ECOLOGICAL SUCCESSION
Ecological succession is the process of change in the species structure of
an ecological community over time
Ecological succession can be defined as the gradual and natural process, of the development
of the biological community. The time taken for such development can be decades or over
millions of years. The process begins with the growth of a pioneering community, initiate
from the bare rock, the lichens, and few plants species.
Primary succession begins on sites that have not previously had plants growing on them,
such as beaches, larva flows, severe land slips, ponds and bare rocks.
It takes time for species/populations/communities to survive here
Secondary succession begins in areas where a disturbance removes some or all species,
but the soil remains
Once vegetation comes back – animals start to make their way into the area as well
A lot quicker than primary, because there was ONCE life there
Pioneer species must be able to withstand extreme conditions, establish rapidly, do not
grow in shade, have spores/seeds that can disperse over long distances. R strategy. Low
growing plants.
Pioneer species build up, stabilize and enrich the soil, they alter the amount of light available
by providing shade these changes allow species that are better adapted to this modified
habitat to replace the pioneer species – which then disappear.
Primary succession pioneers:
1. Lichens – first species on rocks after a disturbance, do not need soil to survive, soil starts
to form as lichen and physical weathering breaks down rocks into smaller pieces, when
lichen dies – they add organic matter to new soil
2. Mosses
3. Ferns, grasses and annuals arrive as the soil layer thickens
4. Faunal pioneers – mites, ants, spiders – small herbivores and other decomposers move
in when more food is available
Secondary succession pioneers:
1. Herbs and weeds (annuals) – first to arrive after a disturbance
2. Grasses and perennials follow
3. In forests – climbers then appear
Intermediate species stage:
o Soil can hold for water, more fertile, temps less extreme (more shade) more
organisms can move in
o Shrubs, bushes
o Larger herbivores (small antelopes, hares) and small carnivores (caracal, wild cats)
and snakes and rats can become part of the community
o Community is now more structurally complex
o “Over many years, due at least in part to changes in the environment caused by the
growth of grasses and other species, shrubs will emerge, followed by small pine,
oak, and hickory trees. Eventually, barring further disturbances, the oak and hickory
trees will become dominant and form a dense canopy, returning the community to
its original state—its pre-fire composition. This process of succession takes about
150 years.”
Ecological succession is the process of change in the species structure of
an ecological community over time
Ecological succession can be defined as the gradual and natural process, of the development
of the biological community. The time taken for such development can be decades or over
millions of years. The process begins with the growth of a pioneering community, initiate
from the bare rock, the lichens, and few plants species.
Primary succession begins on sites that have not previously had plants growing on them,
such as beaches, larva flows, severe land slips, ponds and bare rocks.
It takes time for species/populations/communities to survive here
Secondary succession begins in areas where a disturbance removes some or all species,
but the soil remains
Once vegetation comes back – animals start to make their way into the area as well
A lot quicker than primary, because there was ONCE life there
Pioneer species must be able to withstand extreme conditions, establish rapidly, do not
grow in shade, have spores/seeds that can disperse over long distances. R strategy. Low
growing plants.
Pioneer species build up, stabilize and enrich the soil, they alter the amount of light available
by providing shade these changes allow species that are better adapted to this modified
habitat to replace the pioneer species – which then disappear.
Primary succession pioneers:
1. Lichens – first species on rocks after a disturbance, do not need soil to survive, soil starts
to form as lichen and physical weathering breaks down rocks into smaller pieces, when
lichen dies – they add organic matter to new soil
2. Mosses
3. Ferns, grasses and annuals arrive as the soil layer thickens
4. Faunal pioneers – mites, ants, spiders – small herbivores and other decomposers move
in when more food is available
Secondary succession pioneers:
1. Herbs and weeds (annuals) – first to arrive after a disturbance
2. Grasses and perennials follow
3. In forests – climbers then appear
Intermediate species stage:
o Soil can hold for water, more fertile, temps less extreme (more shade) more
organisms can move in
o Shrubs, bushes
o Larger herbivores (small antelopes, hares) and small carnivores (caracal, wild cats)
and snakes and rats can become part of the community
o Community is now more structurally complex
o “Over many years, due at least in part to changes in the environment caused by the
growth of grasses and other species, shrubs will emerge, followed by small pine,
oak, and hickory trees. Eventually, barring further disturbances, the oak and hickory
trees will become dominant and form a dense canopy, returning the community to
its original state—its pre-fire composition. This process of succession takes about
150 years.”
