Insects in polypore fungi as indicator species: a comparison between forest sites differing in amounts and continuity of dead wood

Abstract

To effectively preserve the threatened fauna of old-growth forest it is important to identify species that are adversely affected by forest management. We focused on insect species living in fruiting bodies of two polypore species and compared their frequency between forests sites differing in terms of the continuity with which their breeding substrate (dead wood) was available (long, short or no continuity). The polypore species studied were Fomitopsis pinicola and Fomes fomentarius, in which the patterns of occurrence were determined for 25 and 27 insect species, respectively. Species showing significantly higher frequency in less managed forests were Oplocephala haemorrhoidalis (Tenebrionidae), Cis quadridens (Cisidae), and Scardia boletella (Tineidae). Some less frequent species showed similar, but non-significant, trends. We suggest that polypore-inhabiting species restricted to sites with a long, continuous supply of dead wood might be used as indicators of sites of high conservation value. Their presence might also be indicative of species of high conservation value in other dead-wood microhabitats with similar temporal and spatial dynamics. The species that we found to be restricted to less managed forests are all included on the Swedish red-list. However, two species not affected by management are also red-listed, showing that numbers of red-listed species must be used with caution as a measure of conservation value.