1. Ecological Succession
TEACHER COPY
Amoeba Sisters

2. What is ecological succession?
A process in which the communities of an ecosystem change over time

3. Regrowth of plants after a disaster.

4. Primary Succession
Primary succession occurs in places where an ecosystem has never existed before.
Soil needs to be created from rock

5. Primary Succession Takes a long time to create the soil from rock
Examples:
Volcanic eruption
Glacial retreats

6. Glacial Retreat (when a glacier melts & recedes)

7. Volcanic Eruption

8. Pioneer Species – a hardy species which is the first to establish itself and start the process of succession by breaking down the rock & dying to create soil.
Mostly mosses & lichens

9. Lichens
Lichens are a symbiotic relationship between an algae and a fungus. The algae makes food for the fungus and the fungus give the algae a place to live.
What type of symbiosis is this?

10. What happens to the pioneers?
After some time, the pioneer species get pushed out once larger slower growing species take over.

12. How does succession end?
The climax community is the final stage of succession  consists of stable hardwood trees.
Examples in Pennsylvania are:
Oak-hickory
Beech
Hemlock
Maple

13. Secondary Succession
Secondary succession is the process that begins in an ecosystem when something has disturbed or destroyed the natural community
Secondary succession happens when soil already exists from previous ecosystem!!

14. Secondary Succession
Secondary succession moves at a faster pace than primary because soil is already established.
New plants begin to grow from the seeds and roots that are still present in the soil. The pioneer species are not necessary to create soil.

15. Causes of Secondary Succession
Natural communities can be wiped out by fires, tornadoes, hurricanes, and other catastrophic events.

16. Causes of Secondary Succession
Other Man-made causes are abandon farmlands, polluted streams, and land after heavy mining.

17. Check for Understanding
Which type of succession occurs after a volcanic eruption?
PRIMARY

18. Check for Understanding
Which type of succession occurs when soil is already established?
SECONDARY

19. Check for Understanding
What is the term for the species that first colonize bare rock?
PIONEER SPECIES

20. Check for Understanding
What is the term for the final stage of succession?
CLIMAX COMMUNITY

21. Check for Understanding
Which type of succession occurs at a faster rate? Explain why.
SECONDARY B/C SOIL IS ALREADY PRESENT.

22. Check for Understanding
Which type of succession occurs after a forest fire or tornado?
SECONDARY

23. Desertification
Desertification is the continuous dilapidation (destruction) of ecosystems in dry regions. Eventually, vegetation, water sources & animals become scarce (desert).

24. Desertification
Cause: Poor soil conservation leading to soil degradation
It is more common in dry climates where the soil is naturally thin

25. Desertification – its all about the soil!
Healthy, productive soil is rich with organic matter called humus.
Humus= soil that's rich in essential nutrients like carbon, nitrogen, phosphorous and sulfur (from decaying organisms)
When topsoil is depleted of humus, it could lead to destructive erosion.

26. Overuse of chemical fertilizers Failure to employ crop rotation
Unsustainable farming methods are a huge contributor to soil degradation!
Cutting down trees and shrubs
Overgrazing animals
Overuse of chemical fertilizers
Failure to employ crop rotation
Irresponsible irrigation practices rob the soil of its nutrients.

27. How to Prevent Desertification
Good farming practices include:
Crop rotation
Heavy composting
Responsible use of chemical fertilizers
These ensure that the soil has enough organic input to support micro- organisms.

28. Desertification Example
The Sahel Region of Africa is a prime example of how overgrazing led to desertification