Ecological Succession
Ecological succession is the gradual process
by which ecosystems change and develop
over time.
It includes a series of changes that a biotic
community undergoes in its maturation
towards a stable condition.
Some species may disappear altogether,
some may become more abundant, even
new species may be formed.
Important terms to know…
Habitat: A place where organisms live.
Eg. Pond
Population: Group of individuals of the same
species in a particular location.
Community: All of the populations of species
in a given area.
Ecosystem: The community, together with
the physical and chemical environment of a
particular area.
Types – based on the habitat
Primary Succession – Begins in areas
where no soil is initially present. The area has
not been changed physically by organisms.
Eg. Colonization of newly exposed island.
Secondary Succession – Begins in areas
where soil is already present. The area is
previously colonized and the soil is
organically enriched. Eg. Abandoned crop
Primary Succession
Secondary Succession
Types – based on the organism
Autotrophic succession – Characterized by
dominance of autotrophic organisms like
green plants.
Heterotrophic succession – Characterized
by dominance of heterotrophic organisms like
bacteria and animals.
The different stages…
Primary Autotrophic Succession
Nudation – The formation of a bare area.
Migration – Movement of organisms into a
bare area.
Colonization – Occupation of bare area by
first or pioneer community.
Ecesis – Establishment of the pioneer
community. They react with the medium and
establish themselves.
The different stages…
Aggregation – The final stage of invasion by
pioneer group. The species reproduce and
aggregate into large population in the new
Competition – Various species compete
among themselves for space, light and
nutrients. Communities which cannot
withstand competition are replaced by other
The different stages…
Stabilization – This is the final stage in the
process of ecological succession. The climax
community becomes stabilized for a longer
period of time and it can maintain itself in
equilibrium. If undisturbed, the climax
community can maintain itself for a long time.
Lichens/mosses on bare rock
Colonization of rock
Small plants growing…
Shrubs beginning to form
Trees – the climax community
Primary succession
Secondary Succession
Pioneer Community – The first species to
colonize an area.
Climax Community – The final, stable
community in a newly developed ecosystem.
This community is not replaced.
Sere – The progression from a pioneer to a
climax community is called a Sere.

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