Gophers needed 1 day after Mount St. Helens erupted to bring explosions of new life

The gophers were grumpy, but they understood the assignment. Brought by helicopter to a barren landscape with pumice stones the size of marbles and golf balls, the animals did what they’ve always done: They started digging.

Just two years earlier, a cataclysm erased life in the landscape. The explosive eruption of Mount St. Helens in 1980 blew out the mountain’s northern flank and destroyed some 135 square miles of forest.

“The blast zone covered the mountainside with very thick ash. I mean, ash that’s so thick that it could bury a car,” researcher Mia Maltz, lead author of a new study about the gopher project, tells NPR.

The eruption in southwest Washington state left fertile soil far below an inhospitable surface. Scientists wanted to know what would happen if pocket gophers, known as “ecosystem engineers” for their outsize effects on habitats, were given a chance to work in fenced-off plots of land.

The gophers were grumpy about being taken from Butte Camp, their home on the southern side of the volcano, to the northern area known as the Pumice Plain. Sharing a photo of one, Maltz says, “She/he was not happy about being stuck there, or being recaptured for transport back home.”

The gophers stayed for only about 24 hours before being whisked away. But their visit altered a landscape where, after the eruption, the pumice “contained no measurable carbon (C) or nitrogen (N),” according to the study.

When scientists returned to the fenced plots six years later, they were stunned to find some 40,000 plants there, while nearby patches of land remained desolate. In the decades since, the effects have kept compounding.

“Who would have predicted you could toss a gopher in for a day and see a residual effect 40 years later?” microbiologist Michael Allen of the University of California, Riverside, another study author, said in a news release about the researchers’ return to the volcano.

So, why did it happen? Part of the credit goes to the gopher’s diligent digging, which cycled fertile materials back toward the surface. But they also left things behind — from their droppings to spores and fungi.

“The gopher is the big star because they brought these mini ecosystems along with them,” says Maltz, a mycologist and assistant professor at the University of Connecticut. “And the fungus is a big part of that mini ecosystem.”

The gophers brought a sampling of life-supporting material from their home forests, including soil spores and seeds held in their digestive tract, in their claws and on their fur. Crucially, they also brought beneficial fungus.

“Mycorrhizal fungi are plant supporters,” Maltz says. “They grow with plant roots and support plants in getting established in inhospitable environments.” 

In exchange for providing nutrients and resources, she says, the fungi get sugars that plants generate via photosynthesis. They also help protect plants from pathogens and stress.

The gophers’ actions seemed small, even to the scientists who were studying them. After all, each one weighed just a handful of ounces. But the lasting impact of their visit holds lessons about helping habitats recover after a disaster, Maltz says.

“We can mimic gophers by scarifying soils or digging with a gardening tool (hoe), and adding in local spores and soil from undisturbed ecosystems,” she says.

When they revisited the area, researchers also found distinct differences in how forested areas have fared depending on whether they had been left as old-growth or underwent clear-cutting before the volcano erupted. Decades later, old-growth forest areas had more carbon and nitrogen and benefited from healthier fungal communities compared to clear-cut areas.

Trees that lost their needles to the eruption’s dense ash coating also got a boost from mycorrhizal fungi, which ferried nutrients that helped the trees regrow.

“The trees came back almost immediately in some places,” environmental microbiologist Emma Aronson said in the UC Riverside news release. “It didn’t all die like everyone thought.”