The Slow Death of Mushrooms

Sudden oak death, deforestation, and livestock have shrunk local mushroom populations.

The mushroom bounty provided by an oak tree-covered canyon soaked with January rainfall can be phenomenal. Todd Spanier, a local mushroom hunter and enthusiast, walks the East Bay hills regularly with a pocket knife, sack, and an eye open for golden wedges protruding from the leaf litter. Some winters he has harvested nearly two-hundred pounds of golden chanterelles from just a handful of patches.

But the best days were at least ten years ago, and things, he says, have changed.

“Now, I can go to the same canyons, do all the same hikes to all the same patches, and collect maybe five pounds of chanterelles,” said Spanier, who operates a Daly City-based mushroom wholesale service called King of Mushrooms.

The reasons for the decline, he speculates, are manyfold — including development, deforestation, and overgrazing by pigs and deer. As much as anything else, though, Spanier blames the blight now sweeping through California’s oak and tanoak forests at a fearful rate: sudden oak death. “In places the forest looks like a checkerboard of dead trees,” Spanier said.

Chanterelles, as well as other species of fungi, are mycorrhizal, meaning they require the presence of particular perennial plants in order to live. Porcini, or king bolete, mushrooms often live in a symbiotic relationship with conifers. Truffles occur among hazelnut trees. But coastal California chanterelles rely strongly, if not quite exclusively, on oak trees, and if the health of an oak forest is compromised, chanterelle abundance may decline. If a forest dies, so will its mushrooms.

Sudden oak death — caused by an airborne brown alga called Phytophthora ramorum — has had particularly devastating consequences in Marin County. There, David Campbell no longer bothers hunting chanterelles in some places where he once regularly found the golden-yellow delicacy but which have since been devastated by the oak-killing blight.

“It’s just gotten so bad,” said Campbell, the former president of the Mycological Society of San Francisco, a group of mycologists, mushroom buffs, and amateur collectors. “Production in areas I’ve collected in is down to less than 5 percent, maybe 2 percent, and the days when I collected a huge surplus — those days are done.”

Brice McPherson, a UC Berkeley entomologist and expert on the coast live oak, says sudden oak death has spread more slowly in the East Bay than in Marin County and along the Central Coast. “The disease’s impacts aren’t as noticeable here yet simply because it hasn’t been here as long,” he said. Yet, several hotspots have emerged, he says — namely Tilden and Redwood regional parks and the coast live oak forests around San Leandro Reservoir — and he believes the blight will grow worse. “I think it’s just a matter of time before it becomes widespread in the East Bay’s parks.”

The tanoak — not actually an oak tree but important to black trumpets, queen boletes, and chanterelles — has meanwhile been decimated by sudden oak death in its native range along the central and north coasts of California. Spanier expects black trumpet and chanterelle populations in those regions to suffer greatly if the spread of the disease isn’t slowed. Matteo Garbelotto, a UC Berkeley research scientist and expert on the tanoak, believes the species could disappear from some particular areas. The tanoak has been especially hard hit near Point Reyes, he says.

Sudden oak death is not the only force impacting wild mushrooms. Suburban sprawl and development have also impacted California mushroom habitat. Currently, a planned expansion at the Oakland Zoo threatens 56 oak-studded acres. In the city of Piedmont, a proposal to build an athletic complex called Blair Park in Moraga Canyon would require the removal of 155 trees, including 55 live oaks.

David Rust, an Oakland resident and cofounder of the Bay Area Mycological Society, once harvested porcini mushrooms from under Monterey and Bishop pines on California’s North Coast, but in several favorite spots — including along Iverson Road near Point Arena — homebuilders have cleared the trees and eliminated the habitat. Campbell describes similar activity on the North Coast and, like Rust, has largely quit hunting for porcini in Mendocino and Sonoma counties.

“It’s happened to all of us,” Campbell said. “You have a great spot, and then someone builds a house, and it’s over.”

Ken Litchfield, another local mushroom hunter and a teacher of landscape horticulture at Merritt Community College, even feels that sudden oak death — among so many other environmental stressors — has been overly vilified. “People complain about the disease, but that disease is one of the symptoms of decades of stressing the ecosystem by chopping up the forest with subdivisions, vineyards, over-grazing, and pumping of the water table, and then a disease that doesn’t kill the trees instantly gets named ‘sudden oak death,'” said Litchfield. “The real ‘sudden oak death’ is bulldozers.”

In San Leandro, resident Norm Andresen blames livestock for the slight decline in chanterelles. “We had more consistent chanterelle crops ten years ago, and now it seems more variable,” said Andresen, who has hunted local chanterelles for thirty years. He says the bovine herds that regularly loiter in the shade of oaks turn seasonal mushroom patches into wintertime mud pits. He has also seen wild pigs — an invasive species — tear up the soil beneath oaks as they root for acorns and other edibles.

Rust has seen the same thing. “And after the pigs come through there’s no mushrooms the next season,” he said. According to the East Bay Regional Park District‘s web site, some 5,000 cows graze in the district’s 65 parks, as well as 1,000 sheep and 1,000 goats.

While chanterelles and other prized wild mushrooms decline in places impacted by human habitation, some mushrooms are now thriving where they didn’t before. “A whole gild of mushrooms are woodchip mushrooms, and they’ve benefitted [from human alteration of the landscape],” said Andresen, who leads group hunts with the Mycological Society of San Francisco. “They were rare before and now they’re common.”

So-called woodchip mushrooms are not mycorrhizal with living plants. Rather, they seem to depend most directly on nourishment in the soil, often provided by decaying wood. Shaggy parasols and blewits — both edible mushrooms pursued by hunters — now occur in greater numbers in developed areas than they once did, Andresen says. Dennis Desjardin, a mycologist at San Francisco State University, says that woodchip piles and other areas of disturbed soils host large numbers of psychedelic mushrooms of the Psilocybe genus. Such mushrooms are commonly found by furtive foragers on the San Francisco State and UC Berkeley campuses. Morels, too — a valuable edible mushroom — also appear in urban areas in the late-spring, Desjardin says.

Mushroom hunting is illegal on many, if not most, public lands — but many avid collectors regularly break such prohibitions, often preferring to take their chances of receiving a several-hundred-dollar fine for the reward of scoring dinner. Many hunt in city parks, others on more strictly guarded state, county, and federal lands. Few hunters use baskets — dead giveaways of what they’re up to — while some are known to carry binoculars and gaze into tree branches to give passersby the impression that they’re watching birds.

Mushroom cultivation is another game entirely, and cultivation of many wild mushrooms — including morels and truffles — is possible. Todd Spanier notes that few mushroom species will likely ever vanish even if their habitats disappear in the wild — but the world will definitely lose something less easily defined, he says.

“Wild mushrooms are our last connection to our ancestral hunting and gathering roots, and cultivated mushrooms can’t replace that,” he said. “If and when we lose the California live oak and tanoak, it’s going to be tragedy in so many ways. It’ll be a culinary loss, a cultural loss, and an ecological and environmental loss.”

Correction: The original version of this story incorrectly stated that San Leandro resident Norm Andresen leads mushroom hunting forays with the Bay Area Mycological Society. While Andresen is a foray leader, he actually works with the Mycological Society of San Francisco.

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