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.
2018
Authors
Even Klyve Dahl Hetron Mweemba Munang'andu Andre van Eerde Jihong Liu Clarke Øystein EvensenAbstract
No abstract has been registered
Authors
Tonje Økland Jørn-Frode Nordbakken Holger Lange Ingvald Røsberg Kjersti Holt Hanssen Nicholas ClarkeAbstract
No abstract has been registered
Authors
John Connolly Maria-Teresa Sebastià Laura Kirwan John A. Finn Rosa Llurba M. Suter Rosemary P. Collins Claudio Porqueddu Aslaug Helgadottir Ole Hans Baadshaug Gilles Bélanger Alistair Black Caroline Brophy Jure Čop Sigridur Dalmannsdottir Ignacio Delgado Anjo Elgersma Mick Fothergill Bodil E. Frankow-Lindberg An Ghesquiere Piotr Golinski Philippe Grieu Anne-Maj Gustavsson Mats Höglind Olivier Huguenin-Elie Marit Jørgensen Zydre Kadziuliene Tor Lunnan Päivi Nykanen-Kurki Angela Ribas Friedhelm Taube Ulrich Thumm A. De Vliegher Andreas LüscherAbstract
Weed suppression was investigated in a field experiment across 31 international sites. The study included 15 plant communities at each site, based on two grasses and two legumes, each sown in monoculture and 11 four-species mixtures varying in the relative proportions of the four species. At each site, one grass and one legume species was selected as fast establishing and the other two species were selected for persistence. Average weed biomass in mixtures over the whole experiment was 52% less (95% confidence interval, 30 to 75%) than in the most suppressive monoculture (transgressive suppression). Transgressive suppression of weed biomass persisted over each year for each mixture. Weed biomass was consistently low and relatively similar across all mixtures and years. Average sown species biomass was greater in all mixtures than in any monoculture. The suppressive effect of sown forage species on weeds in mixtures was achieved without any herbicide use. At each site, weed biomass for almost every mixture was lower than the average across the four monocultures. The average proportion of weed biomass in mixtures was less than in the most suppressive monoculture in two thirds of sites. Mixtures outyielded monocultures, and mixture yield comprised far lower weed biomass.
Authors
Patryk Czortek Jutta Kapfer Anna Delimat Amy Eycott John-Arvid Grytnes Anna Orczewska Halina Ratyńska Antoni Zięba Bogdan JaroszewiczAbstract
Mountain vegetation is often considered highly sensitive to climate and land-use changes due to steep environmental gradients determining local plant species composition. In this study we present plant species compositional shifts in the Tatra Mts over the past 90 years and discuss the potential drivers of the changes observed. Using historical vegetation studies of the region from 1927, we resurveyed 76 vegetation plots, recording the vascular flora of each plot using the same methodology as in the original survey. We used an indirect method to quantify plant species compositional shifts and to indicate which environmental gradients could be responsible for these shifts: by calculating shifts in estimated species optima as reflected in shifts in the ecological indicator values of co-occurring species. To find shifts in species composition, focusing on each vegetation type separately, we used ordination (DCA). The species optimum changed significantly for at least one of the tested environmental gradients for 26 of the 95 plant species tested; most of these species changed in terms of the moisture indicator value. We found that the strongest shifts in species composition were in mylonite grassland, snowbed and hygrophilous tall herb communities. Changes in precipitation and increase in temperature were found to most likely drive compositional shifts in vegetation resurveyed. It is likely that the combined effect of climate change and cessation of sheep grazing has driven a species composition shift in granite grasslands communities.
