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.
2003
Forfattere
Helge Lundekvam Eirik Romstad Lillian ØygardenSammendrag
Norwegian agriculture depends heavily on governmental subsidies, due to small farming units and high costs. Due to a limited home market, many agricultural productions are also quantum regulated. Milk and grain production was regulated starting in the 1950 using region specific prices. At the level of three counties in south-eastern Norway, this policy resulted in an increase in the grain producing area from 30 to 80% of total agricultural area causing a similar reduction in grassland area over a'30 year period. The change in land use caused by this policy more than doubled the estimated soil losses by water erosion. During the late; seventies extensive land levelling in the same region stimulated by subsidies lead to an estimated two-three fold increase in soil erosion. The increase was especially high when former ravine landscapes used for pasture were levelled and turned into arable land that was ploughed in autumn. Very visible erosion and increasing negative offsite effects on water quality together with overproduction put an end to the subsidies for land levelling. Erosion research was started around 1980 and the results from this research lead to the introduction of several kinds of payments in the early 1990 to encourage more sustainable agricultural production. Since the policy changed there has been changes in cultivating systems and a reduction in soil erosion has been estimated. Thus, farmers' behaviour and soil erosion in Norway is strongly influenced by agricultural and environmental policy.
Forfattere
Knut Rydgren Rune H. Økland Tonje ØklandSammendrag
No abstract has been registered
Forfattere
Rune H. Økland Knut Rydgren Tonje ØklandSammendrag
Previous studies point at biogeographic (i.e. evolutionary and demographic) and ecological (i.e. habitat differentiation and disturbance) processes as the most important causes of spatial variation in species richness and species composition. We examined patterns of variation in similarity of vascular plant and bryophyte species composition among 150 1-m2 plots distributed semi-randomly over 11 Norwegian boreal swamp-forest localities that were species-rich islands in an otherwise species-poor forest landscape. For each plot, 53 environmental variables were recorded. By using CCA analyses, we found that c. 20% of the explainable variation in species composition was due to swamp-forest affiliation, in addition to the c. 35% that was due to environmental differences between swamp-forest localities. The unique component of the species composition of each swamp forest was also emphasised by analyses of floristic dissimilarity: plots were significantly more floristically dissimilar if situated in different than if situated in the same swamp forest, even after environmental differences had been corrected for. The lack of any significant relationship between floristic dissimilarity and geographical distance or swamp-forest area indicated that this pattern was not mainly due to demographic processes. We argue that the floristic distinctness of swamp forests, in particular those richer in species and soil nutrients, is due to a combination of factors among which randomness in establishment in infrequently occurring gaps ( ‘windows of opportunity’) are likely to be important. The unique combination of important determinants of the species composition found for boreal swamp forests supports the view that there exists a diversity of explanations for diversity and that these, to a large extent, are system- and/or area-specific.
Forfattere
Tonje Økland Knut Rydgren Rune H. Økland Ken Olaf Storaunet Jørund RolstadSammendrag
No abstract has been registered
Forfattere
Arne Sandnes Toril Drabløs EldhusetSammendrag
No abstract has been registered
2002
Forfattere
Vibeke LindSammendrag
No abstract has been registered
Forfattere
Guro BrodalSammendrag
No abstract has been registered
Sammendrag
No abstract has been registered
Sammendrag
No abstract has been registered
Forfattere
Mehreteab TesfaiSammendrag
No abstract has been registered