Prescribed Burning and Risk in Tasmania

The autumn burn season is well underway in lutruwita/Tasmania. Prescribed burning is important because it helps us to mitigate bushfire risk, and care for and maintain the rich diversity of species and ecosystems across this state. Prescribed burning is also a deeply important and spiritual practice for Aboriginal people as they connect with country and work to keep country healthy.

In Tasmania, the state government funds a cross-tenure prescribed burning program, which means that the government funds and organises prescribed burns across public land, such as national parks and game reserves, and private land, particularly on farms and larger rural properties. Resources and appropriate weather conditions are a constraint. For example, a prescribed burn will only be successful if it is not too wet, but also not too hot, dry and windy. To get the best possible outcomes, given the resources and weather conditions, prescribed burns are prioritised and funded on the basis of risk.

But what is meant by risk?

Risk is about a combination of two things: how likely it is that something (i.e. a major bushfire) will happen; and what are the consequences if that thing happens. The Tasmanian Vegetation Fire Management Policy describes risk in terms of economic or financial loss, physical damage, injury or delay. This definition of risk is pretty restricted and doesn’t do a good job of taking into consideration less tangible factors, such as cultural traditions and landscapes that contribute to a sense of place.

Another important consideration when thinking about risk is ‘natural values’, that is, environments and species that we really value. Some examples include pencil pines, deciduous beech and Huon pines.

These are all examples of rare and endemic (that is, only found here in Tasmania) fire-sensitive species and ecosystems.

They are also increasingly recognised as ‘assets’ for which prescribed burns can be designed, as a way of protecting them from bushfire risks, and as such, are able to fit into the current way of applying risk to prescribed burn planning.

Using this concept of risk to guide and prioritise prescribed burning is important, but we are worried that the current approach to risk assessment only considers how likely something is to burn in any given fire season. What is missing in Tasmania is an assessment of the risk of inappropriate fire regimes, which are often more of a threat than one-off catastrophic bushfire events.

When we think about fire regimes, we are not focusing just on individual events, but the pattern of fire in time and space. For example, fire regimes include the time since the last fire, the season, the fire size, the fire ‘patchiness’ (that is, did it burn everything in its path, or did it burn in patches), the fire interval and the fire intensity.

When fire regimes change in an area, the vegetation in that area changes too, as plants vary in their tolerances to fire. One of the objectives of prescribed burning might be to achieve vegetation change. For example, repeated burning of a dry forest might thin out the tree cover, and cause the forest to change (‘transition’) to a woodland. This might be desirable because woodlands have lower fuel loads. However, the opposite can also occur, with burning triggering a flush of regrowth, which creates higher fuel loads, that is, more fuel to burn next time.

For that reason, a good understanding of ecology is critical to good fire management. Tasmania has lots of vegetation communities that require regular fire for their maintenance and also for the species for which they are habitat. If these vegetation communities are unburned for too long, they can transition to a different vegetation type, which might mean that we lose the original communities forever.

This means that the diversity of the vegetation that we have across Tasmania is a choice. This choice is something that Aboriginal people in Tasmania have always known, because Aboriginal people have been deliberately applying fire to the landscape to nurture and sustain vegetation communities for millennia.

The risk of ecosystem loss due to inappropriate fire regimes is a missing element in the current risk approach to prescribed burning in Tasmania despite being identified as a necessary part of the prescribed burning risk management framework established by Australia’s peak fire council, AFAC.

In Victoria and New South Wales inappropriate fire regimes are factored into the definition of risk and we need to start doing this in Tasmania too.

For these reasons we need to reconceptualise the way we think about prescribed burning in lutruwita/Tasmania. We need to move away from a risk assessment that is only focussed on a narrow definition of risk and develop a holistic approach that protects both assets and the environment.

Until we do this we are going to struggle to maintain habitat for our unique and precious threatened species, such as the New Holland mouse, or our beautiful montane grasslands. We are also going to struggle to protect and maintain internationally significant places, including Aboriginal cultural landscapes in areas such as the Tasmanian Wilderness World Heritage Area – living examples of the effect of millennia of active fire management by the first land managers of this state.