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.

1990

Abstract

In a field experiment in southernmost Norway four young trees of each of eight coniferous species were subjected to artificial inoculation with the pathogenic blue-stain fungus Ophiostoma polonicum, associated with the spruce bark beetle Ips typographus. A dose previously known to be lethal to most Norway spruce trees also killed individuals of Sitka, white, and black spruce, and Douglas fir. All Scots and lodgepole pines, and subalpine firs survived the given load of infection. Douglas fir did not exhibit the induced resinous defence reaction seen in spruce and pine. The fungus did not proliferate in the phloem of Douglas fir, but spread more easily in a tangential direction in the sapwood of this species than in spruce.

Abstract

Nitrogen er det begrensende grunnstoffet for vekst i de fleste arktiske plantesamfunn. Effekten av temperatur og nitrat konsentrasjon på maksimal nitrat reduktase (NR) aktivitet er registrert hos fire arter som vokser i fuglefjell; Cochlearia groenlandica, Oxyria digyna, Chrysosplenium tetrandrum og Saxifraga hieracifolia. Resultatet viser at artenes maksimale NR - aktivitet gir en indikasjon på evnen til å ta opp og utnytte nitrat. Fjellsyre og skjørbuksurt hadde signifikant høyere NR-aktivitet enn stivsildre og dvergmaigull ved alle behandlingene. Dette kan indikere at stivsildre og dvergmaigull utkonkurreres høyt oppe i fuglefjellet der nitratkonsentrasjonen er stor fordi fjellsyre og skjørbuksurt kan utnytte gjødslingen bedre.

Abstract

Spores characteristic of the tree pathogenic blue-stain fungus, Ophiostoma polonicum Siemasko, and other fungi are visible in scanning electron micrographs of pits on the pronotum and elytra of Ips typographus (L.). Inoculation and reisolation experiments showed that O. polonicum was transmitted to logs of generally higher frequencies by live beetles and their excised parts (head, prothorax, or elytra) than by the digestive tract. Other associated fungi isolated at high frequencies from I . typographus were O. bicolor Davidson Wells, O. penicillatum (Grosmann) Siemasko, Graphium sp., and yeasts.

1989