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.
2012
Forfattere
Hild-Marte Bjørnsen Ashok K. MishraSammendrag
Det er ikke registrert sammendrag
Forfattere
Terje Gobakken Erik Næsset Ross F. Nelson Ole Martin Bollandsås Timothy G. Gregoire Göran Ståhl Sören Holm Hans Ole Ørka Rasmus AstrupSammendrag
In this paper two sampling and estimation strategies for regional forestinventory were investigated in detail and results were presented for various geographical scales. Airbornelaser scanner (ALS) data were acquired to augment data from a systematic sample of NationalForestInventory (NFI) ground plots in HedmarkCounty, Norway (27,390 km2). Approximately 50% of the NFI fieldplots were covered by the systematic ALS sample of 53 parallel flight lines spaced 6 km apart. The area was stratified into eight cover classes and independent log-transformed regression models were developed for each class to predict total above-ground dry biomass (AGB). The two laser-ground estimation strategies tested were a model-dependent (MD), two-phase approach that rests on the assumption that the predictive models are correctly specified, and a model-assisted (MA) approach with a two-stage probability sampling design which utilizes design-unbiased estimators. ALS AGB estimates were reported by land cover class and compared to the NFI ground estimates. The ALS-based MA and MD mean estimates differed from the NFI AGB estimates by about 2% and 8%, respectively, for the entire County. At the county level the smallest estimated standard error (SE) for the estimates was obtained using the field data alone. However, the SEs calculated from field and ALS data were based on unequal numbers of ground plots. When considering only the NFI plots in the ALS strips, the smallest SEs were obtained using the MD framework. However, we also illustrated the sensitivity of the estimates of applying different plausible models. All the applied estimators assumed simple random sampling while the selection of flight lines as well as ground plots followed a systematic design. Thus, the estimates of SE were most likely conservative. Simulated sampling undertaken in a parallel research effort suggests that the overestimation of the SEs was probably much larger for the ALS-based estimates compared to the NFI estimates. ALS-based estimates were also derived for sub-county political units and thereby demonstrated how limited sample sizes affect the standard error of the biomass estimates.
Sammendrag
Climate change is a factor that largely contributes to the increase of forest areas affected by natural damages. Therefore, the development of methodologies for forest monitoring and rapid assessment of affected areas is required. Space-borne synthetic aperture radar (SAR) imagery with high resolution is now available for large-scale forest mapping and forest monitoring applications. However, a correct interpretation of SAR images requires an adequate preprocessing of the data consisting of orthorectification and radiometric calibration. The resolution and quality of the digital elevation model (DEM) used as reference is crucial for this purpose. Therefore, the primary aim of this study was to analyze the influence of the DEM quality used in the preprocessing of the SAR data on the mapping accuracy of forest types. In order to examine TerraSAR-X images to map forest dominated by deciduous and coniferous trees, High Resolution SpotLight images were acquired for two study sites in southern Germany. The SAR images were preprocessed with a Shuttle Radar Topography Mission (SRTM) DEM (resolution approximately 90 m), an airborne laser scanning (ALS) digital terrain model (DTM) (5 m resolution), and an ALS digital surface model (DSM) (5 m resolution). The orthorectification of the SAR images using high resolution ALS DEMs was found to be important for the reduction of errors in pixel location and to increase the classification accuracy of forest types. SAR images preprocessed with ALS DTMs resulted in the highest classification accuracies, with kappa coefficients of 0.49 and 0.41, respectively. SAR images preprocessed with ALS DTMs resulted in greater accuracy than those preprocessed with ALS DSMs in most cases. The classification accuracy of forest types using SAR images preprocessed with the SRTM DEM was fair, with kappa coefficients of 0.23 and 0.32, respectively.Analysis of the radar backscatter indicated that sample plots dominated by coniferous trees tended to have lower scattering coefficients than plots dominated by deciduous trees. Leaf-off images were only slightly better suited for the classification than leaf-on images. The combination of leaf-off and leaf-on improved the classification accuracy considerably since the backscatter changed between seasons, especially in deciduous-dominated forest.
