Name Date Class 1 Enrichment Growing from the Ashes

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1 Enrichment Growing from the Ashes

At 8:32 A.M. on May 18, 1980, Mount St. Helens, a volcano in the state of Washington, erupted. First an earthquake collapsed the north side of the mountain, creating a landslide that filled 60 square km of a nearby river valley to a depth of 46 m. The landslide released a blast of superheated gas and rock that traveled from 354 to 1078 km per hour past the landslide. Trees were knocked down for 24 km. The top 396 m of the mountain was blown away. A river of foaming gas and rock as hot as 704?C flowed out of the crater. It destroyed everything in its path as it spread over a fan-shaped area 8 km long. Melted ice, boulders, and soil ran down the sides of the mountain.

National Volcanic Monument

In 1982, Congress set aside 445 km2 of the area as the Mount St. Helens National Volcanic Monument to provide a giant laboratory for scientists to study how nature recovers without human interference. The lessons learned by these scientists have prompted them to reconsider long-held ideas about how nature renews itself.

In the past, it was thought that a large-scale disturbance, such as the blast of a volcano, destroyed all life in the area. Scientists believed that forests recovered after natural disasters when organisms came in from outside the damaged area. Recovery, they thought, took place as various species of plants returned to the area.

Research at the Mount St. Helens National Volcanic Monument has shown that it doesn't have to happen that way.

For example, soon after the explosion, one scientist discovered fungi still living under the ash. Trees such as the Pacific silver fir that were buried in snowdrifts or sheltered by slopes during the blast survived. Seeds of plants, such as the prairie lupine, also survived. Scientists now know that although species that come into the area are important to regeneration, those that are left behind are more important.

A New Beginning

Plants like the prairie lupine, along with the trunks and stems of fallen trees, were the starting points of the next ecosystem. The roots of the lupine contain bacteria that pull nitrogen out of the air, so they could grow in the ash instead of in dirt. And since lupines have tight roots that allow the plants to take over an area, by the time a plant died, its roots had gathered enough bodies of insects and bits of dirt to make humus for other plants to grow in. Dead trees provided perches for incoming birds. The birds' droppings contained seeds. The seeds fell in the shadow of the trees, which protected the seedlings from wind. Water dripped from the trunks into the soil. Peeling bark provided nutrients for plants. The forest began anew.

Twenty years after the explosions, scientists are studying how lessons learned at Mount St. Helens can be used to "jump start" areas disturbed by floods, fires, landslides or other natural disasters, or human activities such as mining and waste disposal.

1. What abiotic factors affected the recovery of the forest at Mt. St. Helens? What were the biotic factors?

2. What role could fungi have played in the mountain's recovery?

3. Were the prairie lupines a population or a community? What role did they play in the forest's recovery?

4. According to the selection, scientists are studying the lessons they learned at Mount St. Helens to "jump start" other areas that have been disturbed. How could these lessons help them do this?

Copyright ? Glencoe/McGraw-Hill, a division of the McGraw-Hill Companies, Inc.

30 Interactions of Living Things

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