Primary succession includes which sequence of stages?

Primary succession includes which sequence of stages?

• A. Series of community changes which take place on a previously colonized, but disturbed or damaged habitat
• B. Secondary succession begins with grasses and shrubs
• C. The stages of secondary succession include pioneer microorganisms and lichens
• D. The stages of primary succession include pioneer microorganisms, plants (lichens and mosses), grassy stage, smaller shrubs, and trees.

Answer: (D)

Primary succession is the process of life establishing itself on a surface where there is no soil yet, such as bare rock left after a lava flow or glacial retreat. It begins with pioneer microorganisms that can survive harsh conditions and start to break down the rock while adding organic material. As this builds a thin soil layer, lichens and mosses move in, further weathering the surface and contributing more organic matter. With soil in place, grasses appear, then small shrubs, and finally trees can become established. This progression—from pioneer microorganisms to lichens and mosses, then grasses, shrubs, and trees—is the typical sequence of primary succession. The other statements describe secondary succession, which occurs on surfaces that already have soil and some life after a disturbance, not on bare rock.

Primary succession is the process of life establishing itself on a surface where there is no soil yet, such as bare rock left after a lava flow or glacial retreat. It begins with pioneer microorganisms that can survive harsh conditions and start to break down the rock while adding organic material. As this builds a thin soil layer, lichens and mosses move in, further weathering the surface and contributing more organic matter. With soil in place, grasses appear, then small shrubs, and finally trees can become established. This progression—from pioneer microorganisms to lichens and mosses, then grasses, shrubs, and trees—is the typical sequence of primary succession. The other statements describe secondary succession, which occurs on surfaces that already have soil and some life after a disturbance, not on bare rock.