Question

What is succession? What are its types? Write any two stages.

Answer 1

Hint: A significant feature of all communities is that, in response to changing environmental factors, their composition and structure continually change. This change, parallel to the changes in the physical world, is systematic and sequential.

Complete Answer:
Ecological succession is the slow and reasonably predictable shift in the composition of species of a given region. Some species colonise an environment and their populations become more abundant through succession, while populations of other species decrease and even vanish.

There are two types of succession-
Primary succession and secondary succession.
Primary succession begins in areas that are bare or devoid of vegetation. The formation of new islands or new volcanic rock, and soil created by glacial retreats are instances of where primary succession may take place. In areas where natural biotic ecosystems have been lost, such as neglected agricultural fields, burnt or cut trees, flooded plains, secondary succession begins.

Pioneer species are the species which invade a bare area. These are usually lichens that are capable of succession on rocks. Later, they open the way for some very small plants, such as bryophytes, which will form in the small amount of soil. With time, they are succeeded by bigger plants and so on until a climax community is reached.

The final stage of succession is the climax community, remaining largely untouched until an incident such as fire or human intervention destroys it.

Note: The ecological succession definition typically focuses on changes in vegetation. However, these vegetative changes affect the food and shelter for different species of animals. Thus, the numbers and forms of species often change as succession continues.