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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.

2004

Abstract

I 1998-2000 ble det biologiske mangfoldet av minerfluer undersøkt i konvensjonelt og økologisk dyrket korn og gras i Sørøst-Norge. Fluene ble fanget med håv i 1x10m store ruter i åkerkanten, 0,5, 5, 15 og 30 m ute i åkeren. Totalt 5822 individer av minst 66 arter ble fanget. Deler av biodiversiteten var høyere i de økologiske feltene. I både konvensjonelle og økologiske felt ble biodiversiteten redusert når en gikk fra åkerkanten og utover i åkeren. In 1998-2000 the species richness and species diversity of Agromyzidae were investigated in conventionally and biologically managed cereal and grass fields in Southeastern Norway.Flies were caught with sweep-net in 1x10 m plots in the boundary, 0.5, 5, 15 and 30 m into the fields. A total of 5822 specimens of at least 66 species were caught. Parts of the biodiversity was shown to be higher in biological fields. In bothconventional and biological fields the biodiversity was reduced when moving from the boundary and into the field.

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Abstract

Cyclic outbreaks of forest moth pest species have long remained a puzzle for foresters and ecologists. This paper presents time-series exhibiting a strong negative relationship between sunspot numbers and population indices of autumnal and winter moths, both in a mountain birch forest in central Norway and in a mixed lowland forest in southern Norway. In the latter area, also the population level of a moth species feeding entirely on lichens was negatively related to sunspot numbers. Low sunspot activity leads to a thinner ozone layer and thus higher surface ultraviolet (UV)-B radiation. As winter moth larvae prefer leaves subjected to enhanced UV-B radiation, we suggest that the causal relationship between sunspots and moths is that the metabolic costs of producing UV-B-protective pigments during periods of low sunspot activity reduce trees" and lichens" resistance to herbivores, and thus increase the survival of moth larvae. Higher peak densities of moth cycles in mountain forests could be explained by the general higher UV-B radiation at higher altitudes.