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.
2018
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Forfattere
Ievina SturiteSammendrag
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Forfattere
Arne BardalenSammendrag
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Many nonlinear methods of time series analysis require a minimal number of observations in the hundreds to thousands, which is not always easy to achieve for observations of environmental systems. As a result, finite size effects often hamper proper interpretation of the results; the estimation of the correlation dimension, Lyapunov exponents or KolmogorovSinai entropies, to name a few, is plagued by huge uncertainties. Eddy Covariance (EC) measurements of the carbon exchange between the atmosphere and vegetation provide a noticeable exception. The turbulent wind fields transporting carbon dioxide to the surface layer show variability over a large range of spatiotemporal scales, and their quantification demand a high temporal resolution, typically at 20 Hz. This generates very long time series even for short measurement periods; usually, the raw data are aggregated to carbon cycle observables, like Gross Primary Productivity (GPP) or Net Ecosystem Exchange (NEE) at half-hourly time steps. In this presentation, we investigate the high-resolution raw data of 3D wind speed and CO2 concentrations measured at a young forest plantation in Southeast Norway since July 2018. After introducing the EC technique and the Integrated Carbon Observation System (ICOS), we present results of complexity analysis, Tarnopolski diagrams, q-Entropy and Hurst analysis, and Empirical Mode Decomposition. This provides insights into not only whether the young forest stand is actually a source or sink of carbon, but also when, how and how strong carbon uptake and release are taking place at the site, and the nature of dynamics of carbon fluxes across this system boundary in general.
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The Norwegian per capita sales of wine have more than doubled over the past 20 years, while the sales of sprits and beer have declined. These changes are likely to be the effect of changes in economic, demographic, and attitudinal factors as well as the availability of wine. We estimated age-period-cohort (APC) logit models using data from a large repeated cross-sectional survey over the period 1991–2015. The estimation results indicate substantial effects of the APC variables as well as income, availability, and attitudes. The model was used to simulate wine consumption over the life cycle in different birth cohorts. The simulation results indicate that wine consumption frequency increases by age, and younger cohorts are expected to increase their consumption frequencies more than older cohorts, which suggests an increased wine consumption over time.
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http://www.sterf.org/Media/Get/2978/annual-report-2017
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Forfattere
Inghild Økland Agnar Kvalbein Wendy Marie Waalen Lise Bjørnstad Trygve S. Aamlid Tatsiana EspevigSammendrag
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