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.
2010
Forfattere
Ommo Hüppop V Dierschke Sverre Kobro J DierschkeSammendrag
The number of Bullfinches recorded on the offshore island of Helgoland (SE North Sea) in the autumn migration periods (late September to late December) from 1972 to 2009 are negatively correlated to the supply of rowanberries in Norway. Many Bullfinches only occurred, when this important winter food was scarce in Norway. As such correlation was found also for trapping sites at the Baltic Sea (Christiansø, Falsterbo), irruptively migratory behaviour of Scandinavian Bullfinches appears to act on a large geographical scale. This is underlined by the results of a linear model, showing that the occurrence of Bullfinches at Helgoland is best explained by trapping numbers in Falsterbo and their interaction with rowanberriy supply in Norway. Actually, not all invasions recorded at Falsterbo reach Helgoland, probably due to its situation far offshore: migrating passerines do not cross the German Bight in any weather situation, but instead often follow the coastline without touching Helgoland. It is stressed that data collected unsystematically are appropriate for analyses of invasions.
Sammendrag
Vi har sju norske storferaser og seks av disse har så små populasjoner at de regnes som truet. Norsk genressurssenter har det siste året tatt et krafttak for å få et fullstendig manntall over disse seks rasene ved å oppgradere slektskapsdatabasen Kuregisteret i samarbeid med Geomatikkseksjonen ved Skog og landskap. Men hva er egentlig en norsk storferase?
Sammendrag
Scenarios of climate changes indicate longer and more frequent spells of mild weather during winter in northern latitudes. De-hardening in perennial grasses could increase the risk of frost kill. In this study, the resistance to de-hardening of different grass species and cultivars was examined, and whether the resistance changes during winter or between years, was tested. In Experiment 1, two cultivars of timothy (Phleum pratense L.) and perennial ryegrass (Lolium perenne L.) of contrasting winter hardiness were grown under ambient winter conditions, transferred from the field in January and April 2006 to the laboratory for 9 d with controlled de-hardening conditions of 3°C, 9°C and 15°C. The timothy cultivars were tested at 3°C, 6°C and 9°C in a similar experiment (Experiment 2) in January 2007. De-hardening, measured as decrease in frost tolerance (LT50), was less in timothy than in perennial ryegrass and increased with increasing temperatures. The northern winter-hardy cultivar Engmo of timothy de-hardened more rapidly than the less-hardy cultivar Grindstad, but had higher initial frost tolerance in both experiments, whereas there was less difference between cultivars of perennial ryegrass in Experiment 1. Cultivar Grindstad of timothy lost all hardiness in early spring at all temperatures, whereas cultivar Engmo maintained some hardiness at 3°C. Cultivar Engmo de-hardened at a lower rate in 2007 than in 2006, in spite of similar frost tolerance at the start of de-hardening treatment in both years. This indicates that the rate of de-hardening was controlled by factors additional to the initial frost tolerance and that autumn weather conditions might be important for the resistance to de-hardening.
Forfattere
Lars Tørres Havstad Trygve S. Aamlid Trond Maukon HenriksenSammendrag
The marked for cereal cover crop straw and herbage seed straw has diminished in many seed production areas due to less lifestock. Seed growers therefore want to chop and return the straw both in the sowing year and in the seed harvest years. The objectives of this research were (1) to compare decomposition rates of straw of barley and wheat cover crops and timothy (Phleum pratense L.), meadow fescue (Festuca pratensis Huds.), and red clover (Trifolium pratense L.) seed crops, (2) to study the effect on soil microbial activity of adding mineral nitrogen or fresh leaves from undersown seed crops, and (3) to evaluate the effect of straw placement / soil contact on straw decomposition rates. Microbial activity / straw decomposition rates were evaluated by regular measurement of CO2 production in four laboratory incubation experiments lasting for 150-161 days. Microbial activity was always enhanced by adding straw on the soil surface. Straw of barley resulted in higher CO2 production than straw of wheat, while straw of red clover and meadow fescue resulted in higher CO2 production than straw of timothy. Inclusion of fresh leaves of white clover and timothy increased CO2 production during the first and second half of the incubation experiments, respectively. Neither in the sowing year nor in the seed harvest year was microbial activity stimulated by adding fertilizer nitrogen, but soil mineral nitrogen by the end of the experiments was higher after adding fertilizer or fresh leaves, and lower after adding grass seed straw. Presumably due to higher humidity, straw decomposition in a field experiment was higher in timothy stubble than in wheat stubble and higher at 2 cm than at 10 cm above the soil surface. For practical seed production, growers are recommended to leave short stubble, to chop the straw as finely as possible, and to distribute the straw evenly on the surface in close contact with soil particles.
