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.
2011
Abstract
Due to sewage sludge application on soils, terrestrial ecosystems are very likely to be exposed to silver nanoparticles (AgNPs) and it is thus important to understand the behavior of Ag NPs once in contact with soil components. The aim of this work was to compare the behavior of silver under three forms, silver nitrate, citrate stabilized AgNPs (C-ANPs) and uncoated AgNPs (P-AgNPs), in two soils with contrasting organic matter content, and over time. The physical and chemical properties of the studied soils as well as the nanoparticles size, shape, crystallographic structure and specific surface area were characterized. Soil samples were spiked with silver nitrate, C-AgNPs or P-AgNPs, and let for ageing 2 hours, 2 days, 5 weeks or 10 weeks before they were submitted to sequential extraction. The ionic silver solution and the two AgNPs types were radiolabeled so that we could detect and quantify silver by gamma spectrometry by measuring the 110mAg tracer in the different sequential extraction fractions. We thereby obtained for each silver form, soil type and time point a distribution of silver in the different fractions. Silver was generally more mobile in the mineral soil, although the fractionation patterns were very different for the three silver types in both cases. Over 20% of the total C-AgNPs concentration were water soluble in both soils (<5% for AgNO3 and P-AgNPs) the first two days after spiking, but the fraction decreased to trace levels thereafter. This was compensated by an increase in the reducible fraction. Regarding P-AgNPs, 80% were not extractable at all, but contrary to AgNO3 and C-AgNPs, the water soluble and ion exchangeable fractions did not decrease over time in the mineral soil, and even increased in the organic soil.
Abstract
A rapid increase in the frequency of Dutch elm disease (DED), a wilting disease of elm trees caused by bark-beetle vectored fungi, was observed in the early 1990s on several wych elm stands around Oslofjord, southern Norway. To examine the current status of the disease and its impacts on elm population, disease frequency and size distribution of elms were recorded at four locations. Northern parts of Lier, a municipality most affected by DED in Norway 15 years ago, showed in the survey season 4% disease frequency, whereas 13.8% of trees were dead, the dead trees having accumulated over several years in the unmanaged stands. In southern parts of the municipality the mean disease and death percentages were 1.9 and 2.4%. Compatible with their low disease incidence in early 1990s, the other two areas now examined, municipality of Larvik and district of Grenland, showed comparably low frequency of DED. Northern part of Lier showed significantly higher overall density of elm trees per hectare than the other examined areas, and also the small elms below 5 cm in d.b.h. were most frequent in this region. In contrast, the density of large trees was lower in northern Lier than in the other examined areas. These data suggest that regeneration of the tree is not prohibited owing to the disease but that the large trees have been locally reduced in frequency as a result of DED. The superior general density of elm trees in northern Lier, owing to the exceptionally rich soil in the warm southern slopes of the region,> may have contributed to the rapid increase of DED in the area 15 years ago and to the subsequent settlement of the disease outbreak as a chronic stage.
Abstract
The Norwegian Public Road Adminstration (Statens vegvesen) is planning a new major road (E6) from Ringebu south to Otta in Gudbrandsdalen. A vegetation project for knowledge development concerning restoration and reestablishment of the vegetation were established in 2009, and accomplished by Bioforsk in cooperation with Vegetation adviser Tanaquil Enzensberger. Gudbrandsdalen with the river “Lågen” is a valley in the middle of southern Norway. The area belongs to the slightly continental section of south-boreal vegetation zone (Sb-C1), a phyto-geographical region which is rare in Norway and contains unique biological diversity. As an example we have the fern Diplazium sibiricum that grows in fertile hardwood forest and is classified as vulnerable (VU) on the National red list, the ligneous plant Salix triandra (VU) that grows on the river banks and the vascular plant Stellaria palustris (EN), prefering swamps on the fluvial-areas. In addition there are many threatened vascular plants connected to the cultural landscape, huge rocks with rare lichens and ravines with unique species communities in the forests. Climate, geology and vegetation of the area are described and different methods for conservation proposed. A method for decisions about which plant or plant communities to conserve by moving or propagation is suggested. Erosion, soil management, availability of phosphorus and nitrogen in the topsoil, alien and invasive species as well as restoration of wetlands are discussed. Five different methods for establishing vegetation are proposed. 1: Conventional sowing on cultivated and other disturbed sites. The seed mixture should be of local origin, but for the time being not accessable. 2: Natural revegetation from topsoil in forest areas, with the exception of forest soils high in plant nutrition, which requires special adjustments as mixing the soil with nutrient-poor forest soil or sowing. 3: Spontaneous revegetation without topsoil on one location with calcareous and coarse mineral soil and drought-tolerant vegetation, where the risk for contamination of weeds is low. 4: Donor-receptor method (“hay method”) for conservation of threatened seminatural meadows and creation of refuges for threatened plant species. 5: Vegetation-mat method (“turf roof method”) on one location with natural pasture containing vegetation of special interest. These five methods in combination with conservation of unique plants and plant communities will minimize the environmental impact of the road construction.
Abstract
Norwegian lamb meat production is mainly based on free grazing in mountainous pastures during the summer. Prior to slaughter in the autumn, some lambs not big enough for slaughter are finished on e.g. cultivated pastures. This study looked at the feed quality of different forages, and the effect on lamb meat quality. Lambs grazed on mountain pastures at Kvaløya in Northern Norway (69°N) and Sør-Fron in Mid Norway (58°N) in 2007, and a subgroup at each location was finished on cultivated pastures for 6 weeks prior to slaughter in September. The fiber content was significantly higher in the cultivated pasture in Mid Norway compared to the mountain pasture while no differences between pastures in Northern Norway were found. In Mid Norway the content of polyunsaturated fatty acid (18:3) was significantly higher in meat from lambs grazing the mountain pasture compared to lamb grazing the cultivated pasture. For Northern Norway, the opposite pattern was observed. The higher 18:3 content may be attributable to lower fiber content at the mountain pasture. In our study, there appears to be an effect of fiber content on the fatty acid composition in lamb meat.
