Fire in grassy places 1
Aussie grasslands and grassy woodlands were once widespread, particularly in places with clay soil, like Victoria’s Volcanic Plains. Other regions with extensive grasslands included the Southern Highlands (NSW and ACT), Queensland’s Darling Downs, and areas north of Adelaide in SA and south of Launceston in Tasmania. Grassy woodlands, with (mostly) eucalypt trees over a ground layer of grasses and herbs, covered even greater areas. In NSW Box-Gum grassy woodlands covered much of the extensive western slopes of the Great Dividing Range. Grassy woodlands also grew on Western Sydney’s Cumberland Plain - this was the vegetation type I studied for my PhD.
Grassland / grassy woodland at Mulligans Flat Nature Reserve, Canberra.
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Most of these grassy places no longer have their original vegetation. European settlers headed straight for these rich pastures, and it didn’t take long for their hard-hoofed animals to trample and eat out grazing-sensitive native plant species. Some grassy places were cultivated, replacing native species with non-native crops. Exotic grasses and herbs were intentionally introduced to enhance fodder value. Many of our cities and towns are built where grassland or grassy woodland once grew.
It took a long time for settler conservationists to recognise the value and rarity of grassy places, and even now I reckon they receive much less attention than they deserve. At first glance, grassy ecosystems lack the charisma of rainforest or heath. Flowers in Aussie grasslands are small, and by definition, low to the ground. However if you encounter a well-cared-for native grassland or grassy woodland when it’s in bloom, you're in for a treat. Plant diversity can be astounding, with many species packed into each square meter. This Gardening Australia story gives you a glimpse (presenter is Jane Edmanson, grassland is in the outer Melbourne suburb of Sunbury).
Remnant grassland at Cambooya, on the rich clay soil of Queensland's Darling Downs, one of few remaining patches of native vegetation within a farming landscape. The pink flower is the native pea Australian Trefoil (Lotus australis). Next to it is the prickle-free Native Thistle (Rhaponticum australe), listed as Vulnerable under the EPBC Act.
The ecology of Aussie grasslands has been illuminated by some excellent research over recent decades. Where rainfall exceeds around 500 mm, dominant grasses readily overwhelm the smaller plants that grow between their tussocks. To keep these smaller species in the system, grass biomass needs to be removed periodically. In most cases, the best method for doing this is fire. Without fire, even the dominant grasses themselves get old and die after a decade or so, allowing weeds to come in more easily.
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I see a lot of synergy between the understanding of fire that researchers and restoration practitioners have developed over recent years, and what I understand of Aboriginal recommendations for caring for grassy country. I also hear tales of fire management in back-block grazing country, past and present, that line up pretty well with other knowledge sources. Frequent, patchy, low intensity fire, applied not by formula but when the land is ready (eg when grasses have accumulated dead thatch, but before they start to decline, and also when they aren’t too dry), accompanied by careful monitoring and management of weeds, seems to be the way to go. This applies particularly to good-quality vegetation in higher rainfall areas.
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Herbs growing among grasses at Mulligans Flat, ACT (see photo at the top of the page). Clockwise from top left: Native Bluebell (Wahlenbergia sp.); Sticky Everlasting (Xerochrysum viscosum) with Lydia Lichen Moth (Asura lydia); New Holland Daisy (Vittadinia sp.); Hoary Guinea Flower (Hibbertia obtusifolia).
As grassland productivity declines (eg as rainfall decreases or soils are less fertile) gaps between tussocks will close more slowly, if at all, and fire or other disturbance will be needed less often. Moving towards the semi-arid zone, herb species that use the spaces between grass tussocks increasingly grow, flower and fruit in response to rain, without the need for preceding fire. However even in desert areas, Aboriginal people use patchy fire to rejuvenate grasses, and reduce wildfire risk.
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Increasingly, people are coming to appreciate our grassy places, and are taking practical steps to conserve and restore them. This is particularly the case in Victoria, where major strides have been made over recent years.
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There is nothing like a Kangaroo Grass patch, studded with tiny wildflower gems: daisies, lilies, orchids, blue-bells, and so much more. It lifts my heart to hear about people, black and white, who are loving this grassy country back to life, using fire as their ally.
Kangaroo Grass (Themeda triandra) interspersed with native herbs, Gundary NSW
Find out more about conservation, management and restoration of Aussie grasslands and grassy woodlands here.
Besides keeping dominant grasses healthy, and mediating their relationship with smaller herbs, in some places fire has another important role, which is to ensure the ground layer isn’t overwhelmed by woody plants. This is the next topic.