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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.

2023

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Abstract

The effects of tree pollen on precipitation chemistry are not fully understood and this can lead to misinterpretations of element deposition in European forests. We investigated the relationship between forest throughfall (TF) element fluxes and the Seasonal Pollen Integral (SPIn) using linear mixed-effects modelling (LME). TF was measured in 1990–2018 during the main pollen season (MPS, arbitrary two months) in 61 managed, mostly pure, even-aged Fagus, Quercus, Pinus, and Picea stands which are part of the ICP Forests Level II network. The SPIn for the dominant tree genus was observed at 56 aerobiological monitoring stations in nearby cities. The net contribution of pollen was estimated as the TF flux in the MPS minus the fluxes in the preceding and succeeding months. In stands of Fagus and Picea, two genera that do not form large amounts of flowers every year, TF fluxes of potassium (K+), ammonium-nitrogen (NH4+-N), dissolved organic carbon (DOC), and dissolved organic nitrogen (DON) showed a positive relationship with SPIn. However- for Fagus- a negative relationship was found between TF nitrate-nitrogen (NO3−-N) fluxes and SPIn. For Quercus and Pinus, two genera producing many flowers each year, SPIn displayed limited variability and no clear association with TF element fluxes. Overall, pollen contributed on average 4.1–10.6% of the annual TF fluxes of K+ > DOC > DON > NH4+-N with the highest contribution in Quercus > Fagus > Pinus > Picea stands. Tree pollen appears to affect TF inorganic nitrogen fluxes both qualitatively and quantitatively, acting as a source of NH4+-N and a sink of NO3−-N. Pollen appears to play a more complex role in nutrient cycling than previously thought.

Abstract

Temperature and humidity were measured in 28 vegetable stores and corelated to quality of stored vegetable through two storage seasons. The vegetables swede, carrot and celeriac were grown at one site within each of the four regions in Norway ROG, MID, INN and OSL, respectively. After harvesting, the vegetables were weighed and visually assessed for any injuries or diseases and stored in different stores within the same region as grown. Four bags dug down in four storage bins in each store. Temperature and humidity were logged in each bag as well as on the top of each bin and on wall of the storage. In general, we found significant differences in the storage quality between the different storages as well as between regions. Correlating data on quality with temperature data shows for carrot a tendency to an increase in the proportion of fresh roots and reduction in incidence of tip-rot by an increased average temperature during the first two weeks of storage. This corresponds to results from tested various wound healing treatments. An increase in accumulated temperature during the storage period showed a tendency to increase the emergence of tip-rot and reduce the proportion of fresh roots. For celeriac, the effect of temperature varied between years, possibly due to a large difference in quality in the two test years, and it was difficult to draw any conclusion. In swede, the results suggest that a decrease in temperature in the first two weeks of storage increased the risk of the symptom shown as black veins in the phloem. Nutrient status was found to be a possibly predisposing factor for reduced storage quality in celeriac. Balance of boron (B) to calcium (Ca) and zinc (Zn) were studied in two sites. Highest incidence of brown spots and lowest proportion of fresh roots following storage was found in celeriac with the lowest Ca/B ratio in leaves, lowest content of Zn in the leaves and roots and lowest soil pH.

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Abstract

Key words: VKM, pest risk analysis, Norwegian Scientific Committee for Food and Environment, Norwegian Food Safety Authority, Sudden oak death, Phytophthora ramorum Introduction The Norwegian Food Safety Authority has asked the Norwegian Scientific Committee for Food and Environment for an updated pest risk assessment of Phytophthora ramorum in Norway. The previous risk assessment of P. ramorum for Norway is from 2009. Since then, the pathogen has been detected repeatedly in Norway, primarily in parks, garden centres, and nurseries in southwestern Norway. The knowledge base concerning P. ramorum has changed since the last pest risk assessment, with increased genetic knowledge about different populations, lineages, and mating types. The risks associated with P. ramorum have also changed, since the disease has become epidemic in new host plants, such as larch trees in England. This updated pest risk assessment will provide important input to the Norwegian Food Safety Authority’s efforts to develop the Norwegian plant health regulation. Methods VKM established a project group with expertise in plant health, forest pathology, horticultural plant pathology, plant disease modelling, and pest risk assessment. The group conducted systematic literature searches and scrutinized the relevant literature. In the absence of Norwegian studies, VKM relied on literature from other countries. The group did a quantitative risk assessment describing the level of confidence in the conclusions and identifying uncertainties and data gaps. The report underwent pre-submission commenting and external expert reviewing before final approval and publication. Results and conclusions Phytophthora ramorum is present in the PRA area but has a restricted distribution, mainly being detected in the southern and southwestern parts of Norway. The only P. ramorum lineage considered to be present in Norway is EU1 with mating type A1. The other lineage in Europe, EU2, has so far mainly been documented from the UK. The most widely distributed multilocus genotype of P. ramorum in Norway is EU1MLG1, which became dominant in Europe (including Norway) after 2008. In North America, the NA1, NA2, and EU1 lineages are known from both nurseries and forests. NA1 and NA2 are of the opposite mating type (A2) than European lineages. Recently, various other lineages of P. ramorum have been described from Asia. The main risks for future problems with P. ramorum in Norway are related to entry and establishment of non-European isolates (of all lineages), as well as emergence of new genotypes in European P. ramorum populations. There are several options for diagnosing P. ramorum to species and lineage (mainly EU1, EU2, NA1, and NA2). From a management perspective it is more important to distinguish these entities than mating type and isolate groups (genotypes). The latter are mainly relevant for research purposes or in cases of unexpected disease developments, such as new hosts, increased spread or more severe symptoms on known hosts. However, for more detailed regulation, monitoring, and management of P. ramorum it could also be useful to test for genotypes, i.e. to distinguish EU1MLG1 from other genotypes. Rhododendron remains the most important host plant for P. ramorum in Norway, both in terms of imported plants and detections (mainly in nurseries, garden centres, and public parks). Species in other ornamental plant genera, such as Viburnum, Pieris, and Kalmia, are also listed as major hosts in Europe, and P. ramorum has been detected at least once on species in all these genera in Norway. In the US, Rhododendron, Viburnum, Pieris, Syringa, and Camellia are considered to be the main ornamental hosts. .....................

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Abstract

Non-native pests, climate change, and their interactions are likely to alter relationships between trees and tree-associated organisms with consequences for forest health. To understand and predict such changes, factors structuring tree-associated communities need to be determined. Here, we analysed the data consisting of records of insects and fungi collected from dormant twigs from 155 tree species at 51 botanical gardens or arboreta in 32 countries. Generalized dissimilarity models revealed similar relative importance of studied climatic, host-related and geographic factors on differences in tree-associated communities. Mean annual temperature, phylogenetic distance between hosts and geographic distance between locations were the major drivers of dissimilarities. The increasing importance of high temperatures on differences in studied communities indicate that climate change could affect tree-associated organisms directly and indirectly through host range shifts. Insect and fungal communities were more similar between closely related vs. distant hosts suggesting that host range shifts may facilitate the emergence of new pests. Moreover, dissimilarities among tree-associated communities increased with geographic distance indicating that human-mediated transport may serve as a pathway of the introductions of new pests. The results of this study highlight the need to limit the establishment of tree pests and increase the resilience of forest ecosystems to changes in climate.