1. Ecological Succession

2. The Standards
SEV3. Students will describe stability and change in ecosystems.
b. Explain succession in terms of changes in communities through time to include changes in biomass, diversity, and complexity.
c. Explain how succession may be altered by traumatic events.

3. Ecosystems change Ecological Succession
A 100 year old forest was once a lake
A tree falls and opens up space for new life
Mosses, grasses, and small shrubs grow in an abandoned parking lot.

4. What is ecological succession?
Gradual process of change and replacement of some or all of the species in a community.
May take hundreds or thousands of years
Each new community makes it harder for the previous community to survive.

5. 2 types
Primary succession – occurs where no ecosystem previously existed (rocks or sand dunes)
Secondary succession – occurs after a disturbance where an ecosystem did previously exist. (more common)

6. Secondary Succession
Begins after a disturbance like fire, volcano, storms, or human activity
Pioneer species are the first species to colonize an area.
Each new species makes it easier for the next species to thrive.
A climax community is a stable community with little change

7. Mount St. Helens
Right after the eruption in See figure 17 on p. 138.
12 years into secondary succession. See figure 18 on p. 139.
What has changed? What has stayed the same?

8. Fire and secondary succession
Important natural cause
Jack pine only germinates after fire
Minor fires can burn out brush and deadwood, preventing major fires.
Some animals eat plants that appear after a fire.
Foresters let minor fires burn when they don’t threaten human life or property.

9. Old field Succession Abandoned farmland Pioneer grasses and weeds
Taller grasses
Fast growing pine trees
Slow growing oak, hickory, beech, and maple

10. Primary Succession
Occurs on new volcanic islands, rock exposed by retreating glacier, or any other surface with no ecosystem.
Slower than secondary succession
Hundreds to thousands of years to create fertile soil.

11. Order of succession Bacteria and lichens Mosses Grasses Shrubs
Pine trees
Hardwood trees

12. Other primary succession
City streets
Rooftops
Parking lots