Inoculum volume effects on competitive outcome and wood decay rate of brown- and white-rot basidiomycetes

Theory predicts that the energetic cost of competition between fungal mycelia might accelerate or retard the rate of wood decomposition, depending on various factors. To evaluate the effect of occupied territory on wood decay rate and competitive outcome, we set up a pairing competition experiment using beech wood blocks colonised by three brown-rot and three white-rot basidiomycetes. All white-brown combinations (totalling nine), and five ratios of wood volume (4:0, 3:1, 2:2, 1:3, 0:4) were performed. Pairings were incubated in the dark at 20 °C for 3 months, and then competition outcome and wood weight loss were determined. Mycelia occupying larger territory were more competitive than mycelia occupying smaller territory. There were negative relationships between wood volume and percentage wood weight loss. Wood decay was slower at the competition front than at the rear of the wood blocks in some cases. These results suggest that wood volume (territory size) affects both competition outcome and wood decay rate in basidiomycete communities.