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.
2010
Forfattere
Matthias ZielkeSammendrag
Det er ikke registrert sammendrag
Sammendrag
VKM"s Panel 9 gives the following main conclusions of part 2 of the risk assessment: 1) Under the present climatic conditions, and if no control measures are taken, an introduction of PWN to the PRA area will not cause increased pine tree mortality. The level of uncertainty of this assessment is low. 2) Assuming the IS92a climate change scenario for the period 2000-2049 (RegClim), which involves a ~2 ºC temperature increase by the end of the period, an introduction of PWN to the PRA area will, if no control measures are taken, cause a minor increase in pine tree mortality (300 trees per year on average). The mortality can become larger if the temperature increases more than 2 ºC, and will gradually increase with time after 2049 due to spread of PWN. The level of uncertainty of these assessments is medium to high. 3) Any effects of PWN presence in the PRA area on export of wood and wood products will be of little importance. The level uncertainty of this assessment is low. 4) It will be almost impossible to eradicate PWN once it has been introduced to the PRA area. The level of uncertainty of this assessment is low. 5) The cost of a single eradication event as described in the preliminary contingency plan for the PRA area is approximately 700 mill. NOK. Due to expected spread, the total cost of eradication attempts following one introduction event will be approximately 2000 mill. NOK for the first 50 years. The level of uncertainty of these assessments is medium. 6) The negative effects of the control measures on the environment will be major. The level of uncertainty of this assessment is low.
Forfattere
Liv Ostrem Mats Høglind Åsbjørn Karlsen Petter Marum Anne Marte Tronsmo Odd Arne RognliSammendrag
An important aim for the project "Understanding the genetic and physiological basis for adaptation of Norwegian perennial forage crops to future climates" is to generate plant material of red clover (Trifolium pratense L.) and lucerne (Medicago sativa) adapted to a variety of climatic conditions which might be used for selection of future cultivars. Mechanistic modelling of plant performance under climate change will be used to identify target traits for these cultivars, and during the project period of 2010-2013 main challenges for winter survival and persistence as well as for early growth in red clover will be elucidated.
Forfattere
Marcel Van Oijen Ad Schapendonk Mats HøglindSammendrag
Background and Aims The carbon balance of vegetation is dominated by the two large fluxes of photosynthesis (P) and respiration (R). Mechanistic models have attempted to simulate the two fluxes separately, each with their own set of internal and external controls. This has led to model predictions where environmental change causes R to exceed P, with consequent dieback of vegetation. However, empirical evidence suggests that the R : P ratio is constrained to a narrow range of about 0·4-0·5. Physiological explanations for the narrow range are not conclusive. The aim of this work is to introduce a novel perspective by theoretical study of the quantitative relationship between the four carbon fluxes of P, R, growth and storage (or its inverse, remobilization). Methods Starting from the law of conservation of mass - in this case carbon - equations are derived for the relative magnitudes of all carbon fluxes, which depend on only two parameters: the R : P ratio and the relative rate of storage of carbon in remobilizable reserves. The equations are used to explain observed flux ratios and to analyse incomplete data sets of carbon fluxes. Key Results The storage rate is shown to be a freely varying parameter, whereas R : P is narrowly constrained. This explains the constancy of the ratio reported in the literature. With the information thus gained, a data set of R and P in grassland was analysed, and flux estimates could be derived for the periods after cuts in which plant growth is dominated by remobilization before photosynthesis takes over. Conclusions It is concluded that the relative magnitudes of photosynthesis, respiration, growth and substrate storage are indeed tightly constrained, but because of mass conservation rather than for physiological reasons. This facilitates analysis of incomplete data sets. Mechanistic models, as the embodiment of physiological mechanisms, need to show consistency with the constraints.
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
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Forfattere
Vitalis Wafula Wekesa S. Vidal R.A. Silva E.M.M. Ortega Ingeborg Klingen Italo Delalibera Jr.Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Organic fields are often assumed to have fewer pests and more beneficials than conventionally managed fields. We monitored 12 Norwegian strawberry fields, 6 organic and 6 conventional fields, by sampling leaves twice a year in 2002 and 2003. Young folded leaflets were visually inspected for eggs and adult females of strawberry mite (Phytonemus pallidus fragariae), and mature leaves were used for extraction of mobile stages of two-spotted spider mite (Tetranychus urticae). The spider mites were examined for infection of the mite-pathogenic fungus Neozygites floridana. Predatory mites (Phytoseiidae) were recorded on both leaf types, and the females mounted and identified. We also sampled leaves from selected plants in the boundary vegetation of most fields to look for sources of T. urticae, phytoseiids and N. floridana. Soil was sampled from each field, to study the natural occurrence of entomopathogenic nematodes. All samples were taken 0-13 metres from the border vegetation. Both pest mites tended to be more abundant in conventional than in organic fields, while the number of phytoseiid mites was very low in both growing systems. Nevertheless, three phytoseiid species were recorded for the first time in Norway: Amblyseius rademacheri Dosse, Neoseiulus kodryensis (Kolodochka) and Neoseiulus reductus (Wainstein). N. floridana infection found in T. urticae females varied from 0-19%, and was higher in 2002 than in 2003. The fungus was recorded at least once in all 12 fields, and there was no consistent difference between the two growing systems. In 2002 there was a significant negative correlation between % T. urticae with N. floridana hyphal bodies found in the first sampling and the number of T. urticae present in the second sampling about 4 weeks later. Beneficial nematodes (mostly Steinernema) tended to occur in more of the organic than of the conventional soil samples. To sum up, both pests (T. urticae and P. pallidus) and one of the beneficial groups (entomopathogenic nematodes) seemed to conform to the expected difference between organic and conventional fields. There are many possible mechanisms related to the differences in pesticide and fertilization regimes that could lead to such a pattern. For the two remaining beneficials (N. floridana and Phytoseiidae) we could not find a consistent correlation between abundance and growing system.