1. Succession

2. Responses to disturbance
1. A community may resist change & remain stable (resistant)
2. A community may change in response to the disturbance but later return to its original state (resilience)
3. A community may be modified from the disturbance and never return to its original state

3. Natural Disturbances Man-Induced Mortality Tree-fall Wildfire Volcano
Flooding
Hurricanes/tornadoes
Insect/disease
Tsunami
Landslides
Glaciers
Sea-level rise or retreat
Logging
Plowing
Mining
Dam Removal
Fire/Flooding
Nuclear blast/warfare

4. What happens when a disturbance is severe enough it eliminates all or most of the species in a community?

5. Ecological Succession
It will undergo a somewhat predictable series of changes called succession

6. Primary Succession
Follows a disturbance so severe that no vegetation or soil life remains from the community that once occupied the site
The biotic community has to rebuild from scratch
Can be caused by…
Sides of volcanoes
Landslides
Glacier retreats
Lakes dries up

7. Pioneer Species: Lichen

8. Pioneer Species
Pioneer species have spores and seeds that can travel long distances
Lichens: secrete acids that break down rock, forming soil
Once soil is in place, small plants, insects & worms have suitable habitats

9. Primary succession
Species diversity increases as time passes

10. Secondary Succession
Begins when a disturbance dramatically alters an existing community but does not destroy all living things or all organic matter in the soil.
Parts of the community remain, and become building blocks
Examples:
Abandoned farmlands
Burned (fire) or cut forests (logging)
Hurricane
Flooding
Heavily polluted streams

11. Secondary Succession
Recovers faster and has different pioneer species than primary succession (no need for lichen)

12. Succession in an Aquatic Biome
Aquatic: transition from pond or lake to terrestrial community (bog or a forest)

13. Climax community
Will remain in place with little modification until some disturbance restarts succession

14. Intermediate disturbance hypothesis:
Communities that experience fairly frequent, moderate disturbances have the greatest diversity of species
Removes organisms
Reduces populations
Creates opportunities for other species to colonize

15. some communities never return to climax state- too disturbed by human impact

16. Restoration Ecology
Restoration Ecology= restoring damaged areas to their pristine environment (what they once looked like)
Difficult
Time consuming
Expensive
Doesn’t always work
*Best to protect natural systems from human degradation

17. Florida Everglades

18. Chesapeake Bay
Too much N, P, and sediment. Restoration of wetlands, oyster reefs, reopening fish passages