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.
2017
Sammendrag
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Sammendrag
De norske askeskogene er en nordlig utløper av større askeskoger i Europa som spredte seg nordover etter siste istid. Vi har undersøkt genetisk variasjon i ask (Fraxinus excelsior) og funnet at asken i Norge fulgte en østlig innvandringsvei fra overvintringsområder i SørøstEuropa. Mens den genetiske variasjonen i stor grad ble opprettholdt gjennom Europa, gikk svært mye av den genetiske variasjonen tapt nordover langs kysten av Norge, hvor vi også finner de største genetiske forskjellene mellom askepopulasjonene. Kunnskap om askens genetiske variasjon er verdifull for forvaltningen med tanke på framtidig restaurering og bevaring av genetiske ressurser nå som asken er truet av askeskuddsjuke.
Sammendrag
The Christmas tree industry in Norway is increasing and Abies lasiocarpa is, together with Abies nordmanniana, the most common exotic species for Christmas tree production. A. lasiocarpa today constitutes ca. 50% of the fir sold in Norway, and there is high demand for sufficient supply of high-quality seed and knowledge of seed sources with a potential for high Christmas tree quality. Two experimental plots were established to identify seed sources with potentially high survival and satisfactory Christmas tree quality. The high variation in traits on the two sites indicates promising possibilities for further selection of A. lasiocarpa clones for growing Christmas trees in Norway. Selection for late bud break to avoid spring frost is important. Pathogens were not found in any of the studied trials, but are an important factor to consider when selecting seed sources for Christmas trees. Due to the early bud break of this species, it is also of high importance to choose planting sites with minimal risks for spring frost. Good localities are slopes where the frost drains away during cold nights. In eastern Norway, A. lasiocarpa should be used with care in districts and sites where spring frost is commonly occurring.
Forfattere
Øyvind M Edvardsen Arne Steffenrem Ragnar Johnskås Øystein Johnsen Tor Myking Harald KvaalenSammendrag
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Forfattere
Milan Lstibůrek Yousri A. El-Kassaby Tore Skrøppa Gary R. Hodge Jørn Henrik Sønstebø Arne SteffenremSammendrag
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Sammendrag
Grantrærne danner høstskudd dersom knoppene som dannes etter vekstavslutning, bryter på nytt samme sommer. Dette kan føre til skader og feil på stammen i form av gankvist og krok som gir redusert virkeskvalitet. Denne rapporten presenterer resultater fra registreringer av høstskudd og toppskader i genetiske forsøk med provenienser, familier og kloner av gran. Den viser at det er stor genetisk variasjon i forekomst av høstskudd på alle tre nivåer, og at det kan være klare sammenhenger mellom frekvens av høstskudd og skader, og mellom høstskudd og tidspunkt for vekststart og vekstavslutning. Samtidig er det store forskjeller mellom år og mellom forsøkslokaliteter - noe som sannsynligvis skyldes variasjon i klima og vekstforhold (bonitet). Det vil være store muligheter for å produsere plantematerialer som gir redusert andel trær med toppskader forårsaket av høstskudd ved å gjøre utvalg enten direkte (mot høstskudd og toppskader), eller indirekte gjennom utvalg for senere vekststart om våren.
Sammendrag
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Sammendrag
The plant hormone auxin is a vital component for plant reproduction as it regulates the development of both male and female reproductive organs, including ovules and gynoecia. Furthermore, auxin plays important roles in the development and growth of seeds and fruits. Auxin responses can be detected in ovules shortly after fertilization, and it has been suggested that this accumulation is a prerequisite for the developmental reprogramming of the ovules to seeds, and of the gynoecium to a fruit. However, the roles of auxin at the final stages of ovule development, and the sources of auxin leading to the observed responses in ovules after fertilization have remained elusive. Here we have characterized the auxin readout in Arabidopsis ovules, at the pre-anthesis, anthesis and in the immediate post-fertilization stages, using the R2D2 auxin sensor. In addition we have mapped the expression of auxin biosynthesis and conjugation genes, as well as that of auxin transporting proteins, during the same developmental stages. These analyses reveal specific spatiotemporal patterns of the different auxin homeostasis regulators. Auxin biosynthesis genes and auxin transport proteins define a prepatterning of vascular cell identity in the pre-anthesis funiculus. Furthermore, our data suggests that auxin efflux from the ovule is restricted in an anther-dependent manner, presumably to synchronize reproductive organ development and thereby optimizing the chances of successful fertilization. Finally, de novo auxin biosynthesis together with reduced auxin conjugation and transport result in an enhanced auxin readout throughout the sporophytic tissues of the ovules soon after fertilization. Together, our results suggest a sophisticated set of regulatory cascades that allow successful fertilization and the subsequent transition of the female reproductive structures into seeds and fruits.
Sammendrag
Stand dynamics and the gap initiation prior to gap formation are not well- understood because of its long- term nature and the scarcity of late- successional stands. Reconstruction of such disturbance is normally based on historical records and den-droecological methods. We investigated gap initiation and formation at the fine- scale stand level in the old- growth reserve of Karlshaugen in Norway. Given its long- term conservation history, and thorough mapping in permanent marked plots with spatially referenced trees, it provides an opportunity to present stand development before, during, and after gap formation. Late- successional decline in biomass was recorded after more than 50 years of close to steady state. Gaps in the canopy were mainly cre-ated by large old trees that had been killed by spruce bark beetles. Snapping by wind was the main reason for treefall. Long- term dominance of Norway spruce excluded downy birch and Scots pine from the stand. Comparisons of the forest floor soil prop-erties between the gap and nongap area showed significantly higher concentrations of plant available Ca within the gap area. Plant root simulator (PRS™) probes showed significantly higher supply rates for Ca and Mg, but significantly lower K for the gap compared to the nongap area. Soil water from the gap area had significantly higher C:N ratios compared to the nongap area. Fine- scale variation with increasing distance to logs indicated that CWD is important for leaking of DOC and Ca. Our long- term study from Karlshaugen documents gap dynamics after more than 50 years of steady state and a multiscale disturbance regime in an old- growth forest. The observed dis-turbance dynamic caused higher aboveground and belowground heterogeneity in plots, coarse woody debris, and nutrients. Our study of the nutrient levels of the forest floor suggest that natural gaps of old- growth forest provide a long- lasting biogeo-chemical feedback system particularly with respect to Ca and probably also N. Norway spruce trees near the gap edge responded with high plasticity to reduced competition, showing the importance of the edge zone as hot spots for establishing heterogeneity, but also the potential for carbon sequestration in old- growth forest.
Sammendrag
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