Fire

Fire is one of the most contentious and difficult land management issues in Victoria. It can bring the protection of nature into conflict with public safety: the material that fuels bushfires is also our biodiversity.

This apparent conflict is often seen as a reason for ‘trade-offs’ in management, or a reason to ‘sacrifice’ nature, but it doesn’t have to be that way.

Fire in the past

Over millennia, our native plants and animals have evolved in the presence of fire. Most plants can handle occasional fire, and some actually benefit from fire. But frequent fire can be a real problem for our plants and animals.

In more recent times, Aboriginal communities learnt how to use fire to promote different food plant species, and to attract animal species they wanted to hunt. They would burn different areas at different times and frequencies, always with a specific purpose. Today, some Aboriginal communities are employing fire management techniques based on traditional knowledge, but the appropriate extent and pattern of burning remains a topic of discussion.

Fire management today

How fire interacts with our native bush has become increasingly complicated by a number of factors:

• climate change is bringing more frequent and more severe fire weather
• introduced pest plants and animals also respond to fire: deer populations can thrive on new green growth after fire, and weeds like cape broom respond well to fire
• infrastructure of one sort or another occupies most areas of Victoria, and is often surrounded by grassland or bushland. This puts great pressure on our land managers to reduce the impact of fire in the landscape, largely through unprecedented levels of fuel reduction burning.

Fire and biodiversity

Fire ecologists have identified the ‘tolerable fire intervals’ for most Victorian habitat types.

The ‘minimum tolerable fire interval’ is the minimum time between fires that will allow an ecosystem to continue to be healthy e.g. the number of years required before re-grown plants are old enough to set seed. The ‘maximum tolerable fire interval’ is the number of years before a forest type gets old and starts to decay or senesce i.e. it needs to be ‘renewed’ by fire before this time.

This system is still contentious, as it is based on known fire responses of some plants only, and does not include impacts on animals and birds, for example. However, it is generally assumed that keeping a broad range of landscape ages between the minimum and maximum tolerable intervals, for each habitat type, is the best way to go.

The Department of Environment, Land, Water and Planning (DELWP) is required to report on the environmental impacts of its fuel-reduction burn program every year. However, in each report so far (for 2012-13, 2013-14 and 2014-5), DELWP has reported that it has failed to meet its objective of protecting biodiversity: about half of Victoria’s native bush is actually below the minimum tolerable fire interval, and much of that area is still subject to management burns.

What can be done to protect biodiversity, and also help public safety?

Studies by fire-behaviour specialists show that fuel-reduction burning is limited in its effectiveness on days of catastrophic fire weather, when the public danger is at its highest. And on those days, planned burns are also most effective if performed close to the settlements they are designed to protect, and less effective further afield.

There are many other important management initiatives we can employ to increase public safety without compromising our natural heritage. They include:

• an increase in rapid attack capability, especially aerial attack. Victoria is already good at this, but there is room for improvement. Aerial preparedness is expensive, but compared to the cost of damage from a severe fire it is a good investment
• an increase in surveillance of fire bugs
• stronger planning regulations, to avoid new house-building in fire-prone areas
• incentives (e.g. interest-free loans for approved household bushfire bunkers)
• compulsory evacuation from a fire zone, unless a householder has an approved fire shelter
• local power generation, to avoid fires caused by faulty power lines
• improved community education.

Fire management is difficult, and public safety will always be a priority, but we need to be clear about the limited effectiveness of fuel-reduction burns. And we have to work out what mix of management programs best achieves the two main objectives of fire management: protecting lives and looking after our natural heritage.

Watch a special presentation from Dr Philip Zylstra, Adjunct Associate Professor, Curtin University

Associate Professor Philip Zylstra’s research has focused on efforts to build a basis for fire management that has sound scientific foundations and applications. We hope his modelling and analyses of climate-vegetation-fire feedbacks will provide the guidance needed in the new climatic reality.

View Dr Zylstra’s presentation: