The puzzling variance of reishi fruiting

Look closely at the photo what do you see? Spread around the base of this stump there are 8 or 9 copper colored reishi mushrooms sadly missed and left to rot from last year (2013).

Here in upstate NY reishi's start fruiting as early as May and by July its usually over. This large hemlock stump that produced such a prolific bounty of reishis in 2013 was completely barren in '14 as you can see in this June 28th photo.

What's puzzling to me is the pattern of rainfall in the summer's of '13 and '14 were so similar, both had above average rain in June and July which led to a great chanterelle season for both years. But the difference in the reishi harvest was night and day. In 2013 I had grocery bags full (too bad I didn't understand how to properly prepare them - but that's a post for another day). Last year I found exactly one.

All this tells me that I need to start keeping better notes when I forage; the date of first fruiting, previous rainfall, location, etc.

Note: The species here is actually a north american sub-species of reishi called Ganoderma tsugae but they are very similar and are believed to have the same beneficial medical properties.