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

High intensity fires help seed germination.Too high and they might be destroyed

large eucalypt overstorey

layer of smaller trees

Bushes, grass and litter layer

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 forestIf 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 foodMany 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 RegenerationEach 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 RegenerationTreeferns 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 RegenerationBark 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.