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The pursuit of greener urban areas in NSW will bring us resilience to climate change and increased liveability but if we’re not careful, urban greening policies could be the kindling for future bushfire events that destroy lives and property. The good news is there are a host of techniques that allow us to vegetate responsibly, such as choosing fire retardant plants and putting them in the right spots. This is a long read but an important piece highlighting an issue that’s been largely overlooked. It’s relevant for other states and territories as well.

Our last bush fire season in eastern Australia has left most of us in shock.  We are being told by scientists that climate change will result in more hot, dry and flammable summers and extended fire seasons.

Meanwhile, the NSW government and the Greater Sydney Commission have been calling for a greater greening of our cities necessary to reduce urban heat as the climate warms. This is in response to a progressive erosion of urban vegetation due urban densification, new infrastructure, complying development and the 10/50 Vegetation Clearing Scheme in bush fire prone areas. So how should we plan our cities to be more resilient when there is this obvious policy tension?

The NSW government has a number of policies to encourage green connected corridors through the urban landscape and an increase in tree canopy coverage. Its aim is not only to mitigate urban heat, but also to improve walkability, liveability, public health, biodiversity and attractiveness. These policy documents include:

  • The Greater Sydney Regional Plan includes a target to increase tree canopy cover to 40 per cent, up from the current 23 per cent as a mechanism to adapt to climate change and manage the urban heat island effect.
  • The Greater Sydney Commission’s five district plans for Sydney incorporate planning priorities to protect and enhance bushland, biodiversity and waterways, conserve and restore bushland corridors, refine detailed design and delivery of the Greater Sydney Green Grid priority corridors, increase urban tree canopy to mitigate the urban heat island effect and reduce vulnerability to extreme heat and reduce exposure of natural and urban hazards.
  • Of the 14 NSW Premier’s Priorities, the 11th aims to increase the proportion of homes in urban areas within a 10 minute walk of quality green, open and public space by 10 per cent by 2023. The 12th Priority aims to increase tree canopy and green cover across Greater Sydney by planting 1 million trees by 2022.

While increased urban greening has enormous advantages, it also raises some challenges – chiefly that vegetating with trees, understorey and grass communities may result in increased bush fire risk near or within identified bush fire prone areas.

Councils have recently prepared draft Local Strategic Planning Statements (LSPS) to articulate how they will revise their Local Environmental Plans (LEPs) and Development Control Plans (DCPs) to implement their District Plan priorities, including greening Sydney, improving resilience and managing hazards. It’s essential, in implementing these planning instruments, that the community remain confident that their lives, assets and neighbourhoods will not be put at risk.

Unfortunately, many urban greening strategies do not adequately consider bush fire risk. In addition, the Rural Fire Service Planning for Bush Fire Protection 2019, which came into effect on 1 March 2020, provides NSW with standards for designing and building on bush fire prone land, but does not mention the need to consider bush fire risk in urban greening strategies.

Given the absence of policy guidance on balancing urban greening with bush fire risk, this piece sets out to fill this gap.

The key is following a set of “place based planning” principles when preparing policies and strategies for urban greening and bush fire risk management.

How bush fires behave

Let’s look at how bush fires behave to get a better idea of how to respond. The term “bush fire” is used to describe fires that occur in any form of vegetation including forest, rainforest, woodland, heath and grass.

Bush fires are unpredictable. Their probability of ignition and location of ignition are difficult to predict and their rate of spread depends on many factors including weather conditions and fuel loading.

Bush fires in Australia are becoming more frequent and more intense. Many put this down to the effects of climate change increasing global temperatures, leading to hotter and drier conditions.

Although bush fires are unpredictable, there are features that we do understand and can use to incorporate into risk assessments for “urban greening”:

  1. Fuel

Without fuel, a fire cannot burn. And fuel, in this context, is the vegetation itself.

The structure and composition of vegetation affect the ability of a fire to take hold and burn quickly. Bush fires need a continuous path of vegetation to be able to continue to burn, meaning the arrangement of fuel is a significant factor in bush fire behaviour.

In forest, woodland and shrubland, fuel can be divided into four layers:

  • Surface fuel – fine fuel including leaves, twigs and bark
  • Near surface fuel – fuel effectively in touch with the ground but not touching it
  • Elevated fuel – mainly upright in orientation with a clear gap to the surface fuels
  • Canopy – the crown of the tallest layer of trees. (Overall Fuel Hazard Assessment Guide)
Fuel layers and bark. Image taken from Overall Fuel Hazard Assessment Guide 4th Edition July 2010 Victorian Government Department of Sustainability and Environment.

