1. Changes in Ecosystems: Ecological Succession

2. What is Ecological Succession?
Natural, gradual changes in the types of species that live in an area
Can be primary or secondary
The gradual replacement of one plant community by another through natural processes over time

3. Primary Succession 1st STEP: Begins in a place without any soil:
Sides of volcanoes
Landslides
Flooding
2nd STEP: Lichens that do not need soil to survive grow on rocks. Mosses grow to hold newly made soil
Known as PIONEER SPECIES

4. What are Pioneer species?
Pioneer species are a group of organisms, such as lichens, found in the primary stage of succession and that begin an area's soil-building process.
MOSS
FIREWEED
LICHENS

5. Pioneer Species
Low, growing moss plants trap moisture and prevent soil erosion
Lichens break down rock to form soil.

6. Primary Succession
Soil starts to form as lichens and the forces of weather and erosion help break down rocks into smaller pieces
When lichens die, they decompose, adding small amounts of organic matter to the rock to make soil

8. Primary Succession
3rd STEP: Simple plants like mosses and ferns can grow in the new soil

9. Primary Succession
The simple plants die, adding more organic material (nutrients to the soil)
The soil layer thickens, and grasses, wildflowers, and other plants begin to take over

10. Primary Succession
These plants die, and they add more nutrients to the soil
4th STEP: Shrubs and trees can survive now

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

12. Stages of Primary Succession1 2 3 4

13. Secondary Succession
STEP 1: Begins in a place that already has soil and was once the home of living organisms
STEPS 2-4: Occurs faster and has different pioneer species than primary succession
Example: after forest fires

14. Secondary Succession

15. Secondary Succession

16. Stages of Secondary Succession1 2 3 4

17. 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

18. Climax Community

19. What are Keystone Species?
Keystone species are a single species that is not usually numerous in a community but exerts strong control on the structure of the community.
If the population of a keystone species declines it can have dramatic changes on the other species in the community.

20. Keystone Species
Hunting of sea otters caused the kelp forest to nearly vanish.
WHY?

21. Keystone Species
Killing of prairie dogs by farmers caused the black-footed ferret to become nearly extinct.
WHY?

22. Keystone Species

23. ANY QUESTIONS?

24. Succession Flow Chart ISN p. ? Divide your page into 8 boxes
Make a flow chart to show the stages of:
Primary Succession vs.
Secondary Succession
Include a description and a picture for each

25. Succession Flow Chart PRIMARY SUCCESSION Step 1: SECONDARY SUCCESSION