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.
2007
Sammendrag
Forest health monitoring may be done with remote sensing. Satellite based SAR is one promising technology as it works day and night and with cloud cover, and because it is sensitive to 3D properties. We here apply an interferometry based XDEM approach, where we assumed that an increasing defoliation would cause an increasing X band penetration downwards into the canopy layer, and that the penetration depth is a function of the amount of leaf area index (LAI) penetrated. We had at hand data for a 4 km2 forest area, having an SRTM X and C band SAR data set from 2000; a discrete-return laser scanning data set from 2003; and ground based measurements of some hundred trees and a forest stand map from 2003. We initially adjusted the XDEM and CDEM using elevation data from some agricultural fields nearby the forest using an official, Norwegian DTM data base having a 25mx25m spatial resolution. All further analyses were carried out on a 10mx10m grid. With the laser data we obtained a DTM and a canopy surface model (CSM), where the latter was set to the 75 percentile of the DZ data in each grid cell. The X band penetrated about six m downwards into the canopy layer, which means that for all grid cells having a forest canopy lower than six m, the XDEM was around zero. With an increasing DSM from six m upwards, the DSM could be approximated by the linear function DSM = 6 + 0.91*XDEM, having a RMSE of 4.0 m. The laser data provided the possibility to estimate LAI in every grid cell and at any height in that cell. For every grid cell, an LAI value was estimated for the forest canopy being above the XDEM height, using the method of Solberg et al (2006), where LAI = C * ln(N/Nb), where LAI is effective LAI above a given height; C is a constant calibrated from ground based measurements with the value 2.0, N is the total number of laser pulses; and Nb is the number of laser pulses below the given height. The median LAIaboveX value was 1.42, and 25-75 percentile values being 0.86-2.15. Also, in order to have a more homogeneous data set we redid the analyses using only spruce dominated stands, and excluding all grid cells at stand borders. The latter was set as grid cells that had neighbour grid cells in a neighbour stand. This had however, only a minor influence on the results.
Forfattere
Odd-Arild FinnesSammendrag
Flis gjør det mulig å ta i bruk alternative driftsmåter i saueholdet
Sammendrag
Bioforsk Økologisk småskriftet "Sauehold" omhandler ulike sider ved sauehold som er spesielt for økologisk drift. Utfordringene for økologisk sauehold er i stor grad knyttet til dyrking av grovfôr og bygningskrav. I tillegg er det satt fokus på riktig fôring, sykdomsforebygging og parasitthåndtering.
Forfattere
Inger HansenSammendrag
Om antipredatoratferd hos ulike saueraser. Leserinnlegg etter fjernsynsreportasje i Schrödingers katt.
Forfattere
Trine A Sogn Espen Govasmark Susanne Eich-Greatorex Anne Falk Øgaard John A. MacLeodSammendrag
Det er ikke registrert sammendrag
Forfattere
Celine ReboursSammendrag
Det er ikke registrert sammendrag
Forfattere
Celine Rebours Åsbjørn KarlsenSammendrag
Seaweeds are considered as important ecological actors in many aspects. Therefore, developing the research around seaweeds to use and expand this natural resource is crucial. The highly developed wild coastline of Norway is a natural laboratory for such studies, but also a logical choice for developing new industries. Using special environments, like the Barents Sea and its related potential sources of conflicts, as pilot case studies, may lead to new tools versus human pollution.
Forfattere
Celine Rebours Åsbjørn KarlsenSammendrag
Seaweeds are considered as important ecological actors in many aspects. Therefore, developing the research around seaweeds to use and expand this natural resource is crucial. The highly developed wild coastline of Norway is a natural laboratory for such studies, but also a logical choice for developing new industries. Using special environments, like the Barents Sea and its related potential sources of conflicts, as pilot case studies, may lead to new tools versus human pollution.
Sammendrag
In winter 2000-2001, there was a serious outbreak of Gremmeniella abietina Morelet in southeastern Norway. During the outbreak, we noted that injured Scots pine trees (Pinus sylvestris L.) developed secondary buds in response to the fungus attack, and we decided to study the relationship between injury, appearance of secondary buds and recovery of the trees thereafter. For this purpose, 143 trees from 10 to 50 years of age were chosen and grouped into crown density classes. Injury was assessed in detail, and buds were counted before bud burst in the spring of 2002. In addition, a subset of 15 trees was followed through the summer of 2002 to assess recovery. All injured trees developed secondary buds, with a clear overweight of dormant winter buds in proportion to interfoliar buds. Healthy control trees did not develop secondary buds at all. The secondary buds appeared predominantly on the injured parts of the tree; interfoliar buds in particular developed just beneath the damaged tissue. Most of the secondary buds died during the winter of 2001-2002, mainly because the fungus continued to spread after the first outbreak. Many of the remaining buds developed shoots with abnormal growth during the summer. Secondary buds may help trees to recover from Gremmeniella attacks, but this strategy may fail when the fungus continues to grow and injure the newly formed buds and shoots.
Sammendrag
In Norway, Nordmann (Abies nordmanniana) and subalpine fir (A. lasiocarpa) are the dominant Christmas tree species and Noble fir (A. procera) the dominant species for bough production. In the spring of 2005 a survey was undertaken to determine the presence of fungi on seeds of these three plant species. Twelve seed samples were tested; five from Nordmann fir, four from subalpine fir and three from Noble fir. The test included seeds produced in Austria (Nordmann fir), Canada (subalpine fir), Georgia (Nordmann fir), Norway (Noble and subalpine fir) and Russia (Nordmann fir). The testing was done in a certified seed laboratory in Norway. One hundred seeds per sample were pre-treated in 1 % NaOCl and plated on potato dextrose agar (PDA), and 100 seeds per sample were pre-treated in H2O2 and plated on water agar (WA). The PDA Petri dishes were incubated for 5 to 7 days at 20 + 2 ºC and the WA Petri dishes for 15 to 19 days at 15 + 2 ºC, both under alternating 12 h NUV-light and 12 h darkness. To date not all of the fungi have been identified, but fungi from several genera have been found: Alternaria, Anthostomella, Aspergillus, Aureobasidium, Botrytis, Caloscypha, Cephalosporium, Chaetomium, Cladosporium, Dictyopolyschema, Epicoccum, Fusarium, Mucor, Penicillium, Phoma, Rhizopus, Trichoderma, and Trichothecium. Caloscypha was only found on one subalpine fir seedlot from Canada and Anthostomella on one subalpine fir seed from Norway. All the other fungi were more commonly found in all the samples. Fusarium species are well known to cause damping off in nurseries, but are not reported to cause problems in production fields. Species of Alternaria, Phoma, Botrytis and Trichothecium can damage seedlings. Anthostomella conorum is reported on cone scales of pine (Pinus spp.), but is not described as pathogenic. Aureobasidium is described as a saprophytic or weakly parasitic cosmopolitan fungal genus. Aureobasidium sp. is commonly found in Norway on buds of subalpine fir which fail to open in spring, and it will therefore be included in a pathogenicity test.