1. Ecological Succession-
Natural, gradual changes in the
types of species that live in an
ecosystem.
Equilibrium-
The sense of balance present in living and non-living systems.

2. Primary Succession
Establishment of a community of living
organisms in an area where there was no life.
Example: volcanic eruption
Pioneer species: lichens
Secondary Succession
Establishment of new species after a disturbance.
Example: fire, hurricane, logging, agriculture
Pioneer species: grasses

3. Primary vs. Secondary Succession
Year
Volcano
Forest Fire 1 4 8 12 17 20

4. All Mt. St. Helens images courtesy of University of Washington
Year Zero
Volcano
Forest Fire
All forest fire images
Courtesy of US Forest Service
Rocky Mountain Research Station
All Mt. St. Helens images courtesy
of University of Washington

5. Year One
Volcano
Forest Fire

6. Year Four
Volcano
Forest Fire

7. Year Eight
Volcano
Forest Fire

8. Year Twelve
Volcano
Forest Fire

9. Year Seventeen
Volcano
Forest Fire

10. Year Twenty
Volcano
Forest Fire

11. Secondary Succession

12. Primary Succession

13. What is the difference between Primary and Secondary Succession?