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.
2022
Authors
Maria Fredriksson Markus Rüggeberg Thomas Nord-Larsen Greeley Beck Emil Engelund ThybringAbstract
The material properties of wood are intimately tied to the amount of moisture contained in the wood cell walls. The moisture content depends on the environmental conditions, i.e. temperature and relative humidity, but also on material characteristics of the wood itself. The exact mechanisms governing moisture equilibrium between wood cell walls and environmental conditions remain obscure, likely because multiple material characteristics have been proposed to be involved. In this study, we used a data exploration approach to illuminate the important wood characteristics determining the cell wall moisture content in the full moisture range. Specimens of nine different wood species (two softwoods and seven hardwoods) were examined in terms of their material characteristics at multiple scales and their cell wall moisture content was measured in equilibrium with both hygroscopic conditions and at water-saturation. By statistical analysis, the chemical composition was found to be the most important predictor of the cell wall moisture content in the full moisture range. For the other wood characteristics the importance differed between the low moisture range and the humid and saturated conditions. In the low moisture range, the cellulose crystallinity and hydroxyl accessibility were found to be important predictors, while at high moisture contents the microfibril orientation in the S1 and S3 layers of the cell walls was important. Overall, the results highlighted that no single wood characteristic were decisive for the cell wall moisture content, and each of the predictors identified by the analysis had only a small effect in themselves on the cell wall moisture content. Wood characteristics with a major effect on the cell wall moisture content were, therefore, not identified.
Authors
Anne-Grete Roer Hjelkrem Heidi Udnes Aamot Morten Lillemo Espen Sannes Sørensen Guro Brodal Aina Lundon Russenes Simon G. Edwards Ingerd Skow HofgaardAbstract
Fusarium graminearum is regarded as the main deoxynivalenol (DON) producer in Norwegian oats, and high levels of DON are occasionally recorded in oat grains. Weather conditions in the period around flowering are reported to have a high impact on the development of Fusarium head blight (FHB) and DON in cereal grains. Thus, it would be advantageous if the risk of DON contamination of oat grains could be predicted based on weather data. We conducted a functional data analysis of weather-based time series data linked to DON content in order to identify weather patterns associated with increased DON levels. Since flowering date was not recorded in our dataset, a mathematical model was developed to predict phenological growth stages in Norwegian spring oats. Through functional data analysis, weather patterns associated with DON content in the harvested grain were revealed mainly from about three weeks pre-flowering onwards. Oat fields with elevated DON levels generally had warmer weather around sowing, and lower temperatures and higher relative humidity or rain prior to flowering onwards, compared to fields with low DON levels. Our results are in line with results from similar studies presented for FHB epidemics in wheat. Functional data analysis was found to be a useful tool to reveal weather patterns of importance for DON development in oats.
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UAV, drone, ortho photo, image analysis, deep learning, wheel rut, monitoring, GIS, method
Authors
Kristina Bringedal GeddeAbstract
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Authors
Hans Pretzsch Andrés Bravo-Oviedo Torben Hilmers Ricardo Ruiz-Peinado Lluis Coll Magnus Löf Shamim Ahmed Jorge Aldea Christian Ammer Admir Avdagić Ignacio Barbeito Kamil Bielak Felipe Bravo Gediminas Brazaitis Jakub Cerný Catherine Collet Lars Drössler Marek Fabrika Michael Heym Stig-Olof Holm Gro Hylen Aris Jansons Viktor Kurylyak Fabio Lombardi Bratislav Matović Marek Metslaid Renzo Motta Thomas Nord-Larsen Arne Nothdurft Cristóbal Ordóñez Jan den Ouden Maciej Pach Marta Pardos Quentin Ponette Tomas Pérot Ditlev Otto Juel Reventlow Roman Sitko Vit Sramek Mathias Steckel Miroslav Svoboda Enno Uhl Kris Verheyen Sonja Vospernik Barbara Wolff Tzvetan Zlatanov Miren del RíoAbstract
Heterogeneity of structure can increase mechanical stability, stress resistance and resilience, biodiversity and many other functions and services of forest stands. That is why many silvicultural measures aim at enhancing structural diversity. However, the effectiveness and potential of structuring may depend on the site conditions. Here, we revealed how the stand structure is determined by site quality and results from site-dependent partitioning of growth and mortality among the trees. We based our study on 90 mature, even-aged, fully stocked monocultures of Scots pine (Pinus sylvestris L.) sampled in 21 countries along a productivity gradient across Europe. A mini-simulation study further analyzed the site-dependency of the interplay between growth and mortality and the resulting stand structure. The overarching hypothesis was that the stand structure changes with site quality and results from the site-dependent asymmetry of competition and mortality. First, we show that Scots pine stands structure across Europe become more homogeneous with increasing site quality. The coefficient of variation and Gini coefficient of stem diameter and tree height continuously decreased, whereas Stand Density Index and stand basal area increased with site index. Second, we reveal a site-dependency of the growth distribution among the trees and the mortality. With increasing site index, the asymmetry of both competition and growth distribution increased and suggested, at first glance, an increase in stand heterogeneity. However, with increasing site index, mortality eliminates mainly small instead of all-sized trees, cancels the size variation and reduces the structural heterogeneity. Third, we modelled the site-dependent interplay between growth partitioning and mortality. By scenario runs for different site conditions, we can show how the site-dependent structure at the stand level emerges from the asymmetric competition and mortality at the tree level and how the interplay changes with increasing site quality across Europe. Our most interesting finding was that the growth partitioning became more asymmetric and structuring with increasing site quality, but that the mortality eliminated predominantly small trees, reduced their size variation and thus reversed the impact of site quality on the structure. Finally, the reverse effects of mode of growth partitioning and mortality on the stand structure resulted in the highest size variation on poor sites and decreased structural heterogeneity with increasing site quality. Since our results indicate where heterogeneous structures need silviculture interventions and where they emerge naturally, we conclude that these findings may improve system understanding and modelling and guide forest management aiming at structurally rich forests.