RAS question
In ecology, 'Ecological succession' refers to:
Correct answer: (D) The gradual process of change in species composition of a community over time.
Ecological succession is the gradual process by which the species composition of a community changes over time.
Explanation
Ecological succession is a community-level ecological process: over time, the mix of species in a community changes gradually. That is why option D is the substantive answer. Succession begins in two standard contexts: primary succession starts on bare rock or lava, while secondary succession starts on disturbed land. The sequence is not random; pioneer stages are followed by intermediate stages and, eventually, a climax community. The SATHEE IIT Kanpur URL was live, but it redirected to SATHEE's NCERT-books index rather than displaying the specific ecosystem chapter text.
Why the other options are wrong
- (A) A conservation technique is a deliberate protection or management method, while ecological succession is the gradual natural change in a community's species composition.
- (B) A type of pollution would describe contamination, whereas ecological succession describes long-term replacement and development of species within a community.
- (C) A weather phenomenon concerns short-term atmospheric conditions, but succession concerns ecological change in community composition over time.
Concept
This tests the Environment and Ecology concept of community dynamics, especially the distinction between primary succession, secondary succession, pioneer stages and climax community. It recurs in RAS because ecology questions often test whether candidates can classify processes rather than merely recognise terms.