The Evolution of Mount St. Helens

Forty years after Mount St. Helens erupted on May 18, 1980, signs of rebirth abound—but not everywhere.

The stunning view of Mount St. Helens to the north—snowy, slumped from its last big eruption 40 years ago but still imposing—is among WSU Vancouver’s signature assets. Students point to its beauty as a reason they appreciate the university. Classes study the mountain. Weekend backpackers hit the trails and visit the interpretive center.

And there is another, more intimate connection between WSU Vancouver and Mount St. Helens. For researchers, understanding the mountain and how it is changing as the years go by is a unique opportunity and a long-term quest. Some of those who have come to study the mountain have become key links in keeping the story of Mount St. Helens relevant to a new generation.

John Bishop, professor in the School of Biological Sciences, has spent 30 years conducting research mostly on the Pumice Plain, where pyroclastic flows, airfall fragments and rock left a barren moonscape. He calls it a “science playground,” a place to gauge the long-term effects of natural catastrophe and to see how a new landscape evolves. The work has attracted many graduate students to WSU Vancouver. “Most of my graduate students come here to work with me because they’re interested in restoration and conservation, and they view this as a way to learn about how systems recover from disturbance,” he said. Several have gone on to career involvement with Mount St. Helens.

Ray Yurkewycz, for one, came to WSU Vancouver via Chicago and Montana to complete a master’s degree with Bishop. He studied the impact of pocket gophers on plants and soil in the main blast zone. After volunteering with the Mount St. Helens Institute, an educational center founded in 1996, he got a job there in 2011 and became executive director in 2014. Dedicated to helping people understand and protect the volcano, the institute develops educational programs that make research discoveries accessible to the public.

“That’s the tool to get people excited about science, the outdoors and public lands,” Yurkewycz said. “Mount St. Helens is bigger than just the volcano. It inspires people to go on to do big things.”

A network of connections

To Bishop, Mount St. Helens has been an ideal laboratory to study one of the fundamental topics of environmental biology—the tenaciousness of life, how it comes back from total devastation. His interests initially focused on “primary succession,” or what comes first and prepares the way. Every summer for the past 30 years, Bishop and his students have camped on the mountain for months at a time, observing patterns of vegetation and recovery.

The first plant to emerge was the purple-flowered lupin, its seeds likely ferried in by wind. Lupins, like all organisms, need nitrogen and phosphorous to survive and, like all legumes, they get nitrogen from the air with the assistance of symbiotic bacteria. They get phosphorous from the new volcanic rock, and Bishop’s work showed that they produce special acid-exuding roots to accomplish this. As each lupin flourished and died and provided more organic matter for the soil, the plants spread. In turn, they attracted herbivores, such as caterpillars. Other predators soon followed.

“When re-forming, the community depends on all the colonists coming from outside, not all will come at once,” Bishop said. “If one plant can survive to reproduce, it can establish a patch that can spread unhindered, until it is found by the insects that feed on it. If their predators haven’t arrived yet, the insect population can grow until it consumes all of its host. Over time the predators and competitors arrive, build up and stabilize the interaction.”

The first woody plants on the Pumice Plain were willows. An invasive insect, the willow weevil borer, quickly arrived and threatened the spread of willows. “Its occurrence at Mount St. Helens alters the dynamics of succession because it kills willows and alters the structure of plant communities,” said Mailea Miller-Pierce, who earned her Ph.D. at WSU Vancouver and now is a post-doc with Bishop.

When the lab experimentally protects willows from the weevil, willows form thickets that dominate other vegetation, but without that protection they do not remain dominant, allowing other species to establish themselves. Already, alders have been taking over some of the wetter areas where willows were growing. The researchers have also seen mosses, wildflowers, grasses, huckleberries, conifers, even maples begin to colonize the Pumice Plain.

In some places there have been very few changes, Miller- Pierce said, but elsewhere, changes can seem quite dramatic. “The plant communities have changed a lot,” she said. “In just four years, I saw plants that were as tall as my knee grow to above my head. The nutrients in the soil have really increased in some areas, causing the plants to grow taller and larger. This allows a greater diversity and richness of birds and insects to establish and be supported by the plant communities.”

“Things are changing out there,” Bishop said. “The harsh environment created by the eruption is being ameliorated, soils are starting to form, and plants that rely on that are colonizing.”

