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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

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Sammendrag

To predict how the function of urban vegetation and the provision of ecosystem services respond to combinations of natural and anthropogenic drivers, a better understanding of multiple stress interactions is required. This study tested combined effects of moderate levels of drought, soil salinity and exposure to diesel exhaust on parameters of physiology, metabolism, morphology and growth of Pinus sylvestris L. saplings. We found that plant responses were primarily dominated by single stressors and a few two-way interactions. Stressor combinations did not have considerable additional negative effects on plant performance compared to single stressors. Hence, synergistic and antagonistic interactions were rare and additive effects frequent. Drought cycles caused most negative effects, from chlorophyll a fluorescence and epicuticular wax content to growth responses, while soil salinity caused fewer negative effects but contributed to reduction in fine root growth and fluorescence parameters at low air contamination. Interestingly, the air contamination alone had only marginal effects on plant morphology and growth, but contributed an antagonistic effect, dampening the negative effect of drought and salinity on the maximum quantum efficiency of PSII photochemistry (Fv/Fm) and fine root biomass. Although, these effects were moderate, it appears that exhaust exposure had a cross-acclimation effect on plant responses to drought and salinity. We also found that salinity had a negative effect on the accumulation of particulate matter on shoots, illustrating that the plant stress situation can affect the provisioning of certain ecosystem services like pollution attenuation. These findings have implications for the understanding of the complex natural and anthropogenic stress situation of urban, and how to maintain the ecological functions and delivery of ecosystem services.

Sammendrag

Consumer resistance against GM crops is still substantial in the United States and Europe. We conducted an internet survey in the United States and Norway with more than 1,000 respondents in each country to estimate consumers’ willingness to pay (WTP) for GM soybean oil, farmed salmon fed with GM soy, and GM salmon. The differences in WTP for the conventional as compared with the GM alternatives are relatively small. Only between 7 and 13% of the respondents indicated that they were willing to pay more than a 20% premium for each of the conventional alternatives as compared to the corresponding GM alternatives. The average WTP premiums range from 7.5 to 9.2%. This suggests a large similarity in WTP in Norway and the United States and across the three products.

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Sammendrag

Aims: Evaluate biological nitrogen fixation (BNF) and its contribution to total N yield in different grass-clover mixtures under a boreal coastal climate and assess how winter conditions affect the survival of clover and its capability to fix nitrogen (N). Methods: Grass-clover mixtures sown with 0, 15 and 30% red and white clover were subjected to two N rates and three levels of tractor trafficking over four years. BNF was estimated by N-difference for each of the two harvests per year, whereas the first harvest was used to estimate the fraction of N derived from the atmosphere (NdfA) and its transfer to grasses by 15N natural abundance. Results: Biological N fixation, mainly by red clover, contributed substantially to total N yield, which was up to 75% greater in grass-clover mixtures than in pure grass stands in the second production year. However, the number of red clover plants and associated BNF decreased dramatically in the third and fourth production year, with N fertilization rate having a more detrimental effect than soil trafficking. Conversely, the amount of biologically fixed N transferred to grass, increased with time, evidencing that some of the biologically fixed N is retained in the system. In the first harvests, NdfA values were generally between 80 and 100%, irrespective of preceding winter conditions. Conclusions: BNF in high latitude grass-clover mixtures can be substantial but is limited by the poor survival of red clover. Variable winter conditions had no measurable effect on winter survival nor on the sward’s capacity to fix nitrogen in spring.