Describe the trend of succession that would take place on a bare rock.

• Succession on bare rock is called primary succession and occurs in three stages.

Pioneer stage

• Bare rock breaks down physically and chemically during the process of weathering
• Rain water assist in weathering because it is acidic. It dissolves some minerals leading to rock disintegration
• These conditions are not favorable for most plants but lichen are the fast to inhabit the rock, they are called pioneer organism.
• Invasion of lichens on bare rock cause further weathering, and their death humus to the soil formed. This makes it possible for invasion of mosses. Moss form a dense mat which trap tiny particles of rock, some organic debris and water.

Spruce stage

• Death of the moss add to the nutrient content of the mat so that eventually the mat support germination of seed of colonizing angiosperm whose bodies also contribute to the growing layer of soil.

Climax stage

• Soon large woody shrubs begin to grow in the newly formed soil
• Lichen and moss may be covered by decaying leaves causing their death.
• Eventually thicker layer of soil develops, leading to growth of big trees
• Animal species immigrate into the forming fauna and the size of animals that invade increase as the size of the vegetation increase.
• After a long time, the mature forest community grows. This is called climax community.