| Primary Succession | Secondary Succession |
|---|
| It occurs in areas that were previously not inhabited | It occurs in areas that were previously inhabited |
| The succession begins with the breakdown of rocks into soil | The succession already has the presence of soil |
| Absence of initial vegetation | Presence of initial vegetation |
| It is the base of all the ecosystems | It occurs only if a primary succession is destroyed |
| Life starts with nothing thus it is a slow process | It already has a head start as compared to primary succession, thus it is comparatively a fast process |
| It takes about 1000 years or more for primary succession to reach the climax community | It takes about 50-200 for secondary succession to reach the climax community |
| Due to the absence of soil, the pioneer species-humus is not present in the initial stages. It enters the succession through external sources | Humus is present as the succession contains soil that has decomposed products in it. |
| The pioneering species found here are liches, fungi, or algae | Grass or other higher pioneering species of the previous communities are already present in the ecosystem |
| Absence of organic matter in the environment | Presence of organic matter in the environment |
| Numerous seral communities can be found in this succession | Fewer seral communities can be found in this succession |
| The succession began in uninhabitable conditions, extreme conditions | The succession began in habitable conditions |
| Areas after volcanic eruptions, glaciers outbursts, sand, nuclear eruptions are good examples of the land ready for a primary succession | Areas after fires, abandoned land, harvested areas, deforested areas, affected by natural calamities, logging, flooded land, etc are good examples of the land undergoing secondary succession. |