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.
1996
Abstract
There is a growing awareness to preserve the biodiversity in the forest ecosystems. A first step in biodiversity research is to find out what species really are found in the forest, using the scientific tool named taxonomy. Still there are species-rich groups of forest insects which have been poorly researched, and which include several unclearities concerning the species identities. One such group is the free-developing gall midges connected with litter, dead wood and fungi in the ground layer of the forest. This papers intends to improve the taxonomy of one genus in this group - Anaretella (Enderlein 1911), including the description of two new species and a key to the current species within the Holarctic region
Authors
Erik Christiansen Øystein AustaråAbstract
Potted Scots pine plants had their water supply severely reduced. N. sertifer larvae remained caged on the plants from larval hatching to cocoon spinning. The treatment accelerated larval development and increased adult size, compared to insects on well-watered controls. Larval mortality tended to be lower in stressed trees, but seemed partly determined by genetical factors. Such factors appeared to be of minor significance for developmental rates and adult size.
Authors
Tore SkrøppaAbstract
No abstract has been registered
Authors
Wenche E. DramstadAbstract
This paper questions whether bumblebees really forage as close to their nests as has commonly been assumed in the bumblebee literature. Three experiments are described that involved marking and reobservation bumblebees. None of these experiments showed any tendency for bumblebees to concentrate their foraging close to (e.g., within 50 m from) the nest. Rather, the results suggested that bumblebees may prefer to forage at some distance from their nest. Further, a closer review of the bumblebee literature showed that similar findings were quite common. Some possible explanations to the observed behavior patterns are given as outlines for further research.
Abstract
No abstract has been registered
Authors
Arnstein Orlund Øystein AustaråAbstract
During 1987-90 heavy infestations of Sitka spruce (Picea sitchensis) plantations by the green spruce aphid Elatobium abietinum were reported from the coastal areas of Møre and Romsdal county, Norway. Annual growth ring width analyses in 1992 showed that minimum growth ring width occurred 6 years after the first infestation. For trees with breast height diameters more than or equal to 20 cm, the loss in diameter increment amounted to an average of 40.5% for 1988-95 compared to control trees (loss equals 3.2 years of normal growth). Growth loss was less pronounced for smaller diameter classes, and the smallest trees even exhibited an increase in increment during the first years of infestation. Possible reasons for different growth patterns are discussed.
Abstract
No abstract has been registered
Authors
Shabani A.O. Chamshama A.G. Mugasha Bjørn LangerudAbstract
No abstract has been registered
Authors
Shabani A.O. Chamshama Bjørn Langerud A.G. MugashaAbstract
No abstract has been registered
Authors
Lars Sandved Dalen Øystein Johnsen Gunnar OgnerAbstract
No abstract has been registered