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Difficulty: MediumEcological Succession

During ecological succession on a newly formed sand dune, a sequence of plant communities gradually replaces one another over time. Which of the following statements correctly describes a feature of secondary succession compared to this primary succession process?

  1. A
    Secondary succession begins on bare, uncolonized rock surfaces that completely lack organic soil.
  2. Secondary succession occurs on pre-existing soil containing organic matter, resulting in a faster rate of community establishment.Answer
  3. C
    Secondary succession depends exclusively on pioneer bryophytes that utilize true vascular root systems for anchorage.
  4. D
    Secondary succession results in an inverted pyramid of energy where primary consumers store more energy than producers.

Answer

Secondary succession occurs on pre-existing soil containing organic matter, resulting in a faster rate of community establishment.
Secondary succession occurs in areas where an established biological community has been disturbed or cleared, but where the soil layer and organic substrate remain intact. This pre-existing soil allows plant seeds, spores, and organisms to colonize and re-establish the community rapidly.

Step-by-Step Solution

1
Identify the key physical difference between primary and secondary succession substrates.
Primary succession starts on newly exposed surfaces devoid of soil (such as sand dunes or lava flows), while secondary succession begins on pre-existing soil left behind after a ecosystem disturbance.
The presence or absence of pre-existing soil dictates the rate and mechanism of pioneer plant colonization.
2
Evaluate the impact of pre-existing soil on community development speed.
Because organic matter, nutrients, and seed banks are already present in the soil, secondary succession proceeds much faster than primary succession.
Pioneer species in secondary succession do not need to spend extensive periods weathering rock to create soil.

Key Concept

Distinction between primary and secondary ecological succession substrate conditions
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Topics

Ecological Succession

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