Transcript Impacts of Bushfires

Impacts of
Bushfires
What effect do bushfires have on
the natural environment, the built
environment and people’s lives?
Impact of bushfire on the natural environment
• Depends on the
type of
environment
• Each fire has
some effect on
the environment
• Environment is
more severely
affected if
there are many
fires over a
period of time
Eucalypt forest
large eucalypt overstorey
layer of smaller trees
Bushes, grass and
litter layer
High intensity fires help seed germination.
Too high and they might be destroyed
Eucalypt forest
Such a fire also
changes the
amount of light,
transpiration and
wind, so that the
nature of the
vegetation cover
can be changed.
Eucalypt forest
If fires are too frequent,
some species, such as the
mountain ash, will
disappear to be replaced
by others that are more
fire-tolerant. The entire
over-storey could be
changed in this way
Eucalypt forest
This diagram shows what happens to light
penetration, transpiration and soil erosion after
a major high intensity fire.
Impact on Animals
Many animals are killed during fires, but rarely so
many as to threaten a species. Some, such as wombats
and echidnas might be able to shelter in burrows or
logs. Snakes flee. Possums may seek safety up high.
Impact on Animals
Some animals are subject to predation after the fire
through lack of cover. Others, like the possum might
find new sources of food
Many insects are killed by the burning of the bark and
litter that are their preferred habitat. Flying insects
can flee.
Impact on Soils
Effect of fire on Soils
• Can sterilise living
tissue in soils
• Ash-bed effect can
increase fertility of soil
• chemical structure of
the soil can be changed
• Changes in soil’s
permeability (its ability
to absorb water)
• Removal of vegetation
• Often results in
erosion.
Impact on Water
Fires can affect
the quality and
amounts of water
in creeks, rivers
and water supply
dams quality
through the
flushing of soil and
nutrients into the
streams if there is
heavy rain soon
after the fire.
Plant Regeneration
Each species has its own
survival features, which
assists it in recovery.
Grass Trees produce
flowers and seeds after
a fire and take
advantage of the
increased nutrient and
light availability.
Banksia seed pods open
and release their seeds
to grow in the ash beds
after a fire
Plant Regeneration
Treeferns are
protected by a thick
layer of bark. New
shoots emerge only a
few weeks after the
fire.
Some eucalypts, are
protected by thick
bark.
Mountain Ash trees
release massive
amounts of seed after
a fire (up to 14 million
seeds/hectare).
Plant Regeneration
Bark protects the
eucalypts' epicormic
buds which sprout new
growth quickly after
fire.
Many eucalypts have
woody swellings called
lignotubers at the base
of their stems. They
can reshoot at ground
level after fire.
Some wattles may
regrow from root
suckers, and/or soil
stored seed.