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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.

2018

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Abstract

Chamber measurements of trace gas fluxes between the land surface and the atmosphere have been conducted for almost a century. Different chamber techniques, including static and dynamic, have been used with varying degrees of success in estimating greenhouse gases (CO2, CH4, N2O) fluxes. However, all of these have certain disadvantages which have either prevented them from providing an adequate estimate of greenhouse gas exchange or restricted them to be used under limited conditions. Generally, chamber methods are relatively low in cost and simple to operate. In combination with the appropriate sample allocations, chamber methods are adaptable for a wide variety of studies from local to global spatial scales, and they are particularly well suited for in situ and laboratory-based studies. Consequently, chamber measurements will play an important role in the portfolio of the Pan-European long-term research infrastructure Integrated Carbon Observation System. The respective working group of the Integrated Carbon Observation System Ecosystem Monitoring Station Assembly has decided to ascertain standards and quality checks for automated and manual chamber systems instead of defining one or several standard systems provided by commercial manufacturers in order to define minimum requirements for chamber measurements. The defined requirements and recommendations related to chamber measurements are described here.

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Abstract

Research infrastructures play a key role in launching a new generation of integrated long-term, geographically distributed observation programmes designed to monitor climate change, better understand its impacts on global ecosystems, and evaluate possible mitigation and adaptation strategies. The pan-European Integrated Carbon Observation System combines carbon and greenhouse gas (GHG; CO2, CH4, N2O, H2O) observations within the atmosphere, terrestrial ecosystems and oceans. High-precision measurements are obtained using standardised methodologies, are centrally processed and openly available in a traceable and verifiable fashion in combination with detailed metadata. The Integrated Carbon Observation System ecosystem station network aims to sample climate and land-cover variability across Europe. In addition to GHG flux measurements, a large set of complementary data (including management practices, vegetation and soil characteristics) is collected to support the interpretation, spatial upscaling and modelling of observed ecosystem carbon and GHG dynamics. The applied sampling design was developed and formulated in protocols by the scientific community, representing a trade-off between an ideal dataset and practical feasibility. The use of open-access, high-quality and multi-level data products by different user communities is crucial for the Integrated Carbon Observation System in order to achieve its scientific potential and societal value.

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Abstract

The major sources of nutrients to organic grown apple trees are fertilizers made from manure, compost, bone meal, etc. Depending on humidity and temperature in soil and air, the nutrients are dissolved or mineralized and made available to the trees during the growing season. In conventional apple growing, the trees are given mineral fertilizers in early spring to improve the nitrogen status in the trees during flowering for better fruit set. Is it possible in an organic production system to increase the plant available nitrogen in the flowering period by application of liquid N-fertilizers? The standard fertilizer in Norwegian organic fruit growing is dried and pelleted chicken manure with bone meal and vinasse (Marihøne plus; NPK 8-4-5). In these experiments, a liquid fertilizer (Pioner Hi-fruit; NPK 4-1-5) based on vegetable matter plus potassium-vinasse was compared to the standard fertilizer. The liquid fertilizer was applied to the soil as fertigation from 2 weeks before the estimated start of flowering. The dry product was applied 2 weeks prior to flowering. To incorporate the fertilizers into the soil, a mechanical hoer (Orizzonti, Italy) was run in all plots after the application of dry fertilizer. The nitrogen and mineral contents in soil, leaves and fruit were analyzed. The liquid fertilization applied on the soil in the spring gave higher N-contents in soil and trees compared to the dried manure product. However, the increase in N-content was not very strong in the leaf samples. Apples from trees given high doses of liquid fertilizers were greener with less cover colour and higher IAD-indexes. Still they were softer and had less starch than fruit from other treatments.

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Abstract

Increased discrimination capability provided by polarimetric synthetic aperture radar (PolSAR) sensors compared to single and dual polarization synthetic aperture radar (SAR) sensors can improve land use monitoring and change detection. This necessitates reliable change detection methods in multitemporal PolSAR datasets. This paper proposes an unsupervised change detection algorithm for multilook PolSAR data. In the first step of the method, the Hotelling-Lawley trace (HLT) statistic is applied to measure the similarity of two multilook covariance matrices. As a result of this step, a scalar test statistic image is generated. Then, in the second step, a generalized Kittler and Illingworth (K&I) minimum-error thresholding algorithm is developed to perform on the test statistic image and discriminate between changed and unchanged areas. The K&I thresholding algorithm is based on the generalized Gamma distribution for statistical modeling of change and no-change classes. The proposed methodology is tested on a simulated PolSAR data and two C-band fully PolSAR datasets acquired by the uninhabited aerial vehicle SAR and RADARSAT-2 SAR satellites. The experiments show that the proposed algorithm accurately discriminates between change and no-change areas providing detection results with noticeably lower error rates and higher detection accuracy values compared to those of a CFAR-type thresholding of the HLT statistic. Also, the performance of the HLT statistic compared to the other statistics applied on the multilook polarimetric SAR data is assessed. Goodness-of-fit test results prove that the estimated generalized Gamma class conditional models adequately fit the corresponding change and no-change classes.

Abstract

This research note offers a critical-constructive discussion of the article ‘Class, Culture and Culinary Tastes: Cultural Distinctions and Social Class Divisions in Contemporary Norway’, written by Flemmen, Hjellbrekke and Jarness (FHJ) (Sociology, 2018(1)). Concerns are raised about the methods and the use of the data. A robustness analysis with alternative data and/or alternative methods is suggested. Conceptually, the analysis of FHJ is considered not to engage adequately with a more qualitative body of historical and ethnological literature, as well as the impact of Norwegian agricultural policy. To describe and understand the evolution of social meaning and social patterns of the consumption of ‘traditional’ Norwegian foodstuffs, a qualitative approach could have contributed constructively. Overall, wider implications for Bourdieu-inspired analyses of cultural consumption are addressed.