Basidiospore dispersal in the old-growth forest fungus Phlebia centrifuga (Basidiomycetes)

Dispersal of the old-growth forest fungus Phlebia centrifuga was studied under natural conditions in an old-growth forest stand in south Sweden using spore trapping with single spore mycelia as bait. Sampling was done not only in the forest but also 500 and 1000 m outside it. Within 100 m of the basidomata source, spore dispersal was very efficient, and it was estimated that 385 spores settled per m(2) during 24 h. The minimum total number of spores calculated to have fallen within the 100 m circle was 1.21 x 10(7). The spore fall decreased significantly with distance from the basidiomata. Almost all of the mycelia were dikaryotised at Im distance, compared with less than half at 10 and 100 m. Dikaryotisation was observed in a small but significant number of mycelia at 500 and 1000 m. Mating success between different single spore mycelia differed significantly and we speculate that effective population size may be affected by mating choice in this species. What factors restrict this species to old-growth forests? In the light of the dikaryotisation observed at 1000 m from the source, it seems unlikely that this fungus is restricted by spore dispersal distance, which implies good prospects for its successful establishment in restored habitats, i.e. first-generation forests with much coarse woody debris.