 mature somatic embryos, 212 (8.4%) converted to plants, and 35 plants have grown over two periods.