Scorched earth not so barren

With dry conditions and high temperatures, the risk of bushfires increases over the Australian summer. But while the destructive nature of fire cannot be denied, fire still plays an important role in some ecosystems.

Evidence of bushfires burning thousands of years before the arrival of Australia’s Indigenous people can be found in the form of ancient layers of charcoal. The size, severity and frequency of these blazes varied, depending on the climate at the time. The importance of fire to the Australian environment is seen in some plant species, including Banksia and Hakea species, whose seed pods only open under intense heat.

Fire mosaics

Australian Indigenous communities developed practices involving the intentional starting of controlled fires. Such fires were small, being restricted to patches of vegetation. These fires are called fire mosaics and formed an important part of Indigenous cultures.

Fire mosaics were used in hunting to reveal or flush out animals, but they had other uses as well. These small, controlled fires prevented vegetation from building up. This in turn prevented larger, uncontrolled fires down the track. The regular burning also encouraged a diversity of different types of vegetation.

Given the often destructive nature of fire, and the fact that it was used for hunting animals, it might seem logical to conclude that fire mosaics lead to reductions in animal populations. However, a study in Western Australia has revealed the opposite to be case.

Kindling the ecosystem

Researchers investigated the fire practices of the Martu people, and counted the number of fresh burrows of a goanna species called the sand monitor. They found that the monitors are most common in the areas they were hunted the most. Rather than decreasing sand monitor populations, the researchers concluded that fire mosaics led to increased numbers of monitors over time.

The researchers suggest that the reason for this is that burning stimulates regrowth of vegetation, and promotes a diversity of niche environments. In turn, this increase in habitat diversity encourages the growth of sand monitor populations.

While this study only looked at one species of goanna, it may also apply to other animal species. At the very least, it highlights that fire is important for life on this hot, dry continent.