Unlogged forests: Important sites for preserving the diversity of mycetophilids (Diptera: Sciaroidea)

The relationship between the mycetophilid fauna and a set of environmental variables was studied in spruce forests of southeastern Norway. At the stand level, the continuous presence of wood in all decay stages combined with a tree cover appeared to be an important factor for increasing the species richness of mycetophilids. However, the spatial representation of suitable stands in the landscape seems to be particularly important, since the % area of old growth in the surrounding 100 km(2) showed the strongest influence on both species richness and abundance within individual species. The present findings indicate that conservation of a species-rich mycetophilid fauna requires networks of stands within dispersal distances. A reserve network in southern Norway should give special priority to little disturbed forests in the more remote submontane areas, since they appear to be very species-rich, and since their strong populations may provide long-term viability for many mycetophilid species. Copyright (C) 1996 Elsevier Science Limited.