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
No abstract has been registered
Authors
Trond HofsvangAbstract
Two Malaise traps were set up at Ås, Southern Norway, during the growing seasons 1992-1997, one trap in an organic grown barley field and one in its boundary. Totally 23 species of Tipulidae (Diptera) were identified, of these eight species belonged to the genus Nephrotoma Meigen, 1803. Of the total specimens collected 93% of the males and 88% of the females belonged to this genus. Comparing the two traps, 80% of the Nephrotoma specimens were recorded in the organic field. It is discussed if larvae of Nephrotoma spp. in Norway can be potential pests in agricultural crops as reported from other countries. To Malaisefeller ble plassert ut i Ås i vekstsesongene 1992-1997, en i en økologisk dyrket byggåker og en i kanten av åkeren. Totalt ble 23 arter av stankelbein (Tipulidae, Diptera) identifisert, 8 av disse tilhørte slekten Nephrotoma. Av det totale antall individer som ble samlet inn, var 93 % av hannene og 88 % av hunnene av slekten Nephrotoma. 80 % av Nephrotoma-individene ble funnet i den fellen som sto ute i byggåkeren. I mange andre land er larver av Nephrotoma-arter skadedyr på mange kulturplanter i jordbruket, og det diskuteres om disse artene kan opptre som skadedyr i Norge.
Authors
Vicki Stone Bernd Nowack Anders Baun Nico van den Brink Frank von der Kammer Maria Dusinska Richard Handy Steven Hankin Martin Hassellöv Erik J. Joner Teresa FernandesAbstract
No abstract has been registered
Abstract
Abstract Two field trials are reported on Jerusalem artichoke (Helianthus tuberosus L.). Firstly, twenty genetic variants were compared with respect to crop yield, morphology and content of sugars and FOS in order to find genotypes suitable for Norwegian production. The highest yield and highest number of tubers per plant was obtained in early flowering variants, e.g. the white variant ‘Tysnes" gave 1.72 kg tubers per plant (28.7 t haa-1). Such early variants had markedly lower portion of smooth tubers. Late variants gave the most preferable tuber shape, but the yield was only half of the most productive ones. Dry matter content (%DM) varied from 19.67 to 23.33. Only a weak correlation was found between dry matter content and total content of FOS (r = 0.255) in the tubers. The mean content of FOS including sucrose through all variants was found to be 11.6 g 100g-1 FW or 55.0 g 100g-1 DW by measurement of non-hydrolyzed plant. Average chain length of FOS in the tubers was found to be DP3.9. There was no difference in tuber FOS content between flowering and non flowering variants. A second trial investigated the above ground part of one flowering and two late or non flowering variants during the growing season. Highest biomass was found for the late or non flowering variants when harvested in September. Total dry matter at time of harvest were found to be 0.21, 0.55 and 0,44 kg plant-1 for the variants ‘Dagnoytral", ‘Elverum" and ‘Krogerup" respectively (5.4, 14.1 and 11.3 t haa-1). At time of harvest stalks of ‘Elverum" and ‘Krogerup" contained 1.25 and 0.77 % fructose (DM) and 3.40 and 1.91 % sucrose. The content of soluble carbohydrates was found to be highest in stalks in August (sucrose and FOS major compounds).
Abstract
The aliphatic biopolyesters cutins and suberins have been suggested to significantly contribute to the stable pool of soil organic matter (SOM), and to be tracers for the above- or belowground origin of plant material. Contrary to other plant-derived aliphatic molecules found in the lipid fraction of soils, the stable isotope derived estimates of turnover of cutins and suberins have never been studied in soils. The aim of this study was to analyse the dynamics of shoot- and root-derived biomarkers in soils using a wheat and maize (C3/C4) chronosequence, where changes in the natural 13C abundance can be used to evaluate the incorporation of new carbon into SOM at the molecular level. The relative distribution of aliphatic monomers in wheat and maize roots and shoots suggested that a,u-alkanedioic acids can be considered as root-specific markers and mid-chain hydroxy acids as shoot-specific markers. The contrasting distribution of the plant-specific monomers in plants and soils might be explained by different chemical mechanisms leading to selective degradation or stabilization of some biomarkers. The changes of the 13C isotopic signatures of these markers with years of maize cropping after wheat evidenced their contrasted behaviour in soil. After 12 years of maize cropping, shoot markers present in soil samples probably originated from old C3 vegetation suggesting that new maize cutin added to soils was mostly degraded within a year. The reasons for long-term stabilization of shoot biomarkers remain unclear. By contrast, maize root markers were highly incorporated into SOM during the first six years of maize crop, which suggested a selective preservation of root biomass when compared to shoots, possibly due to physical protection.
