To burn, or not to burn…
That is the question scientists and land managers have been debating for years.
And for good reason.
On one hand you have the desire to protect life and property, and on the other you have what is sustainable for the environment. Both are important goals, but when it comes to planned burning it seems that you can only have one. But if we ignore one goal over the other, we risk causing lasting damage. The challenge to successful burning is to find the balance between the protection of life and environmental sustainability.
Burning for protection
In the summer of 2009, Victoria was subjected to catastrophic bushfires. Black Saturday alone resulted in almost half a million hectares of land being burned, thousands of homes destroyed and the loss of 173 lives.
In response to these events, the Victorian Government wanted to reduce the risk of such a tragedy occurring again. As such, they established a blanket 5% burn target for the state of Victoria. This target was based on the findings that patches of forest that had been burned prior to Black Saturday resulted in fires that were less severe. A 5% target meant that every year, the government would burn 5% of public land in Victoria- approximately 390,000 hectares- in order to reduce the risk of severe bushfires.
Severe bushfires can destroy homes and lives. Source: Flickr
Burning for sustainability
How regularly a patch of vegetation is burned can affect the species present. Too much or too little fire may result in loss of species. The presence of humans in the landscape has changed fire frequency and intensity over the years and this can have consequences for our vegetation communities.
The type and number of species present in a community can change over time- a process known as ecological succession. Disturbances such as fire can “reset” the community back to an earlier stage in the succession, favouring different species. Vital attributes describe characteristics that are important in determining how a plant responds to disturbance and the succession pathway. For example, good colonisers may do well immediately after a fire, but eventually decrease in number as plants that are better competitors increase in number. Time to reproductive maturity is another example, especially in the case of plants that regenerate by seed. If a second fire was to occur before a species was able to produce viable seed, we would risk losing that species from the community.
Similarly, grasslands require more regular fire than forests: the frequent disturbance prevents woody plants from establishing and converting the grassland into woodland.
Environmental burning attempts to mimic natural fire regimes for the benefit of the species and communities present.
Some plants that regenerate by seed require fire to reproduce. Source: Flickr
Discord between goals
After five years of implementation, the Victorian 5% burn target was found to have some issues.
In terms of reducing risk to life and assets, the 5% target was criticised as ineffective at reducing bushfire risk. Because land managers were struggling to reach such a large target, they commonly burned remote areas that were relatively easy to burn and allowed them to accrue a large number of hectares. Unfortunately this did little to reduce bushfire risk.
In addition to this, a 5% burn target meant that any given patch of land would be burned every 20 years. While some plants, animals and ecosystems may prefer fires at this frequency, others require much longer time periods without fire. By continuing to burn at such short intervals, we risked losing the species that were unable to survive or reproduce with regular fires.
Burning for balance
A 2015 review into fuel management practices recommended that the blanket hectare burn target be replaced with a risk-based method. Thus the Safer Together strategy for fuel management was born. Victoria would be mapped according to bushfire risk. Following this, burning would be strategically planned in order to keep bushfire risk at or below 70%.
The first priority for management is community safety and assets. After this, environmental factors will be taken into consideration where possible. In Victoria, this means planning around vegetation classifications such as Tolerable Fire Intervals (TFI). TFIs are based on the most vulnerable plant species in a vegetation type, and the longest and shortest periods of time between fires that the species can survive at. The shortest period of time is how long the species takes to reach reproductive maturity. The longest period of time is how long the species can live for before it dies or can no longer reproduce. If burns are conducted within the minimum and maximum TFIs, then fuel management practices should maximise biodiversity.
Although the Safer Together approach is in its infancy, it is a step in the right direction to sustainable fuel management.
We can burn for both the protection of life and the environment. Source: Flickr