1. Changes in Ecosystems: Ecological Succession

2. Succession:
Gradual rebuilding of an ecosystem that has been drastically changed.
2 types of succession primary or secondary

3. Primary Succession Begins without soil just rock
After lava flow covers an area
After glaciers melt

4. Starts with PIONEER SPECIES such as lichen and moss that do not need soil to survive.

5. Primary Succession
Lichen and moss break down rocks into smaller pieces
When lichens die, they decompose, adding nutrients to the rock to make soil

7. Primary Succession
Simple plants like weeds and ferns can grow in the new soil

8. Primary Succession
The simple plants die, adding more nutrients to soil
The soil layer thickens, and grasses, wildflowers, and other plants begin to take over

9. Primary Succession
These plants die, and they add more nutrients to the soil
Shrubs and trees can survive now

10. Primary Succession
Insects, small birds, and mammals have begun to move in
What was once bare rock now supports a variety of life

11. Climax Community
A stable group of plants and animals that is the end result of the succession process
Does not always mean big trees
Grasses in prairies
Cacti in deserts

12. Timeline of Primary Succession
Rocks= 0 years
Lichen/Moss= 5 years
Simple Plants= 6-8 years
Grass & Shrubs= years
Young trees= years
Mature trees= 150 years
Climax community= 300 years

13. Secondary Succession Starts with soil
Occurs faster and has different pioneer species (simple plants) than primary succession
Example: after forest fires or abandoned farm