Council conducts prescribed burns to manage bushfire risk and preserve our biodiversity. Our prescribed burns are carefully planned well in advance to protect the community, our assets, and the environment.
Prescribed burning is an important component of bush fire management but cannot completely exclude bushfires. The protection conferred by prescribed burns reduces over time, with fuels accumulating to pre-fire levels within as little as four years in some cases. Even where fuel loads are still very low, extreme weather can allow bushfires to develop and carry. The only safe option on days of Extreme or Catastrophic Fire Danger Rating is to leave early, before a fire even starts.
There are two categories of prescribed burns that Council conducts: hazard reduction burns and ecological burns.
Hazard reduction burns
These are mainly for bushfire protection. They provide strategically located fuel reduced areas in the landscape which reduce the risk of large bushfires, enable the suppression of bushfires that do develop and reduce vulnerability of assets that are susceptible to fire. Hazard reduction burns quickly reduce fuel loads over large areas, however they provide only temporary protection and they are most effective where they complement other bush fire protection measures.
Ecological burns (also known as ecoburns)
Planned with specific biodiversity objectives in mind, such as providing improved habitat for threatened species or regenerating endangered ecological communities. Ecoburns are generally smaller than hazard reduction burns and form part of a broader program of ecological restoration. Weed and pest control activities are integrated with the ecoburn to optimise biodiversity outcomes.
Fire is an essential component of many ecological systems within Australia, but inappropriate fire regimes can reduce biodiversity and cause erosion. The frequency, intensity, and size of burns all need to be within certain parameters to maintain the health of the land.
Fire frequency is the most important environmental consideration. Many plant species rely on fire for their seeds to germinate. If there is a subsequent fire in an area before these plants have had time to mature and produce seed, they may be removed from the system. If fire is absent for too long, the seeds will lose viability and the species will be unable to re-establish. Prescribed burns must be undertaken in accordance with minimum fire intervals stipulated for the vegetation type.
Some fire-dependent plants require heat for their seeds’ dormancy to be broken. If a fire is very cool, only the seeds close to the soil surface will germinate and can also result in a lot of fuel remaining unburnt. Very hot fires can destroy seeds near the soil surface and can also remove a lot of canopy foliage, leaving the soil susceptible to erosion when it rains. High intensity fires are difficult to control and may escape and become wildfires. Prescribed burns are kept to low intensities through rearranging fuel distributions prior to the burn, conducting the burn during suitable weather, and utilising appropriate lighting patterns.
Prescribed burning aims to maintain a mosaic of long-unburnt and recently burnt bushland in the landscape. This ensures animals have a diversity of habitats and acts as an insurance policy in the event that drought or wildfire compromise post-burn regeneration. In Ku-ring-gai the bushland is fragmented and occurs in small, isolated patches and therefore our prescribed burns are generally small in size.
The completion of both hazard reduction burns and ecoburns is dependent on suitable weather, both on the day of burning and over the weeks prior. Therefore planned burns are not scheduled far in advance. Once burns are scheduled the community is notified via letterbox drops so that they can take action to reduce the impacts of smoke and noise.