Examkin

Question

Difficulty: EasyEcological Functions, Nutrient Cycles and Ecological Succession

During primary ecological succession on a completely bare rock surface (xerarch succession), which organisms typically act as the pioneer species to initiate soil formation?

  1. LichensAnswer
  2. B
    Perennial grasses
  3. C
    Mesophytic shrubs
  4. D
    Climax canopy trees

Answer

Lichens act as the pioneer species on bare rock during xerarch succession.
Lichens are uniquely adapted to colonize bare, substrate-barren environments like rocks. By secreting acids that weather the rock surface into tiny mineral particles, they initiate the formation of soil, allowing mosses and small plants to colonize later.

Step-by-Step Solution

1
Identify the type of ecosystem habitat specified
The scenario describes primary succession on bare rock, known as xerarch succession.
Primary succession occurs on newly exposed substrates devoid of organic soil.
2
Determine the organism capable of colonizing bare rock substrate directly
Lichens are able to withstand extreme desiccation and secrete lichenic acids to break down rock surface minerals into primitive soil.
Pioneer species must be stress-tolerant autotrophs capable of initiating soil weathering.

Key Concept

Pioneer Species in Primary Ecological Succession
Estimated Time:45s
Rate this question

Topics

Ecological Functions, Nutrient Cycles and Ecological Succession