Relier Pairs SuccessionVersion en ligne Succession par James Dycus 1 2 3 4 5 6 Pioneer species, like lichens and mosses, establish themselves on the rock substrate. Pioneer species help provide soil and nutrients for other plant species like shrubs and small trees. Bare rock is exposed due to some type of disturbance like a retreating glacier or volcanic eruption. No soil is present. Small and Large trees begin to grow and the community reaches an equilibrium or balance. This results in a climax community. Organisms are driven away or killed by some type of disturbance, like a forest fire, leaving behind only the soil. Pioneer species, like grasses and weeds, begin to grow from the soil. Roots and seeds left over may also begin to grow again.