A fire ignites in the surface fuel, and may carry through each different fuel layer until it reaches the canopy. The rate of spread of the fire and flame height are dependent upon how much of the fuel structure the fire is consuming.

Once in the tree canopy, this is when the fire is most intense, called “crowning”. The size and shape of vegetation determines whether the fire can become developed enough to crown.

The bark of trees is also an important factor in the spread of fires. When bark breaks away from the trunk of a tree while alight, it forms burning embers which can travel long distances ahead of a fire front and create spot fires that increase the rate of spread dramatically.

Burning embers can also penetrate assets (such as houses) leading to their damage or destruction. Evidence has shown that embers are responsible for the majority of house losses in bush fire events.

  1. Climate

Climate has a huge impact on bush fire ignition and behaviour. The hottest and driest days are those when the bush fire risk is elevated. Drought leads to the drying of vegetation and lower fuel moisture content, allowing the fuel to burn more readily.

Wind speed and direction is also an important factor. On the east coast of Australia, winds from the north and west are hot and dry, making bush fires far more likely.

However, bush fires do not exclusively burn under north westerly winds. In fact, they can burn under any wind direction. Particularly dangerous conditions occur when a wind change pushes the fire front in a different direction.

  1. Topography

In simple terms, fires burn faster uphill. This in turn increases the intensity and heat of the fire. Fires do burn downhill but, generally and depending upon climatic conditions, burn at a slower rate of spread.   

Choosing the right plants for the right spots

Given Australia’s long bush fire history, experts have developed an understanding of:

  1. which plants are more fire prone than others,
  2. planting layouts that can minimise fire spread, and
  3. appropriate asset protection zones.

This information is contained in the NSW Rural Fire Service Planning for Bush Fire Protection 2019 and other guidance documents, and should be included in urban greening plans, policies and strategies to reduce bush fire.

One way urban greening and bush fire protection can coexist is to focus on selecting species and planting layouts which, by their very nature, provide mitigation against bush fires.

Although all vegetation can burn in extreme fire conditions, some species are less likely to ignite or burn intensely due to higher moisture, salt and lower volatile oil content in leaves.

Furthermore, the growth characteristics of some vegetation make them less prone to fire spread, including large or hard leaves with simple margins, dense crowns, elevated branches, smooth, hard or persistent bark rather than flaky or ribbon bark and plants that don’t produce a lot of leaf/twig litter below them or suspended in foliage.

Where carefully chosen, rows of trees can “provide a wind break to trap embers and flying debris” that otherwise could reach a house or asset”. A row of trees is not a fire path unless it’s part of a continuous corridor of vegetation that includes surface, near surface and elevated fuels.

An asset protection zone (APZ) is a fuel reduced area surrounding a built asset or structure. Species selection and planting layout with adequate vertical and horizontal separation between plants are very important when replanting in an APZ to avoid increasing fire risk.

Management and Landscaping to Reduce Bush Fire Risk. Source: NSW RFS Standards for Asset Protection Zones p. 10

An APZ distance is applied to a new development through the land use planning system in NSW or to existing development through the Hazard Complaints process. The APZ is based on slope, vegetation type, the nature of the development and location. APZs comprise an Inner Protection Area (IPA) and an optional Outer Protection Area (OPA) component for forest vegetation. Where urban greening is proposed, the standards for asset protection zones could be appropriate for any vegetation planted.

PBP 2019 provides specific vegetation coverage for IPAs and OPAs which should be followed where urban greening is proposed.

Maintaining IPAs and OPAs to those standards should be ongoing and in perpetuity. Compliance can occur through the development enforcement procedures. However, lack of maintenance of APZs is a significant factor in property loss during bush fire events.

Councils need to plan for and invest sufficient resources to ensure maintenance of APZs on public land. Resources also need to be allocated to educating residents and businesses abutting or within bush fire prone areas, about their obligations to maintain their APZs.

Planning for Bush Fire Protection 2019 Vegetation Requirements for Establishing an Inner and Outer Protection Areas.

What about the existing legislative framework? 

Before proposing principles and measures to consider when preparing urban greening and bush fire risk management plans, policies and strategies, we need to summarise the legislative framework.

Strategic Planning Phase

Considering bush fire hazard at the strategic planning phase is required under s.9.1(2) of the Environmental Planning and Assessment Act 1979 (EPA Act) to identify if new development is appropriate based on the identified bush fire risk on a landscape scale.

Historically these decisions have been made on the basis of vegetation patterns at the time of assessment. Now the GSC requires councils to consider urban greening plans such as the green grid, biodiversity corridors and urban canopy in their strategic planning processes. Current legislation allows for their consideration when assessing bush fire hazard at the strategic planning stage.

