Is Chaga harvesting sustainable?

Inonotus obliquus

You must have already seen Chaga high on a tree. At first sight, you thought you had discovered a coal chunk in an unlikely place. The mushroom is a ubiquitous pathogen of birches across north-eastern North-America. It is entrenched in the heart and, after a very long while, breaks the tree where it has pierced its bark. On average, it is found on less than one out of a thousand trees, the most fragile. Locally, it can be abundant: according to Bruno Boulet, in areas most exposed to the rigors of winter, more than 20% of the stems are infected.

Due to its medicinal properties, demand has been rising exponentially for several years now. But could this result in a depletion of the resource? According to Paul Stamets, West-Coast entrepreneur who boosts cultivation rather than foraging, yes : “Chaga is rapidly becoming scarce. Its ability to recover, given the onslaught of commercial harvesters, places its availability and recovery in doubt”.

Should we worry about sustainability? To answer this critical question, we must understand this mushroom’s fascinating life cycle.

The visible part cut from the living tree by the picker is sterile. After having being collected, it grows again so that it can be harvested once more within 3 to 10 years. The fructification and reproduction occurs briefly only after the death of its host. On the ground, it will then disperse its spores before being quickly eaten by insects. According to P. Stamets once more, “the open wounds in the tree are points of infection for pathogenic fungi”. We should recall that Chaga is itself an aggressive parasite and to our best knowledge, no study establishes any damage related to harvesting, either to reproduction or to the hosts themselves.

As part of a US-Russian study on non-timber forest products from Siberia, David Pilz (Fungi Magazine vol.5 # 3, 2012) concludes: "the abundance of Chaga in Russia is such that under the most pessimistic estimates, the resource will never be threatened". Pending further studies, the same conclusion may hold for our area.