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Publications

NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.

2023

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Abstract

Craft breweries are continuously searching for beers made with locally produced raw materials and unique flavor profiles to respond to consumer requests. We explored the behavior of three commercial strains of Saccharomyces cerevisiae in the fermentation of ale beer with a high prevalence of rye malt in comparison to pure barley malt. In total, 34 volatile organic compounds were identified, with esters and alcohols being the quantitatively most abundant classes. The yeast strain appeared to impart more differences in the beer’s volatile profile compared to malt. In particular, S. cerevisiae var. diastaticus Y2 strain was associated with a higher production of esters, while strain S. cerevisiae Y3 was correlated to the higher amounts of terpenes together with the lowest relative abundance of volatile acids. Our findings encourage further investigation of the fermentation performance of several yeast strains to produce beers with unique flavors.

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Abstract

Up-to-date and reliable information on land cover and land use status is important in many aspects of human activities. Knowledge about the reference dataset, its coverage, nomenclature, thematic and geometric accuracy, spatial resolution is crucial for appropriate selection of reference samples used in the classification process. In this study, we examined the impact of the selection and pre-processing of reference samples for the classification accuracy. The classification based on Random Forest algorithm was performed using firstly the automatically selected reference samples derived directly from the national databases, and secondly using the pre-processed and verified reference samples. The verification procedures involved the iterative analysis of histogram of spectral features derived from the Sentinel-2 data for individual land cover classes. The verification of the reference samples improved the accuracy of delineation of all land cover classes. The highest improvement was achieved for the woodland broadleaved and non- and sparce vegetation classes, with the overall accuracy increasing from 51% to 73%, and from 33% to 74%, respectively. The second objective of this study was to derive the best possible land cover classification over the mountain area in Norway, therefore we examined whether the use of the Digital Elevation Model (DEM) can improve the classification results. Classifications were carried out based on Sentinel-2 data and a combination of Sentinel-2 and DEM. Using the DEM the accuracy for nine out of ten land cover classes was improved. The highest improvement was achieved for classes located at higher altitudes: low vegetation and non- and sparse vegetation.

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Plant rooting patterns in bioswales, raingardens and other vegetated infiltration systems are essential, as they contribute biopores which maintain the infiltration function over time. However, fluctuating hydrological conditions, ranging from flooded to drained, can have a heavy impact on plant rooting, as well as consequences for plant contributions to other ecosystem services and ecological functions. This study tested the biomass allocation to roots and the vertical root profile of four plant species, alone or in competition with a grass, and their responses to the experimental manipulation of soil hydrology in soil column microcosms. The hydrological regimes were combinations of flooded and drained conditions, respectively, including Wet cycles (72 and 96 h), Dry cycles (24 and 144 h), Wet-dry cycles (72 and 264 h), and Control group (watered twice per week). When the species were exposed to repeated wet-dry cycling hydrological regimes, we found a clear shift in vertical root distribution and shallower rooting in wetter regimes. It was also found that alongside this shallower rooting, there were no changes to total biomass and only moderate adjustments to biomass investment in roots. Overall, differences in rooting patterns between hydrological regimes and species were moderate when the dicot species were grown alone. The addition of the grass Festuca rubra contributed to a strong increase in total root mass density that evened out the differences in rooting patterns but also gave a deeper rooting. Accordingly, mixed species systems may be a robust approach to vegetated infiltration systems.

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The Arctic is one of the regions most sensitive to global warming, for which climate and environmental proxy archives are largely insufficient. Arctic driftwood provides a unique resource for research into the circumpolar entanglements of terrestrial, coastal and marine factors and processes – past, present, future. Here, first dendrochronological and wood anatomical insights into 639 Arctic driftwood samples are presented. Samples were collected across northern Norway (n =430) and north-western Iceland (n =209) in 2022. The overall potentials and limitations of Arctic driftwood to improve tree-ring chronologies from the boreal forest, and to reconstruct changes in sea ice extent and ocean current dynamics are discussed. Finally, the role driftwood has possibly played for Arctic settlements in the past hundreds of years is examined.

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Abstract

Biochar is a carbon (C)-rich material produced from biomass by anoxic or oxygen-limited thermal treatment known as pyrolysis. Despite substantial gaseous losses of C during pyrolysis, incorporating biochar in soil has been suggested as an effective long-term option to sequester CO2 for climate change mitigation, due to the intrinsic stability of biochar C. However, no universally applicable approach that combines biochar quality and pyrolysis yield into an overall metric of C sequestration efficiency has been suggested yet. To ensure safe environmental use of biochar in agricultural soils, the International Biochar Initiative and the European Biochar Certificate have developed guidelines on biochar quality. In both guidelines, the hydrogen-to-organic C (H/Corg) ratio is an important quality criterion widely used as a proxy of biochar stability, which has been recognized also in the new EU regulation 2021/2088. Here, we evaluate the biochar C sequestration efficiency from published data that comply with the biochar quality criteria in the above guidelines, which may regulate future large-scale field application in practice. The sequestration efficiency is calculated from the fraction of biochar C remaining in soil after 100 years (Fperm) and the C-yield of various feedstocks pyrolyzed at different temperatures. Both parameters are expressed as a function of H/Corg. Combining these two metrics is relevant for assessing the mitigation potential of the biochar economy. We find that the C sequestration efficiency for stable biochar is in the range of 25%–50% of feedstock C. It depends on the type of feedstock and is in general a non-linear function of H/Corg. We suggest that for plant-based feedstock, biochar production that achieves H/Corg of 0.38–0.44, corresponding to pyrolysis temperatures of 500–550°C, is the most efficient in terms of soil carbon sequestration. Such biochars reveal an average sequestration efficiency of 41.4% (±4.5%) over 100 years.

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Abstract

The topography and morpho-anatomical characteristics of floral nectaries and the chemical analysis of nectar have been studied in seven pear cultivars with different susceptibility to Erwinia amylovora. The susceptible cultivarWilliams, the moderately resistant cultivars Bella di guigno, Poire de Cure and the low susceptible cultivar Alexander Lucas originated from Pyrus communis, while highly resistant cultivars Chojuro and Nijisseiki from P. pyraster and Kieffer as interspecies hybrid P. communis x P. pyraster were included in this experiment and studied for the first time. Large differences in size and structure of the nectaries were observed in these seven pear cultivars. The epidermal cells were with cuticle being more or less striated in Alexander Lucas, Kieffer and Williams. Resistant cultivars had a narrow, elongated cell shape of epidermal cells while those susceptible had an isodiametric. Stomata were mesomorphic in all cultivars except in Poire de Cure and Williams, being slightly xeromorphic since they were situated in deep hollows. Guard cells of the modified stomata were much larger in resistant cultivars. Hypanthium cells were larger in resistant compared to susceptible cultivars. The most abundant sugars were glucose, fructose, sorbitol and sucrose in nectar of all studied pear cultivars. The resistant cultivars (Chojuro, Kieffer and Nijisseiki) had a ~2-fold higher level of sorbitol and galactose, ~2.2-fold higher isomaltose, ~2.7-fold turanose, ~3.35-fold maltose, ~4.4-fold melibiose and ~12.7-fold higher melesitose compared to susceptible cultivars. The sum of quantified phenolic acids varied from 0.049 (Williams) up to 4.074 µg CAE/mL (Kieffer), while flavonoid glycosides levels ranged from 1.224 (Williams) up to 11.686 µg RE/mL (Nijisseiki). In the nectar of the resistant cultivars, rutin, apigetrin, together with patuletin and luteolin glycosides were detected but not in susceptible cultivars, which could be considered as the markers of resistance.