The results of scientific research into the effects of fire on different types of bushland are an important influence on our planned burning program.
The information helps us understand the histories and life cycles of native plants and animals, the ways different plants and animals fit into their environment, and how fire affects them. Combined with other local knowledge, this helps us decide where and when to carry out planned burns, and how to reduce the impact of burns on the bushland.
Impacts on trees and plants
We carry out many planned burns specifically to maintain the health of plants and animals. These burns are called ecological burns. When we carry out burns to reduce fuel levels, however, the impact of the burn on plants is an important consideration.
Copying the cycle of fire
When planning burns to reduce fuel, we aim to copy the natural cycles of fire that suit the plants and animals in a particular area.
These natural cycles may have occurred due to events such as lightning strikes or burning practised by Indigenous Australians over the last 30-60,000 years. In a similar way to these natural events, planned burns in these areas are usually patchy, with parts of the area remaining unburnt. The burns are not as hot as bushfires, so most native plants are able to tolerate the heat.
Occasionally an unhealthy tree may die after a fire or planned burn. A small number of dead trees in a forest is normal however and these trees become important habitat for some animals, including some birds, mammals, reptiles and insects.
Fire survival features
Over thousands of years many native trees and plants in Victoria's bushland have developed ways to survive fire.
By the time native trees reach maturity, they have usually lived through more than one bushfire. In the first few years of their lives, they gradually develop features that help them live on after a fire. One way a gum tree does this is by creating a swollen mass of buds just beneath the soil. If a fire damages the tree, the buds quickly re-shoot and grow. Another way gum trees survive fire is to have small buds under the bark on the trunk of tree – ‘epicormic buds’. These are protected by the bark from all but the most intense fires and sprout following fire to ensure the tree has a quick way of producing leaves if the canopy has been burnt.
Protecting fire-sensitive plants
While most native plants need fire to remain healthy, fire can harm some plants, for example those that grow in alpine and rainforest areas where fires are extremely rare. In these areas we may leave long gaps between burns or may actually exclude burns entirely from these areas.
A number of plants, including threatened species, have very specific fire needs. We take special consideration of these plants or plant populations when developing burn plans, and will burn more or less frequently to find an appropriate balance.
Impacts on animals
In the same way that native plants have adapted to survive fire, most native animals have developed ways to live through bushfire or re-populate afterwards. Some animals are however, sensitive to fire.
We work with our partner organisations to carry out research to understand the needs of animals in different types of bushland and the effect of fire on animals and their habitat. We use this information when planning and carrying out a burn.
Lighting the burn
The way we light a planned burn can reduce the risk to native animals. Lighting a burn slowly and working from one end of the burn area to the other, prevents animals from being boxed in and gives them time to move away from the area.
Time to move away
Because the fire in a planned burn is not as hot as a bushfire, the flames are low and the fire moves slowly. This gives birds and other animals a chance to move into the treetops or underground, or to move away from burning areas. Some larger animals, such as kangaroos, can jump low flames and move into already burnt areas.
During a planned burn some areas are left unburnt. These areas are known as refuges. Animals can survive in the refuge areas and gradually return to the burnt areas as the plants recover.