The Role of Fuel Reduction Burning in Fire Management

Above, a well managed approach to mild fuel reduction burning with a series of small spot fires.

Following any wildfire season (known colloquially in Australia as bushfire) there are usually numerous examples in the media of people associated with State fire suppression agencies, as well as academics, putting forward their theories concerning the role of fuel reduction burning. Their theme has been “fuel reduction burning did not stop the bushfires, so it is of no use in fire management”.

Such comments are made by people with apparently little or no understanding or operational experience of wildfire behaviour, fuel reduction burning or wildfire suppression. These critics include academics who dabble in fire management from the supposed sanctity of their ivory towers. By their words it’s obvious that very few of them know anything about the realities of wildfire management. Their baseless opinions, if given credibility, will give rise to very dangerous wildfire management policies and a continuation of an increasing cycle of devastating wildfires, and further loss of lives, property and our beautiful forests.

Fuel reduction burning, sometimes known as prescribed burning, is not designed to stop wildfires. It is designed to make them easier, safer and less costly to suppress. Experienced land managers, firefighters, and genuine wildfire scientists who work closely with them, are in no doubt that the scientific, experiential and historical evidence demonstrates that prescribed burning, done properly, is highly effective at mitigating the wildfire threat, even under severe weather conditions.

The case for a broad scale fuel reduction burning program

  1.  Fuel loading in a forest is the only component of fire that can be modified by land managers.
  2.  No fuel = no fire, less fuel = lower fire intensity.
  3.  The goal of a fuel reduction burning (FRB) program is not to stop fires.  That would only be possible if all fuel was totally removed from all areas (no fuel = no fire).  The goal of a broad scale FRB program is to create a mosaic of burnt and unburnt areas of various ages and reduce the intensity of the inevitable wild fires.
  4.  FRB can be targeted at areas where fires are most likely to ignite – e.g. on ridge tops, dry northern slopes.
  5.  Broad scale FRB across the landscape will reduce the incidence of long distance spotting that occurs when fire intensity becomes extreme.
  6.  Lower fuel quantities mean that when a fire does start it burns less intensely and it is more likely to be contained at the first attack stage – see Photo 1.
  7.  FRB are planned to be slower and patchier than a wildfire. Not all of the vegetation on the ground is burnt and the upper parts of the trees are largely unburnt. This makes it easier for animals to escape the flames and provides habitat immediately after the fire. Due to the lower intensity of fuel reduction burning relatively low levels of smoke and embers are generated in comparison to a wildfire.
  8.  A large scale FRB program creates a mosaic of burnt and unburnt country of different ages which is important for species survival.  This is in stark comparison to mega fires as seen in 2019/20 (Photo 6) that burn millions of hectares, at the same time threatening the extinction of species.
  9.  FRB burns the fibrous bark on trees and make them less prone to spotting during a wildfire event – see Photos 2 and 5.
  10.  Creating a mosaic of burnt and unburnt areas across the landscape gives a strategic advantage to fire controllers when there are multiple fires in the landscape.  Those fires in recently burnt areas can have delayed first attack so that the controller can focus on higher priorities.
  11.  Recovery time for plants, animals and habitats following low intensity FRB is much quicker than after high intensity wildfire.
Photo 1 – Corringle Road area south of Orbost, 31 December 2019. Spot fire about 15 kilometres in front of the main fire head that was burning under extreme conditions (se Photo 3). Spot fire was in an area that was fuel reduced four years ago. Fire was easily contained with a bulldozer line.
Photo 2 – Coastal forest south of Princes Highway near Orbost. Area fuel reduced four years ago. note the light ground fuels, and the fibrous bark that contributes to spotting has been charred.

The arguments against a broad scale fuel reduction burning program

There are a range of arguments put forward against a broad scale fuel reduction burning program.  Some are listed below along with commentary and response.

Fuel reduction burning does not stop wildfires

Much of the debate around the effectiveness of FRB revolves around the fact that many areas which have been subjected to FRB in recent years have burnt again in wildfires. In many cases the statement is true.  However the goal of a FRB program is not to stop fires, which would only be possible if all fuel was totally removed (no fuel = no fire).  The goal of a broad scale FRB program is to reduce the intensity of the inevitable wildfires and assist firefighters to control them before they become mega fires, and minimise damage to the environment.

A one year old FRB can stop an intense wildfire – see Photo 3.

Photo 3 – Painted Line Link Track north of Waygara – main fire front burning from north-west (bottom right) on 31 December 2019, stopped by April 2019 fuel reduction burn – some scorch to vegetation in fuel reduced area for about 20 metres.

A two or three year old FRB can either stop a wildfire or change its characteristics from crown fire to ground fire – see Photo 4. The key issue following a FRB in an area is the lower intensity of any subsequent wildfire, reduced  impacts on the environment and the ability to control the fire.

