EnviroNorth > Kimberley > Fire > Sandstone plants

Impacta of fire on sandstone plants

by Tony Start, CALM WA
From Savanna Burning—Understanding and Using Fire in Northern Australia, Tropical Savannas CRC, Darwin 2001
Bewitching flora of the sandstone ranges

'Bewitching flora of the sandstone ranges' Photo: Tony Start

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.

Fire-sensitive plants survive through isolation and infrequent burning in a rugged landscape.

Fire-sensitive plants survive through isolation and infrequent burning in a rugged landscape.

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.