1. Succession and Change in Ecosystems
Topic 6
Science 7

2. Succession
The gradual process by which some species replace other species in an ecosystem

3. Primary Succession
The gradual growth of organisms in an area that was previously bare, such as rock.

4. Secondary Succession
The gradual growth of organisms in an area that previously had a number of organisms. (ex. Burned forest)

5. Changes are caused by human activity
Some species adapt better than others

6. Pest Control
Sometimes when a pesticide like DDT is used to kill one species it ends up killing beneficial organisms living in the same environment.

7. Biological Control Using a pest’s natural enemy to control pests
But BEWARE when introducing new species

8. Introduced Species
Species brought to an environment where they are not naturally found.
Zebra mussels were introduced by accident to the Great Lakes from ships. With no natural predators their population exploded and they took over the niche of naturally occurring species (plus they clog pipes!)

9. Species in Danger
Extinct: organisms that no longer exist anywhere in the world
Some causes:
Habitat loss
Introduced species
Pollution
Changes in climate

10. Extirpated
When a species no longer exists in a habitat it used to exist in.
caribou

11. Endangered
When a species is threatened with extinction