7.5 Fire

Fire is a significant and ongoing threat to human settlement and ecosystem integrity. An understanding of the role of fire regimes in ecological systems is increasingly being factored into decision-making.

Altered fire regimes since settlement (either too much or too little fire, or fire of too high or too low an intensity) can have major detrimental effects on the structure of most ecosystems and the populations of many endangered species.

Fire is a natural part of the Australian landscape. Getting the right balance between preserving natural ecosystems and the need to ensure community safety and the protection of assets is the key to achieving appropriate fire management.

One of the principal tools for fire management is hazard reduction burning, but the optimal level of burning is still a matter of debate in the scientific and public arenas. Over the past three years about 110,000 hectares of hazard reduction activity per year have been conducted in New South Wales.

Arson is likely to be responsible for over half of all wildfires, and increased community awareness and vigilance has an important role to play in fire prevention.

NSW indicators

A key component of long-term monitoring of the effects of fire on ecological systems is matching fire history to vegetation. The Rural Fire Service (RFS) is compiling fire history data across NSW, in conjunction with land management agencies. While there are still some limitations because of the nature of historical data collection, data accuracy is being significantly improved as it is now being collected on an annual, coordinated basis. Indicators will be able to be measured once a statewide vegetation layer becomes available.

Introduction

Fire has been present on the Australian continent for millions of years and is a key factor in plant and animal population dynamics in most NSW ecological communities. Many Australian animals and plants have evolved not only to survive, but also to benefit from the effects of fire. A substantial proportion of NSW flora depends on fire to assist in reproductive processes.

In Australia, fire has been managed since the earliest human presence. Although the fire regimes practised by Aboriginal people before settlement are not fully understood by the scientific community, it is evident that the pattern of fire in the landscape has changed over the past 200 years (Williams et al. 2001). The introduction of property ownership by private individuals and the need to protect stock and assets has altered fire regimes and therefore the ecology across a variety of landscapes.

Status and trends

Incidence of fire

Bushfires possess immense destructive force and may result in substantial social costs, including the loss of human lives, buildings, infrastructure and livestock. In extreme cases, such as the Canberra bushfires of 2003 and the Victorian bushfires of 2009, they are natural disasters that claim many human lives, inflict broad destruction on assets across the landscape, and severely disrupt essential services. The effects of fires in NSW are conventionally reported in terms of their extent and social impacts and costs.

The incidence of fire varies greatly each year (Table 7.14). The number of fires is closely linked to prevailing weather patterns. Fire bans may be declared by the Minister for Emergency Services for any part of NSW. This is likely when hot, dry and windy conditions occur or are predicted for areas containing dry vegetation where the potential for fire to spread is high. The number of statewide fire bans is indicative of the extent of fire danger weather conditions across NSW during a fire season.

Table 7.14: Bushfires and damage between 2002–03 and 2007–08

Source: RFS data 2008

Notes: * Derived by adding the number of fires from the four RFS regions. Any fire that occurred across the boundary of two regions will be counted twice.
** Section 44 declarations apply to fires where the RFS Commissioner controls operations.

The primary factors determining the severity and extent of bushfires are wind speed, temperature, relative humidity and dryness of the fuel. Other contributing factors include the fuel type, fine fuel load, the physical structure of the vegetation and the terrain in which the fire is burning. The effectiveness of fire suppression actions also determines the extent and severity of running fires.

Fire ecology

The impact of bushfires is commonly reported in terms of areas burnt and lives and assets lost, but this is an insufficient basis to determine the ecological effects of fires, which depend on fire intensity, season and previous fire history. Understanding the ecological outcomes of fire is further impeded by a poor knowledge of the response of animals to fire.

Ecological communities are dynamic systems where fire is just one of the natural disturbances that bring change. Fires shape the structure, composition and function of most plant communities, creating specific habitats required by a range of species. Differing patterns of fire history will differentially favour some species and associations, and suppress others, leading to variability in the landscape.

However, if fires occur too frequently, even fire-tolerant species may become locally extinct when their life cycles are interrupted by, for example, a subsequent fire killing adults and juveniles before they reach reproductive age. Conversely, the exclusion of fire may not provide an opportunity for the regeneration of fire-dependent species, such as those that require fire for germination of seed, also leading to local extinctions. Broad changes in fire patterns may also result in habitat transformation, ranging from structural vegetation changes through to a shift from one vegetation type to another, or decreasing habitat resilience to invasive species.

Altered fire regimes have been described as a threat to over 80% of the state's vegetation classes (see Biodiversity 6.1). High-frequency fire has been identified as a significant cause of biodiversity loss in NSW and is listed as a key threatening process under the Threatened Species Conservation Act 1995.

The interval between fires is a critical factor in the capacity of individual species to survive and reproduce (Bradstock & Kenny 2003). Minimum fire intervals have therefore been developed for the maintenance of biodiversity. These allow sufficient time between fires for species to complete crucial stages of their life cycles essential for regeneration, such as plants being able to reach an age where they are capable of producing adequate seed. Table 7.15 presents minimum fire intervals for a range of vegetation formations, Also included in Table 7.15 are the maximum fire intervals for a number of vegetation formations which serve as a general guide to their longer term requirements for fire to enable renewal of vegetation before senescence. The greatest biodiversity is maintained by varying the length of inter-fire intervals spatially and temporally within the specified range between the minimum and maximum intervals (Kenny et al. 2003).

