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
Abstract
This article aims to explore differences in motivation for and actual use of allotment gardens. Results from questionnaire surveys and semistructured interviews in two Norwegian and one Dutch garden show that growing vegetables and consuming the harvest is a fundamental part of gardening. The same is true for the social element—meeting and talking to other gardeners, and feeling as part of a community. Although gardeners with different socioeconomic backgrounds experience gardening to some extent similarly, access to an allotment seems more important for gardeners with disadvantaged personal backgrounds: both their diets and their social networks rely more on, and benefit more from, their allotments. This underlines the importance of providing easy access to gardening opportunities for all urban residents, and disadvantaged groups in particular. Public officers and policy makers should consider this when deciding upon new gardening sites or public investments in urban food gardens.
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Abstract
I 2014 ble 22 øyer i Breiðaförður, Vest-Island, vegetasjonskartlagt. Hensikten med kartlegginga var å registrere vegetasjonstyper, artssammensetning og gjengroingsstatus på øyer som har ulik størrelse, topografi, geologisk sammensetning, brukshistorie, samt ulikt fugleliv. De fleste øyer i denne undersøkelsen har ikke blitt kartlagt før, slik at prosjektet har bidratt til ny kunnskap om deler av dette unike øyriket i Breiðafjörður. In 2014, 22 islands in Breiðafjörður, West-Iceland were mapped for vegetation. The purpose to this study was to map vegetation types, distribution of plant species and overgrowing status in islands which differs in size, topography, bedrock composition, land use and birdlife activity. Most of the islands in this study have not been mapped before. This project provides new knowledge to part of the unique archipelago of Breiðafjörður.
Abstract
This study addresses changes in visual appearance of unpainted wood materials exposed outdoors. Specimens of Norway spruce (Picea abies) Scots pine (Pinus sylvestris), aspen (Populus tremula), acetylated Radiata pine (Pinus radiata) and DMDHEU-modified Scots pine sapwood were exposed facing south in Ås, Norway for 60 weeks. During this period, surface mould growth development and wasp attack were assessed visually. Development in lightness (L*) and the uniformity of the weather grey colour were assessed by image analysis. The mould rating of the tested wood materials developed in varying speed, but all specimens had reached the maximum rating after 42 weeks. Our results indicate that most specimens continued to darken after the specimens had reached maximum mould rating, and that evaluation of L* can provide additional information about the surface mould growth. Furthermore, our results indicate that most materials developed a less uniform appearance than what was initially, except from DMDHEU which obtained a more uniform appearance as a consequence of the weathering. This study also shows that wasp attack can give a lighter appearance of the wood by chewing off the top weathered layer. Different wood substrates were attacked in varying degree. Aspen was the substrate most severely attacked by wasps while the acetylated wood was not attacked at all during the 60 weeks of exposure.
Authors
Frans-Jan W. Parmentier Daniel Rasse Magnus Lund Jarle W. Bjerke Bert G. Drake Simon Weldon Hans Tømmervik Georg Heinrich HansenAbstract
Extreme winter events that damage vegetation are considered an important climatic cause of arctic browning—a reversal of the greening trend of the region—and possibly reduce the carbon uptake of northern ecosystems. Confirmation of a reduction in CO2 uptake due to winter damage, however, remains elusive due to a lack of flux measurements from affected ecosystems. In this study, we report eddy covariance fluxes of CO2 from a peatland in northern Norway and show that vegetation CO2 uptake was delayed and reduced in the summer of 2014 following an extreme winter event earlier that year. Strong frost in the absence of a protective snow cover—its combined intensity unprecedented in the local climate record—caused severe dieback of the dwarf shrub species Calluna vulgaris and Empetrum nigrum. Similar vegetation damage was reported at the time along ~1000 km of coastal Norway, showing the widespread impact of this event. Our results indicate that gross primary production (GPP) exhibited a delayed response to temperature following snowmelt. From snowmelt up to the peak of summer, this reduced carbon uptake by 14 (0–24) g C m−2 (~12% of GPP in that period)—similar to the effect of interannual variations in summer weather. Concurrently, remotely-sensed NDVI dropped to the lowest level in more than a decade. However, bulk photosynthesis was eventually stimulated by the warm and sunny summer, raising total GPP. Species other than the vulnerable shrubs were probably resilient to the extreme winter event. The warm summer also increased ecosystem respiration, which limited net carbon uptake. This study shows that damage from a single extreme winter event can have an ecosystem-wide impact on CO2 uptake, and highlights the importance of including winter-induced shrub damage in terrestrial ecosystem models to accurately predict trends in vegetation productivity and carbon sequestration in the Arctic and sub-Arctic.
Authors
Calle Nilsson Henrik Ramebäck Callum Aidan Stephen Hill Mehrdad ArshadiAbstract
The self-heating of wood fuel pellets is a well-recognised problem causing fire incidents in the storage of the pellets as well as severe intoxication of workers by elevated carbon monoxide and carbon dioxide levels and oxygen depletion. Possible factors contributing to the self-heating are considered to be autoxidation and microbiological activity, while the role and contribution to the temperature rise caused by the heat of condensation from water vapour condensing during fast changes in the relative air humidity is less investigated. Using Dynamic Vapour Sorption, the water uptake was measured at 25 °C when increasing the RH from 40 to 80% using 35 fuel pellet samples covering a broad variation in pellet raw materials and process equipment found in Europe (both pilot and industrial scale). The equilibrium total water uptake and speed of the uptake were determined. Total water uptake was 4.56% (range 3.69–6.86%) with no systematic difference found related to the scale of production (industry as compared to pilot plant). In addition, the variations within larger groups of raw material (pine, spruce and pine/spruce mixtures) were relatively small, and the mean water uptake did not differ significantly between these groups. An estimation of the overall potential heat release (when raising the RH% from 40 to 80%) made from the experimental results, taking the early fast water uptake process into consideration (2 h counting for half the total uptake), showed that a heat release of 47 kJ/kg of pellets (range 12–63 kJ/kg) and a potential temperature increase of 45 °C is possible. This estimation clearly demonstrates that the heat of condensation released during water condensation in a pellets silo or in a pellets pile should be expected to be a major contributing factor to initiating temperature rise incidents. In addition, such a temperature increase is expected to assist the initiation of, and to increase the speed of autoxidation of fatty acids and other compounds in the material that will further contribute to a temperature rise. Thus, the results in this study have the potential to improve the basis for modelling the self-heating process in pellet silos/storage and to predict the status of a certain pellet batch by presenting a broad basis for expected variation in the important parameters (specific heat capacity CP and thermal conductivity λeff) influencing the process, and thus aid in taking preventive actions like venting or shifting the pellets to another silo/pile to reduce risk for self-heating and possible fire.
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No abstract has been registered
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No abstract has been registered