Wildfires

Question 1

What are wildfires

Answer 1

Wildfires are uncontrolled fires that destroy forests, grassland and other areas of vegetation. They usually occur in rural areas, but if they reach inhabited areas, they will also destroy agricultural land and settlements

Question 2

Ground fire

Answer 2

Ground fire is where the ground itself (e.g.peat and tree roots) burns. It is a slow, smouldering fire with no flame and little smoke.

Question 3

Crown fire

Answer 3

Is where fire moves rapidly through the canopy (the top layer of vegetation). Fires are likely to be intense and fast-moving.

Question 4

Surface fire

Answer 4

Is where leaf litter and low-lying vegetation burn. Fire can be low or high intensity.

Question 5

Vegetation type

Answer 5

Thick undergrowth or closely spaced trees allow fire to travel easily.
Some trees, such as eucalyptus and pine, contain a lot of oil and so burn very easily.
Eucalyptus trees shed strips of their bark which helps the fire to spread quickly.

Question 6

Fuel characteristics

Answer 6

Fine, dry material (e.g. long grass, thin twigs) catch fire and burn most easily.
Large amounts of fuel that form a continuous cover will help the fire burn for longer and spread.

Question 7

Climate

Answer 7

Rainfall must be sufficient for vegetation to grow, so there’s plenty of fuel.
The area usually has a distinct dry season when rainfall is low for a significant time. Warm, dry weather causes water in the vegetation to dry up, so it’s more flammable.
Strong winds provide more oxygen to help the fire burn and spread burning embers

Question 8

Fire Behaviour

Answer 8

Fire burns in different ways-e.g. a creeping fire moves across the ground surface fairly
slowly, whereas a running fire spreads rapidly and is more intense.
Fires can throw out burning debris (firebrands) that help the fire spread and become more intense.

Question 9

Natural Causes

Answer 9

lightning is particularly likely to start a fire if it occurs without much rain. Volcanic eruptions can produce very hot lava, ash or gas, which can start fires.

Question 10

Human Causes

Answer 10

Most fires are started by people. This can be accidental, e.g. by dropping cigarettes, allowing campfires and barbecues to get out of control, or if fireworks or sparks from machinery land in vulnerable areas. Fires can also be started on purpose (arson).

Question 11

Primary Impacts

Answer 11

These occur as a direct result of the fire, e.g. houses burning down.

Question 12

Secondary Impacts

Answer 12

These occur as a result of the primary impacts, e.g. people have to move.