What is crustose lichens stage ?

Explanation

### Step-by-Step Solution:

1. **Definition of Crustose Lichens**: Crustose lichens are a type of lichen that grow tightly attached to their substrate, often appearing as a crust on rocks or tree bark. They are characterized by their flat, crust-like appearance.

2. **Role in Ecological Succession**: Crustose lichens are considered a pioneer community in ecological succession. This means they are among the first organisms to colonize bare substrates, such as bare rock, in a newly formed or disturbed environment.

3. **Pioneer Community**: The term "pioneer community" refers to the first group of organisms that establish themselves in a barren or disturbed area. In the case of crustose lichens, they play a crucial role in initiating the process of soil formation.

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