1. Ecological Succession Notes

2. Ecological Succession
Ecosystems are constantly changing in response to natural and human disturbances.

3. As an ecosystem changes, older inhabitants gradually die out and new organisms move in, causing further changes in the community.

4. Definitions
Ecological Succession – a series of predictable changes that occur in a community over time.
Includes - slow changes in the physical environment or sudden natural disturbances from human activities like clearing forests.

5. Primary Succession – On land, succession that occurs on surfaces where no soil exists.

6. Colonization of new sites by communities of organisms – takes place on bare rock
Pioneer species – the first species to inhabit an area.
Ex. Lichens are the first to colonize lava rocks

7. Primary Succession – Ex. #1
When volcanic eruptions build new islands or cover land with lava rock or volcanic ash.

8. Primary Succession – Ex #2
When bare rock is exposed as glaciers melt.

9. PRIMARY SUCCESSION

10. Secondary Succession – when a disturbance of some kind changes an existing community without removing the soil – takes place on existing soil.

11. Secondary Succession – Ex. #1
When land cleared and plowed for farming is abandoned.

12. Secondary Succession – Ex. #2
When wildfires burn woodlands.

13. SECONDARY SUCCESSION

14. Climax Community –a mature, stable community that undergoes little or no succession.

15. Succession Clip and Mt. Saint Helens
You tube clip: