A 24-hour gopher visit caused decades of benefits to volcano grave

In 1980, Mount St Helens erupted in the western USA, killing 57 people and destroying 350km² of forest.

In 1983, scientists captured 2 wild gophers, and put each of them on a small, fenced enclosure on the ruined volcanic plain. They let the gophers dig for 24 hours, then removed them.

According to a new study, those 2 tiny interventions have caused benefits to the mountain ecosystem that can still be measured decades later.

The study, published in Frontiers in Microbiomes, has found key differences in the fungi and other microbes inhabiting the old gopher plots.

“In the 1980s, we were just testing the short-term reaction,” says study co-author Professor Michael Allen, a microbiologist at the University of California – Riverside, USA, who worked on both the 1983 study and the 2024 update.

“Who would have predicted you could toss a gopher in for a day and see a residual effect 40 years later?”

The team had theorised, in the 1980s, that gophers might be able to help the soil recover after it was choked by lava and ash. They’d do this by digging through the top layer of debris and bringing helpful microbes to the surface.

This worked: 6 years after the intervention, the team found that the ex-gopher plots were covered in plants, while neighbouring land remained thoroughly volcano-scorched.

A big reason for this, says Allen, was the gophers’ ability to return mycorrhizal fungi to the surface.

“With the exception of a few weeds, there is no way most plant roots are efficient enough to get all the nutrients and water they need by themselves. The fungi transport these things to the plant and get carbon they need for their own growth in exchange,” says Allen.

In 2014, the team returned and sampled soil communities from the gopher plots and neighbouring areas. They found clear differences in the microbial diversity from the gopher and non-gopher spots.

They also found a notable difference between areas that had been old-growth forests, and areas that had been clearcut, prior to the volcano catastrophe.

The old-growth forests recovered much better than the clearcut areas.

“These trees have their own mycorrhizal fungi that picked up nutrients from the dropped needles and helped fuel rapid tree regrowth,” says co-author Associate Professor Emma Aronson, a microbiologist at the University of California, Riverside.

“The trees came back almost immediately in some places. It didn’t all die like everyone thought.”

Meanwhile, soil fungi – and the trees that needed it – did not do well in the clearcut areas.

“There still isn’t much of anything growing in the clearcut area,” says Aronson. “It was shocking looking at the old growth forest soil and comparing it to the dead area.”