1. Succession: Organisms Interacting with their Environment
Pre AP Biology

2. Succession:
Is the process by which one community of organisms replace another. This happens after the environment has been disturbed by some sort of change. (ex: volcano, fire, tornado, etc.)

3. Primary Succession:
Begins with bare rock or sand and involves first the building of soil.
Once organisms colonize an area, they change it so that other organisms may follow.

5. Example: after a volcano erupts, it may wipe out the climax community.
The first organisms to colonize the area may be mosses and lichens
These plants may produce acids as a waste product to break down rocks in the formation of soil.

6. Lichens
The beginnings of succession with lichens on a rock producing acid to help with soil formation.
Below, Lichen on a tree

7. Once soil formation is begun, ferns may come in and colonize the area
Once soil formation is begun, ferns may come in and colonize the area. Its rhizoids helping for form more soil, and as they die and decompose, the soil may become more rich suitable for different types of organisms. It is easy to see that organisms can change the environment thy interact with.

9. The following is an illustration of the primary succession found at the southern end of Lake Michigan. This Lake covered a much larger area of the southern part of the state than it does now. Moving south, one can see primary succession occurring.

10. Another example of succession is that found in a pond:
First the pond is barren
But then the aquatic plants die and sediments begin to fill in and begins to be ringed vegetation

11. The beginnings of pond succession. It is barren with little vegetation.
After 2 years. The pond is ringed by vegetation including cotton wood saplings

12. After 50 years, the pond is bordered by mature cottonwood trees.
After years, the pond has become a meadow the pond is ringed by vegetation.

13. Secondary Succession-
Secondary Succession on an abandoned railroad track
soil is present and occurs at a much more rapid rate. Can be the result of fire, tornados, floods and other like events. Examples abandoned crop lands, unused rail roads etc.