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
Abstract
No abstract has been registered
Authors
Ali Hosseini Hans-Christian Teien Till Seehusen Merete Myromslien Marit Nandrup Pettersen Justin Brown Brit Salbu Deborah Helen OughtonAbstract
A series of 131I tracer experiments have been conducted at two research stations in Norway, one coastal and one inland to study radioiodine transfer and dynamics in boreal, agricultural ecosystems. The hypothesis tested was that site specific and climatological factors, along with growth stage, would influence foliar uptake of 131I by grass and its subsequent loss. Results showed that the interception fraction varied widely, ranging from 0.007 to 0.83 over all experiments, and showing a strong positive correlation with biomass and stage of growth. The experimental results were compared to various models currently used to predict interception fractions and weathering loss. Results provided by interception models varied in the range of 0.5–2 times of the observed values. Regarding weathering loss, it was demonstrated that double exponential models provided a better fit with the experimental results than single exponential models. Normalising the data activity per unit area to remove bio-dilution effects, and assuming a constant single loss rate gave weathering half-times of 22.8 ± 38.3 and 10.2 ± 8.2 days for the inland and coastal site, respectively. Whilst stable iodine concentrations in grass and soil were significantly higher (by approximately a factor of 5 and 7 times for grass and soil respectively) at the coastal compared to the inland site, it was not possible to deconvolute the influence of this factor on the temporal behaviour of 131I. Nonetheless, stable iodine data allowed us to establish an upper bound on the soil to plant transfer of radioiodine via root uptake and to establish that the pathway was of minor importance in defining 131I activity concentrations in grass compared to direct contamination via interception. Climatological factors (precipitation, wind-speed and temperature) appeared to affect the dynamics of 131I in the system, however the decomposition of these collective influences into specific contributions from each factor remains unresolved and requires further study. The newly acquired data on the interception and weathering of radioiodine in boreal, agricultural ecosystems and the reparametrized models developed from this, substantially improve the toolbox available for Norwegian emergency preparedness in the event of a nuclear accident.
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Jessica Petereit Christina Hoerterer Adrian A. Bischoff-Lang Luís E. C. Conceição Gabriella Pereira Johan Johansen Roberto Pastres Bela H. BuckAbstract
No abstract has been registered
Abstract
The British forestry sector lacks reliable dynamic growth models for stands of improved Sitka spruce, the most important commercial forest type in Great Britain. The aim of this study is to fill this gap by trialling a new modelling framework and to lay the foundations of a future dynamic growth simulator for that forest type. First, we present single tree diameter and height increment models that are climate sensitive and include explicit competition effects. The predictions from the increment models are pooled to project diameter and height at a given age. These projections are then used as inputs to an integrated taper model from which stochastic tree volume predictions are obtained. Retrospective data from over 1400 trees collected in two extensive genetic trials in Scotland and Wales were used for the purposes of this study. Diameter increment and height increment predictions were highly accurate and diameter and height projections proved consistent. The predicted volume at the time of harvesting also exhibited a high degree of accuracy, which shows the robustness of our approach. Further data will be needed in the future to recalibrate the present models and extend their range of validity to the whole of Great Britain.
Authors
Dypdal Lina FjørkenstadAbstract
No abstract has been registered
Abstract
Defense priming, the sensitization of inducible defenses, has been extensively studied in annual angiosperms. However, we are just beginning to explore defense priming in woody, long-lived plants. The natural compound methyl jasmonate (MeJA) has been used for over 20 years to study spruce inducible defenses. Recently, it was discovered that MeJA not only directly induces defense, but also primes defense responses in spruce. Metabolite and transcriptional analyses of mature trees treated with MeJA and subsequently wounded showed that while terpenes accumulate at the wound site in a primed manner, terpene biosynthesis genes are directly induced by MeJA. Pathogen resistance (PR) genes, on the other hand, are primed. Sequencing of miRNAs suggests that miRNAs have a regulatory role in MeJA-induced defenses in spruce. Additionally, a detailed transcriptional time course of 2- year-old spruce treated with MeJA indicated that the RNA-directed DNA methylation (RdDM) pathway is involved in the establishment and maintenance of primed defenses. When comparing mechanisms of defense priming in spruce to those in Arabidopsis, it seems that many mechanisms are conserved. However, some aspects, such as jasmonic acid-salicylic acid crosstalk, may be different. Identifying these differences and how they affect forest species is important for practical application of defense priming in forest management.
Abstract
No abstract has been registered
Authors
Birgitta Åhman Minna Turunen Jouko Kumpula Camilla Risvoll Tim Horstkotte Élise Lépy Svein EilertsenAbstract
No abstract has been registered