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.
2000
Forfattere
Helge Braastad Bjørn TveiteSammendrag
Det er ikke registrert sammendrag
Forfattere
Oddvar SkreSammendrag
Forsøk viser at mørkerespirasjonen i veksande skot av norsk gran (Picea abies (L.)Karst.) har samanheng med den daglege veksten. Liknande samanhengar er funne i bladskiver av bjørk (Betula pubescens Ehrh.) og alm (Ulmus glabra var. scabra Huds.). Årleg akkumulert respirasjon viser korrelasjon med utbreiingsgrensene til desse treslaga. Det er venta at klimaendringa på langt sikt vil føra til at tregrensene for dei undersøkte treslaga vil stiga med 400 m. Forsøk med bjørk viser at dette treslaget har eit stort potensial for temperaturtilpassing ved ulike kompensasjonsmekanismar.
Sammendrag
Measurement data on air, precipitation and canopy throughfall chemistry from a network of sites have been combined to study scavenging and deposition processes, with particular emphasis on the oxidised nitrogen species.High deposition rates of oxidised nitrogen occur in coastal areas of SW Norway. These are partly caused by high precipitation rates, partly also because a large fraction of the oxidised nitrogen is present as nitrate in large particles, which are rapidly removed by both wet and dry deposition processes.High wind speeds near the coast result in high concentrations of sea-salt particles in the air and high deposition rates of both nitrate and sea-salt particles, particularly in coniferous forest stands. HNO3 contributes on average only about 10-20% to the sum of aerosol nitrate and HNO3 (sNO(3)). Still, the combined dry deposition velocity of sNO(3) to these forest stands may be between 4 and 6 cm s(-1) on average.
Sammendrag
Relationships between crown density and growth of Norway spruce stands are presented, after removal of the effects of major natural influences. On 569 monitoring plots comprising 40 000 trees, crown density has been annually assessed during 1991 to 1996.Stand growth was determined from measurements of diameter and height in 1991 and in 1996. Various models explaining mean crown density and annual growth of the stands as a function of natural factors, like age and site index, were compared.The influence of the natural factors were then removed by recalculating crown density to residual values from one preferred model, and by recalculating growth to relative values given in percent of model predictions.Crown density and its residuals were positively correlated to growth. These relationships were weak in terms of their ability to explain variation (low R2). However, the various relationships consistently indicated that roughly 1% change in crown density corresponded to 1% change in growth. This relationship also included common spatial variation over Norway: a large part of southeast Norway had unexplained low crown density and unexplained low growth.Some other, smaller regional consistencies were found as well. The study supports the use of crown density assessments, and further it encourages the use of growth data in the search for major stress factors responsible for present forest condition.
Forfattere
Torstein KvammeSammendrag
Det er ikke registrert sammendrag
Sammendrag
The effects of forest fragmentation on the abundance of red fox Vulpes vulpes and pine marten Martes martes were studied by combining snow-track data (1994-1997) with forest stands habitat information at landscape level. Thirteen study areas located in boreal conifer and boreal birch forest were selected for the investigation.The decreasing proportion of older forest and increasing proportion of young forest in the landscapes positively affected track density of red fox. With the habitat classification used, landscape composition explained 46% of the spatial variation in fox abundance. Earlier habitat-studies in Scandinavian conclude that pine marten is a habitat specialist, with an affinity for old spruce habitats.With this in mind we surprisingly didn`t find any effects on tracks density along the fragmentation gradient. We have no data to explain this results, but we hypothesis that there is a source-sink population dynamics at regional scale. Still some large landscapes with high proportion of remnant habitats could be a source for the population in highly fragmentated landscapes.The abundance of red fox and pine marten were not negatively correlated, indicating that competition and intraguild predation by red fox do not determine abundance of pine marten on a landscape scale.Anyway, a comparative study from Fulufjllet national park indicate that the impact of red fox on pine marten increase if landscapes were transformed from large-grained patches of remnant to fine-grained mosaics of clear cuts and old forest. We conclude that human-caused forest fragmentation increased the predation pressure of red fox on small game species, but that the evidence against the pine marten is weaker.
Sammendrag
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Forfattere
Jenny Fäldt Halvor Solheim Bo Långström Anna-Karin Borg-KarlsonSammendrag
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Forfattere
Torbjørn OkstadSammendrag
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Forfattere
Torstein Lisland Halvor TorgersenSammendrag
Det er ikke registrert sammendrag