Question

Which of the following is a pioneer species in the primary succession of a bare rock?

• A. Grasses
• B. Lichens
• C. Shrubs
• D. Trees

Hint:

In primary succession, pioneer species like lichens or mosses initiate soil formation on barren surfaces. Identify the earliest colonizers by their ability to survive in harsh, nutrient-poor conditions.

Answer 1

The Correct Option is B

Primary succession occurs on a barren, lifeless substrate, such as a bare rock, where no soil initially exists. Lichens are considered pioneer species in this process because they can colonize bare rocks, secrete acids that weather the rock surface, and contribute organic matter, gradually forming a thin layer of soil. This enables other species, like mosses, to establish.
The other options represent later stages in succession:
- Grasses: Appear in later stages when sufficient soil has accumulated to support herbaceous plants.
- Shrubs: Establish after grasses, in more developed soil during intermediate stages.
- Trees: Appear in the climax community, requiring deep, nutrient-rich soil.
Thus, the pioneer species in the primary succession of a bare rock is lichens.