13. January 2013 / Bonnie Grant

Fighting Fire with Fire

Every year near Christmas time Australia burns. Fire has burnt 50,000 hectares of bushland in Tasmania and grass fires have lashed through Wallan just north of Melbourne. In New South Wales an out of control fire spread across nearly 17,000 hectares in one day. At scales incomprehensible to most of us, the sight of blackened landscapes, days of extreme heat, catastrophic fire warnings, and the periodic evacuation of homes is the unfortunate reality for large swathes of Australia. It’s an inevitability that won’t go away as the country experiences temperatures so high that weather forecasters have needed to create a new scale of colour for the weather maps.

Bushfires burn near Hamilton, Tasmania, January 2013. Photo: Toni Fish

Aftermath of the 2009 fires at the popular Wilsons Promotory National Park, Victoria. Photo: A. Tritschler

Two new colours have been added to the weather maps as temperatures reach into the 50 degrees celsius range. Image source: ABC News

The relationship between climate and fire ecology is clear, wet winters promoting plant growth combined with dry summers characterised by high temperatures and winds provide the ideal conditions for bushfires. Yet fire is a natural part of the Australian environment, a necessity for the health of ecosytems with many plants requiring fire to stimulate their growth.

Lightening strikes have been igniting fires for thousands of years and much of Australia’s land was burned during the 40,000 years of Aboriginal land management.  It is now widely accepted that Indigenous Australian’s used fire very deliberately and skillfully to achieve specific outcomes. The Indigenous method of firestick farming (burning throughout the year, typically under prescribed conditions) was undertaken extensively before the advent of European settlement which lead to societal collapse and associated abandonment of traditional indigenous practices.

So while fires have a terrifying and devastating impact on people, most Australian plants and animals have adapted to survive fires.  For some indigenous plants the release of seed is stimulated by the heat of a fire and germination is encouraged by smoke. When Eucalypts and Hakeas produce seed, the seed is protected from fire in woody fruits, by thick seed coats (e.g. wattles) or by surviving fire underground, in hiding. Some species regenerate from the below-ground parts of plants that are protected from fire by soil and remain alive. Bark can also protect the living inner stems of plants. Following fire the plant shoots from buds under bark, or beneath soil. A fire’s heat can also activate dormant epicormic buds beneath the bark of a tree, which can enable the tree to recover.

Left: Epicormic Shoots, Right: A Xanthorrhoea sprouts after fire. Photos: A. Tritschler

In another example the Desert Banksia (Banksia ornata) takes eight years to produce enough seed to reproduce. It lives for 50–60 years and seed is not stored in the soil. Thus, for this species to survive and flourish the minimum time between fires should be no less than eight years and the maximum no more than 60 years. These sorts of parameters begin to define how fire could be more appropriately managed in Australia.

Fire needs to be strategic and planned carefully. Unfortunately, this is rarely the case in Australia today. Bushfires vary in their intensity depending on the prevailing conditions. Large uniform fires generally have a greater impact on plant and animal species than smaller patchy fires because habitat resources are then affected across wide areas. The sort of large, intense bushfires affecting Australia currently can severely affect habitats while planned burning generally results in lower intensity fires. Low intensity fires are less likely to burn all the vegetation in an area and less likely to kill vulnerable species.

The recent fires in Australia beg further consideration by policy makers and designers of the built and ‘natural’ environments, of how can we better design with fire, flood and the cycles of weather effects.  Designing and building with such erratic phenomena in mind is challenging, but urgent. For Australia the necessity clarifies when we experience such a stretch of 40 plus temperatures, but it is too often forgotten in the middle of a wet winter. What the outcomes of these fires and extreme temperatures will mean on a political scale and in relation to arguments surrounding climate change will unravel in the proceeding weeks, and potentially years, but they draw to attention the increasing frequency of extreme weather events of recent years, requiring a designed response to heat and fire control and mitigation. Impacts can be devastating for the population whose homes, businesses, and livestock are affected by fire, unable to regenerate.

While Australia’s landscape has learned to adapt to the inevitable fires that blaze across the continent, the question that remains is, can we?

 

Bonnie Grant is a Landscape Architect and Urban Planner based in Melbourne, Australia.

 
 
 
 
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