1. Ecological Succession

2. Ecological Succession
Ecosystems are constantly changing due to natural and human disturbances
Examples:
Natural disturbances
Forest fires
Human disturbances
Clearing a forest for agriculture

3. Ecological Succession
Succession- orderly, natural changes and species replacements that occur in an ecosystem
Basically, older organisms die out and new organisms move in, causing further changes in the community

4. Steps in Succession Grass gets taller and weeds start to grow
area looks like a meadow

5. Steps in Succession 2. Bushes grow, trees appear
Different animals enter the area to live

6. Steps in Succession 3. Less light now reaches the ground
Grass slowly disappears

7. Steps in Succession
4. 30 years later, area will resemble a forest

8. Succession
At each stage, different species of plants and animals may be present
Conditions at each stage are suitable for some, but not others

9. 2 types of Succession Primary and Secondary
Primary Succession- takes place on land where there are no living organisms
Ex: when lava from a volcano cools and forms new land

10. Primary Succession Pioneer species- first organisms to occupy new land
Ex: lichens
Decaying lichens and other pioneer species combine with bits of rock to make soil

11. Lichen on Rock

12. Primary Succession
Seeds move into small patches of soil and begin to grow

13. Primary Succession
Primary succession slows down and community becomes stable
Climax community- a stable, mature community that undergoes little or no species change

14. Secondary Succession
Secondary Succession – occurs when community is destroyed or altered but soil is still there
Ex – fire, clear cutting
Regrows to mature, stable community called climax community
May take less time than primary succession

15. Forest Fire Regrowth