Difference between Primary and Secondary Succession

Ecological succession or biotic succession is the natural development of a series of biotic communities at the same site, one after the other till a climax community develops which is a more or less stable community that is in perfect harmony with the environment of the area. 

It is of two types: Primary and Secondary succession. Primary succession is a biotic succession which occurs on lifeless unoccupied areas e.g., newly exposed barren rock, newly formed sand dunes, newly created pond or reservoir. Example: Lithosere (A xerosere on rock), Hydrosere

Secondary succession  is the succession of communities in a previously inhabited area which have been naturally or artificially disturbed. Here soil and some organisms are already present. e.g., cut over forest, abandoned crop land, ploughed fields and lands that have been flooded.

Primary vs Secondary Succession

Primary Succession

1. Primary succession takes a long time for completion, 1000 years or more.
2.It occurs in an area which is barren or lifeless.

3. Soil is absent at the beginning of primary succession and the environment is not suitable for sustaining normal life forms.

4. There is no humus in the beginning as soil is absent.

5. Intermediary seral communities are many as it takes long time for reaching climax stage.

6. Pioneer community comes from outside often crustose lichen in a barren rock.

7. Reproductive structures or propagules of any previous community are absent.

Secondary Succession

1. Secondary succession takes a less time for completion, 50-200 years.
2. Secondary succession occurs in an area which has been denuded recently and previously inhabited.

3. Soil is present at the beginning of secondary succession with some organisms.

4. Humus is present from the very beginning by the decomposition of previous occupants. 

5. Intermediary seral communities are a few compared to primary succession.

6. Pioneer community develops partly from previous occupants and partly from migrants.

7. Reproductive structures of the previous occupants are present in the area.