Refining the frequency of burning appropriate for various vegetation formations in NSW is likely to remain the subject of scientific investigation for some time, in part due to the diverse array of species and communities and the length of time required to assess the long-term impacts of fire. This is also true with respect to gaining a landscape understanding of the ecological effects of changes in fire intensity and the season of burning.

Table 7.15: Fire intervals for vegetation formations

Source: DEC data 2005

Notes: * Vegetation formations are as described in Keith 2004.
** These intervals are absolute minimums with respect to maintaining biodiversity as they provide little or no buffer for adequate seed production.

Fire management

Fire management strategies

The emphasis of fire management should be on hazard reduction and minimising risk (Ellis et al. 2004). The primary objective of fire management by all agencies is to protect human life and property, with biodiversity conservation an important, but secondary, consideration. Asset protection zones provide for reduced fuel loads adjacent to houses and other assets. The most common method of reducing fuel in these zones is by mechanical means.

To achieve fire management objectives (specifically in the strategic fire advantage zones identified in bush fire risk management plans) some areas require fuel loads to be reduced more frequently than is required by the minimum intervals for biodiversity described previously. Reduced minimum intervals have been developed for areas where strategic fire advantage zones have been identified. These intervals are absolute minimums with respect to maintaining biodiversity as they provide little or no buffer for adequate seed production.

Biodiversity requirements can often be incorporated into fire management practices. However, compromises that result in suboptimal outcomes for biodiversity conservation may be required at times (DEC 2005) particularly in asset protection zones. Appropriate assessment is undertaken on a case-by-case basis in these circumstances.

Hazard reduction

Hazard reduction burning to reduce fuel loads outside the peak fire season is a key fire management tool practised widely across the state. This is complemented by other key measures, such as mechanical works to maintain setbacks around strategic assets, firebreaks and fire trails. The annual levels of hazard reduction burning and total areas of hazard reduction management are described in Table 7.16. These figures appear to be relatively stable with hazard reduction activities carried out on around 110,000 ha per year for the period reported.

Table 7.16: Area of hazard reduction management by tenure

Source: RFS annual reports, such as RFS 2008

Notes: * All methods includes burning and mechanical works

** Areas of hazard reduction do not include grazing land.

Ecological burns

Although some managed burns fulfil both hazard reduction and ecological roles, there is limited information available on fires conducted solely for ecological purposes, such as implementing burns to avoid breaching the maximum fire interval. However, the NSW Government is adopting the approach of identifying underburnt and overburnt vegetation types based on both fire history records and the fire thresholds identified in Table 7.15. The work of collecting data across NSW is still in development, although an example is provided in the Ben Boyd National Park and Bellbird Creek Nature Reserve Fire Management Strategy which is available as a series of maps in poster form depicting vegetation, fire management zones, fire history, fire potential and burning interval thresholds for vegetation.

Pressures

Fire, which is the subject of this issue, is itself a pressure on the environment. Therefore the discussion that follows in this section relates specifically to risk factors that exacerbate the threat of fire.

Causes of fire

Data from the 2002–03 to 2004–05 fire seasons indicates that the incidence of fire was markedly higher in densely populated areas along the NSW coast compared with larger but less densely populated areas elsewhere. There appears to be a strong relationship between the incidence of fire and population density.

Data on the causes of fire from both the RFS and NSW National Parks and Wildlife Service (NPWS) indicates that most fires are due to human intervention rather than natural processes. Such fires may result from arson, accidental ignition or escapes from prescribed burn-offs, with arson being the most common cause.

Using RFS data, investigations by the Australian Institute of Criminology into the causes of 466 fires between 2001 and 2004 found that 64% were deliberately lit and the proportion did not vary greatly in subsequent fire seasons. Data from NPWS supports this general pattern, with almost half of the fires started in national parks during 2003–04 attributed to arson, although this proportion has dropped in the latest data available (Table 7.17).

Table 7.17: Causes of investigated bushfires in NSW

Sources: AIC 2005a; AIC 2005b; DEC 2005; DECC data 2008

Fire and climate change

The incidence of wildfire is influenced by fire-weather risk, which is expected to rise as a result of climate change (Hennessy et al. 2006). A recent study projects the likely increase in fire-weather risk across regions of south-eastern Australia (Lucas et al. 2007). The frequency of days with 'extreme' ratings on the Forest Fire Danger Index is predicted to generally increase by 5–25% for the low climate change scenarios and 15–65% for the high climate change scenarios by 2020. By 2050, the increases are generally 10–50% for the low scenarios and 100–300% for the high scenarios. In addition, 'fire danger' seasons are predicted to become longer and start earlier in the year, but there is still some uncertainty as to whether the number of days when it is safe to conduct hazard reduction burning will decrease, or whether the window of suitable days will shift to earlier and later in the year than at present.

