Solution:

• The directional change in the flora and fauna of a given region over a period of time is called ecological succession.
• It is the process of gradual change in the species structure of an ecological community over time.

Three different steps as primary and secondary succession:

Primary succession:

• It is initiated when a new area that has never previously supported an ecological community is colonized by plants and animals. 
• This could be on newly exposed rock surfaces from landslides or lava flows.

Secondary succession:

• It occurs when an area that has previously had an ecological community is so disturbed that the original community was destroyed, and a new community moves in. 
• This is more common than primary succession.
• It is the result of natural disasters such as fires, floods and winds, as well as human interference such as logging and clear cutting. 

Climax stage:

•  when the population comes to a stable stage.