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Savanna Explorer > Cape York > Fire > Tea-tree invasion

Tea-tree invasion on Cape York Peninsula

by Gabriel Crowley, Queensland National Parks and Wildlife Service
From Savanna Burning—Understanding and Using Fire in Northern Australia , Tropical Savannas CRC, Darwin 2001
Effects of fire on wood suckers in different seasons

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.

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.

Star finches

Star Finches are under threat from habitat changes due to grassland thickening. Photo M. Todd

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.