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.
2006
Forfattere
Ann NorderhaugSammendrag
Det er ikke registrert sammendrag
Forfattere
Ken Olaf StoraunetSammendrag
In recent years attention has focused on the consequences of modern forestry on biological diversity. Additionally, past forest management has reduced the structural heterogeneity of forest landscapes, increasing the interest in assessing forest naturalness. General forest history of Norway shows that single-tree and selective logging was the main silvicultural method up to the mid-twentieth century when clearcutting practice took over as the dominating logging regime. Thus, regenerating forests on former clearcut areas have barely reached the stages of maturity, implying that mature forests of today for the most part are remnants from the period of selective logging. This thesis has been part of a comprehensive research project where one of the general objectives was to gain knowledge on the distribution and abundance of rare and threatened species in Norwegian forests....
Sammendrag
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Sammendrag
Endringer i jordas moldinnhold er presentert for en 250 daa forsningsstasjon, basert på målinger i 1952, 1976, 1986 og 2002, og for 291 åpenåkerskifer i sørøst Norge, som ble samplet omkring 1991 og igjen i 2001. Store nedganger ble funnet på forskningsstasjonen, spesielt på jord som hadde et høyt moldinnhold opprinnelig. Nedgangen mellom 1952 og 1976 hadde trolig delvis sammenheng med økt pløyedybde og grøfting, mens nedgangen de senere årene kan delvis være forårsaket av klimaendringer. Nedganger ble også funnet etter 1990 i de fleste av åpenåkerdistriktene, også her proporsjonalt med det opprinnelige moldnivået. Ingen enkel forklaring ble funnet, men andelen av høstjordarbeiding og av radkulturer kan begge være involvert. Det var en midlere relativ nedgang på ca.1% pr. år i forhold til det opprinnelige nivået, både på forskningsstasjonen og i åpenåkerdistriktene. Det kunne dessuten se ut til at den relative årlige nedgangen var omkring en tidel av det opprinnelige prosentnivået. Disse alternativene tyder på at jord med hhv. 4%, 6% og 10% moldinnhold idag, kan komme på et mulig "kritisk lavt" nivå av 3%, om hhv.30-80, 70-165 og 120-230 år fra idag.
Sammendrag
The root-rot causing fungus Heterobasidion annosum can attack both spruce and pine trees and is the economically most damaging pathogen in northern European forestry. We have monitored the H. annosum S-type (fairly recently named H. parviporum) colonization rate and expression of host chitinases and other host transcripts in Norway spruce material with differing resistances using quatitative realtime PCR. Transcript levels of three chitinases, representing classes I, II and IV, were monitored. Ramets of two 33-year-old clones differing in resistance were employed as host material and inoculation and wounding was performed. clones in the area immediately adjacent to inoculation. Fourteen days after infection, pathogen colonization was restricted to the area immediately adjacent to the site of inoculation for the strong clone (589), but had progressed further into the host tissue in the weak clone (409). Transcript levels of the class II and IV chitinases increased following wounding or inoculation, while the transcript level of the class I chitinase declined following these treatments. Transcript levels of the class II and class IV chitinases were higher in areas immediately adjacent to the inoculation site in 589 than in similar sites in 409 three days after inoculation, suggesting that the clones differ in the rate of pathogen perception and host defense signal transduction. This an earlier experiments using mature spruce clones as substrate indicate that it is the speed of the host response and not maximum amplitude of the host response that is the most crucial component in an efficient defense in Norway spruce toward pathogenic fungi such as H. annosum.
Forfattere
Tor Gunnar Vågen Masy-A A Andrianorofanomezana Salmata AndrianorofanomezanaSammendrag
Soils of tropical forests are often inherently nutrient poor, although the extents of extremely infertile tropical forest soils are not as large as previous estimates may suggest. This paper presents findings from a study of change in soil quality in relation to deforestation and land use change in the highlands of Madagascar. A synthesis of some of the available research results related to soil characteristics of tropical forest, and their response to disturbance and conversion (i.e. deforestation) is made. The study was conducted in an area in the eastern highlands of Madagascar. The predominant soil types in the eastern highlands of Madagascar are Oxisols, which are acid and have a high content of low activity clays. The chemical characteristics of forest soils were found to be highly variable, with soil organic carbon (SOC) and total nitrogen (TN) contents ranging from 22.8 to 120.8 and 2.2 to 8.8 g kg(-1), respectively. Conversion of forest to cropland (tavy) reduced SOC contents by 23.8 g kg(-1) in the first year after clearing and by 11.3 g kg(-1) year(-1) on average in the first 3 years of cultivation. Mixed fallow systems recovered SOC at rates of about 6.5 g kg(-1) year(-1). Available phosphorus (P) and exchangeable base cations (Ca, Mg and K) increased after clearing as a result of biomass burning while cation exchange capacity is largely determined by SOC content and follows similar trends as SOC after clearing. The long term trend was, however, in the direction of significant decreases in available P while the sum of base cations showed little change relative to natural forest soils. (C) 2005 Elsevier B.V. All rights reserved.
Sammendrag
Myrjord dekker 2-3 % av verdens landareal og inneholder ca en tredel av jordas lager av organisk karbon og omtrent like mye carbon som i atmosfæren. Drenering og dyrking av myr fører til en mineralisering av organisk materiale. Denne artikkelen omhandler emisjon av drivhusgasser fra dyrket myr i Nord-Norge. CO2-emisjonen økte med temperaturen, mens tilsvarende effekt ikke kunne påvises for N2O- og CH4-emisjonen. Estimert netto emisjon av drivhusgasser fra rør-grøftet myr var ca 2,2 kg for CO2, 0,03 kg for CH4 og 0,13 kg for N2O, uttrykt i CO2-ekvivalenter. Netto C-tap var ca 0,6 kg C per m2 og år. Karbontap kan derfor betraktes som jordforringelse når en tar hensyn til klimagassemisjonen. Resultatene viste betydningen av CO2-emisjonen fra dyrket myr i nord, som var ca 17 ganger høyere enn N2O-emisjonen som CO2-ekvivalenter.
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
The ability of perennial grasses to maintain frost hardiness throughout the winter, and to resist dehardening during periods of mild weather is crucial for winter survival in the northern region. We tested the effects of dehardening conditions on two contrasting varieties of timothy and two of perennial ryegrass. The plants were grown in pots placed close together in the field to simulate sward conditions. Dehardening treatments started in January and April when bags with plants were brought from the field into a phytotron and treated with 3o, 9o and 15oC, 12 h light. The degree of dehardening was measured as loss of frost tolerance (LT50) after the plants were exposed to the dehardening conditions for 0, 2, and 6 and 9 days. Perennial ryegrass was less frost hardy than timothy, and in April the ryegrass plants were in bad shape and had lost almost all hardiness. The `Engmo" timothy had an initial higher degree of frost hardiness than `Grindstad" timothy both in January and April. However, `Engmo lost frost hardiness at the same rate or quicker than `Grindstad" when exposed to 9o and 15oC both in January and April. It however maintained almost all hardiness at 3oC, whereas Grindstad also at this temperature dehardened substantially. The study did not confirm the hypothesis that the more winter hardy cultivars deharden more slowly than the less frost tolerant cultivars. However, further studies need to be conducted to investigate in more detail whether there is a differing cardinal temperature for dehardening between cultivars.
Sammendrag
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