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.
2016
Sammendrag
Sustainable forest management in an era of global changes has always been a central thematic area for the International Boreal Forest Research Association (IBFRA). At the 17th IBFRA conference held on 24–29 May 2015 in Rovaniemi, Finland, the theme of global change was accompanied by a new theme related to the use and value of big data in boreal forest management and research. Keynote presentations had a clear message that sustainably managed boreal forests and peatlands play a significant role in climate change mitigation. However, the choice of the most efficient mitigation options will vary with regional differences in ecology, institutional strength, and management intensity. In addition to changes in greenhouse gas fluxes linked to ecosystem dynamics, the design of climate change mitigation strategies should also account for the fate of harvested wood products and for the substitution of more energy-intensive materials such as concrete and steel. For climate change mitigation, it is therefore not only forest management that matters, but also ensuring the best possible end use for the produced biomass. Key note presentations on use and value of big data in the forest sector demonstrated the role of time series of remote sensing data in forest monitoring and research. In addition, new technologies and methods including terrestrial laser scanning are starting to provide detailed three-dimensional information from forest stands from which management tools and scientific understanding will be developed. Finally, citizen science was shown to offer a vast potential for the generation of forest-based data. Thus, new means are being developed by which forest scientists and managers will be able to obtain new, more frequent, and more detailed information on the forest. The ensuing development of knowledge will benefit the forest sector, create new opportunities for furthering boreal forest science, and finally benefit the society as a whole...
Forfattere
Belachew Gizachew Zeleke Svein Solberg Erik Næsset Terje Gobakken Ole Martin Bollandsås Johannes Breidenbach Eliakimu Zahabu Ernest William MauyaSammendrag
Background: A functional forest carbon measuring, reporting and verification (MRV) system to support climate change mitigation policies, such as REDD+, requires estimates of forest biomass carbon, as an input to estimate emissions. A combination of field inventory and remote sensing is expected to provide those data. By linking Landsat 8 and forest inventory data, we (1) developed linear mixed effects models for total living biomass (TLB) estimation as a function of spectral variables, (2) developed a 30 m resolution map of the total living carbon (TLC), and (3) estimated the total TLB stock of the study area. Inventory data consisted of tree measurements from 500 plots in 63 clusters in a 15,700 km2 study area, in miombo woodlands of Tanzania. The Landsat 8 data comprised two climate data record images covering the inventory area. Results: We found a linear relationship between TLB and Landsat 8 derived spectral variables, and there was no clear evidence of spectral data saturation at higher biomass values. The root-mean-square error of the values predicted by the linear model linking the TLB and the normalized difference vegetation index (NDVI) is equal to 44 t/ha (49 % of the mean value). The estimated TLB for the study area was 140 Mt, with a mean TLB density of 81 t/ha, and a 95 % confidence interval of 74–88 t/ha. We mapped the distribution of TLC of the study area using the TLB model, where TLC was estimated at 47 % of TLB. Conclusion: The low biomass in the miombo woodlands, and the absence of a spectral data saturation problem suggested that Landsat 8 derived NDVI is suitable auxiliary information for carbon monitoring in the context of REDD+, for low-biomass, open-canopy woodlands.
Sammendrag
This paper presents peer-reviewed studies comparing the content of deoxynivalenol (DON), HT-2+T-2 toxins, zearalenone (ZEA), nivalenol (NIV), ochratoxin A (OTA) and fumonisins in cereal grains, and patulin (PAT) in apple and apple-based products, produced in organically and conventionally grown crops in temperate regions. Some of the studies are based on data from controlled field trials, however, most are farm surveys and some are food basket surveys. Almost half of the studies focused on DON in cereals. The majority of these studies found no significant difference in DON content in grain from the two farming systems, but several studies showed lower DON content in organically than in conventionally produced cereals. A number of the investigations reported low DON levels in grain, far below the EU limits for food. Many authors suggested that weather conditions, years, locations, tillage practice and crop rotation are more important for the development of DON than the type of farming. Organically produced oats contained mainly lower levels of HT-2+T-2 toxins than conventionally produced oats. Most studies on ZEA reported no differences between farming systems, or lower concentrations in organically produced grain. For the other mycotoxins in cereals, mainly low levels and no differences between the two farming systems were reported. Some studies showed higher PAT contamination in organically than in conventionally produced apple and apple products. The difference may be due to more efficient disease control in conventional orchards. It cannot be concluded that any of the two farming systems increases the risk of mycotoxin contamination. Despite no use of fungicides, an organic system appears generally able to maintain mycotoxin contamination at low levels. More systematic comparisons from scientifically controlled field trials and surveys are needed to clarify if there are differences in the risk of mycotoxin contamination between organically and conventionally produced crops.
