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Question

Difficulty: MediumEcological Functions, Nutrient Cycles and Ecological Succession

With reference to ecological succession and ecosystem dynamics, consider the following statements:

1. Primary succession takes place on newly exposed substrates such as cooled lava flows or bare rock where no soil or organic matter previously existed.
2. Hydrarch succession occurs in aquatic or very wet environments, progressing over time toward mesic conditions.
3. The community that initially colonizes an uninhabited bare area during primary succession is known as the climax community.

Which of the statements given above is/are correct?

  1. 1 and 2 onlyAnswer
  2. B
    2 and 3 only
  3. C
    1 only
  4. D
    1, 2 and 3

Answer

The correct answer is statements 1 and 2 only.
Statements 1 and 2 accurately describe primary succession on bare substrates and the directional transition of hydrarch succession from hydric to mesic environments. Statement 3 is false because pioneer species, not climax species, are the first to colonize bare areas.

Step-by-Step Solution

1
Evaluate Statement 1 regarding primary ecological succession.
Statement 1 is correct. Primary succession occurs on previously uncolonized land surfaces (such as sand dunes, retreating glaciers, or cooled volcanic lava) where organic soil has not yet formed.
Primary succession requires pioneer organisms (like lichens) to weather rock and begin soil synthesis.
2
Evaluate Statement 2 regarding hydrarch succession.
Statement 2 is correct. Hydrarch succession starts in water bodies (hydric state) and gradually converts the aquatic habitat through seral stages into a stable land forest community (mesic state).
Both hydrarch and xerarch succession ultimately lead to medium-moisture (mesic) conditions.
3
Evaluate Statement 3 regarding colonizing organisms.
Statement 3 is incorrect. The first species to invade a bare area are pioneer species (e.g., lichens, mosses), not climax communities.
A climax community is the final, mature, equilibrium state reached at the end of ecological succession, remaining stable until disturbed.

Key Concept

Ecological Succession Stages and Terminology
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Topics

Ecological Functions, Nutrient Cycles and Ecological Succession