Download Succession

SUCCESSION
Change of ecosystems over time
• New habitats are created when a volcano forms
a new island, a glacier recedes and exposes
new rock or a fire burns all vegetation in an
area.
How does an ecosystem develop?
We can study that by watching
what happens in an area
where there has never been
soil
Primary succession
• Succession that
occurs where plants
have not grown
before is called
primary succession.
Primary succession following
the retreat of a glacier.
Soil begins with weathering of
rocks and establishment of lichens
• First come lichens, which attach to rocks,
reproduce – some die.
Microscopic fungi and bacteria can move
in to decompose the dead lichens. With
decomposition, nutrients are added to the
soil. The soil can now support small fastgrowing plants. Seeds are deposited by
winds or birds.
LICHENS
Mutualism!
Fungi help
fasten the
lichen to rock ,
algae do
photosynthesis
to feed the
fungi
Pioneer species
• The first organisms to
live in a new habitat
are small, fastgrowing plants, called
pioneer species.
As the pioneer species reproduce and die, they
are decomposed and add more nutrients to the
soil.
Before long, the deeper richer soil supports the
life of more types of plants- this is the start of
BIODIVERSITY.
More and larger plants provide a home for insects
and small animals, which move in, reproduce and
die. Their remains makes the soil thicker and
richer.
Primary succession
• The same ground 2
years later,
is now covered in
grasses and
flowering plants,
and a host of
insects and animals
Over time….look what happens!
• SUCCESSION!!!!
Secondary succession
Succession that occur in areas
where there has been previous
growth. Soil is already present.
Secondary succession
• A recently cleared
patch of ground, left
to grow in its wild
state
After flood or fire
Soil is present
• Secondary succession happens quickly
• The stable community that remains will
depend on the climate, and abiotic factors.
• A stable desert community looks very
different from a temperate forest!...WHY??
Does the picture below represent primary or
secondary succession?
One last type of succession…
pond to meadow
HILTON POND- Piedmont NC 1982
The same pond, 10 years later
Flagg Pond
• Our pond on the BHS campus was once used
for canoeing and swimming. It was used to
harvest ice in the winter for Ice boxes, before
refrigerators were common. It is now getting
close to the later stages of succession…..
• Go take a walk- look for the signs of succession!
One thing is constant in
ecosystems…
THEY ARE ALWAYS
CHANGING!!!
