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.
1999
Authors
Bjørn ØklandAbstract
Information about larval ecology is fundamental in entomological research; however, in many insect species the larval habitat is still unknown. In the present project, Diptera insects were reared from various microhabitats and substrates of coniferous and deciduous forests of southern Norway. The material included 54 species that have not been reared earlier and 213 new species-microhabitat relationships. Many new records were found in dead wood of common tree species, such as Picea abies, Populus tremula and Fraxinus excelsior. Microhabitats associated with the root zone of windfelled trees showed the highest number of new species-microhabitat relationships.
Authors
Knute J. Nadelhoffer Bridget A. Emmett Per Gundersen O. Janne Kjønaas Chris J. Koopmans Patrick Schleppi Albert Tietema Richard F. WrightAbstract
No abstract has been registered
Authors
Knute J. Nadelhoffer Bridget A. Emmett Per Gundersen O. Janne Kjønaas Chris J. Koopmans Patrick Schleppi Albert Tietema Richard Frederic WrightAbstract
Humans have altered global nitrogen cycling such that more atmospheric N2 is being converted (\"fixed\") into biologically reactive forms by anthropogenic activities than by all natural processes combined. In particular, nitrogen oxides emitted during fuel combustion and ammonia volatilized as a result of intensive agriculture have increased atmospheric nitrogen inputs (mostly NO3 and NH4) to temperate forests in the Northern Hemisphere.Because tree growth in northern temperate regions is typically nitrogen-limited, increased nitrogen deposition could have the effect of attenuating rising atmospheric CO2 by stimulating the accumulation of forest biomass. Forest inventories indicate that the carbon contents of northern forests have increased concurrently with nitrogen deposition since the 1950s. In addition, variations in atmospheric CO2 indicate a globally significant carbon sink in northern mid-latitude forest regions. It is unclear, however, whether elevated nitrogen deposition or other factors are the primary cause of carbon sequestration in northern forests. Here we use evidence from 15N-tracer studies in nine forests to show that elevated nitrogen deposition is unlikely to be a major contributor to the putative CO2 sink in forested northern temperature regions.
Authors
Nils Kristian Nersten Sjur Spildo PrestegardAbstract
No abstract has been registered
Authors
Oddvar SkreAbstract
The Nordic Subarctic-Subalpine Ecology (NSSE) network was initiated among the Nordic countries in 1977. It was the first joint research initiative under the MAB umbrella in this area and was called the Subarctic Birch Project (SBP). Since the scientific basis for proper ecological planning and use of the subarctic-subalpine birch forest zone was defective in many fundamental areas, the studies were in the forst phase concentrated on basic research in genetic, physiological and ecological adaptations of mountain birch and the interactions between birch and herbivores. The second phase of the study was started in 1989. The aim of this phase is to investigate the response of genetically variant mountain birch, drawn from different provenances, to alterations in climate and nutrients. From these data models of the reaction of mountain birch to global change can be developed. The project group now consists of over ten researchers from Norway, Sweden and Finland. The main organizations participating in the project are: Norwegian Forest Research Institute, Finnish Forest Research Institute, University of Oulu, University of Troms, Abisko Scientific Research Station and Kilpisjrvi Biological Research Station
Abstract
This report focuses on agriculture and its impacts in rural areas. Agriculture is an important activity in the Norwegian periphery, directly and indirectly. A deregulation of agriculture will most probably have negative impacts on agricultural production and employment. This, in turn, will have negative impacts on other sectors. Since agriculture is overrepresented in the periphery, and there are few alternative sources of employment, reduced activity in agricultural can lead to increased centralisation. This can be a problem since the relatively low population densities already imply a danger of depopulation in the periphery. Some motivations for regulating agriculture are based on the sector's importance in the periphery. Regulations are also motivated by other facts. It is very difficult to distinguish precisely between rurality and other motivations. However, part of the motivation is agricultural production itself, or aims that can be deducted from production. Distribution of income is an example of this. From a theoretical point of view, subsidies should, in order to be as efficient as possible, be directed directly towards the problems they are meant to cure. If the aim for granting agricultural support is rural development and not agricultural production, then it is better to grant subsidies that do not depend upon production. Rural development (RD) can be thought of as complementary to agricultural production (AP): (*) RD = f(AP), f'(AP) > 0 This means that you get more RD if AP increases, and less RD if AP decreases. By subsidising AP, you will automatically get more RD. The function (*) does not, however, say anything about the efficiency of subsiding AP for gaining RD, compared to using the same amount of subsidies directly at gaining RD. The function does not describe whether subsidies that are production dependent are preferable to non-production subsidies from a rural development point of view. Using the function (*) and the fact that the secondary effects of reducing agricultural subsidies may be substantial in the peripheries, one may argue, however, that agriculture is important and that agricultural production is an essential industry for rural development. We would also like to underline the fact that agricultural has several non-food impacts and that multifunctionality is much more than rural development. It is especially difficult to distinguish between «rural development» and «cultural landscape». The relationship between them should probably be discussed further.
Authors
Torstein KvammeAbstract
No abstract has been registered
Authors
Jan Erik SundbyAbstract
No abstract has been registered
Authors
P.K. Egeberg Morten Eikenes E.T. GjessingAbstract
In Norwegian lakes, organic nitrogen typically constitutes about 60% of the total dissolved pool of nitrogen. However, evaluation of its effect on aquatic ecosystems and its role as promoter of heterotrophic growth in water distribution systems is difficult because of restricted knowledge about the various forms of organically-bound nitrogen in water. On line standard wet chemical analysis of total nitrogen was combined with high-performance size exclusion chromatographic (HPSEC) separation of natural organic matter (NOM) for investigation of the distribution of nitrogen between size classes of NOM. It was found that the high molecular weight (HMW) size fractions (humic acids) are enriched in nitrogen relative to the low molecular weight (LMW) size fractions (fulvic acids, nominal molecular weights of about 1000 Daltons) by a factor of up to 10. The low molecular weight size fractions (a few hundred Daltons) are interpreted to be of autocthonous origin based on their low C/N ratios, and correlation with the eutrophic status of the source waters. It was observed that NOM from water sources surrounded by large catchments contains relatively more nitrogen in HMW size fractions than NOM from small catchments, except that bog-derived NOM is particularly enriched in HMW nitrogen.
Abstract
No abstract has been registered