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.
2004
Forfattere
Bernt-Håvard ØyenSammendrag
Skogbrann - generelt
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Nils LexerødSammendrag
Det er ikke registrert sammendrag
Sammendrag
Border cells from the seedling root tips were added to the conidium suspensions of two soilborne rootpathogens, Fusarium sp. and Cylindrocarpon sp. The presence of border cells in the suspension clearly stimulated germination of fungal conidia. Conidia of Fusarium sp. and Cylindrocarpon sp.started to germinate within 3 hours after inoculation.When border cells were washed off, the stimulating effect disappeared. Addition of malt extract caused similar stimulation as border cells. Germination of conidia was suppressed in Al-treated plants.
Sammendrag
Extensive monitoring of forest health in Europe has been carried out for two decades, based mainly on defoliation and discolouration. Together these two variables reflect chlorophyll amounts in the tree crown, i.e. as an indicator of foliar mass, and chlorophyll concentration in the foliage, respectively.In a current project we try to apply remote sensing techniques to estimate canopy chlorophyll mass, being a suitable forest health variable. So far, we limit this to Norway spruce only. LIDAR data here play an important role, together with optical and spectral data, either from survey flights or from satellites. We intend to model relationships between foliar mass and LIDAR data for sample trees, and then scale up this to foliar mass estimates for the entire LIDAR area.Similarly, we try to scale up chlorophyll concentrations in sample trees, by modelling a relationship between sample tree chlorophyll and hyper-spectral data. The estimates of foliar mass and chlorophyll concentrations are then aggregated to every 10x10 m pixel of a SPOT satellite scene which is also covered by airborne data, providing an up-scaled ground truth. If we are successful with this, it might be a starting point for developing a new nationwide forest health monitoring system in Norway.
Forfattere
Birger VenneslandSammendrag
Det er ikke registrert sammendrag
Forfattere
Anders BrynSammendrag
Det norske kulturlandskapet er i rask endring. Årlig legges ned over 3000 bruk. Dette har store konsekvenser for verdiene i kulturlandskapet. Skal kulturlandskapets verdier debatteres, må det tenkes helhetlig.Kulturlandskapet er møtepunktet mellom natur og kultur, og rommer derfor tverrfaglige verdier. Kulturlandskapet er en direkte konsekvens av jordbruket, vår historie, lokale tradisjoner og mye annet.
Forfattere
Kjell VadlaSammendrag
Det er ikke registrert sammendrag
Sammendrag
A home designed diffusion chamber was used during the isolation of fluoride from plant material. The chamber contained two beakers, one for the sample (milled plant material) and the other for the trapping solution (0.1M NaOH). Hexamethyldisiloxane (HMDS) in 3.5M perchloric acid was added into the sample beaker through a septum, after the chamber was closed.Fluoride in the sample reacts with HMDS and forms the volatile trimethylfluorosilane (TMFS), which is trapped and hydrolyzed to fluoride. The diffusion time was 2h and 20 samples were handled at the same time. The fluoride concentration was determined by a flow injection analysis (FIA) system using an ion selective electrode (about 50 samples/hour).The results by acid extraction were compared to the results obtained after an ashing/alkaline fusion. Both a certified sample of timothy grass (NIST 2695, high level) and more typical vegetation from forest were analyzed. For the timothy grass, the recovery increased from 48 to 84% when ashing/alkali fusion was used before the diffusion. However, higher recovery was not obtained by using ashing/alkaline fusion for the determination of fluoride in natural vegetation from forest. Acid extraction in combination with addition of HMDS was sufficient as pretreatment in these types of plant materials.The method was routinely used for the determination of fluoride both in research and forest monitoring.
Sammendrag
Conventional extreme value statistics and the calculation of return periods implicitly assume stationarity of distributions and statistical independence at least asymptotically (most extreme events).We demonstrate, using a collection of river runoff time series from Southern Germany, that these assumptions are invalid, and that temporal as well as spatial correlations prevail instead: temporal differences of distributions are nearly synchronized within a region, and there are systematic trends of percentiles especially at low flow conditions within the 20th century.As a consequence, the estimated return periods of a given threshold flow are fluctuating, in some cases even in a dramatic fashion. On the other hand, a general trend towards an increase in flood frequencies cannot be stated on basis of our investigations, in accordance with other recent findings (Mudelsee et al. 2003), but contrary to general expectations drawn from climate change studies.