Down wind from the volcano, the
ashfall coated trees and buried the small plants growing on the forest
floor.
Down wind from the volcano, the
ashfall coated trees and buried the small plants growing on the forest
floor.
Most plants were killed where the
ash was six or more inches deep (15 cm). Some buried plants were able to
grow stems or roots up through the ash. These plants survived the thick
ash deposits.
After rain washed the ash off the
leaves, the trees in the area grew rapidly.
The thick ash acted as a mulch. It
trapped water in the newly formed soil.
The ash also reduced competition
for nutrients. Only a few plants other than trees and shrubs
survived.
As the ash was washed off, some
plants thrived in the abundant sunlight, water, and nutrients provided by
the original soil.
Because beargrass grows on steep,
rocky surfaces, it was often sheltered from the ash.
Ashfall
Plants and Animals
Mount St. Helens
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