Fire Regenaeration
Fossil evidence suggests that fire was a part of the Australian landscape long before the existence of human beings. Natural fir= es were caused by lightning, occasional volcanic activity or spontaneous combustion probably became more frequent as the Australian continent became drier. It appears that, with the arrival of humans over 50,000 years ago the frequency of fire may have increased. Aboriginal people used fire skilfully, managing various areas to sustain their own survival and that of future gen= erations. They used fire as a tool for a variety of purposes such as hunting, warmth = and cooking, to encourage grassland development in some areas and also to incre= ase the abundance of plant foods and animals.
With the arrival of Europeans the fire regimes changed. Fires are now less frequent, but when they do occur they are more intense a= nd often cause a lot of damage.
Many plants have interesting adaptations to fire, some= of which include:
• eucalypt species produce = shoots (known as epicormic) from burnt trunks and boug= hs. These shoots are eventually able to establish leaves, and so provide nourishment to the trees.
• Banksias and hakeas store seed in woody fruits which= open as a result of fire. Consequently the seeds germinate and grow on the burnt ground with reduced competition from grasses and sedges.
• Grass trees (Xanthorrhoea austr= alis) flower prolifically after fire due to a fire-initiated release of the gas acetylene, which initiates the growth of the flower spike and the early rel= ease of seed.
• Some native orchids only flower immediately after fi= re and sprout from bulbs which may have lain dormant in the soil for up to 20 year= s.
• Sclerophyll is a term used to describe plants with an adaptation for survival in extreme conditions. Adapati= ons includes leaves that are hardened, thickened and resistant to moisture loss, such as those of a eucalypt tree or the native heath. Most sclerophyll vegetation is also well adapted to fire
Fire and fauna
Fire plays an important role in shaping the habitat fo= r many animal species. Like plant species, some animal species benefit from regular firing of their habitat whilst others are disadvantaged.
Some animals are able to survive fires, although an exceptionally intense fire can lead to the widescale</= span> loss of individuals. Arboreal (flying) mammals, such as pygmy possums and s= ugar gliders, can be killed by intense fires due to the loss of the tree canopy = in which they live.
Less intense fires pose a much smaller risk to animal survival. Highly mobile species are able to move out of danger while birds = and other flying species can fly away. Burrowing animals, such as the wombat, a= re often able to survive within their burrows. Similarly, some invertebrates c= an shelter underground. Hopping mammals such as Bennetts wallabies can bounce back through brea= ks in the fire front.
Advantages of fire
Fire can also create a rejuvenated habitat for many an= imal species. Herbivorous mammals like the fresh pickings associated with the regrowth that follows fire.
Within a week after buttongrass</= span> moorland has been burnt, the vegetation starts to regrow succulent shoots a= nd attract herbivorous animals such as Bennetts wallabies, wombats and grasshoppers. However, these species, particularly wallabies and wombats, require nearby areas of unburnt habitat where they c= an shelter. Among bird species, the critically endangered orangebellied parrot prefers buttongrass moorland habitat whi= ch has been burnt recently.
Disadvantages of fire
Small mammals such as the swamp rat, broadtoothed mouse and swamp antechinus cannot survive in recently burnt buttongrass moorland as there is very little cover to provide protection from predators. They may have to wait five years or more before they can move back into the= se habitats.