Ecological Succession

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