Logging-residue extraction does not reduce the diversity of litter-layer saprotrophic fungi in three Swedish coniferous stands after 25 years

Abstract

Logging residues, consisting of branches and treetops, are increasingly being extracted for biofuel purposes in Fennoscandia, thereby decreasing the availability of fine woody debris (FWD). Little is known about the importance of FWD and litter to fungal diversity, although they constitute the major components of dead organic matter in both managed and natural forests. We investigated the long-term effects of removing logging residue on the saprotrophic fungi community in the litter layer by using an experiment established 25 years ago, comprising stands with and without removal of clear-cut slash. The fungal communities were identified using terminal restriction fragment length polymorphism from standardized baits of wood and needles left in the litter layer for 30 months. A total of 74 fungal taxa were recorded. No differences in species richness or frequency of abundant species were detected between the stands with and without slash removal, suggesting that the extraction of logging residues has a negligible long-term impact on abundant saprotrophic fungi. Twenty-five of the 36 abundant species colonized wood and needles indiscriminately, while 10 species occurred exclusively on wood or needles and only one species mainly on wood. The importance of litter to certain wood-inhabiting fungi may therefore be underrated. The frequent records of Trichaptum abietinum (Dicks.) Ryvarden indicate that wood-inhabiting species may, surprisingly, be found in the litter layer.