Question

Which of the following statements regarding ecological succession is correct?

• A. It is the rapid change that takes place only in the abiotic components of an ecosystem
• B. It is the gradual and predictable change in species composition that occurs in a given area
• C. It always occurs in areas where no living organisms ever existed
• D. The numbers and types of different species remain constant during ecological succession

Answer 1

The correct option is B It is the gradual and predictable change in species composition that occurs in a given area

Ecological succession is a steady, gradual change in the composition and structure of biotic communities of an area. It is predictable, sequential and occurs in accordance with the changing physical environment i.e the abiotic components such as duration of sunlight, water, soil, etc. Hence, option b is correct.

During succession, some species become more in number as they colonise the area. Some other species may become less in number and even disappear. Hence, option d is incorrect.

cological succession is of two types :

• Primary succession - Succession where a newly formed area is colonised for the first time by a species or living organisms. Such areas would have never been previously inhabited i.e it is barren and lacks fertile soil. For example, newly cooled lava, newly created pond reservoir, etc.

• Secondary succession - Succession where natural communities develop in an area that was earlier occupied by living organisms that were somehow lost. It begins in areas where natural biotic communities have been destroyed such as in abandoned farm lands, deforested lands, lands that have been flooded, etc.