Sammendrag
Frøavl av stedegne planter til restaurering etter inngrep i fjellet kan bli en viktig nisjeproduksjon for norske frøavlere. Måla med prosjekt FJELLFRØ (2007-2011) var (1) å samle inn mormateriale, (2) å oppformere dette materialet, (3) å utføre frøavlsforsøk, og (4) å anlegge demonstasjonsfelter med utprøving av stedegent plantemateriale i utvalgte anleggsområder i fjellet. Prosjektet ble eid av Telemark frøavlerlag (hovedeier), Norges Vassdrags- og Energidirektorat (NVE), Statkraft Energi AS, Forsvarsbygg og Felleskjøpet Agri. Innovasjon Norge, Innovasjon Telemark, NVE og Statkraft Energi AS finansierte prosjektet gjennom kontantbidrag, og samtlige prosjekteiere gjennom egeninnsats. Til å utføre det faglige arbeidet i prosjektet engasjert styringsgruppa Bioforsk, som igjen fikk hjelp av Norsk Landbruksrådgivning Østafjells til forsøk og første generasjons oppformeringsfelt. Ut over i prosjektperioden fikk Bioforsk også en annen viktig rolle i prosjekt som autorisert frøforretning med ansvar for kontraktstegning, rensing, frøanalyser, salg og markedsføring av frøet som produseres hos frøavlerne i Telemark. Ved avslutning av FJELLFRØ-prosjektet videreføres mye av aktiviteten gjennom delprosjekt III (Location, seed crop management and commercialization) av prosjekt ECONADA (2011-2014). Foreliggende rapport gir en oversikt over aktiviteten i FJELLFRØ i siste prosjektår 2011, samt en kort oppsummering av hele prosjektperioden.
Forfattere
Mette Thomsen Bertalan Galambosi Zsuzsanna Galambosi Marja Uusitalo Ruth Mordal Alpo HeinonenSammendrag
In the present study we evaluated the effect of phenological stage at harvest and drying temperature on the content of secondary metabolites in six year old cultivatedclones of Rhodiola rosea. The experimental work was performed in cooperation between MTT in Finland and Bioforsk in Norway. In spite of the differences in growing season, we found similar development in biomassproduction and content of secondary metabolites in the two field experiments.During the period with intensive shoot growth the dry weight of the rootdecreased until budding / full flowering followed by an increase towards thelast harvest after wilting. The % dry matter followed the same development. The content of total rosavins in the dry rhizomes was highest at flowering at both sitesand the average content for spring was 24 % respectively 21% higher than inautumn in Finland and Norway (P=0,002). In Finland the average content of salidroside in spring of the dry rhizomewas 68 % higher than in autumn. While in Norway there were no differences insalidroside content at the different phenological stages (P = 0,097), lowvariation in the content of cinnamic alcohol at both sites was observed, but atendency to a small increase after flowering. The content of total rosavins was significantly higher at drying temperatures at or below 50˚C (P
Forfattere
Merete Dees Leslie A WannerSammendrag
Common scab (CS) is an important disease and quality problem in potato crops worldwide. CS degrades the appearance of the potato tubers, thereby diminishing market value. Knowledge of CS has expanded considerably over recent years, enabling improved detection of the causal pathogens and increased understanding of mechanisms of pathogenicity, and providing potential methods of modulating pathogen response for disease resistance. However, effective control of this disease remains elusive, and will require increased understanding of both the host and the pathogen. Traditional control strategies such as irrigation and reduced soil pH are not sufficient and often fail. Optimizing environmental conditions for reduction of CS can also lead to favorable conditions for other diseases. The most desirable control method would be disease-resistant potato cultivars. However, no currently available commercial potato cultivar has been shown to be completely resistant to CS. In this review, we provide an overview of potato CS caused by plant pathogenic Streptomyces species, recent research on mechanisms and management of the disease, and knowledge gaps that limit successful control of this ubiquitous and troublesome disease.
