Explain the concept of ‘ Ecological succession’. Enumerate the differences between Primary succession and Secondary succession.

Explain the concept of ‘ Ecological succession’. Enumerate the differences between Primary succession and Secondary succession.


  • First, explain the concept of Ecological succession
  • Then write the differences between Primary succession and Secondary succession
  • At the end give a conclusion
Model Answer :

Ecological succession is the process of change in the species structure of an ecological community over time. The community begins with relatively few pioneering plants and animals and develops through increasing complexity until it becomes stable or self-perpetuating as a climax community. It is a phenomenon or process by which an ecological community undergoes more or less orderly and predictable changes following a disturbance or the initial colonization of a new habitat. Succession may be initiated either by formation of new, unoccupied habitat, such as from a lava flow or a severe landslide, or by some form of disturbance of a community, such as from a fire, severe windthrow, or logging.



Succession that begins in new habitats, uninfluenced by pre-existing communities is called primary succession, whereas succession that follows disruption of a pre-existing community is called secondary succession.The major differences among the two successions are as follows:


Properties Primary Succession Secondary Succession
Occurrence It takes place in areas which are lifeless or barren It takes place in areas which were previously inhabited or recently denuded
Example Barren rock, ponds, desert, etc Natural calamities, covered under deforestation, etc
Soil Soil is absent at the beginning of primary succession and the environment is not suitable for sustaining normal life forms. Soil is present at the beginning of secondary succession with some organisms
Time Relatively slow and it takes approx. 1000 years or more. Relatively fast and it take approx 50-200 years.
Observance Primary succession is much more difficult to observe than secondary succession.  Easy to observe
Humus Humus is absent in the starting as there is no soil Presence of Humus due to the previous occupants and their decomposition
Pioneer Community(first biotic community) Pioneer community comes from outside often crustose lichen in a barren rock. Pioneer community develops partly from previous occupants and partly from migrants.
Intermediary seral communities Intermediary seral communities are many as it takes long time for reaching climax stage. Intermediary seral communities are a few compared to primary succession.



Thus, Ecological succession provides diversity and depth to a biotic community. Without it, life cannot grow or progress. Succession is the gateway to evolution.

Subjects : Ecology and Environment