Responses

Fire protection and management

Under the Rural Fires Act 1997 (RF Act), the RFS is responsible for the prevention, mitigation and suppression of bushfires within rural fire districts. All functions performed by the RFS are required to be consistent with the principles of biodiversity conservation and ecological integrity stipulated by the Protection of the Environment Administration Act 1991.

The RF Act provides for the establishment of the NSW Bush Fire Coordinating Committee (BFCC) and district Bush Fire Management Committees (BFMCs) which are required to prepare and adopt bushfire risk management plans and operations coordination plans for each rural fire district. The risk management plans identify assets at risk from wildfire, including environmental assets, and specify a range of strategies and actions appropriate for the protection of these assets and the agencies responsible for implementing them. These include hazard reduction, property planning, community education, preparedness and ignition management strategies.

Operations coordination plans establish guidelines for coordinated firefighting and contain environmentally based restrictions. Operations maps also include provision for the consideration of environmental assets during firefighting operations.

The Bush Fire Environmental Assessment Code 2006 provides a framework for the environmental assessment and approval of bushfire hazard reduction. Environmental assessments consider the impacts of prescribed burning and mechanical works on natural values, including vegetation, threatened species and heritage items, as well as their effects on soil stability, air and water quality. Minimum fire intervals (see Table 7.15) and threatened species guidelines are a critical component of environmental assessments. Outcomes of these assessments are used by the RFS and some other authorities to issue conditional bushfire hazard reduction certificates that provide approval for conducting these activities.

Integrating bushfire protection into the planning system through the Planning for Bush Fire Protection framework will ensure safer developments in bushfire-prone areas. A key approach is the consideration during the planning phase of setbacks around dwellings to provide protection from bushfires. Proposed developments may be resited if the environmental impacts of these setbacks are likely to be significant. Higher building construction standards may also be adopted to offset the distance required for setbacks.

Community education and prevention

The FireWise program provides community-based support for at-risk groups and is a key component of the hazard management program. The RFS is also establishing the AIDER Program to assist infirm, disabled and elderly residents living in bushfire-prone areas to undertake fuel reduction and to support these residents in living safely and confidently in the community.

The Hotspot Project is a new program involving agencies and non-government organisations to assist landholders develop and implement fire management plans for their properties. Although the primary focus of these programs is on protection of life and property, all the elements of the programs take environmental issues into consideration when they are developed.

A range of measures has been implemented to reduce the rate of arson in NSW. In response to the 2001 Christmas bushfires, the Crimes Amendment (Bushfires) Act 2002 was passed, adding the new offence of lighting bushfires to the Crimes Act 1900. While some strategies, such as educational programs for school students and the thorough screening of volunteer firefighters, are designed to prevent the crime, others focus on developing better investigative techniques so that more arsonists will be apprehended.

Knowledge and information

The Bushfire Risk Information Management System (BRIMS) is maintained by fire authorities and public land managers. BRIMS provides a vital resource for the storage of data on fires across the state. Long-term data on where fires start and how they spread will be invaluable for determining fire management strategies, the allocation of firefighting resources, and the prevention of arson and accidental ignitions. Collated data on prescribed burns will also provide insight into the effect of fire history both operationally and from an environmental impact perspective. Only six years of data has been included to date so the full potential of the database is yet to be realised.

The NSW Government has funded the Centre for Environmental Risk Management of Bushfires at the University of Wollongong to conduct research into bushfire management issues. It also supports work being done by other research institutions such as the Bushfire Cooperative Research Centre (CRC).

Future directions

The incidence of high fire-risk days – and consequently the frequency of wildfire – is expected to rise due to climate change. The number of days when it is safe to conduct hazard reduction burning may be reduced or shift to earlier and later in the year. This creates the need for a flexible approach to the implementation of bushfire hazard reduction.

A recent innovation is the introduction of seasonal work crews to assist rural fire brigades with hazard reduction preparation. The extra assistance will allow fire brigades to concentrate on conducting more burns safely and effectively, thereby saving time and capitalising on windows of suitable weather.

Fire management strategies will increasingly be based on better knowledge of fire behaviour and ecology, and better techniques for fire suppression. This will help to counteract, to some extent, the effects of climate change.

Fire patterns have generally been approached as a natural response by fire to unnatural fire management regimes. Evidence is now emerging that, particularly near more populated areas, the pattern of fire is largely not of natural causes. The incidence of arson and knowledge of the behavioural patterns of arsonists is being increasingly incorporated into fire management strategies.

It is imperative to support new and ongoing research into all aspects of fire behaviour, management and suppression, as well as fire ecology, building design, property management and community resilience, to enhance our capacity for living with fire.

It is recognised that there is scope for better maintenance and use of the data and information that is collected about fire, and more could be collected. Alignment of the data held by agencies is improving, resulting in greater consistency of the figures reported. Information is also improving, leading to more sophisticated analyses of wildfire patterns, effects and environmental impacts, and particularly the use of decision-support and related applications for fighting fires and managing hazards.