by Tony Start, CALM WA
From Savanna Burning—Understanding and Using Fire in
Northern Australia, Tropical Savannas CRC, Darwin 2001
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'Bewitching flora of the sandstone ranges'
Photo: Tony Start
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There are some truly rugged sandstone ranges embedded in
Australia’s savannas. Their dramatic scenery is the heart of
many national parks, and visitors find their extraordinary and
beautiful flora bewitching.
Yet few people, including some managers, appreciate the enigma
posed by their vegetation. Many shrubs that are killed by fire find
shelter in the rugged landscape. If burnt, they are totally
dependant on surviving seed to found a new generation; this must
then develop to flowering size to replenish the seed bank before
another fire.
But spinifex relishes the same habitat. Spinifex is a perfect
fuel because its resin-rich, needle-like leaves form
well-ventilated hummocks. And it does burn, for everywhere but on
the most isolated cliff ledges one can find charcoal, scorched
branches or other evidence of fire at some time.
Despite this, the fire-sensitive shrubs are often seen growing
profusely amongst spinifex hummocks in the sandstone.
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Fire-sensitive plants survive through isolation
and infrequent burning in a rugged landscape.
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How can this be?
The secret lies in how frequently these habitats burn. Provided
the shrubs can replenish their seed banks (they often take five or
more years to flower and longer to shed enough seed) they can live
with the risk of fire because, in this rugged landscape, bare rock
creates sheltered areas. Fires do get there sometimes, from
lightning or from burning leaves blowing in, but they have been
infrequent.
This is changing. For many reasons and in many places, fire is
now more frequent in the sandstone. The consequence is local
extinction of many fire sensitive shrubs in their former
strongholds.
