In which order do organisms
return to an ecosystem during
primary succession after an area's
ecosystem has been wiped out?
A. trees, shrubs, lichens
B. lichens, trees, shrubs
C. lichens, shrubs, trees
During primary succession, the first organisms to return to an ecosystem are usually lichens. Lichens are able to grow on bare rock and break it down into soil, which allows other organisms to grow. Once soil has formed, small plants like mosses and ferns can grow. These plants help to further break down the soil and add nutrients to it. Eventually, trees and shrubs can grow in the area, completing the process of primary succession. Therefore, the correct order of organisms returning to an ecosystem during primary succession is lichens, trees, and shrubs.