Succession in
Ecosystems
SuccessionSuccession:
a series of changes in a
community in which new
populations of organisms
gradually replace existing ones
Primary successionPrimary Succession:
colonization of new sites by
communities of organisms –
takes place on bare rock
Primary successionNew bare rock comes from 2
sources:
1. volcanic lava flow cools
and forms rock
Primary successionNew bare rock comes from 2
sources:
2. Glaciers retreat and expose
rock
Pioneer organismsPioneer organisms:
the first organisms to colonize
a new site
Ex: lichens are the first to
colonize lava rocks
Primary SuccessionRock
Climax communityClimax community:
a stable, mature community that
undergoes little or no
succession
Example:
a mature
forest
Primary succession-
Secondary successionSecondary succession:
sequence of community changes
that takes place when a
community is disrupted by
natural disaster or human
actions – takes place on
existing soil
Secondary successionEx:
A fire levels
portions of a
forest
Secondary successionEx:
A farmer
plows his
field
Secondary succession-
Secondary succession-
Pond Succession
Check for understanding…
The diagram below represents a process that occurs in
nature.This diagram can be used to illustrate the
(1) effects of reduced competition between different
types of plant life
(2) effect of human intervention on a stable ecosystem
(3) ecological succession from bare rock to stable
ecosystem
(4) evolution of mosses to trees over 200 years
Which statement best describes one of the stages
represented in the diagram below?
(1) The mature forest will most likely be stable over a long
period of time.
(2) If all the weeds and grasses are destroyed, the number of
carnivores will increase.
(3) As the population of the shrubs increases, it will be held
in check by the mature forest community.
(4) The young forest community will invade and take over
the mature forest community.