Planning for Bush Fire Protection (PBP) 2019, states that draft LEPs should aim to protect life, property and the environment from bush fire, by discouraging the establishment of incompatible land uses in bush fire prone areas and encouraging sound management of those areas.

According to the PBP guidelines, the NSW RFS Commissioner should be consulted in the development of regional strategies and plans and is legally required to be consulted in the preparation of draft LEPs to ensure that appropriate strategies are developed and future conflicts do not occur.

Furthermore, when amendments are proposed to a DCP, proof of compliance or conflict with the requirements in PBP is required. It is also recommended that the Commissioner be consulted. Similarly, consultation should occur with the NSW RFS for any Masterplan or Precinct Plan on bush fire prone land. Although not specifically mentioned in PBP, this process should include urban greening strategies, policies and plans.

Bush fire prone land maps

Identification of Bush Fire Prone Land (BFPL) is required under s.10.3 of the EPA Act.

Each council prepares a BFPL map in accordance with NSW RFS Guide for Bush Fire Prone Land Mapping 2015 and each map is to be certified by the NSW RFS Commissioner. The maps are revised and recertified at least every five years and the Commissioner can amend the map at any time. (NSW RFS PBP 2019).

The NSW RFS guidelines for preparing BFPL maps state “Changes to the landscape may occur from time to time and therefore the certified bush fire prone land maps may not be a true indication of bush fire risk.” Consequently, councils are required to regularly monitor and review their maps depending on the extent of vegetation changes within the LGA, which includes vegetation regrowth and clearing as well as changes to the urban development footprint.

BFPL maps indicate appropriate buffers ranging from 30-100 metres based on three fire prone categories and provide councils with a clear indication of where greening is appropriate, where it must be carefully planned and managed, and where it is unsuitable.

For urban release areas, land/vegetation should be mapped as bush fire prone where it has been rezoned as environmental protection or areas where a riparian corridor, nature reserve or similar is proposed and management is not guaranteed.

This is required even if the area has not been fully established or the vegetation in its current form is in its infancy.

Place-based planning

The place-based planning (PBP) guidelines provide guidance for place based urban greening that relate to:

  • asset protection zones,
  • vegetation formations and classification,
  • fuel loads,
  • low threat vegetation exclusions (based on size and dimensions of the vegetated area),
  • exotic vegetation, and
  • assessment of remnant bushland and narrow vegetation corridors.

The relevant principles include:

  • Undertake a bush fire landscape assessment to determine bush fire risk at the macro-scale, looking at fire runs, topography, especially steep slopes, vegetation, weather and the amount of development interfacing vegetation and areas of isolation;
  • Consider fire-fighting access and evacuation potential;
  • Facilitate appropriate ongoing land management practices (The intention of an APZ is that it is managed in perpetuity if imposed by a development consent condition);
  • Exclude inappropriate development in high bush fire risk areas; =
  • Consider the potential to adversely effect other bush fire protection strategies or place existing development at increased risk; and
  • Assess remnant bushland and narrow vegetation corridors for suitable asset protection zones that may be less than for larger bushland parcels.

Low threat vegetation exclusions not required to be considered for the purposes of PBP include:

  • Single areas of vegetation less than 1 ha and greater than 100m separation from other areas of Category 1 or 2 vegetation;
  • Multiple areas of vegetation less than 0.25 ha and not within 20m of the ‘site’ or each other or other areas of classified vegetation;
  • Strips of vegetation less than 20m wide, regardless of length and not within 20m of the “site” or to each other, or other vegetation in category 1,2 or 3; and
  • Vegetation of low threat (low flammability and fuel load) including managed grassland and lawn, mangroves, saline wetlands, maintained public reserves and parks, sporting fields, gardens, nature strips and windbreaks.

Ideally, councils should clearly define the areas within their urban greening programs that are excluded from PBP for transparency purposes and update their BFPL map accordingly.

Bush Fire Risk Management Plans

Each Council has a representative on a Bush Fire Management Committee who are responsible for preparing a Bush Fire Risk Management Plan (BFRMP).

The purpose of the plan is to reduce human-induced bush fire ignitions, manage fuel, reduce the community’s vulnerability by improving preparedness and containing fires. Although it is currently not specified in guidelines, urban greening programs need to be taken into account when preparing these plans.  

10/50 Vegetation Clearing Scheme

The 10/50 Scheme was developed to improve public safety in fire prone areas with minimal “red tape”. It has proven controversial and a blunt tool to empower land owners of existing buildings to clear trees on their property within 10 metres of existing homes and to remove underlying vegetation on their property within 50 metres of a home without seeking approval.

