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.
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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