The ecosystems of Mount St. Helens



by LORENZO CIOTTI

The ecosystems of Mount St. Helens
© Handout / Handout Getty Images

Mount St. Helens became famous for its eruption on May 18, 1980, the deadliest and most destructive volcanic event in U.S. history. 57 people lost their lives, while 47 bridges, 200 homes, 24 km of railways and 298 of motorways were destroyed.

The 1980 eruption marked a serious crisis for terrestrial ecosystems, while, on the contrary, aquatic ones benefited considerably from the quantities of ash, as it allowed underwater species to reproduce more quickly. Six years after the eruption, most lakes in the area have returned to their normal state.

Mount St. Helens© Craig Mitchelldyer / Stringer Getty Images

After its eruption in 1980, the volcano recorded more or less continuous volcanic activity until 2008.

Geologists predict that future eruptions will prove more destructive, since the conformation of the lava domes will require more pressure for the eruption to occur 'eruption. The current configuration of the lava domes in the crater indicates that much more pressure will be needed for the next eruption, which is why the level of destruction will be higher.

A significant ash fall could spread across an area of 100,000 km², posing among other things serious risks for air traffic. A large flow of lahars would likely wash over the banks of the Toutle River, causing destruction in populated areas along I-5.

The ecosystems of Mount St. Helens

The slopes of Mount St. Helens provide habitat for living things typical of the Western Cascades ecoregion. This area experiences abundant rainfall, with an annual average of 2,373 mm in Spirit Lake.

Thanks to high rainfall, dense forests up to 1,600 m thrive, including western hemlock, Douglas fir and western red cedar. Above this range, sweet fir stands out up to 1,300 m. Finally, below the tree line, the forest consists of Mertensian hemlock, sweet fir, and Nootka cypress.

The tree line is at a fairly low altitude on site, approximately 1,340 m. Such an anomaly is due to the frequency of eruptions, as it is believed that the limit can be traced to areas located at a higher altitude during periods of quiescence.

Snow goats inhabited higher elevations than the peak, although large numbers of them perished after 1980.[58] Among the large mammals found in the area include the Roosevelt wapiti, the black-tailed deer, the American black bear and the puma.