Print PageCompetition determines the structure and function of fungal communities. During wood decomposition, brown and white rot fungi utilize different forms of carbon while competing for the same space. It is possible that the dynamic of wood-degrading fungi is not driven alone by niche partitioning but also random processes if the competitive forces of two fungi are similar.
A microcosm system was used to let brown and white rot fungi invade and compete on wood substrates (oak, birch, pine and spruce). In a first experiment, brown rot (Gloeophyllum trabeum) was inoculated in larger amount than white rot (Irpex lacteus), simulating a stronger brown rot population due to earlier colonization. In a second experiment, substrates were precolonized by brown rot for 1, 3 and 5 weeks before microcosm decomposition. All microcosms were incubated at room temperature for 8 weeks. Harvested samples were tested for mass loss, water content, pH, alkaline solubility and carbon composition. In the future, quantification PCR can reveal the relative abundance of fungi in our samples. The design was based on previous experiments where white rot achieved dominancy over brown rot, likely by faster spread rate. Experiments here were to test this dynamic, giving the brown rot fungus a 'head start'.
Results/Conclusions
Characters of decay residues showed diversified patterns of fungal competition. By observation, both experiments produced wood residue covered with mycelium of either brown or white rot. In the first experiment, characters of residue correlated well with the dominancy of fungi. For example in pine, brown rot residue grouped with low pH (3.48), high solubility (52.9%), water content (27.6%) and mass loss (26.9%), comparing to that of white rot residue (pH = 3.84, solubility = 19.0%, water content = 13.6%, mass loss = 4.8%). Materials with light brown rot precolonization (1 week) had similar patterns of diversified decay residues. But extensive precolonization (3 and 5 weeks) resulted in residues closer to brown rot decay.
Our research indicated that coexistence of brown and white rot can be achieved by proper timing of colonization, which resulted in random colonization and extinction of fungi. At least in our experiment, a given initial condition diversified into totally different outcomes, which maintained the successes of both fungi. It is possible that the competitive force of both fungi reached relatively equal states despite their different life strategies; however, our future work needs to explain which environmental variables drive an apparent substrate-specificity among many wood-degrading fungi.
