Choose the correct sequence of transitional communities in Xerach succession.

Options

A. Mosses `to` Lichens `to` Grasses
B. Bryophytes `to` Forest `to` Shrubs
C. Bryophytes `to` Herbs `to` Shrubs
D. Lichens `to` Mosses `to` Herbs

Answer

To determine the correct sequence of transitional communities in xerarch succession, we need to understand the characteristics of xerarch succession and the organisms involved.

### Step-by-Step Solution:

1. **Understanding Xerarch Succession**:
- Xerarch succession occurs in dry environments where the initial colonizers must be able to withstand low moisture levels.

2. **Identifying the Organisms**:
- The options provided include:
- Option 1: Moss, Lichen, Grass
- Option 2: Bryophyte, Forest, Shrubs
- Option 3: Bryophyte, Herb, Shrubs
- Option 4: Lichen, Moss, Herbs

3. **Evaluating Each Option**:
- **Option 1**: Moss requires moisture, so it cannot be the first in a dry succession. Thus, this option is incorrect.
- **Option 2**: Bryophytes (mosses) also require moisture, making this option incorrect.
- **Option 3**: Again, bryophytes are moisture-dependent, so this option is also incorrect.
- **Option 4**: Lichens are well-suited for dry conditions as they can survive with minimal moisture. They can colonize bare rock and are often the first organisms in xerarch succession. Following lichens, mosses can establish as they require slightly more moisture. Finally, herbs can grow after mosses.

4. **Conclusion**:
- The correct sequence of transitional communities in xerarch succession is **Lichen → Moss → Herbs**. Therefore, the correct answer is **Option 4**.