Dr. Ray L. Winstead
Professor of Biology, Indiana University of Pennsylvania

Ecological Succession


Ecological Succession is an orderly sequence of different communities over a period of time in a particular area.

Important General Principles Associated with Ecological Succession

1. The physical environment determines which communities can exist in a particular place.

2. Succession is community controlled, i.e., succession is caused by modification of the surrounding physical environment by the existing community, i.e., a successional community will alter the environment so that the environment is then more favorable for a different community than the existing one.

3. Ecological succession is directional - and therefore predictable.

4. Succession ends in a stabilized community and ecosystem called the ecological climax.  It is in equilibrium with the physical environment of that particular area and perpetuates itself.*

* Usually an external disturbance to the area, e.g., fire, puts the area back into an earlier successional stage.

 This tendency for the ecosystem to reach a stage where it stays in equilibrium is an example of Homeostasis developing and maintaining stability.

5. High diversity produces stability.


Types of Ecological Succession

1. Primary Succession begins on an area that has not been previously occupied by a community, e.g., newly exposed rock.  There is no soil.  Soil is a combination of broken down rock plus organic matter (humus* and small, living organisms). 

*Humus is accumulated, decomposed plant and animal material.

Primary succession takes place very slowly with a low rate of production of biological material.

2. Secondary Succession begins on an area where a community has previously existed.  Secondary succession usually begins on an already established soil.

   Secondary succession has a higher level of production of biological material at a faster rate than primary succession.

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Dr. Ray L. Winstead
Direct e-mail Link: RWinstea@iup.edu