The entire sequence of communities that successively change in a particular area are called
- (a)Ecological succession
- (b)Sere
- (c)Community dynamics
- (d)Pyramid of biomass
Correct — B, a sere. In ecology, a sere (or seral series) is the entire sequence of communities that successively replace one another in a given area during ecological succession — running from the pioneer community, through a series of transitional (seral) stages, to the stable climax community. The question's exact wording, 'the entire sequence of communities that successively change,' is the textbook definition of a sere. Each individual transitional community within it is a seral (or seral stage) community.
- (a)Ecological succession — Succession is the process or phenomenon of gradual, orderly change in communities over time — not the sequence of communities itself. The sequence produced by succession is the sere; the two are related but distinct, and the question asks for the sequence.
- (c)Community dynamics — A loose, general phrase for changes within communities; it is not the specific ecological term for the successional sequence of communities.
- (d)Pyramid of biomass — A pyramid of biomass depicts the amount of living matter at each trophic level at one time — a structure, not a temporal sequence of communities.
Ecological succession is the gradual, more-or-less predictable change in the species composition of a community over time, ending in a relatively stable climax community. The whole ordered sequence of communities that develop at one site during this process is called a sere; each intermediate community is a seral stage. Seres are named by starting substrate — e.g., a hydrosere begins in water, a xerosere on dry bare ground/rock, a lithosere on bare rock.
This is a precise-terminology question that hinges on distinguishing the process (succession) from the sequence it produces (sere). The tempting distractor is 'ecological succession', because the two ideas are taught together. Read the stem carefully: it asks for 'the entire sequence of communities', which is the definition of a sere, not the process word.
- Sere = the whole sequence of communities from pioneer to climax at a site
- Ecological succession = the process that generates the sere
- Each transitional community in the sere is a seral (stage) community
- Types by substrate: hydrosere (water), xerosere/lithosere (dry land/bare rock); primary vs secondary succession
- Bare rock / substrate
- Pioneer community (e.g., lichens)
- Mosses & herbs (seral stage)
- Grasses & shrubs (seral stage)
- Climax community (e.g., forest)
The full ordered sequence of communities — pioneer to climax — is the sere; the process driving it is ecological succession.
- Choosing 'ecological succession' (the process) when the stem asks for the sequence (the sere)
- Mixing up a sere (temporal sequence of communities) with an ecological pyramid (trophic structure)
UPPSC/UPSC test succession terminology (sere, seral stage, pioneer, climax) and the mechanics of primary succession — for example, which organisms first colonise bare rock.
Lichens, which are capable of initiating ecological succession even on a bare rock, are actually a symbiotic association of
- (a) algae and bacteria
- (b) algae and fungi
- (c) bacteria and fungi
- (d) fungi and mosses
Answer(b) algae and fungi
Same concept — ecological succession. UPPSC asks for the name of the community sequence (sere); UPSC tests the pioneer stage of that sequence, where lichens (an algae–fungi symbiosis) initiate primary succession on bare rock.
In the grasslands, trees do not replace the grasses as a part of an ecological succession because of
- (a) insects and fungi
- (b) limited sunlight and paucity of nutrients
- (c) water limits and fire
- (d) None of the above
Answer(c) water limits and fire
Same concept — ecological succession. Here UPSC probes why a sere can be arrested short of a forest climax (water stress and fire hold grasslands at a sub-climax stage), complementing the UPPSC term 'sere' for the community sequence.
- practice — not a real PYQ
A sere that begins its development in a water body (e.g., a pond) is called a:
- (a)Xerosere
- (b)Lithosere
- (c)Hydrosere
- (d)Halosere
Answer(c) Hydrosere — a sere whose primary succession starts in water and proceeds towards a land climax community.
- practice — not a real PYQ
In ecological succession, the first community to colonise a previously barren area is the:
- (a)Climax community
- (b)Pioneer community
- (c)Seral community
- (d)Sub-climax community
Answer(b) Pioneer community — the first colonisers (e.g., lichens on bare rock) that begin the sere.