The first conifers to emerge were Douglas and Noble firs. More recently, western hemlocks have appeared—most likely a sign that soils are becoming more fertile.

“Another big change in the last five years is that a lot of those Doug and Noble firs are starting to produce cones,” Bishop said, “so now you have local sources of seeds. We think that’ll accelerate the colonization of these trees.” These seeds wouldn’t establish in a competitive environment—they need bare ground. But there is still a lot of room for them on the Pumice Plain.

Long-term implications

Changes in soil composition are both a result of evolutionary change and an agent of future change. Most every experiment Bishop’s team has conducted with plants and insects examines the changes in the soil to which growth is responding. In particular, they have been looking at phosphorous, nitrogen and carbon, which are essential for life but, in excess, also can be harmful. Excesses often result from human factors such as fossil fuels and agricultural fertilizers, which turn potentially beneficial nutrients into pollutants that damage the environment. For example, nitrous oxide caused by burning of fossil fuels is believed to play a significant role in climate change. The research may have implications for controlling those pollutants as well.

Microbes, particularly underground fungi, are key to soil remediation. They decompose organic matter that reaches the soil and convert it to forms that plants can use. “Most plants have a mutually beneficial association with fungi,” Bishop said. “The fungus helps the plant get nutrients from the soil, and the plant provides the fungus with carbon.”

Becca Evans, a Ph.D. student working with Bishop, is currently looking at microbial communities and how carbon and nitrogen rely on microbes to accumulate in the soil. Soil stores carbon, and Evans’s research is examining how soil may be used to increase carbon storage. “Studies show volcanic soils store a lot of carbon, but we don’t really know why,” she said.

It’s an important question. “With climate change, you hear how carbon dioxide is polluting our atmosphere,” Evans said. “One of the best things we can do is get carbon stored somewhere, and I’m trying to find out how carbon gets stored in the soil, and what humans are doing that affects or alters that, such as invasive species or pollutants.” As the Mount St. Helens ecosystem comes back from catastrophe, it provides a natural laboratory to study the question.

“This gives us a chance to look at how you go from nothing to eventually a system that can support plants and more,” she said. “We can also ask about invasive species and nitrogen pollution, and how to understand what effect those have. In the long run, policy might be able to change those things. But for now we are just looking at the science.”

Ongoing stewardship

“Mount St. Helens is a dynamic place where students can engage in the outdoors and science in a meaningful way,” said Tom Wolverton, past president and current board member at the Mount St. Helens Institute. He worked in Bishop’s lab under the Murdock Charitable Trust’s program to offer research experiences to high school students. Now a science teacher at Vancouver's iTech Preparatory School, he played an important role at the Institute as a long-time board member and was instrumental in getting the high school outdoor school experience off the ground.

Wolverton grew up in La Center, Wash., and watched the volcano erupt from his backyard. “It is powerful to me as an educator to have a say in the educational programs on Mount St. Helens,” he said.

Many agencies and individuals serve as stewards of Mount St. Helens, ranging from ecological scientists like Bishop to the staff at the U.S. Geological Survey and the Forest Service, staff and volunteers at the Institute, state agencies, funders, members of the Cowlitz Indian tribe and others. The Natural Register of Historic Places recognizes Mount St. Helens as a Traditional Cultural Property of the Cowlitz Indian Tribe and the Confederated Tribes and Bands of the Yakama Nation.

Now, 40 years after the eruption, the first generation of scientists to study the mountain has mostly retired, and the second generation is approaching retirement.

“It’s an interesting time in the history of Mount St. Helens,” Yurkewycz said. “How does this place stay relevant? There are so many more stories to be discovered or told, and it’s such a unique landscape, it’s important to keep that scientific discovery going and bringing in new generations of researchers to do that.”

Natural change is gradual, yet often driven by striking shifts in what Bishop calls “boom and bust dynamics.” That is, the network of connections among species is still weak, and the system is unstable and unpredictable. The forest that covered Mount St. Helens before the eruption won’t come back for generations, if then. Or maybe nothing much will happen until a larger network of interdependent connections builds up to support birds and wildlife. Nevertheless, watching it unfold is wondrous.

Yurkewycz hopes people see Mount St. Helens as “more than a piece of history.” He hopes it will always be “something that means something to people right now and will continue to in the future. It has erupted so many times, and it’s going to do it again.” ■

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