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
Forfattere
Miguel D. Mahecha Markus Reichstein Holger Lange Nuño Carvalhais T. Grünwald Dario Papale G. SeufertSammendrag
Characterizing ecosystem-atmosphere interactions in terms of carbon and water exchange on different time scales is considered a major challenge in terrestrial biogeochemical cycle research. The respective time series currently comprise an observation period of up to one decade. In this study, we explored whether the observation period is already sufficient to detect cross-relationships between the variables beyond the annual cycle, as they are expected from comparable studies in climatology. We investigated the potential of Singular System Analysis (SSA) to extract arbitrary kinds of oscillatory patterns. The method is completely data adaptive and performs an effective signal to noise separation. We found that most observations (Net Ecosystem Exchange, NEE, Gross Primary Productivity, GPP, Ecosystem Respiration, Reco, Vapor Pressure Deficit, VPD, Latent Heat, LE, Sensible Heat, H, Wind Speed, u, and Precipitation, P) were influenced significantly by low-frequency components (interannual variability). Furthermore, we extracted a set of nontrivial relationships and found clear seasonal hysteresis effects except for the interrelation of NEE with Global Radiation (Rg). SSA provides a new tool for the investigation of these phenomena explicitly on different time scales. Furthermore, we showed that SSA has great potential for eddy covariance data processing, since it can be applied as a novel gap filling approach relying on the temporal correlation structure of the time series structure only.
Forfattere
Mekjell Meland Magne MoeSammendrag
The performance of the plum rootstocks Marianna, Pixy and Wangenheim using St. Julien A as a standard to the cultivars `Avalon", `Edda", `Excalibur", `Jubileum", `Reeves" and `Victoria" was assessed in a field trial in western Norway at 60" North. Trees were planted in spring 1999, the plant material was one-year-old whips, spaced 2.0 x 4.5 m and formed with a central leader as free spindles. Soil management was grass in the alleyways and herbicide strips 1-m wide along the tree rows. Tree vigour, yield, fruit size and yield efficentcy were evaluated for the six subsequent years. Tree size was significantly affected by the rootstocks after six years growth. Wangenheim produced the smallest and St. Julien A and Pixy the largest trees as measured by trunk cross-sectional area in average for the different cultivars. St. Julien A and Pixy were the most productive rootstocks for the cultivars. However, Pixy produced significant larger yields per tree to the cultivar `Reeves" than St. Julien A. Trees on Pixy were the most yield efficient for all cultivars with the exception of `Victoria". The fruit sizes were in general large for all cultivars and became little affected by the different rootstocks. Fruit quality characterized by the content of soluble solids was in general high and did not differ between trees on the various rootstocks. The cultivar `Avalon" had the highest contents of soluble solids.
Sammendrag
To avoid problems with seed borne diseases in organic cereal production, seed health testing should be compulsory in certification of organic seed. In general, significantly lower infection frequencies of seed borne diseases are recorded on seedlings than on seed. Thresholds for the amount of seed borne inoculum that can be accepted for organic production are therefore needed. The aim of the work presented is to compare transmission rates of Drechslera on barley and oats under organic and conventional conditions, to be able to decide if existing thresholds used to assess the need of chemical seed treatment, can be applied for acceptance of organic seed lots, or for recommendation of alternative treatments. Field experiments were carried out in 2005 in conventional and organic fields situated close to each other at each of three locations (south/east-Norway, east-Norway and mid-Norway). 10 seed lots of barley and 10 lots of oats, with a range of seed infections (barley: 0-94 % Drechslera teres, average 31.4 %; oats: 0-66 % Drechslera avenae, average 22.0 %) were planted in rows of 100 seeds with 8 replicates in each location/`growing system". Percent emergence and seedlings with primary infections were recorded at BBCH 12-13. On average in the three locations 2.5 % and 1.8 % barley seedlings were infected when grown in conventional and organic fields, respectively. In oats, 2.0 % and 0.9 % infected seedlings were recorded in conventional and organic fields, respectively. Similar experiments will be carried out in 2006 and results from this will also be presented.
