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.
1997
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Trond MæhlumAbstract
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Guro BrodalAbstract
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Nina Elisabeth Nagy Kirsten Bjørklund Holven Norbert Roos Haruki Senoo Naosuke Kojima Kaare Reidar Norum Rune BlomhoffAbstract
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We compared diversity of birds in 35 study plots of equal size (58 ha) and productivity in western Norway, ranging from pure native pine Pinus sylvestris forests (n = 7), through different mosaics of native pine forests and spruce Picea spp. plantations (n = 21), to pure spruce plantations (n = 7). Diversity was evaluated by means of species richness, diversity indices, relative abundance curves and rarefaction. The diversity indices appeared to be less suitable for our purpose. Species richness was higher in pine forest than in spruce forest. However, a peak in species richness was found in mosaic forest. For pooled samples (408 ha), 11 bird species recorded in pine forest were not found in spruce forest, seven species were found in spruce forest but not in pine forest, and seven species were confined to the medium mosaics of pine and spruce forest (on average 56% pine and 44% spruce). We argue that, when mixing two habitat types A and B, the ratio of these habitats that maximize avian diversity depends on the ratio of species confined to habitat A and B, as well as the number of species favoured by the mixture of A and B. Existing spruce plantations (13% of the area) in native pine forests of western Norway have reduced the diversity of birds locally, but increased the diversity of birds on the landscape and regional scale.
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Twenty-five year old Norway spruce trees (Picea abies) were inoculated with four blue-stain fungi. Each tree was inoculated three times with each fungus and three times with sterile agar as a control, giving a total of 15 inoculations per tree. There was little variation in the extent of phloem necrosis produced in response to the different fungi, but five weeks after inoculation necrosis induced by Ceratocystis polonica and Ambrosiella sp. were significantly longer than those for the other fungi. At the same time, C. polonica had induced sapwood desicc-ation twice as deeply into the wood as any other fungus.Hyphal growth of the fungi into phloem and sapwood followed the same pattern as necrosis length and desiccation depth. Five weeks after inoculation C. polonica had penetrated phloem and sapwood further than any other fungus. It grew slower than the other fungi in both tissues the first week after inoculation, but the four following weeks it grew faster than all other fungi.