The western United States is experiencing yet another intense wildfire season, with fires like the Caldor and Dixie Fires sweeping through forests and towns in and around the Sierra Nevada. For mushrooms that grow in the aftermath of flames, these events are a much-needed part of their life cycle. However, as big and hot fires become more common, even the most fire-loving mushroom reaches a limit to how much heat it can withstand.
Kristen and Trent Blizzard, owners of the business Modern Forager, create burn maps of western states every year to show foragers which areas have mushroom growth and can be accessed given restraints like wilderness regulations or private property boundaries. The species they track in particular is the morel, a favorite among foragers who seek out burn areas in the seasons following the summer wildfires.
Morels tend to pop up in the spring and are known as pyrophilus fungi, which means they rely on fire to fruit. Since the Blizzards started tracking morels nearly a decade ago, they have noticed a change in morel growth throughout the west.
“One of the interesting changes is that as fires have gotten worse, they’ve charred the forests beyond even what the morels will pop up after. Some of these hard fires are just moonscaping the forest,” said Trent Blizzard.
For the mushrooms that are not fire-loving and grow on living tree roots, these hard fires, sometimes called stand-replacing fires, can be especially destructive to the fungi.
“As more of the landscape turns to younger forest, you’ll certainly see a shift in the fungi associated with that forest,” said mycologist Thomas Bruns, a professor emeritus of UC Berkeley. “Things we might refer to as late-stage fungi that show up in mature forests are going to be harder to find, and some of those are going to be some of your favorite species like chanterelles or matsutake.”
These species are known as mycorrhizal fungi and grow on trees in a symbiotic fashion, with both the tree and the mushroom benefiting from their closeness. Many healthy forests can be seen teeming with mychorrhizal mushrooms that are edible, which, along with chantrelles and matsutake, include truffles and porcini mushrooms.
“I have observed over the years trees that did not have a good mycorrhizal association that just don’t grow that fast. They survive, but the same species of tree just a little ways away with one or more fungi on it will be doing much better,” said Michael Sampson, president of the Sacramento Area Mushroomers. As stand-replacing fires become more common in the west, it is possible that this mycorrhizal fungi will become more difficult, but not impossible, to find.
“I don’t think you’ll eliminate mushroom species except very locally – you might have a favorite patch that is burned and gone for decades, but over the whole landscape it’s likely still there somewhere,” said Bruns.
For most research related to how mushrooms are being impacted by climate change and increasing wildfires, only time will tell the long-term effect of hotter and more fire-conducive weather on forests and fungi.
“What you have to remember is that California is a fire-prone region and always has been, so all of the tree species in California have historically lived with fire. They have ways of dealing with it, and the fungi have ways of dealing with it as well,” Bruns said. “These fires are more of a threat in how they interact with humans than the California ecosystem.”
Claire Carlson writes about the environment for the Ally. Support her work by hitting the donate button above.
