Ecological Succession

1. Ecological Succession A series of predictable changes that occurs in a community over time.

2. Change • Ecosystems are constantly changing in response to natural and human disturbances • Can you think of any examples?

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

4. Primary Succession • On land, succession that occurs on surfaces where no soil exists is called primary succession Example: Volcanic eruptions Glaciers receding First species to populate the area = Pioneer species

5. Primary Succession THE STEPS IN PRIMARY SUCCESSION: • Lichen (algae and fungi) are the first to grow on the volcanic rocks • They help break up the volcanic rocks • When the lichen die, they add organic matter to help form soil • Plants start to grow on the soil

6. Pioneer species– first species/organisms to inhabit an area (usually small – example weeds) • Climax community – stable, mature community that undergoes little or no succession • Biome – large group of ecosystems with the same climax community (determined by climate)

7. Bare rock → lichen → soil with small plants (weeds, mosses, grass) → larger plants (shrubs) → trees

8. Secondary succession • changes that occur when a community is disrupted by natural disaster or humans. • Leads to new climax community. • Starts from soil → small plants → large plants • Examples – fire, flood, hurricane, abandoned farm

9. Secondary Succession

10. Aquatic ecosystems– will “fill in” with dirt over time to create a land ecosystem – if no manmade intervention primary succession.