NSW State of the Environment 2012

SoE 2012 > Biodiversity > 5.5 Fire

Biodiversity chapter 5

5.5 Fire

Fire is a significant and ongoing threat to human settlement. While fire plays an important role in the health of natural ecosystems, it is also a threat to ecosystem integrity. An improved understanding of the role of fire in natural systems is increasingly being factored into fire management.

Fire is a natural part of the Australian landscape. Altered fire regimes since European settlement – 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 many threatened species.

The key to achieving appropriate fire management is achieving the right balance between maintaining natural ecosystems and ensuring community safety and the protection of property, infrastructure and livestock.

One of the principal tools for fire management is hazard reduction burning. The level of hazard reduction activity in New South Wales has increased over the past three years to cover an average of about 138,000 hectares per year.

More than 50% of all bushfires are started by humans in most years, with arson being the major cause of such fires.

NSW indicators

Notes: These indicators only apply to areas managed by the NSW National Parks and Wildlife Service (NPWS).
Terms and symbols used above are defined in About SoE 2012 at the front of the report.

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. Much of the flora of NSW depends on fire to assist in reproduction and growth.

In Australia, fire has been managed since humans first settled on the continent. Although the fire regimes practised by Aboriginal people before the arrival of Europeans are not fully understood by the scientific community, 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 corporations and the need to protect dwellings, infrastructure, such as fences and sheds, and livestock have altered fire regimes and resulted in ecological impacts across a variety of landscapes.

Status and trends

Incidence of fire

The effects of bushfires in NSW are generally described in terms of their extent, social impacts and costs. Bushfires can be extremely destructive 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 have claimed many human lives, destroyed valuable property and infrastructure, and severely disrupted essential services.

The incidence of fire varies greatly each year (Table 5.18) with the number of fires closely linked to prevailing weather patterns. Total fire bans may be declared by the Minister for Emergency Services in any part of NSW, generally when hot, dry and windy conditions are predicted to occur in areas where vegetation is dry and fire could easily spread. The number of statewide total fire bans declared each year is indicative of the extent of forecast fire-weather conditions across NSW and hence the severity of the fire season.

The main factors determining the severity and extent of a bushfire are:

• weather conditions, including wind speed, temperature and relative humidity
• the dryness of the fuel, the type of fuel and the fuel load
• the physical structure of vegetation and the terrain in which the fire is burning
• the effectiveness of fire suppression actions.

Table 5.18 shows the number of fires and the severity and length of the fire seasons over the past nine years.

Table 5.18: Data on NSW bushfires, 2002–03 to 2010–11

Source: NSW Rural Fire Service (RFS) data 2011

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

Fire ecology

The impacts of bushfires are commonly described in terms of areas burnt and lives and assets lost, but this description provides little information on their ecological effects. These depend on:

• the intensity of a fire
• the season of the burn
• the previous fire history of an area
• the sensitivity of ecosystems affected.

Understanding the ecological outcomes of fire is further impeded by a poor knowledge of the responses of vegetation and wildlife to fire. Ecological communities are dynamic systems and fire is a natural disturbance that creates change. Fires shape the structure, composition and ecological function – including soil and nutrient cycles – of most plant communities, creating specific habitats required by a range of species. Differing patterns of fire history will favour some species and associations, and suppress others.

However when fires occur too frequently, even fire-tolerant species may become locally extinct due to their life cycles being interrupted. For example, a second fire in too short a time frame could kill all young plants and seedlings before they reach reproductive age, leading to the extinction of local populations of species. Conversely, the lack of fire may mean that fire-dependent species cannot regenerate, such as those that need fire for seed germination. Broad changes in fire patterns may result in habitat transformations, such as changes in the structure of vegetation, shifts from one vegetation type to another and reduced 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 5.2). 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 needed to maintain biodiversity have therefore been developed. These allow sufficient time between fires for species to complete the crucial stages of their life cycles essential for regeneration, such as plants being able to reach an age where they can produce adequate seed. Table 5.19 presents minimum fire intervals for a range of vegetation formations. Table 5.19 also shows the maximum fire intervals generally needed by various vegetation formations to allow them to regenerate before they become too old. The greatest biodiversity is maintained by varying the length of fire intervals between the maximum and minimum requirements as well as the location of fires (Kenny et al. 2003).

Table 5.19: Fire intervals for NSW vegetation formations

Source: Department of Environment and Conservation (DEC) data 2005

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

Refining knowledge about the frequency of burning and appropriate fire intervals for various vegetation formations in NSW is likely to remain the subject of scientific investigation for some time, due to the diverse array of species and communities and the time taken to determine the long-term effects of fire.

A key component of long-term monitoring of the effects of fire on ecological systems is matching fire history to vegetation formations. The NSW Rural Fire Service (RFS) is compiling fire history data across NSW, in conjunction with land management agencies. While there are still some limitations due to the nature of the historical data, it is now being collected on an annual, coordinated basis. The information on statewide vegetation is also being improved.

