Image shows Mount Saint Helens before and after the eruption

Source: Mount Saint Helens Before and After, Renee, days with me Daughter

Ecosystems change over time. These changes can be caused by natural events or human caused events. The changes can be small or large scale. The accidental pollution of a small pond would be a small scale, human caused disturbance. On the other hand a volcano eruption would be a large scale, natural disturbance. Ecological Succession is a series of changes over time that occur in a community particularly after a disturbance.

On May 18, 1980, Mount Saint Helens, located in Washington, erupted. The images of Mount Saint Helens, pictured on the right, show how the mountain looked like before and after the eruption.

Video segment. Assistance may be required. Watch the following video to see how Mount Saint Helens looks like after many years of regrowth and succession.

Source: Mount St. Helens Ecosystem,, YouTube