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.
2008
Forfattere
Thomas Hartnik Bjarne StyrishaveSammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Yijie WuSammendrag
Luftforurensninger og klimaendringer påvirker kjemien i kronedrypp og jordvann i boreale skoger. Løst organisk materiale (DOM), inklusiv løst organisk karbon (DOC) og løst organisk nitrogen (DON), spiller en nøkkelrolle, og det er derfor nødvendig å forstå hvordan DOM blir påvirket, ikke bare av luftforurensninger og klimatiske faktorer, men også av andre faktorer. Denne avhandling undersøker faktorer som påvirker DOC og DON i norske skogøkosystem, med bruk av data fra de norske ICP Forests Level II-flater og andre studier...
Sammendrag
Quota regulations that prevent output expansion of farms and reallocation of output between farms can cause lower growth in output and productivity. The aim of this study was to explain the output growth rate of Norwegian dairy farms since 1976, and to decompose it into output, input, socioeconomic and technical change components. Instead of using the standard distance function approach for multi-output technologies, we use a growth rate formulation, which automatically removes the farm-specific effects. This formulation also helps to impose non-negativity constraints on marginal products of inputs (input elasticities), which are often violated for many observations, especially when flexible functional forms are used. The farm-level panel data cover three periods: before the quota scheme was introduced (1976-1982); the period with the most output-restricting quota scheme (1983-1996); and the period with a more flexible quota scheme (from 1997 onwards). Results show that the milk quota regulations had a significant constraining effect on output growth, in particular on milk output in the period 1983-1996. Furthermore, the output mix has shifted towards meat production for the average farm. What emerges from this study is that output growth and technical change are negatively influenced by policy aims where productive performance has not been the primary objective, and that there is scope for increased farm growth if the quota regime is liberalised.
Sammendrag
The most important and widespread disease on golf courses is Microdochium nivale. Attempt to control the disease is mainly by prophylactic spraying with fungicides in fall. The aim of this project has been to understand how inoculum of M. nivale survives from spring to fall and to clarify the efficiency of selected fungicides. Snow mould symptoms and the occurrence of M. nivale in leaves and stems of grasses sampled from golf greens and foregreens was reduced during the growth season. We also found that M. nivale could be isolated from locations without visible symptoms. Despite a lower isolation rate in autumn, M. nivale was again isolated in some of the originally locations, the following spring. The M. nivale isolation rate was similar from sites located on greens compared to foregreens, and from greens located at more sunny sites compared to more shadowy located greens. We conclude that this fungus seem to survive from year to year within the same locations on greens and foregreens. A significant correlation was found between mycelial growth rate of M. nivale isolates at 2?C compared to growth at 20?C. At 20?C, a greater variation in growth rate was registered between strains isolated right after snow melt, compared to strains isolated in spring, summer, autumn or prior to snowfall. No clear picture emerged in growth rate differences between groups of M. nivale strains isolated at different time points throughout the year. Significant reduction in mycelial growth rate of M. nivale was registered on agar added low concentrations of all the fungicides tested.The products were: Acanto Prima (cyprodinil, pikoksystrobin), Amistar (azoksystrobin), Amistar duo (azoksystrobin, propikonazol), Baycor (bitertanol), Bumper (propikonazol), Comet (pyraklostrobin), Proline (protiokonazol), Rovral 75WG/Chipco Green 75WG (iprodion), Sportak EW (prokloraz), Stratego 250 EC (propikonazol, trifloksystrobin), Topsin WG (tiofanatmetyl). It was large variation among the fungicides in the effect on fungal growth rate. Sportak, Stratego and Topsin were the most efficient products; 90-100% reduction in mycelial growth rate was registered on agar added 0.1% of the fungicide concentration recommended for disease control on golf greens. Acanto Prima, Bumper, Comet and Stratego were also tested for their effect to reduce snow mould damage on golf greens. Due to severe water damage on the greens the second season, only results from one season of the fungicide field trial could be used. Acanto prima was ranked as the best product, significantly reducing winter injury on average from 21% (in control plots) to 6% in the treated plots.
Forfattere
Lise GrøvaSammendrag
Flått forårsaker sjodogg hos sau. Bioforsk Økologisk forsker på omfang og mulige forebyggende tiltak.
Forfattere
Ragnhild Nærstad Vinh Hong Le Arne Hermansen Asko Hannukkala Bent J. Nielsen Jens Grønbech Hansen Lina Grönberg Björn Andersson Jonathan YuenSammendrag
A new potato late blight forecasting model based on hourly weather date is developed based on trials with spore traps and trap plants. The model is built up of sub models for for the different steps in the epidemiological cycle, spore production, release, survival and infection. Long humid periods are suitable for spore production, at moderate humidity the process goes slower. The amount of viable attached sporangia is reduced by drought, and some spores are washed off during rain. Spores are released into the air by a drop in humidity or increased radiation, but the release is inhibited at high leaf wetness. The amount of viable released spores is strongly inhibited by solar radiation. The spore load is also reduced by precipitation and by germination. The leaf wetness duration have to sufficient for the spores to germinate and infect. The risk of blight development is a function of the amount of viable released spores and the duration of leaf wetness.
Sammendrag
Runoff time series are known to contain long term structures on interannual to decadal time scales. Investigating spatial patterns of long term structures is a way to elucidate the relationship between external forcings and watershed properties. This would be a valuable contribution to an improved water resources management. Singular System Analysis (SSA) is a powerful technique to identify and extract significant long term components from time series. However, many observations from natural systems are prone to missing data that hamper many analysis techniques, including the SSA in its original formulation...
Sammendrag
Wood is a unique building material, but is by nature designed to deteriorate. A detailed understanding of the factors and interactions involved are important when working with service life prediction of wooden components in buildings. Wood may experience exponential fungal degradation caused by variation in the climatic factors within a small limited area and by minor imperfection in the wooden component. In this paper we put forward a new term: critical in-situ conditions (CIC). This is meant to bring the attention to the importance of looking into details in the construction design, the specific climatic factors and interactions involved. Gaining realistic and useful data for prediction of service life is only possible by controlling and understanding the factors that are target specific for a wooden component or even only a part of it. Performing measurements in a right way and in the proper part of the wooden component are vital for getting useful data for further processing. The objective in this paper is to exemplify the CIC in inservice situations and to describe the factors and interactions that control the service life. Case studies were performed on a building at Bryggen in Bergen, on a hunting cabin on Svalbard, on several wooden windows in the southern part of Norway and on an external wall of a residence house in Ås.
Sammendrag
Tree-killing bark beetles conquer healthy trees by means of pheromone mediated mass-attacks. The initial attackers select trees through a process of random landing and processing of tactile and short-range chemical stimuli. Inside acceptable hosts they produce aggregation pheromones that attract additional attackers. In a recent field experiment we induced defense responses in 60-year-old Norway spruce trees and monitored colonization by the spruce bark beetle Ips typographus. Induced stem sections had significantly less beetle colonization than control sections, with shorter parental galleries and fewer eggs deposited. In addition, fewer beetles were attracted to beetles tunnelling in induced bark. This reduced ability to attract conspecifics suggests that induced host defenses interfere with beetle pheromone production or emission. The mechanisms responsible for this are unknown, but may involve emission of volatile terpenes such as (E)-b-farnesene and linalool, which have been shown to increase up to 100-fold in induced Norway spruce trees. These compounds have been reported to attract natural enemies of herbivores or repel herbivores directly in other conifer-insect interactions.