by Gabriel Crowley, Queensland National Parks and Wildlife
Service
From Savanna Burning—Understanding and Using Fire in
Northern Australia , Tropical Savannas CRC, Darwin 2001
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The effects of fire in different seasons on the
development of wood suckers. These consequences of fire are not
unique to Cape York Peninsula. Except for the potential high
density for tea-tree suckers, similar effects occur in many grazed
and ungrazed woodlands.
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A fire-dependent habitat
Grasslands in Cape York are being invaded by woody plants,
particularly tea-tree ( Melaleuca spp.), in the absence of
fires or under limited burning. The diagram below illustrates the
effects of fires at different seasons on development of woody
suckers.
Grasses compete with tea-trees through the wet season, but die
off earlier in the dry season than the deeper-rooted trees. Fires
cut back tea-trees, but also stimulate growth. The small amount of
grass regrowth following an early dry season fire is soon grazed
out or dies, while the tea-trees continue to grow.
The later in the dry season that a fire is lit, the smaller the
tea-trees will be by the next wet season. Only very late dry season
fires or storm-burns will keep most re-suckering tea-trees below
the grass height. After four or five years with no fire or early
dry season burns, the grasslands can be completely lost to tea-tree
woodland.
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Star Finches are under threat from habitat
changes due to grassland thickening. Photo M. Todd
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Impacts on birds
A major implication of grassland thickening on Cape York is the
ensuing loss of habitat, particularly for granivorous birds such as
the golden-shouldered parrot, star finch, Gouldian finch,
buff-breasted button-quail and black-faced woodswallow.
The processes involved in loss of habitat include changes in
vegetation structure. This has led to more successful predation by
birds such as pied butcherbirds and loss of perennial grasses such
as cockatoo grass ( Alloteropsis semialata ), which
seed-eating birds rely upon for food at critical periods of the
year (especially the early wet season). Vegetation thickening also
results in loss of termite mounds in which the golden-shouldered
parrots nest.
