Gina Brown
Ecological Succession – Simplified Notes (Easier to understand)
Definition: Gradual process of change in species structure of an ecological
community over time
Species have a set of environmental conditions under which it will grow and
reproduce most optimally
Under a set of environmental conditions, the species which can grow the most
efficiently and produce the most viable offspring will become the most
abundant organisms (these organisms flourish as long as the environmental
conditions remain constant)
Cause of ecosystem change: the impact that established species have upon
their own environments
If the environment is altered, the original species may no longer flourish (but a
different species, better suited to the new environment may flourish)
Changed environmental conditions: previously dominant species may fail, and
another species may become ascendant
Ecological Succession may occur when conditions of environment suddenly
and drastically change (fires/storms/agriculture)
This may destroy species and alter dynamics of ecological community
This triggers a scramble for dominance among species that are still present
Primary Succession
Definition: The establishment of a community where none existed before
Pioneer Species: first organisms to establish themselves to the new
environment
Have adaptations which enable them to survive harsh conditions (high/low
temperatures & dehydration)
Following development of soil on a bare rock, lichens/mosses/hardy annual
plants with wind-dispersed seeds will build/improve the soil
Ecological niches are created for other species and the stage is set for the
replacement of pioneer species
The ‘following’ species are larger/more specialized – so they grow over the
top original pioneers (competing for sunlight, and winning)
Gradually the ecosystem develops, and supplies of water/nutrients become
more predictable (grasses and other small plants invade the community and
are available for herbivores)
1
Ecological Succession – Simplified Notes (Easier to understand)
Definition: Gradual process of change in species structure of an ecological
community over time
Species have a set of environmental conditions under which it will grow and
reproduce most optimally
Under a set of environmental conditions, the species which can grow the most
efficiently and produce the most viable offspring will become the most
abundant organisms (these organisms flourish as long as the environmental
conditions remain constant)
Cause of ecosystem change: the impact that established species have upon
their own environments
If the environment is altered, the original species may no longer flourish (but a
different species, better suited to the new environment may flourish)
Changed environmental conditions: previously dominant species may fail, and
another species may become ascendant
Ecological Succession may occur when conditions of environment suddenly
and drastically change (fires/storms/agriculture)
This may destroy species and alter dynamics of ecological community
This triggers a scramble for dominance among species that are still present
Primary Succession
Definition: The establishment of a community where none existed before
Pioneer Species: first organisms to establish themselves to the new
environment
Have adaptations which enable them to survive harsh conditions (high/low
temperatures & dehydration)
Following development of soil on a bare rock, lichens/mosses/hardy annual
plants with wind-dispersed seeds will build/improve the soil
Ecological niches are created for other species and the stage is set for the
replacement of pioneer species
The ‘following’ species are larger/more specialized – so they grow over the
top original pioneers (competing for sunlight, and winning)
Gradually the ecosystem develops, and supplies of water/nutrients become
more predictable (grasses and other small plants invade the community and
are available for herbivores)
1