Forfattere
Klaus MittenzweiSammendrag
De internasjonale matvareprisene for korn og meieriprodukter har økt betydelig i den senere tid. Om økningen vil være varig avhenger av flere faktorer, deriblant økonomisk vekst i Asia og dreining av forbruksmønster i den regionen mot vestlige matvaner. Dersom dette skulle bli en realitet, er det muligheter for at de internasjonale matvareprisene vil legge seg på et høyere nivå sammenlignet med situasjonen i perioden 2000-2005. For norsk jordbruk kan dette bety et økt handlingsrom til å utforme nasjonal landbrukspolitikk. I lys av de pågående WTO-forhandlingene om en ytterligere liberalisering av handelen med matvarer, innebærer dette at de forventede effekter av tollreduksjoner motvirkes av høyere importpriser. For å vurdere det økte handlingsrommet er det gjennomført kvantitative beregninger med den partielle likevektsmodellen Jordmod. Modellen omfatter mesteparten av dagens jordbruk og beregner et aktivitetsnivå (dvs. først og fremst innenlandsk produksjon og innsats av areal og arbeidskraft) i norsk jordbruk ut i fra de rammebetingelsene (importpriser, støttenivå og bruksstruktur) som legges til grunn i de enkelte scenariene. Grunnet modellens natur er resultatene alene ikke et tilstrekkelig grunnlag for en samlet vurdering av de scenariene som er utformet i denne analysen. Modellresultatene må derfor tolkes med forsiktighet og suppleres med annen kunnskap om konsekvensene av en ny WTO-avtale for norsk jordbruk. I en samlet vurdering tyder analysen på at en videreføring av viktige trender i dagens jordbrukspolitikk vil fortsatt kreve en aktiv tilpasning av norsk landbrukspolitikk. I en slik situasjon vil den relative betydningen av en eventuell ny WTO-avtale basert på Falconers forslag til avtale fra juli 2007 blir mindre. Falconer er formann i WTOs jordbrukskomité. Økte verdensmarkedspriser alene kan innebære at den totale støtten til norsk jordbruk kan reduseres uten at dette vil gå utover bøndenes inntekter. Med en ny WTO-avtale på plass vil det være et ytterliggere innsparingspotensialet. Økte verdensmarkedspriser kan gi høyere matvarepriser innenlands. Den samlede samfunnsøkonomiske effekten av høyere konsumutgifter for matvarer og en reduksjon i støtten til norsk jordbruk vil trolig likevel være positiv.
Forfattere
Susanne Eich-Greatorex Anne Falk Øgaard Trine A SognSammendrag
In parts of the world, Se availability in the soil is so low that Se contents in the crops produced there are well below recommended values. Since the difference between Se essentiality and toxicity is very small, the addition of Se via fertiliser is controversial. Therefore, it is important to utilise the Se added in the best possible way. The objective of the present study was to investigate the influence of soil organic matter on the one hand, and addition of organic material (slurry) on the other hand on plant availability of selenium (Se) in soil. Pot experiments with the Se addition in the form of selenate were conducted with a peat, a loam and a peat/loam mixture at a range of pH values between 5 and 6.8. Se uptake from added Se fertiliser was higher in the soil types with high organic matter content than in the loam at pH 6 and below. The opposite occurred at a soil pH above 6.4, where Se uptake was higher in the loam than in the peat. In a pot experiment using only peat and loam at two pH levels, cattle slurry added together with selenate was found to increase the Se concentration in grain at the higher pH. At the lower pH there was no significant effect of slurry on Se concentration in grain. Application of slurry also increased the residual effect of Se that had been applied to the loam in the preceding growing season. In the peat, no residual effect of Se was found either with or without the addition of slurry.
Sammendrag
Det er umulig å forutsi om en vil få angrep av soppsjukdommer om vinteren, og hvor sterke angrepene eventuelt vil bli. En soppbekjempelse om høsten er derfor en forsikring. Behovet må vurderes etter hvor stor risikoen for angrep er. I den vurderinga må en ta hensyn til hvor stor risikoen for langvarig snødekke er på skiftet, hvor store plantene er ved innvintring, halmbehandling m.m. Hvis angrepene blir kraftig vil normalt et storbilurinholdig preparat være best, mens det ved moderate angrep er små forskjell mellom det godkjente midlene. En behandling koster rundt 40 " 50 kr, og forventet avlingsgevinst bør derfor være rundt 25 kg for å dekke direkte utgifter.
Forfattere
Christer Magnusson Karl Thunes Hans Nyeggen Hans Overgaard Trond Rafoss Solveig Haukeland May Bente Brurberg K. A. Strandenæs Bjørn Økland Bonsak HammeraasSammendrag
The detection in 1999 of the pine wood nematode (PWN), Bursaphelenchus xylophilus, in Portugal triggered survey activities in many European countries. With the assumption that PWN would reach frequency 10 times lower than the native B. mucronatus and the requirement of a 95 % confidence limit suggested 2 995 samples to be required for a safe statement on the absence of PWN from the territory surveyed. Samples were taken from 10 circular areas with 50 km diameter erected from a point of import of risk materials. In the period 2000-2006 3 165 wood samples, 2 880 from Pinus sylvestris, 279 from Picea abies and 6 from unknown wood, were collected from 446 logging sites, in 84 municipalities and 13 counties. Of the total material 85 % of the samples came from cutting wastes, timber or lying trees. Wood showing signs of insect activity (incl. Monochamus) formed 73 % of the total material. Nematodes were recorded in 85 % of the samples. The order Rhabditida was most frequent, followed by the orders Aphelenchida, Tylenchida and Dorylaimida. Rhabditid nematodes were equally frequent in pine and spruce, while Aphelenchida (Aphelenchus, Aphelenchoides, Cryptaphelenchus, Seinura and Bursaphelenchus) and Tylenchida (Filenchus, Lelenchus, Ditylenchus, Deladenus and Nothotylenchus) tended to be more common in pinewood. Aphelenchoides was the most common genus. The genus Bursaphelenchus occurred in 1 % of the samples. B. mucronatus was detected in 0,3 % of the samples and most often in cutting waste of pine. The pine wood nematode (PWN), B. xylophilus, was not detected in this survey. The unexpected low natural occurrence of B. mucronatus indicates that the number of potential niches for PWN also is lower than expected, and hence it will be necessary to continue this surveillance program to reach 10 000 samples. The present zone sites in central and south-eastern Norway will be supplemented with 1-2 zone sites in southwestern region of the country. In the future these zone sites will function as permanent observation areas. Care will also be taken to collect all samples from detached wood with signs of Monochamus activity.
