Lichen are ecologically important as they

Options

A. are source of some medicines
B. are pioneers of succession on barren rocks (Lithosere)
C. are symbionts of algae and fungi
D. are associated with mycorrhizal roots

Answer

**Step-by-Step Solution:**

1. **Understanding Lichens**: Begin by defining what lichens are. Lichens are a symbiotic relationship between fungi and algae (or cyanobacteria). This relationship allows them to thrive in various environments.

2. **Evaluating the Options**: Look at the provided options regarding the ecological importance of lichens:
- Option A: They are the source of some medicines.
- Option B: They are associated with mycorrhizal roots.
- Option C: They are symbionts of algae and fungi.
- Option D: They are pioneers of succession on barren rocks.

3. **Analyzing Each Option**:
- **Option A**: While lichens may have medicinal properties, this does not directly relate to their ecological role.
- **Option B**: Lichens are not associated with mycorrhizal roots, which are a different symbiotic relationship involving fungi and plant roots.
- **Option C**: This statement is true but does not answer the question about their ecological importance.
- **Option D**: This option states that lichens are pioneers of succession on barren rocks, which is significant ecologically because they can colonize and break down rocks, creating a substrate for other plants.

4. **Identifying the Correct Answer**: The correct answer is Option D: "They are pioneers of succession on barren rocks." This highlights their ecological role in creating habitats for other organisms.

5. **Conclusion**: Lichens play a vital role in ecosystems by being the first organisms to colonize barren environments, contributing to soil formation and facilitating the growth of other plants.

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