A charred landscape
The current fire season has had a devastating impact on the natural world across Australia. The extent of the bushfires has been of a scale that is very difficult to comprehend. Images and footage of the immense suffering of animals have been confronting and heartbreaking.
People often ask about the impact on plants. Charred landscapes of immense size are predominantly images of burnt plants – trees and the understorey species that comprise those ecosystems. But can we state how many plants have been killed?
Assessing the impact of fire on plants
It is difficult to estimate the number of plants impacted by fire. Published tree densities in different ecosystems are 500–1,200 trees per hectare. If we multiply this by the area burnt in the current fires (10 million hectares and counting), assuming 60 per cent was natural ecosystems, it could mean that 3–7.2 billion trees have been impacted, with as many understorey species (and this doesn’t even begin to take into account organisms such as fungi, lichens and algae). The impact on understorey species is usually much more dramatic, and final, as they are likely to be burnt completely.
However, the answer to this question is much more nuanced. The flora of Australian has evolved with fire. As the continent has become more arid, species such as eucalypts and wattles have come to predominate, and these plants have numerous adaptations to cope with fire.
In eucalypts, epicormic buds protected by bark spring to life after a fire with amazing haste, while seed of wattles and banksias are stimulated to germinate and grow once it rains enough for successful establishment. In some cases, we even see species of plants grow that have not been observed for a long time.