1. Succession

2. Succession
Succession is the
gradual change in a
community over time.
During succession
the organisms within
an ecosystem
change its abiotic
conditions.
This allows better
adapted organisms to
colonize the area,
replacing its current
inhabitants.
Primary succession occurs when
organisms colonize a lifeless habitat.
Secondary succession occurs
when organisms recolonize
a devastated
ecosystem.

3. A series of predictable changes that
occur in a community over time due to
events in the environment.
The changes may happen suddenly
or very slowly.

5.  The series of changes that occur in an
area where no ecosystem previously
existed.
 Eventually,
primary
succession
will lead to
equilibrium.

6. Primary Succession – the
series of changes that
occur in an area where no
ecosystem previously
existed.

7. An area of rock
uncovered by a
melting ice sheet
A new island formed
by the eruption of an
undersea volcano
Human made ponds

8. The first species to populate an
area are the pioneer species.
They break up rock and begin soil
formation

9. Primary Succession
•Soil starts to form as lichens and
the forces of weather and erosion
help break down rocks into smaller
pieces
•When lichens die, they
decompose, adding small amounts
of organic matter to the rock to
make soil

10. Lichen pictures

11. A combination of
fungus and algae

14. Mosses break down rock
and add more soil

15. Grasses and small
plants – protect the
soil and add more
nutrients

16. •The simple plants die, adding more
organic material
•The soil layer thickens, and grasses,
wildflowers, and other plants begin to
take over

17. •These plants die, and they add
more nutrients to the soil
•Shrubs and trees can survive now
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18. •Insects, small birds, and mammals have
begun to move in
•What was once bare rock now supports
a variety of life
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19. Larger plants with deep roots
continue to break up rock and
make more soil.
A diverse forest ecosystem
takes hundreds of years

20. 1. Ground is solid rock
2. Rock begins to weather, pioneer
species begin
3. Weeds and grasses grow in soil making thicker, richer soil
4. Eventually trees and shrubs sprout community of organisms develops
5. Ecosystem reaches equilibrium

22. Reaching a stable community
can take centuries.

23. Equilibrium

25. Secondary Succession
The series of
changes that occur
after a disturbance
in an existing
ecosystem.
It can occur more
rapidly than
primary succession.

26. Secondary Succession
Begins in a place that already has
soil and was once the home of
living organisms
Occurs faster and has different
pioneer species than primary
succession

28. Natural disturbances:
Fires, hurricanes,
and tornadoes
Human disturbances:
A pasture
abandoned by a
farmer
Logging, or mining

29. Secondary Succession –
The series of changes that
occur after a disturbance
in an existing ecosystem.

31. 1. Varies depending on the type of
2.
3.
4.
5.
disturbance
A disturbed area returns to its
previous condition, eventually reaches
equilibrium
Soil and seeds are already present
Organisms move in
There is a quick recovery of the
ecosystem

32. Climax Community
•A stable group of plants and
animals that is the end result of
the succession process
•Does not always mean big trees
– Grasses in prairies
– Cacti in deserts
• Equilibrium restored
• State of balance
• No sudden changes in
community

33. Secondary succession usually
requires less time to form a
climax community, since soil is
already in place.

34. Equilibrium

36. Succession Review

37. What
happens
to the
ecosyste
m
Length of
Time
Example
Primary
Creates a new
ecosystem
Secondary
Restores a
previous
ecosystem
May take a long time
to reach equilibrium
A shorter time to
reach equilibrium
New land created by
An area
volcanic eruption
destroyed by fire

39. How do primary and secondary succession help
maintain equilibrium in an ecosystem?
Answer:
By fostering stability, over time, in the number and
species of organisms in a community.

40. What is a pioneer species?
Answer:
The first species to populate an area.

41. Identify two natural disturbances and
two human disturbances that can
result in secondary succession.
Answer:
Natural Disturbances: fire, hurricanes,
volcanoes, tornadoes. Human
Disturbances: farming, logging,
mining.

42. Grass poking through the cracks in the
sidewalk is an example of succession. Is
this primary or secondary succession?
Answer:
Secondary Succession; before the
sidewalk was built, an ecosystem
existed there.

43. Primary Succession occurs where no
previous ecosystem exists and
establishes equilibrium.
Secondary succession occurs after a
disturbance restores equilibrium.