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.
2010
Abstract
The blue-stain fungus Ceratocystis resinifera colonizes wounds on living Picea spp. and other conifers in Europe and North America. Little is known regarding the pathogenicity of this fungus and consequently, four Norwegian C. resinifera isolates were inoculated on to Norway spruce (Picea abies) using two different techniques. These included single-point inoculations on young trees (two inoculations per tree on 14-year-old trees) and mass-inoculations on older trees (∼200 inoculations per tree on 34-year-old trees). In both experiments, C. resinifera induced minor symptoms that in most cases did not differ significantly from inoculation with sterile agar. The virulent blue-stain fungus C. polonica, which was inoculated for comparative purposes, induced extensive symptoms, causing 83% dead cambium circumference and 82% blue-stained sapwood, and long necrotic lesions in the phloem. The results suggest that C. resinifera is non-pathogenic or only mildly pathogenic to Norway spruce and does not present a threat to these trees.
Authors
Øyvind Johan Korsøen Tim Dempster Jan Erik Fosseidengen Anders Fernø Einar Heegaard Tore S KristiansenAbstract
Farmed Atlantic cod (Gadus morhua) are occasionally exposed to buoyancy changes in sea-cages, through lifting or lowering of cage nets. Physiological processes regulate the level of gas in the closed swim bladders of cod and thus the ability of cod to control their buoyancy. Rapid net lifting may cause positive buoyancy, leading to barotrauma, while net lowering may lead to negative buoyancy and alter cod behaviours. We tested how groups of farmed cod responded immediately after lifting events from 5 different start depths equivalent to 40% pressure reductions, and how long they took to return to pre-lifting pressure levels. In addition, we tested immediate responses and recovery times to cage lowering events equivalent to 100– 300% pressure increases. Trials were conducted with 100 cod of 1.1–1.7 kg in a 63 m3 sea-cage at the lower (5 °C) and upper (16 °C) water temperature limits experienced during culture. Swimming behaviours were measured at fixed intervals before and after cage lifting or lowering, and a feeding test was used to assess appetite. In general, lifting events increased swimming speeds 1.5–4 times and tail beats 2–3 times and fish swam with an average −14° head-down angle, indicating positive buoyancy. The depth before lifting affected the immediate response as the fish became more active after lifting events from shallow compared to deeper depths. Appetite levels decreased for about 2 h after cage lifting, independent of temperature or start depth. The overall recovery time of 8 h after lifting did not depend upon start depth or temperature. Lowering events appeared to cause negative buoyancy. Swimming speeds (1.3–2.3 times) and tail beat frequencies (1.4–2.3 times) increased immediately after cage lowering, and cod swam with an average 30° head-up swimming angle. Neither pressure level nor temperature affected this immediate response. Time to recover to neutral buoyancy for 300% pressure increases took 42–90 h, but only 18–34 h for 100% pressure increases. We conclude that a 40% pressure reduction is an upper limit for lifts of healthy farmed cod. Secondary lifts should not be done until at least 10 h after the first lift. Cage lowering should be done slowly to avoid potentially stressful crowding of negatively buoyant fish on the cage bottom, especially at low temperatures.
Abstract
The coastal heath region along the western coast of Norway, dominated by Calluna vulgaris, is undergoing rapid change. Vegetation changes are caused by changes in management, including reduced frequency or abandonment of periodic heath burning and reduced cutting and grazing. The islands of Froan, in the outermost part of Sør-Trøndelag County in mid-western Norway, are dominated by coastal heath in a state of recession due to reduced traditional land use. The coastal heath is acknowledged as vulnerable and valuable by national environmental authorities, and local landscape management is supported by different national subsidies. The authors mapped the vegetation on Froan and used rule-based GIS-modelling to predict the relative potential for future vegetation changes. The model was based on a range of map layers, including management themes such as history of heath burning and peat removal, current practices of sheep grazing, and also themes derived from the vegetation map, such as soil nutrients, soil moisture and present management status. The resulting model output provides relative probabilities of future changes under different land-use scenarios, and highlights where management efforts should be focused in order to maintain the traditional landscape character.
Authors
C. Rahn K. Zhang R. Lillywhite R Ramos J. Doltra JF De Paz Hugh Riley M. Fint C. Nendel K. Thorup Kristensen A. Pedersen F. Piro C. Firth U. Schmutz F. Rayns K. StrohmeyerAbstract
No abstract has been registered
Abstract
The water quality in the western part of Lake Vansjø in south eastern Norway is classified as very poor due to excessive growth of blue green algae. It has been shown that phosphorus (P) losses are high from a subcatchment where potatoes and vegetables are grown on 25 % of the agricultural area. The water quality of the lake is of great concern because it is the drinking water reservoir of 60.000 inhabitants and an important recreation area for people living in the area. An integrated project funded by the government was started in 2008 in order to improve the water quality of the lake. Within this project, the public agricultural management, agricultural advisors, farmers and the Norwegian Institute for Agricultural and Environmental Research (Bioforsk) collaborate to attain the target of improved water quality. The farmers are encouraged to sign a contract where they will receive a financial support for covering extra costs for committing to a set of restrictions and mitigation options aiming at reduced P losses. Vegetable- and potato fields give large challenges when aiming at reduced P losses. A large part of the research activity is therefore related to possible mitigation options on these fields, e.g. effect of reduced P fertilization on yields and quality of bulb onion (Allium cepa), carrots (Daucus carota) and white cabbage (Brassica oleracea var. capitata alba), and evaluation of catch crops as a mitigation option for reduced soil erosion from these fields. Development of constructed wetlands to include filters that adsorb P and measurement of P losses through tile drains are also included in the project.
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No abstract has been registered