 |
by Tim Steury photography by Robert Hubner
“No biological legacy.”
The phrase John Bishop uses to describe the effect of Mount St.
Helens’s eruption on the main blast zone, the pumice plain, holds
an understated charm. By now, everyone has heard the story of Mount
St. Helens—how it blew on a Sunday morning in May 1980, after
rumbling for weeks, an earthquake triggering an enormous landslide,
hot gas and rock debris blasting across the landscape at 1,100
kilometers an hour, devastating 60 square kilometers and killing 60
people. But it is impossible to accept the immensity of the
mountain and the eruption’s legacy, unless you are able to stand
beneath the enormous crater on the pumice plain—and hear Bishop, an
ecologist at Washington State University at Vancouver, talk about
lupines.
No biological legacy. Trees, birds, elk, bacteria, spring
flowers, humans—all simply vaporized. A whole region was completely
sterilized.
But this devastation left a rare and perfect laboratory, a clean
slate on which to observe the fundamental process of “primary
succession,” the reestablishment of life where there was none.
Here on the pumice plain, on a perfect August morning 23 years
after the eruption, plumes of dust and ash blow off the volcano’s
rim, now 1,200 feet lower than it was before the eruption. The
students working for Bishop have scattered across the plain,
checking experiment sites. Grasshoppers clatter around us, and a
raven whoosh-whooshes overhead, toward Spirit Lake to the south.
Elk scat is everywhere. The occasional rumble of rockfalls in the
crater drifts across the plain. Life has returned to the pumice
plain, but the echoes of cataclysmic drama are very much with
us.
Imagine how startling it must have been, when in the midst of
this devastation, scientists discovered a lone lupine plant barely
a year after the eruption. How could it possibly have gotten there?
Lupines are not mobile, says Bishop. Birds, which serve as
distributors of many plants, don’t seem to care for lupine seeds.
And lupine seeds are hard and heavy, lacking the adaptations of
wind-borne seeds. Normally, lupines spread slowly. The seed heads
shatter, the seeds fall to the ground and sprout, and the lupines
march incrementally, albeit inexorably, across the landscape.
Bishop has observed voles gathering seeds. But no vole journeyed
across the barren pumice plain to plant a lupine.
So how else could that original seed have arrived, except by
wind? Lupinus lepidus var. lobbii is considerably
smaller than most lupines. It is adapted to hot, dry, alpine
conditions and grows mainly on the slopes of volcanoes. Its seeds
are small, and the wind blows fierce in these mountains. So the
seed could have—no, must have—arrived by wind. But the original
plant’s conception is still no less mysterious, for a very basic
reason.
Page
1
2
3
Continued
|
|
 The massive landslide that triggered the 1980 eruption swept into
Spirit Lake, raising its elevation by 60 meters. Trees mowed off by the
following lateral blast still cover the surface of the lake.
| |