Hello

• Primary Succession - Succession that begins in new habitats or lifeless areas that are uninfluenced by pre-existing communities is called primary succession.

• Primary succession is a series of events occurring in an order to develop a stable ecosystem.
• The new environments are usually formed due to natural events like volcano or glacier eruption that causes the lack of soil or the absence of living organisms.
• The groups of organisms that colonize these environments are termed ‘pioneer organisms’ and are usually composed of lichens, algae, and fungi (https://microbenotes.com/characteristics-of-fungi/) .
• Primary succession begins with the weathering of rocks to form soil to inhabit the pioneer species.
• The initiation of primary succession usually occurs either due to a biological factor or an external factor.
• Once some amount of soil is formed, organisms like lichen that have few soil requirements, begin to grow in these areas. These organisms enter the new environment from a different environment
• Some examples of primary succession include the formation of a new ecosystem after a volcano, glacier outbursts, or a nuclear explosion

• Secondary Succession - Succession that follows the disruption of a pre-existing community that existed in the same ecosystem is called secondary succession.

• Unlike primary succession, secondary succession begins in an environment with pre-existing soil.
• Secondary succession thus takes place in an environment where the initial succession has been disrupted, but some plants and animals might still exist.
• This type of succession usually follows disasters like a forest fire, hurricane, or harvesting, causing the existing ecosystem to be destroyed.
• The initiation of secondary succession always occurs due to some external factors.
• After a forest fire, the tall trees become destroyed, and the first plants that grow in such areas are usually annual plants.
• The following annual plants are grasses and low-lying plants and other pioneer species.
• The early colonizers in secondary succession are also termed ‘pioneer species’ like in primary succession.
• These pioneer species, unlike those in primary succession, mostly arise from the pre-existing groups of organisms of the community
• Some examples of secondary succession include succession after fire, harvesting, logging, or abandonment of land or the renewal after a disease outbreak.

All the best !!