What is ecological succession? Distinguish primary succession from secondary succession.

Explanation

It is the fairly and gradual replacement of species composition in an area .
Primary succession is also referred as .perisere . and is a type of biotic succession that ocurrs on a subsratum deviod of any previous life like bare, sand dunes , new islands exposed out of the sea etc. where there was previously no life.
Secondary succession is the biotic succession that occurs in an area , which had an existing biotic community and has become bare due to destruction by fire , landslide , earhquake etc.