Fire management

Fire management strategies

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

The RFS develops regional bush fire risk management plans in consultation with the community. To achieve the objectives of these plans, some areas called 'strategic fire advantage zones' require fuel loads to be reduced more frequently than is specified by the minimum intervals for maintaining biodiversity (Table 5.19). Reduced minimum intervals have been developed for these areas that are absolute minimums for 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 is a key control strategy practised widely across the state. This burning is complemented by mechanical works, such as bulldozing, to maintain setbacks around properties, firebreaks and fire trails. The annual levels of hazard reduction burning and the total areas of hazard reduction management are described in Table 5.20. Over the past three years (for which data is available), the level of hazard reduction burning has increased to an average of about 138,000 hectares per year, from the previous level of about 112,000 hectares per year.

Table 5.20: Area of hazard reduction management by tenure

Source: RFS annual reports, such as RFS 2011

Notes: All values in hectares
* Includes burning and mechanical works, but not grazing of land.

Rapid response to outbreaks of fire

The early detection and rapid suppression of bushfires is a key control strategy for managing and preventing their spread. As access to fires that start in remote areas is often difficult, special remote area fire teams have been set up by the RFS and the NSW National Parks and Wildlife Service (NPWS) to enable a rapid response to fires that start in such areas.

Ecological burns

Although some managed burns meet both hazard reduction and ecological needs, there is limited information on fires conducted solely for ecological purposes, such as those that aim to ensure the maximum fire interval is not exceeded. However, the NSW Government is identifying areas where vegetation formations are underburnt or overburnt, based on both fire history records and the fire intervals identified in Table 5.19.

Effectiveness of fire management

To monitor the effectiveness of fire management through hazard reduction burning and rapid response in NSW national parks and reserves, NPWS is developing performance indicators for fire management. 'Average area of bushfires in the NSW reserve system' gives an indication of the effectiveness of rapid response techniques in preventing the spread of fires. 'Ratio – area of bushfires to area of management burns' provides an indication of the effectiveness of bushfire suppression through hazard reduction burning, improved detection and rapid response techniques.

Table 5.21 shows that results for both indicators are well below the 10-year average over the past four years, which may appear to demonstrate that the two strategies are being implemented successfully. However, climatic conditions over this period have not produced extended seasons of severe fire-weather and it is still far too early to assess the overall effectiveness of these strategies in controlling bushfires.

Table 5.21: Areas of hazard reduction and bushfire in NSW national parks

Source: NPWS data 2012

Notes: All areas shown are in hectares.

Pressures

Since fire is itself a pressure on the environment, this section discusses the risk factors that exacerbate the threat of fire.

Causes of fire

Data has consistently shown that the incidence of fire is markedly higher in the more densely populated areas along the NSW coast than in less densely populated areas elsewhere. There appears to be a strong relationship between the incidence of fire and population density. The proportion of fires caused by humans is higher in RFS data than the data compiled by NPWS as many national parks are located in less accessible areas.

RFS and NPWS data on the causes of fires indicates that most fires are due to human intervention rather than natural processes (Table 5.22). Such fires may be caused by arson, accidental ignition or escapes from prescribed burn-offs. Arson is the most common cause, responsible for over half of all fires. Investigations by the Australian Institute of Criminology into the causes of 466 fires using RFS data between 2001 and 2004 found that 64% were deliberately lit (AIC 2005a; AIC 2005b). However the number and proportion of deliberately lit fires has decreased over the past three years.

Table 5.22: Causes of investigated bushfires in NSW

Sources: RFS data 2012; NPWS data 2012

Notes: * Redefined from 'burn-off' in previous cycles of reporting

The main natural cause of fires is lightning strikes and the number and proportion of natural fires is highly variable from year to year. The proportion of naturally caused fires is higher in national parks and reserves, which are generally more remote from human settlement.

Fire and climate change

Bushfires are associated with high fire-weather risk which is expected to increase as a result of climate change (Hennessy et al. 2006). Projections indicate an increase in fire-weather is likely across south-eastern Australia (Lucas et al. 2007). The frequency of days with 'extreme' ratings on the forest Fire Danger Index (FDI) is predicted to increase by 5–25% for low climate change scenarios by 2020 and by 15–65% for high climate change scenarios. By 2050, the increases are forecast to rise 10–50% for low climate change scenarios and 100–300% for high scenarios.

A more recent study (Clarke et al. 2011) has predicted that the forest FDI is likely to increase strongly in southern NSW by 2100, but remain stable in the north of the state, as shown in Figure 5.8. Royal National Park and the forested escarpment behind Wollongong, including the Woronora Plateau, are at particular risk of more frequent and intense fires (Climate Commission 2011).

