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.

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

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

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

Year One Volcano Forest Fire

Year Four Volcano Forest Fire

Year Eight Volcano Forest Fire

Year Twelve Volcano Forest Fire

Year Seventeen Volcano Forest Fire

Year Twenty Volcano Forest Fire

Secondary Succession

Primary Succession

What is the difference between Primary and Secondary Succession?