Authors
Sigrun KværnøAbstract
Rapporten presenterer kartlagt fosforstatus (P-AL) i jord i Vannområde Haldenvassdraget i Akershus/østfold. Statistiske analyser er basert på P-AL-verdi i jordprøver tatt ut i perioden 1990 - 2008. Mesteparten av dataene kommer fra Jorddatabanken ved Bioforsk, mens noe data er samlet inn av landbrukskontorene i fire Haldenvassdragskommuner. Jordprøvene er stedfestet ned på gårds- og bruksnummernivå. Prosentvis dekningsgrad av jordprøvetaking var 65 % i Haldenvassdraget. Variasjonsområdet for de ulike delområdene var 50 til 72 % dekningsgrad. Arealmessig manglet det mest data i delområdet Bjørkelangen. Bare 52 % av jordprøvene som de statistiske analysene og kartene var basert på, var fra 2000-tallet, og 21 % fra 2005 eller senere. P-AL i jord varierte mellom 0 og 71 mg/100 g jord i enkeltprøver, med en middelverdi på 10 mg P-AL/100 g jord for Haldenvassdraget (P-AL-klasse "middels til høyt", eller 8-10 mg/100 g). Delområdene hadde middelverdier mellom 8 og 11 mg/100 g jord. Prøver med P-AL ≥ 11 mg/100 g jord (motsvarer ingen P-gjødsling) utgjorde 29 % i Haldenvassdraget. Iddefjorden hadde størst andel P-AL ≥ 11 mg/100 g jord: 46 %.
Authors
Xiaoren Chen Sonja Klemsdal May Bente BrurbergAbstract
The oomycete Phytophthora cactorum can cause economically important diseases on numerous host plants worldwide, such as crown rot on strawberry. To explore the molecular mechanisms underlying the pathogenicity of P. cactorum on strawberry, transcriptional analysis of P. cactorum during strawberry infection and cyst germination was performed by applying suppression subtractive hybridization (SSH) and effector-specific differential display (ESDD) techniques. Two SSH cDNA libraries were generated, enriched for P. cactorum genes expressed during infection or during cyst germination, respectively, and 137 unique differentially expressed genes were identified. To specifically select RxLR effector genes from P. cactorum, ESDD was performed using RxLR and EER motif-based degenerate primers. Eight RxLR effector candidate genes as well as 67 other genes were identified out of 124 selected fragments. The expression levels of 20 putatively up-regulated genes were further analyzed using real-time RT-PCR, showing that, indeed 19 of these 20 genes were up-regulated during at least one of the studied developmental stages or during strawberry crown invasion, relative to the mycelium. This study provides a first overview of P. cactorum genes that are up-regulated immediately prior to or during strawberry infection and also provides a novel method for selecting RxLR effector genes from the unsequenced genome of P. cactorum.
Abstract
Det er ikke registrert sammendrag
Authors
Ole Tobias Rannestad May-Guri Saethre Amon P. MaerereAbstract
The banana weevil, Cosmopolites sordidus Germar (Coleoptera: Curculionidae) is a major pest in banana (Musa spp.) growing areas. The weevil is known to be relatively sedentary and closely associated with its host plant, but little is known about the species" ability to migrate between banana fields and in non-host habitats. Mark-recapture experiments were conducted to assess the weevils" migration potential, possible differences between the sexes, and the relative attractiveness of pseudostem and pheromone baits. One thousand two hundred marked weevils were released in non-host habitat at five distances (5, 10, 20, 40 and 70 m) from fresh pseudostem, and from pitfall traps baited with 45 mg Sordidin. Two hundred males and 200 females were marked and released at five distances (5, 10, 20, 40 and 70 m) from pheromone traps. Distance and distance/bait interactions had a significant effect on recaptured weevils (binary logistic regression). The two baits were almost equally attractive to weevils from 0-10 m, while the pheromone was more attractive from 10-100 m. Distance, bait, and distance/bait interactions had a significant effect on the time elapsed from release to recapture (regression with life data). However, the pattern observed was not consistent. There was no significant difference between males and females with respect to distance or time elapsed from release to recapture.
Authors
Frank Asche Kristin Helen Roll Ragnar TveteråsAbstract
Det er ikke registrert sammendrag
Authors
Elisabeth Conrad Louis F Cassar Michael Jones Sebastian Eiter Zita Izaovičová Zuzana Barankova Mike Christie Ioan FazeyAbstract
The involvement of the public in decision-making is established as a key feature of many planning policies. However, there is evidence from the literature of a prevailing gap between participation rhetoric on paper and participation at the operational level. We assess whether this is also the case with landscape policy and review landscape characterization and assessment initiatives in England, Norway, Slovakia and Malta, focusing on five dimensions of good practice: (i) scope of public participation, (ii) representativeness of those involved, (iii) timeliness of public involvement, (iv) extent to which participation is rendered comfortable and convenient for the public, and (v) eventual influence of public input on decisions. Reviewed reporting results indicate weaknesses in the implementation of public participation, with public involvement largely limited to consultation, with few efforts to ensure representativeness of participants, with predominantly late involvement of the public, and with limited influence of the public on outputs. Furthermore, few efforts appear to be made to facilitate participation for the public. Although the cases studied differ, none of them are fully satisfactory in relation to the European Landscape Convention's participatory targets. The reporting of public participation processes thus suggests that practices may fail to match the rhetoric.