Sammendrag
Flere studier har avdekket store forskjeller i lønnsomhet mellom gårdsbruk. Usikkerhet knyttet til indre og ytre faktorer i gårdsdrifta gir en kompleks og skiftende beslutningsprosess som krever tilgang til mange informasjonskilder. At det er også variasjon på bruk med samme produksjon og like ressurser er en indikasjon på at indre faktorene som kan påvirkes av bonden er viktige for det økonomiske resultatet. Selv om bønder kan ha svært forskjellige mål for virksomheten, er det rimelig å anta at det er forbedringsmuligheter på de fleste brukene. Det er derfor viktig å prøve å avdekke årsakene til den store variasjonen i økonomisk prestasjon i primærlandbruket. I dette prosjektet har vi undersøkt hvordan lønnsomhet varierer mellom gårdsbruk i det enkelte år og på enkeltbruk mellom år. Vi har sett på forskjeller mellom driftsformer, regioner og bruksstørrelser. Hensikten med dette har vært å identifisere de variablene som synes å ha størst betydning for variasjon i lønnsomhet, og i hvilken grad dette er faktorer som kan påvirkes av den enkelte bonde. Prosjektet er gjennomført som en kvantitativ undersøkelse av datamaterialet fra driftsgranskingene i perioden 2010 – 2014, med driftsformene melk, sau og korn. I tillegg har vi undersøkt variasjonen innen bruk mellom år, gjennom en panelstudie av de brukene som var med i samtlige år i 2010 – 2014. Vi har brukt driftsoverskudd per enhet som resultatmål i prosjektet, fordi det mulig å sammenligne bruk fra hele landet med ulike størrelser og produksjonsvilkår. Datamaterialet ble undersøkt med hjelp av beskrivende statistikk. Det ble også utført en regresjonsanalyse på melkebrukene for å kunne si noen om hvordan ulike faktorer påvirker lønnsomheten. Vi har sett på variasjon og spredning i driftsoverskudd i forhold til produksjonsstørrelse for hver av de tre driftsformene i 2014. Alle brukene ble deretter delt i tre grupper ut fra oppnådd resultat i hvert enkelt år i perioden 2010 – 2014, der vi sammenligner resultatene for den beste tredelen med den tredelen med svakest lønnsomhet.
Forfattere
Tomasz Leszek Woznicki Anita Sønsteby Kjersti Aaby Berit Karoline Martinsen Ola M. Heide Anne-Berit Wold Siv Fagertun RembergSammendrag
BACKGROUND Marked effects of the climatic environment on fruit chemical composition have often been demonstrated in field experiments. However, complex covariations of several climatic factors in the natural environment complicate the interpretation of such experiments and the identification of the causal factors. This can be better achieved in a phytotron where the various climatic factors can be varied systematically. Therefore, we grew four black currant cultivars of contrasting origin in a phytotron under controlled post-flowering temperature and photoperiod conditions and analysed the berries for their ascorbic acid, sugar and organic acid contents. RESULTS The analyses revealed significant effects of genotype on all investigated compounds. Particularly large cultivar differences were observed in the concentrations of l-ascorbic acid (AA) and sucrose. The concentrations of both AA and dehydroascorbic acid (DHAA), as well as the concentrations of all major sugars, decreased consistently with an increasing temperature over the temperature range 12–24 °C. Fructose and glucose were the predominant sugars with concentrations several fold higher than that for sucrose. AA was the main contributor to the total ascorbate pool in black currant berries. The AA/DHAA ratio varied from 5.6 to 10.3 among the studied cultivars. The concentration of citric acid, which was the predominant organic acid in black currant berries, increased with an increasing temperature, whereas the opposite trend was observed for malic and shikimic acid. Quninic acid was always present at relatively low concentrations. By contrast, photoperiod had no significant effect on berry content of any of the investigated compounds. CONCLUSION It is concluded that the post-flowering temperature has marked effects on the concentration of important chemical compounds responsible for taste and nutritional value of black currant berries, whereas photoperiod has no such effect in the studied cultivars. © 2016 Society of Chemical Industry
Sammendrag
The growing season is longer than earlier and especially autumn temperatures have increased during the last 30 years (Hanssen‐Bauer et al 2015). A longer growing season increases the potential for forage production as an earlier spring, and warmer autumn implies that farmers can take more cuts with larger yields than earlier. Nevertheless, a warmer autumn can promote considerable regrowth after the last cut, and farmers report that they are uncertain if this regrowth should be harvested. The cost of harvesting forage is high, and feed quality of late harvested forage may be sub‐optimal. Changing precipitation patterns where there may be more episodes of heavy rains during autumn, late harvesting of grass swards can increase the risk of soil compaction and damage plant cover. This was the background to a study where we examine how different harvest time in autumn affects overwintering and yields the following year. We have established randomized block field experiments with 3 replicates in established leys dominated by timothy (Phleum pratense L.) at two sites in Norway in 2015; Kvithamar 63o29’N, 10o53’E, and Holt 69o38’N, 18o57’E. In the Kvithamar field, the main harvests were made June 30 and August 10. Thereafter, in one treatment, plots were left unharvested till next spring, while in other treatments plots were cut 4, 6, 8 or 10 weeks after the second main harvest. At Holt, the first harvest was made July 7, and the second harvest either August 11 or August 27. The regrowth after these treatments were either left uncut or harvested 4, 6 or 8 weeks after the last main cut in August 10, or 6 weeks after the cut in August 28. Dry matter yields were measured from all cuts. The results were analysed using ANOVA with MiniTab. No significant differences in yields were found between the different cutting treatments at either site, even though temperatures were between 2.2‐ 2.5oC higher than normal (1961‐1990) in September and between 1.1‐1.6 warmer than normal in October. Global radiation decreases rapidly from September onwards, and is a limiting factor for the growth potential of timothy‐dominated leys. In spring, we will measure winter survival and growth rate and yields in all treatments. The results from these measurements will be presented at the conference.
