Factors influencing fructification phenology of edible mushrooms in a boreal mixed forest of Eastern Canada

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Given the rise in commercialization of edible forest mushrooms in Eastern Canada, it is advantageous to understand the fruiting patterns of fungal species. The aim of this study is to understand the phenology of edible species within the mixed boreal forest. Weekly surveys were conducted in 481 quadrats during the mushroom growing season over three consecutive years (2005–2007). The initial fruiting dates, as well as the duration of fruiting, were examined relative to year and stand type. Species phenology was also considered in relation to soil temperature and moisture on temporal (interannual) and spatial scales (across sampling quadrats). Our results show no significant influence of stand type on the phenology of edible ectomycorrhizal mushrooms. Neither the composition of dominant species nor the age or origin of the stand (natural regeneration or plantation) appears to have a direct influence on species phenology. On a temporal scale, the effect of year, as well as soil temperature and moisture, strongly explains the initial fructification date but is only weakly linked to the length of the fruiting. Soil conditions influence the phenology of all fungal species but each species has a specific response. For example, average soil moisture can either stimulate (e.g. Boletus aff. edulis and Lactarius deterrimus) or delay (i.e. Cortinarius caperatus and Catathelasma ventricosum) the initial fruiting date. On a spatial scale, soil conditions are correlated with the phenology of certain species; however, this source of variation seems less important to the overall phenology of all species. The effect of year, coupled with soil temperature range (difference between maximum and minimum temperatures during the growing season), shows the strongest relations with the initial fruiting date in six of the seven species studied. That is, the wider the soil temperature range, the earlier the fruiting bodies appear. The stimulation of fructification by a marked decrease in temperature, a phenomenon known as cold-shock, is well known in the laboratory. According to our results, this phenomenon seems also important in situ to initiate fruiting of edible fungi in the mixed boreal forest and could help to optimize the harvest.