During ecological succession

• Time gradual and fairly predictable change in the species composition of a given area is called ecological succession.
• Ecological succession leads to a stable unchanging final state called climax community which is in equilibrium with the environment.
• During succession, some species colonize an area and their populations become more numerous, whereas populations of other species decline and even disappear.

Hence, during ecological succession, the gradual and predictable change in species composition occurs in a given area.