Successions
Most successions contain a number of stages that can be recognized by the collection of species that dominate at that point in the succession. Successions begin when an area is made partially or completely devoid of vegetation because of a disturbance. Some common mechanisms of disturbance are fires, wind storms, volcanic eruptions, logging, climate change, severe flooding, disease, and pest infestation. Succession stops when species composition changes no longer occur with time, and this community is said to be a climax community.
Formation of a primary succession
A: Bare rock colonised, by pioneer community, for example, lichens, mosses, bacteria, that can survive in hardy conditions, and need few nutrients.
B: Rock slowly weathered creating thin soil.
C: Plants die, creating humus, leading to a more fertile soil, grasses replace the mosses and lichens as the dominant species.
D: Grasses decrease in number, quick-growing shrubs become dominant.
E: Fast growing trees dominate.
F: Over time slower growing trees such as oak become dominant and form the climatic climax community.
B: Rock slowly weathered creating thin soil.
C: Plants die, creating humus, leading to a more fertile soil, grasses replace the mosses and lichens as the dominant species.
D: Grasses decrease in number, quick-growing shrubs become dominant.
E: Fast growing trees dominate.
F: Over time slower growing trees such as oak become dominant and form the climatic climax community.
The following table shows a comparison of plant, community and ecosystem characteristics at the early and late stages of a succession: