1. Changes in Ecosystems: Ecological Succession
Bozeman Science – ecological succession

2. Definition: Sequence of changes that: Regenerates a damaged community
Creates a community in a previously uninhabited area.

3. Primary Succession
Ecosystem is established in an area that was previously uninhabited.
1. Bare rock is exposed.
2. Pioneer species (first organisms in an area) such as lichen and moss blow in, break down rock to form soil.

4. Lichen
Symbiotic relationship between fungi and algae ( or cyanobacteria)
Algae photosynthesize and provide food for the fungi.
Fungi provide protection and CO2 for the algae.

5. Soil Formation
Weathering of the rock also forms soil. (wind, freezing and thawing of water in cracks, erosion.)

6. Primary Succession
3. Seeds blow in, small flowers, shrubs grow.

8. Primary Succession
4. Simple plants die, soil thickens. Small trees grow, provide shade for new tree species to grow.

10. Secondary Succession A damaged ecosystem is reestablished.
Cause of damage includes floods, fires, and landslides.

11. Mt. St. Helens Example of Secondary Succession Pre-Eruption of 1980
Weeks after Eruption
2012

12. Climax Community
Final stage of ecological succession in which a relatively constant environment is reached.
Generally consists of large trees.