Transcript Succession PPT

Ecological
Succession
TEACHER COPY
Amoeba Sisters
What is ecological succession?
A process in which the communities
of an ecosystem change over time
Regrowth of plants after a
disaster.
Primary Succession
Primary
succession occurs
in places where an
ecosystem has never
existed before.
Soil needs to be created
from rock
Primary Succession
Takes
a long time to
create the soil from
rock
Examples:
Volcanic
eruption
Glacial retreats
Glacial Retreat (when a
glacier melts & recedes)
Volcanic Eruption
Pioneer
Species – a
hardy species which is
the first to establish
itself and start the
process of succession
by breaking down the
rock & dying to create
soil.
Mostly mosses &
lichens
Lichens
Lichens
are a symbiotic
relationship between an algae
and a fungus. The algae
makes food for the fungus and
the fungus give the algae a
place to live.
What type of symbiosis is this?
What happens to the
pioneers?
After
some time, the
pioneer species get
pushed out once larger
slower growing species
take over.
How does succession end?
 The
climax community is the final stage
of succession  consists of stable
hardwood trees.
 Examples in Pennsylvania are:
Oak-hickory
Beech
Hemlock
Maple
Secondary Succession
Secondary
succession is the
process that begins in an
ecosystem when something has
disturbed or destroyed the natural
community
Secondary succession happens
when soil already exists from
previous ecosystem!!
Secondary Succession
Secondary
succession moves at a
faster pace than primary because
soil is already established.
New plants begin to grow from the
seeds and roots that are still present
in the soil. The pioneer species are
not necessary to create soil.
Causes of Secondary Succession
Natural communities can be
wiped out by fires, tornadoes,
hurricanes, and other catastrophic
events.

Causes of Secondary Succession
Other
Man-made causes are
abandon farmlands, polluted
streams, and land after heavy
mining.
Check for Understanding
Which type of succession occurs
after a volcanic eruption?
PRIMARY
Check for Understanding
Which type of succession occurs
when soil is already established?
SECONDARY
Check for Understanding
What is the term for the species
that first colonize bare rock?
PIONEER SPECIES
Check for Understanding
What is the term for the final
stage of succession?
CLIMAX COMMUNITY
Check for Understanding
Which type of succession occurs
at a faster rate? Explain why.
SECONDARY B/C SOIL IS
ALREADY PRESENT.
Check for Understanding
Which type of succession occurs
after a forest fire or tornado?
SECONDARY
Desertification
Desertification
is the
continuous dilapidation
(destruction) of
ecosystems in dry
regions. Eventually,
vegetation, water
sources & animals
become scarce (desert).
Desertification
Cause:
Poor soil
conservation leading
to soil degradation
It is more common
in dry climates
where the soil is
naturally thin
Desertification – its all about
the soil!
 Healthy,
productive soil is rich with
organic matter called humus.
 Humus= soil that's rich in essential
nutrients like carbon, nitrogen,
phosphorous and sulfur (from decaying
organisms)
 When topsoil is depleted of humus, it
could lead to destructive erosion.
Unsustainable
farming methods
are a huge contributor to soil
degradation!
Cutting
down trees and shrubs
Overgrazing animals
 Overuse of chemical fertilizers
 Failure to employ crop rotation
 Irresponsible irrigation
practices rob the soil of its
nutrients.

How to Prevent Desertification
 Good
farming practices include:
 Crop rotation
 Heavy composting
 Responsible use of chemical
fertilizers
 These ensure that the soil has enough
organic input to support microorganisms.
Desertification Example
The
Sahel Region of Africa is a
prime example of how overgrazing
led to desertification