The Day Gophers Revived Mount St. Helens: A 24-Hour Miracle

In 1980, the eruption of Mount St. Helens devastated local ecosystems, but an experimental introduction of gophers has demonstrated a long-term positive impact on the soil and plant life.

Scientists observed that gophers, considered pests, could regenerate vital bacteria and fungi, significantly aiding plant recovery. Forty years later, this single-day experiment continues to show benefits, with certain areas displaying a dramatic increase in plant diversity and resilience thanks to the persistent effects on microbial communities.

Mount St. Helens Eruption

When Mount St. Helens erupted in 1980, the lava incinerated every living thing for miles. In an experimental effort to help the ecosystem recover, scientists introduced gophers to the scorched mountain for just 24 hours. The impact of that single day proved significant—and is still evident 40 years later.

Once the ash and debris cooled, scientists hypothesized that gophers, by digging and disturbing the soil, could bring beneficial bacteria and fungi to the surface, potentially aiding in the restoration of plant and animal life. Two years after the eruption, they put this theory to the test.

“They’re often considered pests, but we thought they would take old soil, move it to the surface, and that would be where recovery would occur,” explained UC Riverside’s Michael Allen.

Long-Term Effects Observed in Soil

They were right. The scientists, however, did not anticipate that the effects of this brief experiment would remain evident in the soil today, in 2024. A recent paper in Frontiers in Microbiomes describes how the areas where gophers were introduced show lasting changes in fungal and bacterial communities, unlike nearby areas where gophers were never added.

“In the 1980s, we were just testing the short-term reaction,” said UCR microbiologist Michael Allen. “Who would have predicted you could toss a gopher in for a day and see a residual effect 40 years later?”

In 1983, Allen and Utah State University’s James McMahon helicoptered to an area where the lava had turned the land into collapsing slabs of porous pumice. At that time, there were only about a dozen plants that had learned to live on these slabs. A few seeds had been dropped by birds, but the resulting seedlings struggled.

After scientists dropped a few local gophers on two pumice plots for a day, the land exploded again with new life. Six years post-experiment, there were 40,000 plants thriving on the gopher plots. The untouched land remained mostly barren.

Microbial Role in Plant Survival

All this was possible because of what isn’t always visible to the naked eye. Mycorrhizal fungi penetrate into plant root cells to exchange nutrients and resources. They can help protect plants from pathogens in the soil, and critically, by providing nutrients in barren places, they help plants establish themselves and survive.

“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,” Allen said.

Comparative Study: Old-Growth Forests vs. Clearcut Areas

A second aspect of this study further underscores how critical these microbes are to the regrowth of plant life after a natural disaster. On one side of the mountain was an old-growth forest. Ash from the volcano blanketed the trees, trapping solar radiation and causing needles on the pine, spruce, and Douglas firs to overheat and fall off. Scientists feared the loss of the needles would cause the forest to collapse.

That is not what happened. “These trees have their own mycorrhizal fungi that picked up nutrients from the dropped needles and helped fuel rapid tree regrowth,” said UCR environmental microbiologist and paper co-author Emma Aronson. “The trees came back almost immediately in some places. It didn’t all die like everyone thought.”

On the other side of the mountain, the scientists visited a forest that had been clearcut prior to the eruption. Logging had removed all the trees for acres, so naturally there were no dropped needles to feed soil fungi.

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

Learning From Nature’s Resilience

These results underscore how much there is to learn about rescuing distressed ecosystems, said lead study author and University of Connecticut mycologist Mia Maltz, who was a postdoctoral scholar in Aronson’s lab at UCR when the study began.

“We cannot ignore the interdependence of all things in nature, especially the things we cannot see like microbes and fungi,” Maltz said.

Reference: “Microbial community structure in recovering forests of Mount St. Helens” by Emma L. Aronson, Lela V. Andrews, Hannah Freund, Hannah Shulman, Rebecca R. Hernandez, Michala Phillips and Mia R. Maltz, 22 August 2024, Frontiers in Microbiomes.
DOI: 10.3389/frmbi.2024.1399416

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