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Plants use an array of responses to pathogenic infection. Understanding of the underlying defence mechanisms may lead to new strategies for reducing the damage. Our objective here was to study histological and cytological responses in Norway spruce of different ages (from seedlings to mature trees) to infection with several pathogenic organisms (Pythium dimorphum, Ceratocystis polonica and Heterobasidion annosum) and compared them to effects of mechanical wounding. To visualize the reaction on infection/wounding we used different histological staining techniques followed by laser confocal microscopy and TEM. Primary roots of Norway spruce seedlings were infected with P. dimorphum, while mature trees (about 30 years old) were infected with C. polonica, H. annosum and wounded. In seedling roots the hyphae of P. dimorphum penetrated the tissue rapidly and colonized the root within 24 hours. In the infected tissue the lignin concentration doubled within 6 days compared to non infected roots. General response to infection by C. polonica and H. annosum in mature trees was the production of lignosuberised wound periderm, accumulation of polyphenolic aggregates in living parenchyma cells in the phloem and development of traumatic resin ducts in the xylem. Upon wounding, we observed a similar, but less intense response. In conclusion, although we tested fungi belonging to different taxonomical and ecological groups, the responses were similar, differing in intensity and timing of the defence response mainly. The response seems to be similar but dependent on the degree of susceptibility in the individual trees and clones.
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Degelia cyanoloma (Schaer.) H. H. Blom & L. Lindblom is resurrected from synonymy and elevated from varietal rank to species. The taxon was earlier referred to D. plumbea (Lightf.) P. M. Jørg. & P. James, however, several discontinuous character states distinguish the two species. Degelia cyanoloma is characterized morphologically by having a large thallus that is pale greyish when dry, lobes that are composed of consecutive trough-shaped segments with an upper surface without squamules, no isidia or soredia, and apothecia discs that are dark reddish brown to blackish. Degelia cyanoloma has a euoceanic distribution and is known from western Europe (Norway, France, Great Britain, Ireland, Portugal, Spain). Based on results from studies of morphology, we hypothesize that D. atlantica (Degel.) P. M. Jørg. & P. James is the closest relative of D. cyanoloma among the European species of the genus whereas D. plumbea is closely related to D. ligulata P. M. Jørg. & P. James.
Forfattere
Hans Haavardsholm Blom Louise LindblomSammendrag
Degelia cyanoloma (Schaer.) H.H. Blom & L. Lindblom is resurrected from synonymy and elevated from varietal rank to species. The taxon was earlier referred to D. plumbea (Lightf.) P.M. Jørg. & P. James, however, several discontinuous character states distinguish the two species. Degelia cyanoloma is characterized morphologically by having a large thallus that is pale greyish when dry, lobes that are composed of consecutive trough-shaped segments with an upper surface without squamules, no isidia or soredia, and apothecia discs that are dark reddish brown to blackish. Degelia cyanoloma has a euoceanic distribution and is known from western Europe (Norway, France, Great Britain, Ireland, Portugal, Spain). Based on results from studies of morphology, we hypothesize that D. atlantica (Degel.) P.M. Jørg. & P. James is the closest relative of D. cyanoloma among the European species of the genus whereas D. plumbea is closely related to D. ligulata P.M. Jørg. & P. James.
Sammendrag
Det er ikke registrert sammendrag