The correct answer is it always occurs in a predictable pattern.
Ecological successsion is defined as a <em>change in the structure of species of an ecological community over a period of tim</em>e. The succession that begins in a new environment by uninfluence of pre-existing species is called primary succession. The disruption of pre-existing community because of succession is called secondary succession. Ecological succession happens in a predictable pattern. The ecological communities undergoes predictable change which creates a disturbance or initial formation of new habitat. This changes occurs in an orderly manner and can be best explained by the example of trees how they grow bigger and bigger.
Stable elements are those which have atleast one isotope with no tendency to "decay", i.e., change into anotherelement.
Organisms are classified into domains and kingdoms based on their cell type, their ability to make food, and the number of cells in their bodies.
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