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Surtsey Island is an existing
example of succession.
What is succession?
· The colonisation of an area by communities of
plants and animals which are replaced by other,
more varied communities over time.…read more

Slide 3

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This occurs from the starting point of an
empty inorganic surface, such as bare
rock or a sand dune. This can be seen
after a volcanic eruption.
Primary succession
As plant biodiversity
Pioneer species (e.g. lichens and Once soil is present, other species
increases, so the diversity
mosses) penetrate the rock (grasses and ferns) can establish root
of animals that can be
surface. This helps to break it systems. When the roots die and
supported also increases.
into grains and traps organic decay the humus formed is added to
Eventually the
material that will break down to the soil. As the soil layer develops,
biodiversity and range of
form humus. The inorganic rock more water and nutrients are retained
species is generally
grains and the organic humus and become available for plant roots
constant and a climax
start to form soil. so that less hardy species can survive.
community is reached. A
climax community is self-
sustaining.…read more

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Climax community
Climatic climax community ­ a community that
remains generally constant over time.
Plagioclimax ­ a final community which is partly
the result of human intervention, e.g. chalk
grassland and lowland heath.…read more

Slide 5

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This is the evolution of an ecosystem from
existing soil that is clear of vegetation. It
occurs as rivers shift their courses and
after fires and floods.
Secondary succession
The soil is already formed and
contains seeds, roots and
organisms, so the numbers of The time it takes for a climax
plants and animals present right community to develop varies
at the beginning are much higher greatly. It depends on:
than in primary succession. · Temperature
· Rainfall levels
· Underlying fertility of the soil…read more

Slide 6

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Studying an ecosystem
Take a transect to study the topography of an area
­ the shape, height and depth of the land surface.
Use quadrats to measure the numbers and types of
plants ­ valid and reliable results.
To investigate animal communities use:-
quadrats,
nets,
pitfall traps,
soil samples.…read more

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