The impact of wildfire on an area which has been subjected to FRB will depend on how long since the FRB was conducted and what proportion of fuel was removed during the FRB. In some fuel types the FRB has an impact on fire behaviour for many years – see Photos 1 and 2.

Photo 4 – 41/2 Mile Track north of Orbost – main fire front burning from north-west (top left) on 31 December 2019 stopped by two year old fuel reduction burn – some ground fuel burnt again in FRB area.

 The opponents of fuel reduction burning fail to realise the operational difficulty of fighting a wildfire in extreme conditions. The only option or tool that the land manager has available is the manipulation of fuel in the fire triangle: heat/ignition, oxygen/air and fuel.

There is no question that on extreme fire days fire control personnel would not attempt a direct attack in areas with heavy fuel loads. Even in a fuel reduced area, on extreme days there is no question that fires would burn through those fuels as well, but the moderating effect of that fuel reduction activity is quite profound and is very useful in assisting fire control personnel in the periods of the day when those extreme fire behaviours wane.

To claim that one individual FRB failed because a fire spotted over it or burnt through it demonstrates a lack of understanding of the science of a broad mosaic of burnt and unburnt areas. Many houses burn in open paddocks from flying embers that can travel through the air for kilometres. Fires need to be high intensity to create the updraft for these long distant spotting events to occur—fuel load is an important determinant of creating the fire intensity needed. So, if there is a mosaic of burnt and unburnt forest it is likely that there will be less intense fire behaviours and less long distant spotting.

The window of opportunity to burn is becoming shorter because of changes in climate

Though changed temperature and climate conditions might reduce the “windows” to carry out FRB around traditional and historical seasons, they will also open up opportunities to burn into late autumn and winter.

While it is recognised that in some years weather conditions are not optimal for FRB operations this should not be an excuse to not burn.  What is required is adaption to the changing circumstances:

  • Retain summer fire crews into the autumn and early winter to provide the necessary labour.
  • Burn into the evenings instead of during “normal working hours” when weather conditions are too hot.
  • Burn later into the season.
  • Burn through the winter in some locations, particularly ridge tops and road edges.
  • Incorporate a multi-stage burning approach for large burn units i.e. burn ridges and north and west facing slopes late autumn and south and east facing slopes early season.

There is normally an opportunity for a fuel reduction burning program to be carried out if the land manager has allocated adequate planning and resources to the program and is opportunist in application of the plan.

Some fuel reduction burns do “get away” and cause damage

The balance for when it is safe to conduct a FRB is a fine one between hot and sufficiently dry fuels to burn, but not so hot and dry that fire is likely to get out of control. Resorting to good science and good planning usually get the balance right. However, when dealing with natural systems it is possible for an unexpected change in conditions and a FRB may break from its planned boundaries. Dealing with the possibility of a breakaway is part of the planning for a FRB and when something does go wrong all the equipment and resources are on site to deal with it and the damage caused is usually relatively insignificant.

In rare cases there is more significant damage from a breakaway e.g. Lancefield and Wilsons Promontory, and then the media report it as though it is the normal outcome rather than an aberration. These instances lead to a more risk adverse approach by government. This is an issue which needs to be addressed and there needs to be support for those carrying out a difficult community service. Whilst such damage is regrettable it is insignificant compared with the damage from large high intensity uncontrolled wildfire.

Fuel reduction burning kills birds and animals

Fuel reduction burns are planned to be slower and more patchy than a wildfire. Not all of the vegetation on the ground is burnt and the upper parts of the trees are largely unburnt. This makes it easier for animals to escape the flames and provides habitat immediately after the fire. Due to the lower intensity of fuel reduction burning relatively low levels of smoke and embers are generated in comparison to a wildfire. A cool FRB will burn about 70% of the area leaving unburnt refuge areas for wildlife – see Photo 5 compared with the impact of wildfire  shown in Photo 6.

Photo 5 – Recent fuel reduction burn – crowns intact and patches unburnt over the planned area.
Photo 6 – Recent wildfire – 100% burnt including crowns.  No remaining habitat

FRB in recent years have been too hot and have caused damage to the environment

Some FRB in recent years have been hotter than planned. This is often due to aiming for the FRB to remove all the long term fuel load in one burn rather than a staged approach.  It is also due in part to the staff not adapting to two factors:

  • Fuel for FRB in recent years is the normal fine fuels: leaves and twigs, but also much of the heavy fuel: fallen branches, and logs, due to drought conditions.
  • Drier burning conditions.

Both of these factors require an adaptive approach when burning takes place – later in the day, later in the season, multi-stage burning or changed lighting patterns. Regardless of the fact that some FRB may have been too hot in recent years:

  • They have played a significant role in protecting communities.
  • They do not burn the gully systems so there is still protection of riverine ecosystems.
  • They do not burn the duff layer as do intense wildfires.
  • They do not burn 100% of the area so there are still islands for wildlife, etc.
  •  In comparison, the alternative is a large high intensity uncontrolled wildfire possibly with a crown fire burning 100% of everything.

