Name Current Event Ecology



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Name_______________ Current Event – Ecology
Mount St. Helens–


Today, many areas around the volcano still have

a desert-like appearance, but the vast majority of

plant and animal species that were found at Mount

St. Helens before the 1980 eruption have returned.

Some, like the Roosevelt elk, have returned in

numbers that far exceed pre-1980 populations.

In the blast zone, the establishment of plants was

slow for the first few years following the eruption.

Three years after the eruption, the average plant

coverage on research plots was only 1 percent.

Fourteen years after the eruption, plant coverage

on those plots was up to 38 percent. Twenty

years after the eruption, plant coverage was

approximately 66 percent.

Wind played a key role in initiating early-succession

processes by blowing in spiders, insects, and seeds

from nearby undisturbed areas. One plant found

early on is the pearly everlasting. This plant has

lightweight seeds that were easily carried by wind.

Prairie lupine, a purple-blue wildflower, was also

one of the first plants to grow on the barren land.

Charlie Crisafulli, a research ecologist, arrived at

Mount St. Helens when he was 22 years old. He

and another ecologist were the first to spot a lone

lupine plant.

Lupines do not usually colonize the middle of an

empty landscape. The deep volcanic ash where he

found the lupine held few nutrients. But lupines,

like other plants in the pea family, are able to

“fix” nitrogen, thus enriching the soil. Each lupine

plant created a microhabitat that was hospitable

to several other plant species. Besides enriching

the soil with nitrogen, the lupines also physically

trapped windblown debris and attracted insects.

As the insects died on or around the plant, they

enriched the soil with organic matter.

Within a few years, the lupine patches became

biological hotspots facilitating the growth of other

plant species and attracting numerous insects,

birds, and small mammals. The flourishing of life on the Pumice Plain of Mount St. Helens today may

have begun with that lone lupine. Crisafulli said that

it was the lupine wildflowers that taught him one

of the key lessons of succession: the importance of

chance.


For the next 30 years, Crisafulli observed the

development of ecological relationships across

the volcanic landscape. He saw that a log carried

downstream in a mudflow may transport nutrients,

microbes, fungi, and even small animals to an area

devoid of organisms. He also observed that whole



A Story of Succession

On May 18, 1980, the Mount St. Helens volcano

in Washington State exploded violently after

two months of intense earthquake activity and

intermittent weak eruptions, causing the worst

volcanic disaster in the recorded history of the

United States. This cataclysmic eruption and related

events rank among the most significant geologic

events in the United States during the 20th century.

During the eruption, a 300-mile-an-hour lateral blast

of hot air and debris flattened the surrounding old growth

forest. A cloud of ash climbed to 80,000

feet in 15 minutes and circled the globe in 15 days.

All told, the eruption blasted more than 230 square

miles of forests, lakes, meadows, and streams.

Virginia Dale was in the first helicopter-load of

ecologists to land at Mount St. Helens after it

erupted. “I just remember how bizarre it was going

out into that landscape,” she says of the suddenly

gray, ash-covered terrain. “It gave the impression

of total lifelessness.” Dale studies ecological

succession or how an environment recovers after

a major disturbance. She jokingly calls herself a

“disturbed ecologist.” When it comes to studying

devastation, she says, “Mount St. Helens was off

the scale.”

Although areas in the blast zone around Mount St.

Helens appeared barren and lifeless after the 1980

eruption, some plants and animals did survive.

Pocket gophers in underground burrows, fish in

ice covered lakes, and salamanders hibernating in

mud were protected from the hot, stone-filled wind

of the blast. Plants such as willow, vine maple,

and black cottonwood were able to re-sprout from

roots protected in moist soil. Those plants are

called survivors, and they were very important to

the re-initiation of plants on the barren landscape.

Some snow-protected Pacific silver fir and mountain

hemlock trees also survived. They served as

important sources of seed for establishing the future

forest inside the blast zone at Mount St. Helens.

Despite surviving the eruption, many of those

plants and animals were unable to live in the harsh

new environment. But some were able to tolerate

the extreme conditions and helped to pave the

way for new colonizers. Winds brought light seeds

and insects to the area, enabling them to enter the

area and become established. Plants and insects

attracted birds, deer, and elk from nearby areas.

Heavier seeds “hitchhiked” on the feathers of birds

and in elk droppings. Ponds and springs created by

the eruption became the centers of life for survivors

and colonizers.

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