Succession
We are looking at this section of the
specification:
To achieve the following grades, you should be
able to complete the tasks below:
Grade
D/E
C
B
A/A*
Learning outcome
Task
I can define the terms ‘succession’,
‘pioneer species’ and ‘climax
community’ (use the internet if
necessary).
Write the definitions of succession,
pioneer species and community.
I can identify a pioneer species and
put a range of organisms in the order
in which they would appear in a new
community.
Put a range of organisms in the correct
order in which they would appear in a
new environment.
I can explain why organisms appear in
a particular order.
Create a flow chart showing how one
organism would prepare the
environment to enable the next one to
grow.
I can evaluate ways of managing
habitats and conservation.
Successfully answer evaluation
question.
Succession
Succession is the
gradual change in a
community over time.
Primary succession occurs when
organisms colonize a lifeless habitat.
During succession
the organisms within
an ecosystem
change its abiotic
conditions.
This allows better
adapted organisms to
colonize the area,
replacing its current
inhabitants.
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Secondary succession occurs
when organisms re-colonize
a devastated
ecosystem.
© Boardworks Ltd 2009
Bare rock or barren land may result
from….
Glaciers
Lakes formed due to land subsidence
Silt and mud at river estuaries
Colonisation by pioneer species
5
minutes
The pioneer species is the first to colonise a new area.
Which type of organism would be well adapted to
colonising a bare, hostile (i.e. no nutrients, no shelter)
environment?
Discuss together and write a LIST of what the organisms
would need to do. Think about:
• How does the organism get there in the first place (seeds,
spores etc.)?
• What do the seeds/spores then need to do?
• Where do energy, carbon and nitrogen come from?
• Will there be shelter, water, habitats?
Succession
Each species in a succession changes the
conditions to make it more suitable for
subsequent species to survive.
Each stage is known as a ‘sere’ or ‘seral stage’.
Look at the animation on the next slide to see
how succession occurs on a sand dune (this is
also called a ‘psammosere’).
Sand dune succession
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© Boardworks Ltd 2009
Species adaptations during succession
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© Boardworks Ltd 2009
Succession on a rocky surface
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© Boardworks Ltd 2009
From pioneer to climax community
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© Boardworks Ltd 2009
Click the link below to watch a video
about succession:
http://educationportal.com/academy/lesson/ecologicalsuccession-from-pioneer-to-climaxcommunities.html#lesson
Making use of our knowledge of
succession
Each seral stage of
succession has distinct
biotic and abiotic
characteristics. It may
be necessary to halt
the process of
succession preventing
the climax community
forming, in order to
conserve unique
species.
Conservation of habitats
Unlike other plants, grass leaves
have their meristems at their base,
allowing them to continue growing
even when cut. Thus grasslands can
be maintained by mowing or grazing.
This can help to conserve some rare
wildflower populations which are
endemic to grassland ecosystems.
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© Boardworks Ltd 2009
North Yorkshire Moors – the heather would not
be there if the moors were not ‘managed’
So the grouse can be
shot…………..
Heather enables grouse to breed
(food and shelter)
Without conservation the NY moors would look
like this
The North Yorkshire Moors are not naturally covered in heather; without human
intervention they would be colonised with bracken. The moor is ‘managed’ – bracken is cleared
with herbicides to enable the heather to grow. The heather is important for the grouse (they
nest within the heather and young shoots provide food for their young). Heather is deliberately
burnt every year to enable the young shoots to regrow.
People who shoot grouse - ‘guns’ - rely on the moors being ‘managed’ so that they
have a supply of grouse to shoot (shooting season begins August 12th when the baby grouse are
big enough to shoot). Without the revenue from shooting the land owners could not afford to
manage the land and it would revert to bracken.
Evaluate the decision by the land
owners to manage the land. You
need to consider points for and
against maintaining the heather.
(a) Explain the meaning of the term
primary succession.
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[2]
starts with previously uncolonised area / bare
ground / bare rock / AW;
ref to pioneer species / named pioneer;
series of recognisable, seres / stages;
progresses to, climax / final equilibrium stage;
(b) Explain the role of pioneer plants in
succession on a bare rock or sand dune.
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[3]
stabilise environment;
soil development / increase humus / organic material;
change soil pH;
hold more water;
release more minerals or nutrients / increase N content or fix N / hold ions;
form microhabitat / reduce exposure / provide shelter / reduce erosion;
The figure below shows a primary succession in a
temperate climate.
X represents an example of deflected succession.
(c)Suggest two ways in which deflected
succession at X could be caused.
[2]
any two from following:
grazing;
burning;
mowing / application of fertilizer / application of
selective herbicide;
exposure to wind;
grass able to continue to grow (linked to a statement
above);
(d) Explain how biomass changes during a
primary succession.
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[2]
increases;
plants at later stages are large / plants in early stages are small;
trees / shrubs. are woody, appear later in succession;
Answer the application question on the back of
your sheet.
Show all of your work to your teacher.
Collect a set of exam questions.
Complete the questions.