It should be noted that when an area is burnt by a mega fire, any recent FRB area, even if it was hotter than planned, becomes the only green refuge for wildlife. There are numerous examples of this in East Gippsland following the recent fires – see Photo 7 as one example.

Photo 7 – Princes Highway at McKenzie River between Orbost and Cann River looking west.  Main fire front burning from the north-west at top right burnt all bush in the area except the area on the right which was fuel reduced two years ago.  It is the only remaining green bush in the locality.

Areas subjected to FRB will burn again

Those who use this argument against a broad scale FRB program do not understand the intent of the program, which is to set up a mosaic of burnt and unburnt country of varying ages to reduce fire intensity and rate of spread and to assist fire suppression operations.

A very recent FRB cannot burn again (no fuel= no fire) – see Photo 3.  However fuel will build up over the years following a FRB and the area will burn again.  The issue is, at what intensity it will burn. For instance, if an unburnt area of bush carries 12 tonne/hectare of available fuel and an adjacent area recently subjected to a FRB has built up to 4 tonne/hectare then the recently burnt area will burn at one ninth the intensity of the unburnt area.  This will almost certainly ensure that there will not be a crown fire and the subsequent ground fire will be controllable with ground resources.

The key is that the fire is less intense and hence environmental damage is lessened.

FRB creates smoke that may cause health issues and is annoying to some

It cannot be argued that FRB operations do not generate smoke over a period of days or weeks depending on atmospheric conditions. However, there is a relatively low level of smoke and embers generated in comparison to a wildfire  burning over a period of months as has  occurred during mega fires.

The smoke from a FRB can be controlled to some extent by when burns are planned and the anticipated weather conditions as compared with the intense smoke from wildfire, which is uncontrolled and unplanned in area and time.

FRB leads to species extinctions

Diversity of habitat is the most important factor in ensuring the survival of species.   A broad scale FRB program creates a mosaic of burnt and unburnt forest with varying ages since burn.  The diverse range of habitats this creates is an aid to species survival, particularly in comparison to the impacts of mega fires that burn 100% of large tracts of habitat and remove all diversity. 

Many research projects have provided no evidence of loss of components of diversity through FRB.  Research indicates that FRB certainly can change the species abundance on some sites but no species have been recorded as becoming extinct due to FRB.

Discussion

A broad scale fuel reduction burning program is not designed to stop wildfires.  The purpose is to make them easier and safer to control and to reduce their impact on the environment, and communities and their assets.

Reducing fuels works with nature rather than trying to control nature.  The natural scheme of fuel management was regular burning of the vegetation through lightning strikes and aboriginal burning that created a mosaic of burnt and unburnt land.  Therefore, when a wildfire occurred under extreme conditions its forward progress was slowed and the environmental damage was limited.  A broad scale FRB program seeks to duplicate this outcome.

To be effective, a FRB program needs to be across the landscape and burn between 5% and 10% of the landscape each year.  

Opposition to fuel reduction burning ignores the difficulty of fighting wildfire in extreme conditions. The only option available to land managers within the fire triangle is the manipulation of fuel loads. In extreme wildfire conditions a direct attack is futile and this can also be the case in areas where there have been FRB, however the moderating effect of fuel reduction activity is profound, and is very important during periods of the day when extreme fire behaviors wane. FRB across the landscape allows land managers greater flexibility and more options to suppress wildfire.

Summary

We have a choice. We can continue with the current policies and at regular intervals have large intense fires with the resulting loss of life, assets and ecosystems or we can work with nature and reduce fuel loads over large areas of the forest.

The irony is that to refuse to burn large areas of forest in a mosaic planned manner eventually results in the destruction of whole ecosystems and loss of life and assets in massive uncontrolled infernos. In recent history we have allowed this to occur over and over again.

If we do not try to modify fuels to change fire outcomes then what are we going to do?  To continue with the status quo is to accept more of the same outcomes with the same impacts on communities, community assets and the environment.

We need to act because more of the same is unacceptable!

2 thoughts on “The Role of Fuel Reduction Burning in Fire Management

  1. Dan

    HR burns are not substitute for Tradition Indigenous land management . The main reason for this is that within the 4 to 5 year time frame of HR burns thresholds, most areas treated with HR have almost the same fuel loads as before due to the dominance of mid story fire prone species. And lets not blame the forest threshold here because if we burn hot again with HR, research has proven that we lose species that are meant to be within that country type. Indigenous land management is the answer here. I do agree that the Australian landscape needs fire but has to be the right fire at the right time, done by the right people

    1. howittsoc

      Apologies for the delay responding, Dan. It’s an interesting issue you raise and we are thinking about how we could respond with the intent of raising it as a discussion opportunity on the website.

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