Forfattere
Sabine Rosner Jan Světlík Kjell Andreassen Isabella Børja Lise Dalsgaard Robert Evans Saskia Luss Ole Einar Tveito Svein SolbergSammendrag
Top dieback in 40–60 years old forest stands of Norway spruce [Picea abies (L.) Karst.] in southern Norway is supposed to be associated with climatic extremes. Our intention was to learn more about the processes related to top dieback and in particular about the plasticity of possible predisposing factors. We aimed at (i) developing proxies for P50 based on anatomical data assessed by SilviScan technology and (ii) testing these proxies for their plasticity regarding climate, in order to (iii) analyze annual variations of hydraulic proxies of healthy looking trees and trees with top dieback upon their impact on tree survival. At two sites we selected 10 tree pairs, i.e., one healthy looking tree and one tree with visual signs of dieback such as dry tops, needle shortening and needle yellowing (n = 40 trees). Vulnerability to cavitation (P50) of the main trunk was assessed in a selected sample set (n = 19) and we thereafter applied SilviScan technology to measure cell dimensions (lumen (b) and cell wall thickness (t)) in these specimen and in all 40 trees in tree rings formed between 1990 and 2010. In a first analysis step, we searched for anatomical proxies for P50. The set of potential proxies included hydraulic lumen diameters and wall reinforcement parameters based on mean, radial, and tangential tracheid diameters. The conduit wall reinforcement based on tangential hydraulic lumen diameters ((t/bht)2) was the best estimate for P50. It was thus possible to relate climatic extremes to the potential vulnerability of single annual rings. Trees with top dieback had significantly lower (t/bht)2 and wider tangential (hydraulic) lumen diameters some years before a period of water deficit (2005–2006). Radial (hydraulic) lumen diameters showed however no significant differences between both tree groups. (t/bht)2 was influenced by annual climate variability; strongest correlations were found with precipitation in September of the previous growing season: high precipitation in previous September resulted in more vulnerable annual rings in the next season. The results are discussed with respect to an “opportunistic behavior” and genetic predisposition to drought sensitivity.
Sammendrag
Det er ikke registrert sammendrag
Sammendrag
Convergent Cross Mapping (CCM) has recently been introduced by Sugihara et al. for the identification and quantification of causal relationships among ecosystem variables. In particular, the method allows to decide on the direction of causality; in some cases, the causality might be bidirectional, indicating a network structure. We extend this approach by introducing a method of surrogate data to obtain confidence intervals for CCM results. We then apply this method to time series from stream water chemistry. Specifically, we analyze a set of eight dissolved major ions from three different catchments belonging to the hydrological monitoring system at the Bramke valley in the Harz Mountains, Germany. Our results demonstrate the potentials and limits of CCM as a monitoring instrument in forestry and hydrology or as a tool to identify processes in ecosystem research. While some networks of causally linked ions can be associated with simple physical and chemical processes, other results illustrate peculiarities of the three studied catchments, which are explained in the context of their special history.
Sammendrag
I denne rapporten er det gitt en vurdering av samfunnsøkonomiske konsekvenser og effekter på klimagassutslipp som følge av innskrenkninger i adgangen til nydyrking av myr. Restriksjoner mot nydyrking av myr vil i liten grad begrense mulighetene for matproduksjon i Norge, men kan føre til reduserte muligheter for nydyrking i områder med små arealer med alternativ dyrkbar jord. Et generelt forbud mot nydyrking av myr antas å føre til en reduksjon i klimagassutslipp mellom 200 000 og 600 000 tonn CO2-ekvivalenter i 2050, avhengig av hvor store arealer myr som ville blitt nydyrket uten et forbud. Et forbud som bare omfatter djup myr antas å føre til en utslippsreduksjon på mellom 150 000 og 450 000 tonn CO2-ekvivalenter i 2050. Nydyrking av myr ved omgraving forventes å gi lavere utslipp enn tradisjonell dyrking, men effektene på kort og lang sikt er foreløpig svært usikre.