Authors
Eva Lieungh Eriksen Heidrun Asgeirsdatter Ullerud Rune Halvorsen Sigrun Aune Harald Bratli Peter Horvath Inger Kristine Volden Anders Kvalvåg Wollan Anders BrynAbstract
Questions: Substantial variation between observers has been found when comparing parallel land-cover maps, but how can we know which map is better? What magnitude of error and inter-observer variation is expected when assigning land-cover types and is this affected by the hierarchical level of the type system, observer characteristics, and ecosystem properties? Study area: Hvaler, south-east Norway. Methods: Eleven observers assigned mapping units to 120 stratified random points. At each observation point, the observers first assigned a mapping unit to the point independently. The group then decided on a ‘true’ reference mapping unit for that point. The reference was used to estimate total error. ‘Ecological distance’ to the reference was calculated to grade the errors. Results: Individual observers frequently assigned different mapping units to the same point. Deviating assignments were often ecologically close to the reference. Total error, as percentage of assignments that deviated from the reference, was 35.0% and 16.4% for low and high hierarchical levels of the land-covertype system, respectively. The corresponding figures for inter-observer variation were 42.8% and 19.4%, respectively. Observer bias was found. Particularly high error rates were found for land-cover types characterised by human disturbance. Conclusions: Access to a ‘true’ mapping unit for each observation point enabled estimation of error in addition to the inter-observer variation typically estimated by the standard pairwise comparisons method for maps and observers. Three major sources of error in the assignment of land-cover types were observed: dependence on system complexity represented by the hierarchical level of the land-cover-type system, dependence on the experience and personal characteristics of the observers, and dependence on properties of the mapped ecosystem. The results support the necessity of focusing on quality in land-cover mapping, among commissioners, practitioners and other end users.
Abstract
The aim of this research is to determine if the polyesterification of sorbitol and citric acid in wood has a future potential as a wood modification process. Pine wood was impregnated with an aqueous solution containing citric acid and sorbitol and was thereafter cured at 103 or 140°C for 18 hours. The dimensional stability and leaching resistance were studied for both modification temperatures. The leachates from the modified wood samples were analysed by HPLC and the susceptibility to decay and staining fungi were studied. Impregnated samples cured at 140°C showed a permanent (leach-resistant) increased dimensional change, but samples treated at 103°C were not stable to leaching. Treated samples cured at 103 and 140°C showed significant resistance to white-rot (Trametes versicolor) and brown-rot decay (Postia placenta) after a leaching procedure. Furthermore, samples cured at 103 and 140°C (leached and unleached) were significantly less susceptible to blue-stain fungi than the untreated controls.
Authors
Milica Fotiric-Aksic U Gasic T Tosti Jasminka Milivojevic Vlado Licina Z Tesic Mekjell MelandAbstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Kine Svensson Oda Marie Kjørlaug Matthew J. Higgins Roar Linjordet Svein Jarle HornAbstract
Post-anaerobic digestion (PAD) treatment technologies have been suggested for anaerobic digestion (AD) to improve process efficiency and assure hygenization of organic waste. Because AD reduces the amount of organic waste, PAD can be applied to a much smaller volume of waste compared to pre-digestion treatment, thereby improving efficiency. In this study, dewatered digestate cakes from two different AD plants were thermally hydrolyzed and dewatered, and the liquid fraction was recirculated to a semi-continuous AD reactor. The thermal hydrolysis was more efficient in relation to methane yields and extent of dewaterability for the cake from a plant treating waste activated sludge, than the cake from a plant treating source separated food waste (SSFW). Temperatures above 165 °C yielded the best results. Post-treatment improved volumetric methane yields by 7% and the COD-reduction increased from 68% to 74% in a mesophilic (37 °C) semi-continuous system despite lowering the solid retention time (from 17 to 14 days) compared to a conventional system with pre-treatment of feed substrates at 70 °C. Results from thermogravimetric analysis showed an expected increase in maximum TS content of dewatered digestate cake from 34% up to 46% for the SSFW digestate cake, and from 17% up to 43% in the sludge digestate cake, after the PAD thermal hydrolysis process (PAD-THP). The increased dewatering alone accounts for a reduction in wet mass of cake leaving the plant of 60% in the case of sludge digestate cake. Additionaly, the increased VS-reduction will contribute to further reduce the mass of wet cake.
Abstract
No abstract has been registered