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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

Abstract

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.

Abstract

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.