SpruceRoots Magazine - November, 1999

The Biology of Mushrooms

by Brigid Cumming

There's a lot more to mushrooms than meets the eye, quite literally. Mushroom biology is complicated and the forest/mushroom relationship is just beginning to be studied on Haida Gwaii.

Rob Draeseke's, Overview of existing economic information regarding Non-timber Forest Products in British Columbia, a 1998 Ministry of Forests publication, explains that there are three general classes of edible mushrooms: pathogens, saprobes and mutualists. Pathogens attack and often kill living tissue; saprobes live only on dead organic matter. Mutualists (also called micorrhizal) include chanterelles, boletes and pine mushrooms, which are the best known and studied commercially-harvested species.

These particular mushrooms are the short-lived visible out-croppings or 'fruiting bodies' of miles and miles of underground mycelial networks. Mutualists enhance a tree's ability to extract water and nutrients from the soil while tapping the tree's store of photosynthetically generated simple sugars and vitamins. This mutually beneficial relationship is called commensal, with the mushroom and tree roots combining to form a hyfal net. While harvesting trees kills the associated mutualist mushroom species, no-one has studied what effect (if any) harvesting mushrooms has on the trees.

Mushrooms are both perennial (coming back year after year) and cyclic, with the number of mushrooms varying, sometimes dramatically, from year to year.

"I've never seen two big bumper crops in a row," said Brian Pear-son, a Queen Charlotte mushroom picker and buyer. "You get a really big year, you get a nominal year, and then some years - you know, the odd year out of the, 3-4 year cycle almost, if you could call it that - you'll get a really low volume."

This uncertain annual supply dictates a flexible, portable mushroom industry. Pickers and buyers have to go where the product is. And often enough, that's the Charlottes.

SpruceRoots Magazine - November, 1999