The influences of litter cover and understorey vegetation on fruitbody formation of Tricholoma matsutake in southern Finland

Removing the litter layer from an area known to contain matsutake (Tricholoma matsutake) is believed to enhance mushroom productivity in Asian countries where it occurs. This study aimed to understand the effect of understorey vegetation and litter cover on matsutake fruitbody formation and to evaluate the utility of litter derived dissolved organic matter (DOM) as a growth medium. An inventory of understorey vegetation and litter cover was conducted in a productive forest site mainly including conifers that contained 15 plots in which fruitbodies had formed in successive years and 15 nearby control plots without fruitbodies. Litter composition of fruiting plots was investigated. Two T. matsutake isolates were incubated for one month in DOM derived from decomposing spruce or birch litter and mycelial growth was estimated by monitoring the concentration of ergosterol. Although plant diversity was rather uniform in the study site, total vegetation cover was substantially lower and litter cover was somewhat higher in fruiting plots. We concluded that litter derived carbon has a positive impact on T. matsutake fruitbody formation. This was confirmed by in vitro culture experiments where T. matsutake was able to grow in spruce litter derived DOM.