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
rw ( at ) raywinstead ( dot ) com