By – N.G.Palit

Ecological Succession

What is Ecological Succession?

ECOLOGICAL SUCCESSION IS: The observed process of change in

the species structure of an ecological community over a period of time

What is Ecological Succession?

Ecosystems are constantly changing. Ecological succession is a gradual process of change and replacement of the types of species in a community. Each new community makes it harderfor the previous community to survive.

Types of Ecological Succession

There are two main types of Ecological Succession: Primary Succession: It is the process of creating life in an area where no life existed earlier.

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 Begins in a place without any soil, like: * Sides of volcanoes * Landslides * Flooding Starts with the arrival of living things such as lichens that do not need any soil to survive. They are called Pioneer Species

Pioneer Species

Primary Succession When lichens die, theydecompose, adding small amounts of organic matterto the rock to make soil. Simple plants like mosses and ferns can grow on this new soil

Primary Succession The simple plants die, adding more organic material. The soil layer thickens, and grasses and other plants begin to take

over.

Primary Succession These plants die, and they add more nutrients to the soil. Shrubs and treescan survive now, on this

soil.

Primary Succession Insects, small birds and mammals can now begin to move in. What was earlier only bare rock, now supports a variety of life

Primary Succession

Primary Succession

Primary Succession

Secondary Succession Secondary Succession is the process of re-stabilization

that follows a disturbance in an area,

where life has formed an ecosystem.

Types of Ecological Succession

Secondary Succession occurs on a surface where an ecosystem has previously existed. It is the process by which one community replaces another community which has been partially or totally destroyed, might be by natural process such as floods, earthquake etc.

Primary Secondary

Secondary Succession When an existing community has been cleared by any type of disturbance, such as fire, cyclone etc and the soil remains intact, the area begins to return to its natural community. Because these habitats previously supported life, secondary succession begins.

The Circle of life in Secondary Succession

Why does Ecological Succession Occur?

Because it is the process of life for plants and other living organisms. Because organisms alter soil structure and the species communities constantly change over a period of time. Succession will continue until the environment reaches its final stage – the Climax Community

Gradual Change from Pioneer Stages to Climax Community

How Ecological Succession takes place?

Succession will continue until the environment reaches it’s final stage, ---- the Climax

Community.

Climax Community A climax community is a mature, stable community that is the final stage of ecological succession This type of community remains the same through out the time, if it is not disturbed.

Climax Community A stable group of plants and animals which is the end result of succession process, does not always mean only big trees. They could be: * Cacti in deserts or * Grasses in fields

These are Climax Communities

Physical Factors The two main physical factors that determine the nature of the

community that develops in an area are: 1. Temperature 2. The amount of rainfall.

Threats to Succession The grasses that move in as pioneer species are often thought as weeds. The subsequent growth of shrubs are considered undesirable “brush”.

Threats to Succession But, without these intermediate

stages, the disturbed habitat can’t

return to forest.

How do Humans affect Ecological succession? Clearing the land for garden and preparing the soil for planting is a type of major external event that radically re-structure and disrupt a previously stabilized ecosystem. This disturbance may immediately begin a process of ecological

succession.

Does Ecological Succession ever stop? Over a long period of time, the climate conditions of an ecosystem is bound to change.

No ecosystem has existed or will remain unchanged over a Geological Time Scale

Any Question

Thank You By – N.G.Palit

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