Figure 5.8: Predicted changes in fire frequency and magnitude

'Fire danger' seasons are predicted to become longer and start earlier in the year, but it is less certain 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. More intense fires will pose higher risks to human health, property and infrastructure (Williams et al. 2009) and increased fire frequency is likely to have detrimental effects on biodiversity and long-term consequences for terrestrial ecosystems (Banks et al. 2011).

Responses

Established responses

Legislation

Under the Rural Fires Act 1997 (RF Act), the RFS is responsible for preventing, mitigating and suppressing bushfires in rural fire districts. All functions performed by the RFS must be consistent with the principles of biodiversity conservation and ecological integrity stipulated by the Protection of the Environment Administration Act 1991.

Coordination of fire management

The RF Act provides for the establishment of the NSW Bush Fire Coordinating Committee (BFCC) and district Bush Fire Management Committees (BFMCs) which prepare and adopt bush fire risk management plans and operations coordination plans for each rural fire district. The risk management plans identify assets at risk from bushfires, including environmental assets, and specify a range of strategies and actions to protect these assets and the agencies responsible for their implementation. Strategies and actions include hazard reduction, property planning, community education, preparedness and ignition management strategies.

Bush Fire Environmental Assessment Code

The Bush Fire Environmental Assessment Code 2006 provides a streamlined environmental assessment and approval process for bushfire hazard reduction works. Assessments under the code consider the impacts of prescribed burning and mechanical works on natural values, including vegetation, threatened species, heritage items, soil stability, and air and water quality. Minimum fire intervals for vegetation formations (see Table 5.19) and threatened species guidelines must be considered. The code is currently being reviewed to further streamline environmental approvals for hazard reduction.

Planning and land use

Land-use planning decisions are intrinsic to fire management and environment protection strategies. Integrating protection against bushfires into the planning and development system through the BAL Risk Assessment Application Kit ensures safer developments in bushfire-prone areas. One strategy is to set development back from bushland at the planning stage to protect dwellings from bushfires. Proposed developments may be re-sited or redesigned if the environmental impacts of these setbacks are likely to be significant. Higher building construction standards may also be adopted to offset the setback distance required and contingency measures for fighting fires incorporated into the construction design.

Enhanced Bushfire Management Program

The Enhanced Bushfire Management Program (EBMP) was set up by the NSW Government in response to the findings of the 2009 Victorian Bushfires Royal Commission to prepare for a potential increase in the threat of bushfires. EBMP funding has been allocated to NPWS between 2011 and 2016 to increase the level of hazard reduction works conducted annually and improve bushfire response capability in parks and reserves.

A key component of the EBMP is the establishment of teams across the state to conduct hazard reduction works and respond quickly to outbreaks of fire in remote areas. These teams include specially trained and equipped personnel with dedicated planes on standby to enhance the capacity for early detection and rapid suppression of fires in remote areas. NPWS will monitor the effectiveness of these strategies through a suite of key performance indicators.

Community education

Community engagement activities and resources are a key component of the bushfire risk management program. The Hotspots Fire Project involves state agencies and non-government organisations and provides landholders and land managers with the skills and knowledge they need to protect life and property while protecting and maintaining biodiversity. The project promotes the understanding that well-informed and prepared communities complement the roles of land managers and fire agencies.

The RFS has also established the AIDER Program to assist infirm, disabled and elderly residents living in bushfire-prone areas to undertake fuel reduction activities.

Arson prevention

A range of measures have been implemented to reduce the rate of arson in NSW. Information sharing between agencies responsible for preventing and investigating arson-related fires has vastly improved, through establishment of the Bushfire Arson Taskforce and a whole-of-government intelligence database. The development of cross-agency strategies by Arson Prevention District working parties has also reduced the incidence of arson-related fires in those areas where they have been established. NSW will continue to support the National Strategy for the Prevention of Bushfire Arson implemented in 2009.

Knowledge and information

The Bushfire Risk Information Management System (BRIMS) stores data on fires across the state and is maintained by fire authorities and public land managers. 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 fires caused by arson and accidental ignition. Collated data on prescribed burns will also provide greater insight into how fire history affects fire management and environmental impacts.

Future opportunities

Fire management strategies will increasingly be based on better knowledge of fire behaviour and ecology, and better techniques for fire suppression.

There is scope for better maintenance and use of the data and information that is collected about fire. Information is improving, leading to more sophisticated analyses of bushfire patterns, effects and environmental impacts, and the use of decision-support and related applications such as digital mapping systems for fighting fires and managing hazards.

Support for new and ongoing research is essential for all aspects of fire behaviour, management and suppression. There is a need to learn more about fire ecology and how to improve building design, property management and community resilience to better cope with fire.

The incidence of high fire-risk days – and consequently the frequency of bushfires – is expected to rise. The number of days when it is safe to conduct hazard reduction burning may be reduced or move to earlier and later in the year. Under such scenarios, fire management strategies will need to be flexible and informed.