Although exclusions apply, such as vegetation listed under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999 and critically endangered vegetation under the NSW Biodiversity Conservation Act 2016, the tool largely relies on self-assessment and no consultation with experts or councils, leading to destructive consequences for biodiversity and urban canopy.

The 10/50 Code does not protect endangered ecological communities or threatened species listed under NSW law from removal under the code. Consequently, it is challenging for councils to influence or maintain urban greening on private property adjacent to or within fire prone areas or protect biodiversity values as they lack the statutory powers.

How to achieve greener cities without creating additional bushfire risk

From what we know about bush fire behaviour, vegetation, planting layout and asset protection zones, as well as the legislative framework, the following principles should be applied to urban greening plans, policies and strategies:

  1. Do not increase vegetation connectivity or canopy in or near bush fire prone areas beyond Planning for Bush Fire Protection Guidelines 2019 vegetation requirements for establishing Inner and Outer Protection Areas – Where existing bush fire prone land exists, any new vegetation or regeneration of a vegetation community which has previously deteriorated next to or close to that vegetation, increases bush fire risk. Land does not need to be formally mapped as bush fire prone for this to be an issue, as some bush fire prone land maps are not fully up to date. The NSW RFS Bush Fire Prone Land Mapping Guidelines include criteria for pockets of vegetation which are excluded from the definition of Bush Fire Prone Land by virtue of their lack of connectivity to other areas of bush fire prone vegetation. Increasing connectivity to these areas could make them and adjoining land, bush fire prone.
  2. Keep the size of vegetation minimal – Small and narrow areas of vegetation are less likely to support a fully developed bush fire. Fire behaviour calculations for development planning assessment, apply the flame length and fire head width generated to determine its radiant heat impact upon assets. If the flame length and head width can be minimised, so can property impacts. These principles are discussed within the NSW RFS Short Fire Run Methodology.
  3. Choose vegetation to minimise fuel load and fire intensity – Different classifications have different fuel loads. Keeping the fuel load to a minimum in any new vegetation can ensure that the bush fire risk is also kept to a minimum. For example, a rainforest community has a much lower fuel load than a sclerophyll forest community.
  1. Manage vegetation structure to ensure it is less likely to support a fire or obstruct fire-fighting access or evacuation potential – Vegetation can be managed in a minimal fuel state to ensure that the full vegetation structure is not present. This would be akin to managing fuel as an asset protection zone (APZ) (see APZ discussion below).
  2. Minimise continuous fire pathways – The shape and length of vegetation can support corridors of fire. When corridors are continuous, they can lead the fire to assets. Providing breaks within corridors can break or slow the spread of a fire and thus reduce the risk.
  3. Assess topographic risk factors – As topography is a key risk factor in fire spread, the lay of the land should be carefully considered when introducing or regenerating existing vegetation. Ridge tops and steep slopes are particularly dangerous in a bush fire. When coupled with considerations of aspect, assess whether it would be appropriate to introduce new vegetation.

Measures to ensure urban greening and bush fire risk management policies, strategies and regulations are not in conflict

