19.2.3  Using fire to manage plants

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Land management can be achieved through use of fire because of these differential responses of species to fire regimes. For example, weed infestation can be reduced through judicious use of fire, as demonstrated in some coastal Victorian national parks where boneseed (Chrysanthemoides monilifera) is known to be restricted by two fires lit in short succession.

Effects of smoke on germination are not widely exploited by land managers as yet but they have potential for propagation of species previously considered unamenable for cultivation (e.g. Verticordia spp.). Evidence that smoke is biologically active when perfused through water and progress in isolating the active constituents from smoke open the way for dormancy breaking in these fire-dependent species. Some commercially useful species can be induced to flower by exposure to heat and the gases which fires release; Christmas bells (Blandfordia grandiflora) and kangaroo paws (Anigozanthos spp. from Western Australia) both flower more profusely in response to fire.

Animal habitat is also affected by fire, not only immediately after burning but also through long-term shifts in plant community composition. Exploitation of fire to maintain open sclerophyllous woodlands is thought to have been practised locally by Aboriginal Australians for tens of thousands of years (Section 19.4). Maori in New Zealand burnt the largely coniferous lowland forests, thereby eliminating podocarp stands and opening the landscape to grasses. Conifers of the southern hemisphere such as araucarias, podocarps and even the drought-tolerant Callitris spp. are generally intolerant of fire because they lack seed resistance to heat and a capacity to resprout.