Ecological succession

Ecological succession is the gradual process by which ecosystems change and develop over time. It is therefore a series of predictable temporary communities or stages leading up to a climax community. Each stage/temporary community is called a successional stage. Each step prepares the land for the next successional stage. All habitats are in the state of constant ecological succession. Environment is always kept on changing over a period of time due to
(i) variations in climatic and physiographic factors, and
(ii) the activities of the species of the communities themselves.
Ecological Succession is an orderly sequence of different communities over a period of time.

       Types of ecological succession

1.Primary succession is the process by which an area first
changes from bare rock into a functioning ecosystem.

2.Secondary succession is the process by which an already
existing plant community is replaced by another plant
community.

           Primary succession

• The development of an ecosystem in an area that has never had a community living
within it occurs by a process called PRIMARY SUCCESSION.
• An example of an area in which a community has never lived before, would be a new lava or
rock from a volcano that makes a new island.Primary succession is the process by which an area first
changes from bare rock into a functioning ecosystem.

            Secondary succession

• SECONDARY SUCCESSION begins in habitats where communities were entirely or partially destroyed by some kind of damaging event.
• When an existing community has been cleared by a disturbance such as a fire, tornado, etc...and the soil remains intact, the area begins to return to its natural community.
• Because these habitats previously supported life, secondary succession, unlike primary succession, begins on substrates that already bear soil. In addition, the soil contains a native seed bank.
• Since the soil is already in place, secondary succession can take place five to ten times faster than primary succession.Secondary succession is the process by which an ecosystem that has been destroyed gradually returns to its previous state.

           

               The Climax Community

• A climax community is a mature, stable community that is the final stage of ecological succession.
• In an ecosystem with a climax community, the conditions continue to be suitable for all the members of the community.
• Any particular region has its own set of climax species, which are the plants that are best adapted for the area and will persist after succession has finished, until another Disturbance clears the area.

Process / Stages of Ecological Succession

Nudation- 

Succession begins with the development of a bare site, called Nudation (disturbance). Invasion
• Migration- It refers to arrival of propagules (seeds), dispersion.

• Ecesis- 

It involves establishment and initial growth of vegetation.

• Aggregation- 

It involves increase in number of species. Competition- As vegetation became well established, grew, and spread, various species began to compete for space, light and nutrients. This phase is called competition. Stabilization- Reaction phase leads to development of a climax community.