Question

usually crustonse lichens form a pioneer species" - Discuss​

Answer 1

Answer:

Lichens are typically the first organisms to colonize bare rock. They are therefore the pioneer species in primary succession. Many organisms require soil before they can colonize an area. Lichens that colonize bare rock secrete acids that break down the rock and start the soil-production process

Answer 2

The species that invade a bare area are called pioneer species. In primary succession on rocks, these are usually crustose lichens. So usually they are known as pioneer species.