2000: Blast zone a study in creation, renewal

By studying Mount St. Helens for 20 years, scientists have gained valuable insights into the mysteries of life

May 12, 2010 

Life returned to Mount St. Helens even before the search for the dead had ended.

National Guard rescue crews looking for human casualties during the week after the 1980 eruption found that flies and yellow jackets had arrived before them. Curious deer and elk trotted into the blast zone just days after the dust settled.

Helicopter pilots who landed inside the crater that first summer reported being dive-bombed by hummingbirds, which mistook their neon-orange jumpsuits for something to eat.

In the 20 years that have passed since then, the return of life to the Mount St. Helens blast zone has been watched with fascination by biologists, entomologists, zoologists, mycologists and ecologists.

By observing the natural recovery of the land cleared by the volcanic blast, scientists have been able to add a number of conceptual blocks to the complex puzzle of life.

They've gained useful insights that are applicable to environmental catastrophes caused by humans - things such as strip mines, oil spills and polluted industrial sites.

And, more broadly, they've learned to regard the entire phenomenon of exploding volcanoes differently. Volcanic eruptions are no longer viewed in scientific circles as "disasters," but as a natural part of the Earth's cycle, as regular as the changing seasons.

"Volcanoes do not destroy; they create," said Peter Frenzen, the chief scientist at Mount St. Helens National Volcanic Monument.

By blocking rivers, volcanic mudflows create new wetlands, Frenzen notes. The ash and pumice volcanoes spew out produces well-drained, productive soils. Airborne ash contributes to the global carbon cycle.

Use the word "devastation" to describe what happened at Mount St. Helens in 1980, and chances are Frenzen will correct you. He prefers to call what happened "a dramatic alteration of the landscape" or "a disturbance."

Frenzen and other scientists who have studied Mount St. Helens regard the blast zone not as a gradually healing wound on the surface of the Earth but as a natural phase.

The Earth is not seeking equilibrium at Mount St. Helens, they say, but simply undergoing a different stage in a geographical region that is in constant flux.

"Disturbance is a way of life for plants and animals living in the Cascade Range," Frenzen said.

As the landscape around Mount St. Helens changed over the past two decades, dynasties of species rose and faded, like a cast of characters flitting across a stage.

Even at the volcano's most extreme, Frenzen says, with ground temperatures at hundreds of degrees Fahrenheit, microscopic organisms that had been dormant burst into life. For them, the conditions were ideal.

Freed from predators and competition, some organisms exploded into weird, unbalanced communities for a time. They then either leveled off at much reduced numbers or disappeared entirely.

A geophysicist doing research near the volcano a year after the eruption recalls hiking over the top of a ridge and seeing an entire hillside move.

Looking closer, he realized the movement was not the soil but thousands of toads, squatting foot-to-foot on the ash. They had survived the blast in an embryonic state, under the cover of ice in a nearby lake. There were so many of them that when they hopped, the whole landscape fibrillated.

Other lakes spawned other unusual dynasties, according to Charles Crisafulli, a research ecologist who has been working at Mount St. Helens since shortly after the eruption. In some, he said, there were legions of rough-skinned newts; in others, hordes of Pacific tree frogs or brown salamanders.

Crisafulli explains that the return of life to Mount St. Helens was a collaboration, rehearsed over millions of years, between "colonizers," the plants and animals that returned to the blast zone after the eruption, and "survivors," those species that never left.

Immediately after the eruption in 1980, scientists discovered far more survivors near the mountain than they expected. Fireweed, thistles and blackberry vines shot up through as much as eight inches of ash. In places, young trees that had been bent over and buried in snow escaped unharmed.

Pocket gophers had survived in their underground burrows, as had at least 13 other species of small mammals, including deer mice, wandering shrews, voles and weasels.

The survivors were joined by a determined march of colonizers that began almost immediately.

Overhead, the air was filled with a constant rain of insects, spores, seeds and eggs that came drifting in from surrounding forests. Shortly after the eruption, entomologists identified 75 species of spiders on the inhospitable plain of pumice directly in front of the crater. All of them had drifted in from miles away, hang-gliding on long filaments of web.

Interrelationships between plants and animals - elaborate linkages that usually are far more difficult to see - were more obvious in the volcano's simplified surroundings. Scientists working in the blast zone found it was more apparent how each act affected others: windblown seeds collected in the footprints of elk, melting snow washed away the ash and exposed fertile soil, fallen trees slowed erosion.

What emerged from the studies was a vision of the planet as a intricately balanced mechanism, Frenzen said - balanced not season by season, rainstorm to rainstorm, but on a geological scale that stretches back millions of years.

Viewed from the perspective of geologic time, that makes good sense. But day-to-day in the national monument, it's sometimes hard to maintain the dispassionate scientific view - even for Frenzen.

Hiking on a trail in the blast zone last fall, Frenzen and a group of visitors came upon the remains of two dead elk, gristle and tufts of hair still stuck to their bones.

Frenzen took the opportunity presented by the elk carcasses to make a point about natural balance. There are currently more elk in the monument than there is food, he said. In the winter of 1998-99, as many as 200 elk starved to death inside the monument.

Left alone, the elk population eventually will reach equilibrium, Frenzen said. But most people in the group recoiled at the sight of the elk, seeing them not as evidence of the wonder of the natural order, but as two pitiful dead creatures.

Even Frenzen is not immune to such feelings. "It was pretty sad to see elk out here last winter," he said. "They couldn't even get up, they were so weak."

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* Reach staff writer Rob Carson at 253-597-8693 or rob.carson@mail.tribnet.com.

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SIDEBAR: Amazing numbers

The eruption

11,000

Number of rabbits killed in the eruption

11,000,000

Number of fish killed

880

Height in feet of new dome inside crater

1

Minimum warning time in hours geologists expect before an eruption

25,000

Volcano-related deaths worldwide during the 1980s

50,000

Number of years Mount St. Helens has been erupting

60

Average number of earthquakes detected under Mount St. Helens per month

1.8

Distance in miles across the volcanic crater from north to south

123

Number of years between last two eruptions of St. Helens

0.00000024

Tilt of ground surface detectable by new measurement devices in inches

50

Age geologist David Johnston would have been this year

1,000

Weight in pounds of insects that land on the blast zone each year

Originally published on May 15, 2000.

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