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Difficulty: EasyEcological Succession

Following a volcanic eruption, a newly formed island of solid basalt rock is completely devoid of soil and organic matter. Which of the following organisms is most likely to act as a pioneer species to initiate primary ecological succession on this substrate?

  1. LichensAnswer
  2. B
    Herbaceous grasses
  3. C
    Vascular ferns
  4. D
    Hardwood trees

Answer

Lichens act as the pioneer species on bare volcanic rock during primary succession.
Primary succession begins on newly exposed, completely sterile surfaces where no soil layer exists. Lichens serve as pioneer colonizers because their symbiotic algal and fungal components allow them to photosynthesize, withstand drought, and dissolve rock surfaces chemically to create the first layers of soil.

Step-by-Step Solution

1
Identify the initial ecosystem conditions described.
The habitat is bare volcanic rock devoid of topsoil, organic matter, and pre-existing seed banks.
Primary succession takes place on previously uncolonized, soil-free substrates.
2
Determine which organism type can colonize bare substrate without soil.
Lichens are specialized pioneer organisms that tolerate harsh, nutrient-poor conditions and weather rock faces into soil.
Pioneer species must initiate soil formation to allow subsequent plant communities to establish.

Key Concept

Pioneer species in primary ecological succession
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Topics

Ecological Succession

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