Spatial development of populations of a decomposer fungus, Mycena galopus

Abstract

Past and recent research on the distribution of the vegetative mycelium and basidiomes of Mycena galopus in a Picea sitchensis plantation is reviewed as an example of a litter-decomposing member of the Basidiomycotina, occupying a spatially continuous resource that is replenished throughout the year. Using a variety of methods, the mycelia were found to be concentrated in the F1 horizon and the basidiomes produced nonrandomly in aggregations or arcs around the trees. Evidence was obtained of rapid dikaryotisation of homokaryons and of the ability to outbreed with a strain from Quercus woodland. The dikaryotic mycelia (genets) were up to 2.5 m in diameter, perennial or renewable mycelium occupying longstanding positions. A hierarchy of causal factors, including a competing saprotroph, a mycophagous collembolan, and variations in soil properties around tree boles, is discussed. Examination of relationships between NH4+-N content, moisture, or pH of the litter and distance from a tree or relative positions of basidiomes showed that there was significantly (P < 0.01) more NH4+-N at the arc position than the average for positions either side and a tendency for pH to reach maximum values in this region. The arc system with mycelium at its centre is contrasted with typical free and tethered fairy rings. Key words: Basidiomycotina, saprotrophs, Picea, tree litter, competition, fairy rings.