Competitive Hierarchies of Wood Decomposing Basidiomycetes in Artificial Systems Based on Variable Inoculum Sizes

In the laboratory, 12 species of wood decay basidiomycetes from various stages of fungal succession in logs of Norway spruce were investigated for their relative competitive ability. Pie slices of different sizes were cut from wood discs made from Norway spruce. After inoculation, the pieces were confronted in most species combinations on water agar in Petri dishes, and were left for six months. With this method the inoculum sizes could be varied, while the contact area remained the same. Photos of the discs were taken regularly during this time. At the end of the experiment, samples of the wood were taken from all discs and the remaining fungi were isolated. Combative success was measured as the ability to take over substrate from competing species by the end of the experiment. Both within and among successional stages, mycelial replacement occurred in a non-random fashion. Species usually producing fruit bodies in the later stages of succession in the field were strong competitors in the laboratory tests, while the species which often fruit during the earlier stages of field succession were weaker competitors.