When over a period of time the species structure of the community changes this is termed as ecological succession.
The succession can be of two types - primary and secondary.
When a new community is established in an area which was previously not occupied is termed as primary succession and the organisms that inhabit these area are forms the pioneer organisms.
Primary succession occurs on the bare rocks, sand surfaces, areas of lava flows etc.
When the succession occurs in an area which was previously occupied but the community was replaced due to any ecological disturbance then the formation of new community after this is termed as secondary succession.