Abstract
Peatland drainage results in several environmental impacts such as release of greenhouse gas to the atmosphere and leaching of nutrients to watercourses. These hazardous environmental effects can partly be controlled with soil management, and different drainage and remediation practices. Grading is a new method developed for soils with low conductivity suffering from poor drainage, water logging and ice. The soil surface is graded towards the ditch to increase surface runoff and drainage. The present study compares environmental effects of peatland grading compared to traditional intense pipe drainage. Detailed measurements of hydrology, climate, leaching and gas emissions were carried out at adjacent drainage areas with grass cultivation. Additional measurements were made at plots that were abandoned, cultivated with perennial crops, and remained as pristine peatlands. The results show that the leaching of nutrients is highest from pipe drainage. Climate gas emission was considerably higher at all managed sites than from the reference pristine site. Drainage, soil hydrology and soil nutrient status seemed to control gas emissions. The gas emissions were higher than assumed for Norwegian cold conditions. The results confirm observations made on peat soils in other climatic regions. The highest emissions of CO2 was observed when the soil temperature was high and groundwater table low. The N2O emission showed a large variation with no clear pattern. However, at some locations it peaked after a dry period when NO3-N was leached. More CH4 was emitted from the intensively drained site than the graded site, but more CO2 was emitted from the graded site. The difference in leaching and emission properties is partly due to differences in near surface hydrology. At grade sites, a faster runoff response to rainfall occur probably due to shallow throughfall or overland flow which provides better drainage. Also, the graded site was prepared recently, and this can have exposed fresh peat for decay. Therefore the drainage history must be well known in peatland studies as peat change in time due to drainage and cultivation. Abandoned peat field continue to leach greenhouse gases in a same way as cultivated sites.
Abstract
Microbial disfigurement of coated wooden surfaces is considered a major maintenance concern and will shorten the aesthetic service life of wooden facades. The effect of the physical surface structure of a paint film when applied on wood may have an impact on the susceptibility to mould growth. Six model paints were formulated to give the following physical surface structures: glossy, matt, soft, hard, hydrophobic, and a film with air inclusion. The model paints and a standard paint, with and without fungicide, were applied on panels of Norway spruce (Picea abies L Karst.) and exposed outdoors for nearly three years according to a modified version of EN 927-3. A logistic regression model was fit to the data, and the degree of mould growth varied with exposure time and type of paint. Hard model paint was significantly more susceptible than the other model paints and had a performance close to the standard paint without fungicide. Soft model paint provided the best performance, with the least mould growth. Temperature, relative humidity, and precipitation did not significantly contribute to the model. (C) 2010 Elsevier Ltd. All rights reserved.
Abstract
While forest inventories based on airborne laser scanning data (ALS) using the area based approach (ABA) have reached operational status, methods using the individual tree crown approach (ITC) have basically remained a research issue. One of the main obstacles for operational applications of ITC is biased results often experienced due to segmentation errors. In this article, we propose a new method, called "semi-ITC" that overcomes the main problems related to ITC by imputing ground truth data within crown segments from the nearest neighboring segment. This may be none, one, or several trees. The distances between segments were derived based on a set of explanatory variables using two nonparametric methods, i.e., most similar neighbor inference (MSN) and random forest (RF). RF favored the imputation of common observations in the data set which resulted in significant biases. Main conclusions are therefore based on MSN. The explanatory variables were calculated by means of small footprint ALS and multispectral data. When testing with empirical data the new method compared favorably to the well-known ABA. Another advantage of the new method over the ABA is that it allowed for the modeling of rare tree species. The results of predicting timber volume with the semi-ITC method were unbiased and the root mean squared error (RMSE) on plot level was smaller than the standard deviation of the observed response variables. The relative RMSEs after cross validation using semi-ITC for total volume and volume of the individual species pine, spruce, birch, and aspen on plot level were 17, 38, 40, 101, and 222%, respectively. Due to the unbiasedness of the estimation, this study is a showcase for how to use crown segments resulting from ITC algorithms in a forest inventory context. (C) 2009 Elsevier Inc. All rights reserved.
Authors
Bringas Carlos M. Salas Tore Filbakk Geir Skjevrak Odd-Ivar Lekang Olav Høibø Reidar Barfod SchüllerAbstract
No abstract has been registered
Abstract
Scots pine (Pinus sylvestris) sapwood was investigated for variation in treatability using the wood modifying agent, furfuryl alcohol (FA) in water. The variation in treatability within trees, between trees and between different stands of Scots pine was studied. Investigated variables that reduced the residual variance significantly were: site location, latitude of site, height of trees, annual ring width, vertical and horizontal position in the tree and method of drying. Linear mixed model statistics were used and tree number was handled as a random variable. The best model reduced the treatability residual variance by 67%. Location was the single factor affecting treatability most. Differences in latitude between locations may be the reason for that. Latitude correlated negatively with the treatability. Within the trees, the treatability of sapwood increased with distance from ground and with distance from heartwood border. A small, but significantly better treatability was found for kiln dried wood (60A degrees C) compared to air dried wood (20A degrees C).