Ecological succession is the gradual replacement of one community by another over time. Primary succession occurs when a community is wiped out, such as after a volcanic eruption, and pioneer species are the first to colonize an otherwise lifeless area. Secondary succession occurs when an existing community is replaced, such as after a forest fire, and the pioneer community establishes a new ecosystem that eventually matures into a climax community.

1. How Ecosystems Change
Chapter 6, Lesson 6
ecological succession
primary succession
secondary succession
pioneer species
pioneer community
climax community

2. ecological succession – the
gradual replacement of one
community by another

3. primary succession – the gradual
build up of a community that was
wiped out

4. secondary succession – the
gradual replacement of one
community by another, but there
is already some
ecosystem/community there

5. secondary succession – the
gradual replacement of one
community by another
secondary succession – the
gradual replacement of one
community by another, but
there is already some
ecosystem/community there

6. ecological succession – the
gradual replacement of one
community by another

7. pioneer species – the first
species to grow in an otherwise
lifeless area

8. pioneer community – when the
first animals in a community
arrive as a result of a pioneer
species. A new ecosystem
forms.

9. pioneer community – when the
first animals in a community
arrive as a result of a pioneer
species. A new ecosystem
forms.

10. climax community – an established
community. Few new organisms arrive,
few leave. Things are relatively safe and
balanced, until another major disaster
arises.