Across much of Australia, fire plays an invaluable and varying role in ecosystems. Its role in shaping the evolution of the Tasmanian environment is becoming increasingly well-understood, and its impacts on vegetation communities have been the subject of considerable investigation.
Fire tolerant communities
Some plant species have evolved to survive repeated bushfires. Some of these communities, such as eucalypt forest, rely on occasional fires as part of their regeneration process - even though the short-term impacts of fire in these communities can appear to be severe.
The species within fire tolerant communities have a range of interesting adaptations to fire. Unless destroyed by a very intense fire, most eucalypt species are able to produce epicormic growth. Banksias and hakeas store seed in a woody fruit capsule which opens as a result of fire. The seeds germinate and grow on the burnt ground free of competition. Grass trees (Xanthorrhoea australis) 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 release of seed. Many native orchids flower after fire, particularly in fire-prone habitats such as dry forests and heathlands. Indeed, some orchids are fire-dependent and sprout from bulbs which may have lain dormant in the soil for up to 20 years. Casuarinas and Oyster Bay pines can both cope well with low-frequency fire. Many shrubs, some herbs such as native peas, lilies, grasses and bracken resprout after fire.
Fire sensitive communities
Other species and communities can be killed and destroyed by a single fire.
In the last century over one-quarter of Tasmania's rainforest has been burnt. Following fire, the burnt vegetation passes through a number of stages and if undisturbed will culminate in the return of mature rainforest after several hundred years. If fires are small and not too intense, rainforest trees may survive and organic soils may not be destroyed. In a such a case, rainforest species may regenerate without intermediate stages.
Tasmania's native conifers are also highly susceptible to fire. In certain areas of the state, extensive stands of dead 'stags' give testimony to the ravages of previous fires. Some species may never recover due to their very slow growth and poor seed dispersal abilities.