Although severe fires can kill a species of plant or tree, many more will persist and even thrive. Nature is always able to recover from fire.
In March 2019 more than 14,500 hectares of bush and open grasslands were burned and homes, sheds and outbuildings destroyed, when lightning sparked a fire in the Bunyip State Forest in the state’s south east.
The rolling hills of an area known for its farms and equestrian training centres were left blackened, and the features of the landscape merged into one. The fire killed or damaged most of the plants in its path. However, only seven months later the landscape paints a very different picture – as shown by the photos of the Bunyip fire, below.
Apart from a few telltale signs – a lick of fire on an errant fence paling, a blackened trunk of a tree or a gate not yet rebuilt – you wouldn’t know that fire had ravaged the area. Green shoots extend from the base of trees like recently planted saplings. The landscape is lush and green and the dense valleys at the bottom of rolling hills are a sanctuary for both new and recovered tall tree ferns.
Plants have evolved with fire for millions of years. Some trees and plants have adapted to survive fire while others such as the mountain ash depend on fire to germinate and survive. The fire intensity, fire history, and the plant species fire response mechanism will determine whether it will survive or die
The sapling-like shoots from the base and canopy of burned trees is known as epicormic growth. It’s the plant’s response to damage and the stress caused by the fire. The growth is born from buds that lie dormant beneath the bark, sometimes within only a few weeks of a fire going through. CFA’s Team Leader Vegetation Management Owen Gooding said these dormant buds are an important stage in the healing of the plant or tree, keeping it going until the canopy recovers.
“Eucalyptus trees may be great conductors of fire but they’re also great survivors of fire,” Owen said. Like the eucalyptus, other woody species have evolved to protect dormant buds from fire under bark. In nonwoody plants, such as grass trees and tree ferns, the new growing tips are protected from fire by the trunk. “New life also springs from underground,” Owen continued. “Soil insulates parts of plants which can re-shoot after fire.
“Grass, lilies and some ground ferns are often the first signs of life after fire. Other species persist because fire simulates germination of a seed bank that lies dormant in the ground. Some plants are stimulated to flower after a fire. Grass trees are a great example.”
Eucalyptus trees have a second mechanism to survive after a fire. They can re-sprout from their roots and the woody swelling at their base called lignotubers. Their ability to regrow and replenish from both beneath the bark and their root systems ensures they grow new leaves and branches within weeks to feed the rest of the tree.
Longer fire seasons and the increasing dryness of the landscape means habitats will always be changing. We need to be prepared that this change may not always be what we want or expect.
“A fire’s footprint is a shape on the map, but we know that the areas burned within that footprint are patchy. The fire intensity varies and some areas are not burned. It’s these patches that plants and animals use as a home base of sorts to repopulate and persist,” Owen said.
Fire is a disturbance that can change the diversity of species. If the fires are too frequent in an area, individual plants may not mature and there’s a risk of a species dying out locally. The patchier the fire landscape the greater diversity of animal and plant species because there are more opportunities for a species to persist.
“There’s a tendency to think of the bush as a natural, ideal state, but it’s dynamic. It has always changed and it always will. Fire is a key player in that story.”