Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
1997
Forfattere
Michael J. Wingfield T.C. Harrington Halvor SolheimSammendrag
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Sammendrag
Nåleprøver ble innsamlet fra 180 grantrær på 45 flater i Sørøst-Norge. Det var generelt lavere konsentrasjon av kationer og mineralnæringsstoffer henholdsvis i humuslaget og i nåler i den sørligste del av landet, samt et høyere innhold av N. Ved fortsatt tilførsel av N, er det sannsynlig at det i trærne vil oppstå sterkere mangel på næringsstoffer som K og P. På grunn av den geografiske spredningen i materialet styres trærnes vitalitet i hovedsak av de naturlige vekstbetingelsene, samt av konsentrasjonen av nitrogen i nålene og pH i humuslaget, og viser ingen geografiske trender.
1996
Sammendrag
The diversity in different groups of obligate saproxylic beetles was related to ecological variables at three levels of spatial scale in mature spruce-dominated forest. The variables were connected to: decaying woodwood-inhabiting fungilevel of disturbancelandscape ecologyvegetational structure. Several strong relationships were found at medium (1 km2) and large scales (4 km2), while only weak relationships were found at a small scale (0.16 ha; 1ha=104m2). This may be explained by the local variations in habitat parameters and the high mobilities of many beetle species. Factors connected to decaying wood and wood-inhabiting fungi were clearly the most important factors at all scale levels. In particular, the variables diversity of dead tree parts, number of dead trees of large diameter and number of polypore fungi species increased the species richness of many groups and increased the abundance of many species. Eight species were not recorded below a certain density of decaying wood per 1 or 4 km2. Former extensive cutting was a negative factor at large scale, probably because of decreasing recolonization with increasing distance to source habitats. Thinning reduced the diversity of species associated with birch. The development of guidelines favouring the diversity of saproxylic beetles are discussed below
Sammendrag
In the present study the predation rate of Chrysoperla carnea (Stephens) on eggs and larvae of the lepidopterous species Mamestra brassicae (L.) was investigated including the prey"s influence on survival and development. The experiments were done at 20 +/- 1 degrees C and L:D = 16:8. C. carnea larvae were fed on eggs and first instar larvae of M. brassicae, respectively. In both cases the daily predation rate of C. carnea increased slowly during the two first instars and reached a peak in the third larval instar. During the third instar 87% and 85% of the total numbers of M. brassicae eggs and larvae, respectively, were consumed. C. carnea preyed on a mean total of 312 M. brassicae eggs and 232 M. brassicae larvae during its larval development. The mean daily predation rate of C. carnea reached a maximum of 106.6 eggs of M. brassicae and 46.1 larvae of M. brassicae. C. carnea consumed a total of 32 mg of M. brassicae eggs and 70 mg of M. brassicae larvae during its larval development. The developmental time of C. carnea fed on M. brassicae eggs and larvae was 27.4 and 21.5 days, respectively. Almost 10% of C. carnea died when reared on M. brassicae eggs and 15% died when reared on M. brassicae larvae. The quality aspect of the prey is discussed.
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Forfattere
Dan AamlidSammendrag
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