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.
2019
Abstract
Temperature during seed maturation can induce an epigenetic memory effect in growth phenology of Norway spruce (Picea abies (L.) Karst.) that lasts for several years. To quantify the epigenetic modifications induced by natural climatic variation, common garden experiments with plants originating from different provenances and seed years were performed. Plants from warmer seed years showed delayed phenology with later bud flush, bud set and growth cessation. This effect was quantified by linear models of phenology traits as a function of climate indices for the origin and seed year of the plants. Significant effects of the temperature during seed production (seed year) was found for the bud set in seedlings in their first growing season and for bud flush and growth cessation in the 7th-8th growing season from seed. The models suggest that growth start and growth cessation are delayed 0.7–1.8 days per 100 additional degree days experienced by the seed during embryo development and seed maturation. Models that include factors that are known to induce epigenetic effects could be used to better predict future performance of forest reproductive material.
Abstract
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Authors
Lalisa A. Duguma Joanes Atela Peter A. Minang Alemayehu N. Ayana Belachew Gizachew Zeleke Judith M. Nzyoka Florence BernardAbstract
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Fasil Eregno Arve HeistadAbstract
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Simone Russo Jana Sillmann Sebastian Sippel Monika J. Barcikowska Claudia Ghisetti Marek Smid Brian O'NeillAbstract
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Tomas Persson Mats Höglind Marcel van Oijen Panu Korhonen Taru Palosuo Guillaume Jégo Perttu Virkajärvi Gilles Bélanger Anne-Maj GustavssonAbstract
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Abstract
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. Eddy Covariance (EC) measurements of the carbon exchange between the atmosphere and vegetation provide a noticeable exception. They are taken at high temporal resolution, typically at 20 Hz. This generates very long time series (many millions of data points) even for short measurement periods, rendering finite size effects unimportant. In this presentation, we investigate high-resolution raw data of 3D wind speed, CO2 concentrations, water vapor and temperature measured at a young forest plantation in Southeast Norway since July 2018. Guiding for the analysis is the gain or added value of the high resolution compared to more aggregated data, i.e. the scaling behavior of nonlinear properties of the time series. We present results of complexity analysis, Tarnopolski diagrams, q-Entropy, Hurst analysis, Empirical Mode Decomposition and Singular System Analysis. This provides detailed insights into the nature of dynamics of carbon fluxes across this system boundary at different temporal scales.
Authors
J. William Allwood Tomasz Leszek Woznicki Yun Xu Alexandre Foito Kjersti Aaby Julie Sungurtas Sabine Freitag Royston Goodacre Derek Stewart Siv Fagertun Remberg Ola M Heide Anita SønstebyAbstract
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Authors
Kristi Parro Kajar Köster Kalev Jogiste Katrin Seglinš Allan Sims John A. Stanturf Marek MetslaidAbstract
Boreal forests are an important carbon (C) sink and fire is the main natural disturbance, directly affecting the Ccycle via emissions from combustion of biomass and organic matter and indirectly through long-term changes in C-dynamics including soil respiration. Carbon dioxide (CO2) emission from soil (soil respiration) is one of the largest fluxes in the global C-cycle. Recovery of vegetation, organic matter and soil respiration may be influenced by the intensity of post-fire management such as salvage logging. To study the impact of forest fire, fire and salvage, and recovery time on soil respiration and soil C and N content, we sampled two permanent research areas in north-western Estonia that were damaged by fire: Vihterpalu (59°13′ N 23°49′ E) in 1992 and Nõva (59°10′ N 23°45′ E) in 2008. Three types of sample plots were established: 1) unburned control with no harvesting (CO); 2) burned and uncleared (BU); and 3) burned and cleared (BC). Measurements were made in 2013, 21 years after wildfire in Vihterpalu and 5 years after wildfire in Nõva. Soil respiration ranged from 0.00 to 1.38 g CO2 m−2 h−1. Soil respiration in the burned and cleared areas (BC) was not reduced compared to burned and uncleared (BU) areas but the average soil respiration in unburned control areas was more than twice the value in burned areas (average soil respiration in CO areas was 0.34 CO2 m−2 h−1, versus 0.16 CO2 m−2 h−1, the average soil respiration of BC and BU combined). Recovery over 20 years was mixed; respiration was insignificantly lower on younger than older burned sites (when BC and BU values were combined, the average values were 0.15 vs. 0.17 g CO2 m−2 h−1, respectively); soil-C was greater in the older burned plots than the younger (when BC and BU values were combined, the average values were 9.71 vs. 5.99 kgm−2, respectively); but root biomass in older and recently burned areas was essentially the same (average 2.23 and 2.11 kgm−2, respectively); soil-N was highest on burned areas 20 years after fire. Twenty years post-fire may be insufficient time for carbon dynamics to fully recover on these low productivity sandy sites.