In the wake of a devastating bush fire season in eastern Australia, scientists are already predicting that climate change will lead to still more hot, dry, flammable summers.
The NSW government and the Greater Sydney Commission have called for a greening of our cities to alleviate urban heat as the climate warms. This is due to a progressive erosion of urban vegetation because of urban densification, fresh infrastructure, compliance, and the 10/50 Vegetation Clearing Scheme in bush fire prone regions. So how do we proceed?
The NSW government has instituted policies intended to facilitate green connected corridors through the urban landscape and an enhancement of tree canopy coverage. The government wants to relieve urban heat, and to enhance walkability, liveability, good health, biodiverse elements and visual appeal. These policies are:
- The Greater Sydney Regional Plan features a target to expand tree canopy cover to 40 per cent, up from the present 23 per cent as a means to adjust to climate change and mitigate the urban heat island effect.
- The Greater Sydney Commission’s five district plans integrate planning priorities to protect and enhance bushland, biodiversity and waterways, conserve and restore bushland, perfect design and delivery of the Greater Sydney Green Grid priority corridors, expand urban tree canopy to combat the urban heat island effect and lessen vulnerability to intense heat and lessen exposure of natural and urban dangers.
- Of the 14 NSW Premier’s Priorities, the 11th intends to add to the percentage of residences in urban regions within a 10-minute walk of green public space by 10 per cent by the year 2023. The 12th Priority intends to enhance tree canopy and green cover across Greater Sydney by the planting of 1 million trees by the year 2022.
While enhanced urban greening has its benefits, it also poses problems – mainly that the act of vegetating with trees, understorey and grass communities might amount to enhanced bushfire danger near or within specified bush fire prone regions.
Councils have of late developed draft Local Strategic Planning Statements (LSPS) to specify how they will amend their Local Environmental Plans (LEPs) and Development Control Plans (DCPs) to put into action District Plan priorities, including the greening of Sydney, enhancing resilience and handling hazards. Throughout this process, the community must stay confident that their lives and homes will not be in danger.
The majority of urban greening strategies do not take into account bush fire risk. And the Rural Fire Service Planning for Bush Fire Protection 2019, which took effect 1 March, supplies NSW with standards for designing and constructing on bush fire prone property, but does not reference the need to take into account bush fire risk in urban greening plans.
The answer to this quandary is a collection of “place-based planning” principles that must be considered when making policy in regards to urban greening and bush fire risk managing.
In formulating this plan, we must first have a sound understanding of bush fires. The term “bush fire” defines fires that strike any type of vegetation like forest, rainforest, woodland, heath and grass.
It is tough to predict when and where bush fires will strike, and their degree of severity.
Bush fires in Australia are happening more often and more intensely—with many attributing this to the result of climate change elevating global temperature, rendering the weather hotter and drier.
Common features of bush fires include:
Fuel. Vegetation is actually the fuel that ignites bushfires. Surface fuel includes leaves, twigs and bark. Near surface fuel does not make contact with the ground. Elevated fuel is an upright source with a clear gap to surface fuels.
Canopy. This is the crown, consisting of the tallest layer of trees.
A fire sparks in the surface fuel, and may travel through each fuel layer before reaching the canopy. The rate of the fire’s spread will depend on the percentage of the fuel structure the fire is affecting.
Once it reaches the tree canopy, the fire crowns. The size and shape of the vegetation is the deciding factor as to whether the fire can crown. Tree bark and burning embers also play roles in this process.
Climate is another deciding factor, as the fire risk is worst on the hottest, driest days. On the east coast of Australia, winds incoming from the north and west are hot and dry, increasing the likelihood of bush fires.
Fires burn at a greater speed uphill.
The refined art of what and how to plant in order to avoid bushfires is included in the NSW Rural Fire Service Planning for Bush Fire Protection 2019 and other documents, and should be featured in urban greening plans, policies and strategies to lessen the frequency of bush fire.
All chosen plant species and planting layouts must protect against bush fires.
Plants less likely to ignite include large or hard leaves with simple margins, dense crowns, heightened branches, smooth, hard or persistent bark, and plants that fail to produce leaf/twig litter beneath them or suspended in foliage. Planted rows of trees can provide a fire barrier for a house or other target.
An asset protection zone (APZ) is a fuel reduced area around a built asset or structure. Species selection and planting layouts should include enough vertical and horizontal separation between plants–vital when replanting in an APZ to mark a decrease in fire risk.
The APZ is determined by slope, vegetation type, the nature of the development and location. APZs make up an Inner Protection Area (IPA) and an optional Outer Protection Area (OPA) component for forest vegetation. Failure to maintain APZs is a substantial factor in bush fire property loss during bush fire events.
Councils must fund the maintenance of APZs on public land, as well as the education of residents and businesses in bush fire prone areas.
Laws are in place to help with this effort. The consideration of bush fire hazard at the strategic planning phase is mandated under s.9.1(2) of the Environmental Planning and Assessment Act 1979 (EPA Act) to determine if new development is needed based on identified bush fire risk on a landscape scale. And the GSC requires councils to contemplate urban greening plans like the green grid, biodiversity corridors and urban canopy in strategic planning processes.
Planning for Bush Fire Protection (PBP) 2019, specifies that draft LEPs should aim for the protection of life, property and the environment from the dangers of bush fire, through good management and planning processes.
The NSW RFS Commissioner must be consulted in the development of regional strategies and plans, with any variances or modifications subject for approval.
The identification of Bush Fire Prone Land (BFPL) is mandated under s.10.3 of the EPA Act, and each council must prepare a BFPL map in compliance with NSW RFS Guide for Bush Fire Prone Land Mapping 2015. Each map must be certified by the NSW RFS Commissioner, and are revised and certified every five years—sooner if the region’s vegetation plan changes.
Place-based planning (PBP) guidelines supply guidance for place based urban greening related 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.
Related principles include the undertaking of a bush fire landscape assessment to determine bush fire risk at the macro-scale, a look at fire runs, topography, particularly steep slopes, vegetation, weather and the degree of development interfacing vegetation and areas of isolation; fire-fighting access and evacuation possibilities; good land management practices; the exclusion of inappropriate development in high bush fire risk areas; and other factors.
Low threat vegetation exclusions include solitary areas of vegetation less than 1 ha and more than 100m separation from other regions of Category 1 or 2 vegetation or multiple areas of vegetation less than 0.25 ha and not within 20m of the site; and low-threat vegetation of low threat, such as monitored grassland and lawn.
Each Council maintains a representative on a Bush Fire Management Committee tasks with preparing a Bush Fire Risk Management Plan (BFRMP) intended to reduce human-prompted bush fire ignitions, manage fuel, and lessen the community’s vulnerability by well preparing it.
Otherwise, some good basic greening guidelines include limiting the amount of vegetation near bushfire prone areas, limiting the size of vegetation, and selecting vegetation that minimises fuel loads and fire intensity. Minimise continual fire pathways, and assess topographic risk factors.
By working together and following basic guidelines, we can achieve a greener—and safer—Australia.