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Global Climate Change, Food Trees, and the Mushrooms That Orchestrate It All

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Earth ball mushroom with sweet chestnut and husk.

Six years ago a squirrel planted a sweet chestnut seed in my plant nursery and forgot about it. The tree grew, and grew and grew. Today I harvested the first nuts from that tree (and roasted them for dinner, mmm yum). While harvesting the nuts I noticed a few puffball mushrooms growing on the soil scattered around the tree. I didn't think anything about them, other than they were some of the first mushrooms I'd seen since establishing the perennial nursery many years ago. Later that day I reconsidered what I had seen, because...

A few weeks ago I came across a scientific article that compared the ecological function of two groups of soil mycorrhiza (mushrooms). The paper suggests that "Ectomycorrhizal and ericoid mycorrhizal (EEM) fungi produce nitrogen-degrading enzymes, allowing them greater access to organic nitrogen sources than arbuscular mycorrhizal (AM) fungi. This leads to the theoretical prediction that soil carbon storage is greater in ecosystems dominated by EEM fungi than in those dominated by AM fungi." (Colin Averill

These mushrooms typically have associations with plants, and when I read this, I immediately did a search to find out which families of trees associated with the high "soil carbon storage" EEMs. The family Fagaceae, which includes the sweet chestnut, Castanea sativa, associates with EEM fungus. And it is interesting to note almost all of the EEM tree hosts include the best hard wood trees on the planet like chestnut, oak, and mahogany! (I don't know the science involved here, but it is an interesting correlation, carbon sequestering fungal host=really hard wood full of lots of carbon.)

Then a light bulb lite up in my head. The puffball fungus I saw growing under my chestnut tree is the common earth ball, Scleroderma citrinum, one of the EEM fungus that both associates with chestnuts and it turns out is a carbon sequestering power house!

Thus, a delicious, staple crop food tree fights climate change by way of it's carbon accumulating mushroom partner... How cool is that! And wait till you consider some of the other EEMs that grow under food trees... did someone say Porchini!

Common earth ball, Scleroderma citrinum (unfortunately not edible :(

Photos by Eric Toensmeier and others.

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