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Christian Guido Bruckner Kerstin Mammitzsch Günter Jost Juliane Wendt Matthias Labrenz Klaus JürgensSammendrag
Pelagic marine oxygen-depleted zones often exhibit a redox gradient, caused by oxygen depletion due to biological demand exceeding ventilation, and the accumulation of reduced chemical species, such as hydrogen sulfide. These redox gradients harbour a distinct assemblage of epsilonproteobacteria capable of fixing carbon dioxide autotrophically in the dark and potentially of utilizing hydrogen sulfide chemolithotrophically by oxidation with nitrate. Together, these two processes are referred to as chemolithoautotrophic denitrification. The focus of this study was the recently isolated and cultivated representative strain of pelagic epsilonproteobacteria, 'Sulfurimonas gotlandica' strain GD1, specifically dark carbon dioxide fixation and its substrate turnovers during chemolithotrophic denitrification. By connecting these processes stoichiometrically and comparing the results with those obtained for dark carbon dioxide fixation and nutrient concentrations measured in pelagic redox gradients of the Baltic Sea, we were able to estimate the role of chemolithoautotrophic denitrification in the environment. Evidence is provided for a defined zone where chemolithoautotrophic denitrification of these epsilonproteobacteria allows the complete removal of nitrate and hydrogen sulfide from the water column. This water layer is roughly equivalent in thickness to the average overlapping region of the two substrates, but slightly larger. Such a difference may be explained by a variety of reasons, including, e.g. utilization of substrates present at concentrations below the detection limit, alternative usage of other substrates as thiosulfate or nitrous oxide, or comparable activities of other microbes. However, the combined results of in vitro and in situ studies strongly suggest that epsilonproteobacteria are primarily responsible for hydrogen sulfide and nitrate removal from pelagic Baltic Sea redox gradients.
Forfattere
Claire Coutris Knut-Erik Tollefsen Mussie Woldehawariat John W Einset Erik J. Joner Deborah Helen Oughton Steven BrooksSammendrag
Norway has the world’s largest facility for testing and improving CO2 capture. The aim of carbon capture technology is to minimize greenhouse gas emissions through a reaction between amines and effluents from gas power plants. During the overall process of CO2 capture, amines and their transformation products might escape to the environment through emissions, leakage, and as solid waste. The two main groups of transformation products with the most potential to cause environmental harm have been identified as nitrosamines and nitramines, both of which are considered to be carcinogenic. Recent theoretical modelling as well as laboratory experiments have found nitramine compounds, 2-nitroaminoethanol (CAS: 74386-82-6) and dimethylnitramine (CAS: 4164-28-7) to be present. However, despite the likelihood of these compounds increasing in the environment, no environmental toxicity data for these compounds currently exist. The aim of this project was to provide an environmental risk assessment for the selected nitramine compounds taking into account the key trophic groups within freshwater, marine and terrestrial environments. The toxicity assessment was made using a suite of standardised bioassays for the measure of acute and chronic toxicity. In the soil environment, the most potent compound was 2-nitroaminoethanol, which impaired the reproduction of earthworms and the seedling emergence of sunflower and ryegrass. The opposite was found in the aquatic environment, with freshwater and marine species consistently more affected by dimethylnitramine. All the tested freshwater species were more sensitive to nitramines than marine species. The selected amines were not acutely toxic to aquatic and soil species, with EC50 in the mg/L range. Both nitramines increased the nitrogen and carbon transformation activity of soil microorganisms.
Forfattere
Nicholas ClarkeSammendrag
This report aims to summarise briefly the findings in the scientific literature concerning the effect of both stem-only and whole-tree harvesting on soil carbon stocks. Although the findings reported by previous authors vary, it is possible to draw some general conclusions about the effect of harvesting on soil carbon, and on whether whole-tree harvesting has a greater effect than stem-only harvesting. In general it appears that the organic C content in the soil’s organic layer is reduced after stem-only harvesting, sometimes by as much as 50%. This reduction has been explained in several ways. After a period of maybe 20 years, the carbon content of the organic layer starts to increase again. In the mineral soil a reduction is not always apparent and the C content can even increase, probably because of the incorporation of residues into the soil. Some studies have shown that this increase is short-lived, while others have found a longer-term increase. Unsurprisingly, thinning appears to affect the soil carbon content much less than clear-cutting; the effect tends to be proportional to the thinning intensity. The soil carbon content appears to be higher after selection cutting than after clear-cutting. Studies comparing effects of whole-tree harvest with those of stem-only harvest have tended to show smaller carbon contents in the mineral soil after whole-tree harvest than after stem-only harvest, although once again results vary greatly. There are many factors affecting soil C content and thus accounting for the observed differences, including temperature, moisture content, and harvesting type. Variation in the results obtained may depend on site-specific factors such as site nutrient status, especially with regard to the most common limiting nutrient nitrogen, which will affect growth in the next rotation. Making sure there are enough nutrients available, if necessary by compensatory fertilisation, will improve carbon sequestration in both trees and soil.