Forfattere
Thomas Hartnik Henning MatthiesenSammendrag
Piling as a foundation technique on cultural layers has the advantage that the amount of excavated material is reduced. On the other hand, piling can have an adverse impact on the preservation of cultural layers in the ground due to physical deterioration and by enhancing biological degradation. The study presented in this report aimed at assessing the effect of piling and associated construction techniques on the environmental conditions in cultural layers that control biological degradation. Physical and chemical investigations in two excavated soil profiles near Hotel Klubben in Tønsberg were performed where piling was used as a foundation technique, and where drillings had earlier indicated a reduced organic content and worse state of preservation of the deposits close to the pile. Environmental conditions were assessed conducting field and laboratory measurements of basic physical and chemical parameters, as well as measurements of redox sensitive parameters. The results of the measurements revealed high oxygen concentrations near the foundation wall of the building where the cultural layers had been exchanged by porous fill masses. While areas that were not affected by oxygen intrusion had iron and sulphate reducing conditions that represent good preservation conditions in cultural layers, redox conditions near the building were aerobic and nitratereducing. These conditions enhance degradation of cultural layers. Oxygen intrusion into the ground is most likely facilitated by coarse material that was refilled next to the building when a girder was built under the foundation walls of the building. This coarse material enables diffusion of air into cultural layers as well as percolation of oxygen rich rain water into the ground . A possible adverse effect of the pile on environmental conditions is totally overshadowed by the effect of the girder and refilling material and could not be detected. It was not possible to investigate the conditions closer than approximately 50 cm from the pile. Nor was it possible to investigate the conditions deeper than 2.2 m beneath the soil surface, and thus this report cannot conclude anything about the conditions and possible impacts outside the investigated area.
Forfattere
Heidi KnutsenSammendrag
Kulturlandskapet i fjordbygdene på Vestlandet er formet av det jordbruket som drives langs fjordene. Flyfoto viser tydelige endringer i landskapet, marginale arealer gror til med busker og trær, men også bakkeplanering, spesialisering og nye dyrkingsteknikker setter tydelige spor i landskapet.
Forfattere
Ievina Sturite Trond Maukon Henriksen Tor Arvid BrelandSammendrag
We have studied to what degree Italian ryegrass (Lolium multiflorum Lam.), white clover (Trifolium repens L.) and meadow fescue (Festuca pratensis L.) are able to preserve nitrogen (N) and phosphorous (P) in shoots and roots from one growing season to the next in a northern temperate climate. Field experiments were performed during four consecutive winters in central southeast Norway (60 degrees 42'N, 10 degrees 51'E), and N and P in plant biomass were measured in the autumn and in the spring. We also measured the contents of total N, total P and organic carbon (C) in seepage water that percolated through the aboveground plant material. Uptake of N and P in Italian ryegrass and white clover was substantially larger than in meadow fescue. The winter losses varied greatly from year to year, depending on the winter climate. On the average for all three of the plant species, the winter losses of N from aboveground biomass were 6, 35, 68 and 10% in the four experimental years, respectively. The corresponding P losses were 11, 36, 60 and 22%. On the average for all plant species and experimental years, 43 (+/- 12)% (S.E., n = 12) of the N, 34 (+/- 9)% of the P and 4 (+/- 1)% of the C that was lost from the aboveground plant biomass during the winter, was recovered in seepage water, basically as a nutrient pulse in melt water in early spring. The very low C recovery rate in seepage water suggested a considerable microbial growth on lost plant C. Assuming that all un-recovered plant C was consumed by microorganisms not included in measurements of the seepage water, modelling showed that microbial immobilisation theoretically might explain the unexpectedly low recovery rates of N and P. The study was not designed to investigate the possible effects of psychrophilic microbes on N and P cycling. Therefore, it is inconclusive and underlines the need for more knowledge on this matter. (c) 2006 Elsevier B.V. All rights reserved.