  1. Review “Planning for Bush Fire Protection” and urban greening policies to ensure complementary outcomes and appropriate risk management 
  • Urban greening policies and strategies should include the need for a bush fire risk assessment.
  • Bush fire policies and strategies should address the need for urban greening.
  • Consult with the NSW RFS and emergency management professionals in the planning process including the preparation of LSPSs, LEP/DCP amendments, masterplans, precinct plans and urban greening strategy documents and plans, to ensure that urban greening and corridor creation outside of identified bush fire prone areas do not increase bush fire hazard risk in new areas. This issue could also be considered in future updates of the metropolitan plan and district plans as well as a regular consideration when updating Bush Fire Risk Management Plans and Fire Prone Land Maps.
  • Councils should clearly define which areas within their urban greening programs are subject to PBP for transparency purposes. Council’s Bush Fire Prone Land Map should be updated at the earliest opportunity to reflect this.
  • Reserve/park plans of management, bushland rehabilitation plans, street tree planting programs, urban greening programs, urban canopy/green grid strategies and biodiversity off-sets should consider the potential amplification of bush fire risk to urban areas and measures to lower them, particularly in relation to climate change in the long-term (50-100 years). Consideration should be given to applying the Australian Standard AS 5334 – 2013 Climate Change Adaptation for Settlements and Infrastructure – A Risk Based Approach as well as the Department of Planning, Industry and Environment Guide to Climate Change Risk Assessment for NSW Local Government 2019 in this process.
  • The 10/50 Vegetation Clearing Scheme could be amended to require that canopy trees identified as part of an endangered ecological community or threatened species habitat under the NSW Biodiversity Conservation Act 2016 requires consultation with council and the NSW RFS before it is cleared to avoid unnecessary removals and allow for the opportunity to explore other options such as canopy thinning and removal of surface, near surface or elevated fuel.
  1. Councils should develop a list of fire retardant plants and landscaping guidelines that are place or LGA specific for development control, education and greening programs
  • Although the NSW RFS provides some information on fire retardant plants and landscaping to reduce fire spread risk in their Standards for Asset Protection Zones, the information is limited and generalised. Urban greening policy and strategy documents need to become more place based, and more specific direction is required for the public and private domain to suit the characteristics of the area. Already some councils, such as Blue Mountains City Council, have prepared guidelines on how to select plants with low flammability for gardens and how to space them vertically and horizontally to make them less likely to promote the spread of fire. They have also provided a useful plant list as an initial guide.
  • The list of fire retardant plants and landscaping guidelines could apply to areas within or adjoining bush fire prone land and be included in:
  • Development Control Plans
  • Urban greening programs, strategies, plans and projects
  • Public education programs undertaken by council, the NSW RFS or local commercial nurseries to assist the public in choosing appropriate plants for fire prone areas
  • The list should exclude noxious and environmental weed species to avoid negative environmental impacts, conflict with weed or biodiversity protection laws and policy and additional costs to control them.
  • When developing fire retardant plant lists, councils should consult with ecologists to ensure the plants do not risk harm to endangered ecological communities or threatened or endangered species or their habitat.
  • The state government should consider requiring commercial nurseries to label plants which have a low, medium or high flammability.
  • Fire retardant plant lists could be verified by the CSIRO or appropriate authority
  • Councils need to ensure that mixed messages are not given to their communities in relation to backyards for wildlife, community revegetation, tree giveaways or bush rehabilitation programs such as “Plant a Tree Day” or Bushcare that can increase fire risk through inappropriate planting and landscape design. Asset protection zones must be maintained in perpetuity if imposed by a development consent condition. Wildlife habitat can still be enhanced through alternative means including water features, habitat boxes, retaining bush rock and rockeries as well as applying the planting and landscape guidelines of the NSW RFS.
  1. Encourage retention of water in the landscape to reduce bush fire risk
  • Measures on public and privately owned land to capture storm water and integrate it into bush fire prone areas and APZs include: water detention basins, rain gardens, swales, wetlands, lakes, ponds and dams. Properties and facilities could also benefit from wastewater / grey water areas being positioned in APZs.
  • Development control plans could be amended to require suitable water sensitive urban design in bush fire prone areas or near bush fire prone areas that retain more water in the landscape.
  • Park and reserve plans of management could include more water sensitive urban design measures to retain water in the landscape.

It’s possible to achieve bushfire-safe urban greening but we need to know more

This paper has outlined some of the ways in which land use planning policy in NSW can be improved to take account of and mitigate against bush fire risk in the preparation of urban greening policy and strategy.

Certainly, we have shown that measures can be put in place to go some way towards resolving conflicting priorities.

Bush fire is a comprehensive subject and this paper has only lightly touched on the unfolding issue and possible resolution. Further investigation is required into the current policy position and potential avenues to ensure bush fire risk is not introduced or increased within our urban areas.

Isabelle Connolly is principal consultant at EConPlan who has advised the state and local government on urban greening policy. Catherine Ryland is a senior urban planner and leading reviewer of Planning for Bush Fire Protection 2019 for the NSW RFS. The authors would like to thank Dr Stuart Little, Brendan Smith, David Connolly and Jess Miller for their advice and encouragement.

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  1. Thanks Isabelle & Catherine for your article

    As you may be aware, it’s also important to incorporate First Nations’thousands of years’ knowledge on caring for Country using cultural burning. For example, Firesticks is keen to share, build and spread cultural burning knowledge across Australia to help transform sick bush to healthy biodiverse bush, which can also reduce fire risk to life and property. From my experience, I see Firesticks as a powerful initiative which helps to heal the bush and humans

  2. A lesson from the suburban fires in Canberra some years back was that the fire travelled along timber boundary fences, then got under the eaves of the houses. So fire resistance is not just about vegetation.

  3. Bushfire intensity is a function of wind speed, temperature humidity and fuel load. As the recent fires has demonstrated we can get fires anywhere, wheat fields, grass lands, rainforests nothing is safe. Planting trees close together forces them up so the canopy is further out of reach and the high canopy slows wind speed. Trees need to be where they shelter roads or public places. Building artificial wetlands will increase humidity and provide water for fire fighting and a last ditch safe spot.