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.
2011
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
A rapid increase in the frequency of Dutch elm disease (DED), a wilting disease of elm trees caused by bark-beetle vectored fungi, was observed in the early 1990s on several wych elm stands around Oslofjord, southern Norway. To examine the current status of the disease and its impacts on elm population, disease frequency and size distribution of elms were recorded at four locations. Northern parts of Lier, a municipality most affected by DED in Norway 15 years ago, showed in the survey season 4% disease frequency, whereas 13.8% of trees were dead, the dead trees having accumulated over several years in the unmanaged stands. In southern parts of the municipality the mean disease and death percentages were 1.9 and 2.4%. Compatible with their low disease incidence in early 1990s, the other two areas now examined, municipality of Larvik and district of Grenland, showed comparably low frequency of DED. Northern part of Lier showed significantly higher overall density of elm trees per hectare than the other examined areas, and also the small elms below 5 cm in d.b.h. were most frequent in this region. In contrast, the density of large trees was lower in northern Lier than in the other examined areas. These data suggest that regeneration of the tree is not prohibited owing to the disease but that the large trees have been locally reduced in frequency as a result of DED. The superior general density of elm trees in northern Lier, owing to the exceptionally rich soil in the warm southern slopes of the region,> may have contributed to the rapid increase of DED in the area 15 years ago and to the subsequent settlement of the disease outbreak as a chronic stage.
Foredrag – National Forest Inventory in Norway
Karl Thunes, Mariela Covault Tyrihjell, Rasmus Astrup
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Jan Svtlík Isabella Børja Toril Drabløs Eldhuset Holger Lange Frank Newell Kidder Douglas Lawrence GodboldSammendrag
Fungi are the main degraders of organic matter and are associated symbiotically with over 80% of terrestrial plants (Smith and Read 1997). Thus, the extent of the mycelial network is an indicator of the decomposing or symbiotic activity. Although the importance of fungi in soil is undisputable, the determination of the extent of hyphal mats and the hyphal biomass is difficult to assess. Methods for estimating hyphae in soil are mostly based on the gridline intersect method originally developed to determine the root length or recently by measuring of the ergosterol content, fungal sterol found in the cell membranes....
Sammendrag
Styrt beitedrift ved bruk av inngjerding kan være en løsning for å unngå store tap til rovvilt. Det er imidlertid en oppfatning at denne driftsformen kan være en utfordring med hensyn til dyrevelferd, helse og kjøttproduksjon. I løpet av en tre-års periode har Bioforsk Nord Tjøtta kartlagt åtte sauebesetninger med tilhørende fem beiteområder i Indre Namdal, som benytter denne driftsformen. Målet med prosjektet er å finne en god balanse mellom arealgrunnlaget og dyretall ved hjelp av estimering av beitekapasitet, og velferdsvurdering av sauene for å sikre god dyrevelferd og tilfredsstillende kjøttproduksjon på inngjerdete beitearealer. Dette prosjektet viser at det er mulig å oppnå tilfredsstillende dyrevelferd og produksjonsresultater på inngjerdet beite men at det krever en del oppfølging av dyrene i beitesesongen, spesielt med hensyn til parasittproblematikk og beitetilgang.
Forfattere
Anna Maria Jönsson Susanne Harding Paal Krokene Holger Lange Åke Lindelöw Bjørn Økland Hans Peter Ravn Leif Martin SchroederSammendrag
The Eurasian spruce bark beetle, Ips typographus, is one of the major forest insect pests in Europe, capable of mass-attacking and killing mature Norway spruce trees. The initiation and development of a new generation are strongly controlled by temperature and a warmer climate may affect the number of generations that is produced per year and hence the outbreak dynamics. Experimental knowledge regarding reproductive diapause adaptations is, however, too sparse for largescale assessments of future trends. We developed a model description of diapause induction, and used gridded observational temperature data to evaluate multiple combinations of day length and temperature thresholds to find the model parameterisation most coherent with I. typographus monitoring data from Scandinavia. The selected model parameterisation is supported by European literature data, though further experimental studies are required to analyse population specific adaptations and capacity for adjustments to changing climate conditions. Implementing the model description of reproductive diapause in a temperature driven model of bark beetle phenology (swarming activity and development from egg to mature bark beetle), enabled us to assess the length of the late summer swarming period that is a critical determinant of the risk of forest damage. By using regional climate model data we show that higher temperatures can result in increased frequency and length of late summer swarming events, producing a second generation in southern Scandinavia and a third generation in lowland parts of central Europe. Reproductive diapause will not prevent the occurrence of an additional generation per year, but the day length cues may restrict the length of the late summer swarming period.
Forfattere
Igor A. Yakovlev Carl Gunnar Fossdal Tore Skrøppa Harald Kvaalen Jorunn Elisabeth Olsen Øystein JohnsenSammendrag
Det er ikke registrert sammendrag
Forfattere
Igor A. Yakovlev YeonKyeong Lee Bjørn Rotter Tore Skrøppa Jorunn Elisabeth Olsen Øystein Johnsen Carl Gunnar FossdalSammendrag
Det er ikke registrert sammendrag
Forfattere
Igor A. Yakovlev YeonKyeong Lee Bjørn Rotter Tore Skrøppa Øystein Johnsen Jorunn Elisabeth Olsen Carl Gunnar FossdalSammendrag
Det er ikke registrert sammendrag