Secrets of the mallee
Simon Watharow and Steve Cook
To stand among the mallee is to feel lost in the timeless grandeur of the wilderness. The ocean-like waves of vegetation rise up and down for kilometres, following the flow of sand dunes.
By definition, mallee refers to a habitat of ‘multi-stemmed eucalyptus trees’. The trees are low-growing, rarely getting over 7–8 m high, and they often have three or more trunks with deep-tapping root systems, which can disperse 1–3 m from the tree. This explains the clear and almost measured gaps between the trees. Beneath the soil, though, they spread their extensive roots deep and wide in order to obtain moisture.
You can find mallee habitats in the semi-arid areas of southern Australia, in New South Wales, Victoria, South Australia and Western Australia. Living within these low-lying biogeographic regions are numerous species of wildlife. Sadly, there are a large number of threatened animals within specific mallee regions, including lizards like the Heath Skink (Liopholis multiscutata).
A fragile landscape
In our ever-increasing desire to ‘cultivate’ land, we have made war on the mallee regions of Australia since the late 1890s. Land clearing around mallee has been extensive and destructive. Without the benefits of organophosphate fertiliser, these regions would have barely been worth the trouble to cultivate barley or wheat, or run sheep.
Initially, cropping the actual mallee landscape was given up on because ploughing the ground was exceptionally difficult due to the mallee roots (lignotubers), with their regenerating shoots. After the novel invention of the stump-jump plough, the clearing began in earnest through the 1900s.
Several mallee land schemes were put in place for returned soldiers after the First and Second World Wars in Victoria and South Australia, and this expanded the clearance further. The large tracts of exposed soil that followed this push into the bushy landscape caused the infamous massive red dust storms over Melbourne during the 1930s. In Western Australia, where a small percentage of original mallee remains, the majority of these areas were cleared from the late 1950s through to 1968.
It’s a harsh environment to farm, and frequent periods of drought see rural communities battle stoically to survive. During the Depression of the 1930s and the recession of the 1980s, farmers sold mallee stumps and timber as firewood to inner capital cities. More recently, Broombush (Melaleuca uncinata) was harvested to make fencing but this caused extensive damage to the regions and was finally banned in the 1990s.
Protection efforts
A significant area of mallee is still privately owned in one form or another. Eucalypt oil is often made from mallee tree leaves and the large areas of nectar-providing Banksia species that grow in the mallee entice some apiarists to place their hives for a few months each year in South Australian and Victorian regions. Mallee trees are also possible sources of wood, as a component in medium density fibreboard (MDF), and this is even used to activate carbon offsets. It is estimated that over 110,000 km² has been degraded and destroyed since clearing began.
In a positive move, many farmers now use mallee trees to reduce salinity in the soil, especially in Victoria, South Australia and Western Australia. There are now thousands of hours put into extensive vegetation projects, weed control and feral animal control to protect and rebuild the regions. Along with the usual wild dogs and foxes, feral goats are a large-scale issue in some areas and control of them is underway.
Some notable regions are mobilising further to protect these amazing biodiversity areas. In New South Wales, Mallee Cliffs National Park and Yathong Nature Reserve have been declared protected areas. Victoria has the Hattah-Kulkyne, Murray Sunset, Wyperfeld and Little Desert national parks, in addition to the Big Desert Wilderness Park and several significant reserves. In South Australia there are also the Ngakrat (pronounced Narr-kat), Billiatt and Karte conservation parks.
Mallee secret
Hummock grass is the lifeblood of this region. It is estimated to cover 25 per cent of the continent with a wide range of associated plant communities. Hummock has tips with silica and they can break off and cause local infections in our skin. Seeds from the triodia genus that forms the hummocks were used to make the seedcakes of the staple diet for local Aboriginal communities. There are around 64 species of triodia in Australia, ranging from southern semi-arid regions across the arid through to tropical northwestern Australia.
Mallee vegetation
When you wander around the mallee areas, one of the first things you notice are the levels of plants, such as relatively taller eucalypts, mid-level bushes and low-lying grasses, succulents and annuals. In mallee regions water runs quite deep under the sandy soil and the plant communities have quite wonderful flora–water adaptations.
The eucalypts have small, waxy leaves that reduce light and heat and they sink deep roots down into the deeper layers to survive. Succulents store water in fleshy stems or leaves; for example, the enchylaena, Pigface (carpobrutos), myoporum, einadia and atriplex (saltbush) species. Annuals or fast-germinating/propagating species occur in the mallee where they can avoid drought or prolonged heat by fast propagation and a wide dispersal of seed. Seeds such as the senecio and bracteantha species germinate quickly when rain comes.
Top storey
Brown Stringybark (E. arenacea)
Coastal or Soap mallee (E. diversifolia)
Desert Banksia (Banksia ornata)
March or Slender-leaf mallee (E. leptophylla)
Narrow-leaf Red Mallee (E. leptophylla)
Red Mallee (E. oleosa)
Red Mallee (E. socialis)
Ridge-fruited or Angular Yellow mallee (E. incrassate)
Slaty Sheoak (Allocasuarina muelleriana)
White Mallee or Dumosa Mallee (Eucalyptus dumosa)
Yorrel (E. gracilis)
Mid storey
Baeckea (baeckea spp.)
Broom Heath Myrtle or Silver Broom (Baeckea behrii)
Myrtles (Calytrix spp.)
Other saltbushes (maireana and atriplex spp.)
Pink Velvet-bush (Lasiopetalum behrii)
Ruby Saltbush (Enchylaena tomentosa)
Scrub Cypress Pine (Callitris verrucosa)
Scrub or Swamp Sheoak (Allocasuarina paludosa)
Tufted Yacca Grass Tree (Xanthorrhoea semiplana)
Yacca (Xanthorrhoea caespitose)
Low storey
Baeckea (baeckea spp.)
Common Porcupine Grass (Triodia scariosa and T. irritan)
Green tea-tree (Leptospermum coriaceum)
Myrtles (calytrix spp.)
Scrub Cypress Pine (Callitris verrucosa)
Fires
The mallee is prone to fires, typically after lightning strikes that occur when the understorey is at its highest after above-average rainfall. This promotes excessive growth, causing an accumulation of fuel load.
Respective state bodies set key fire-management regimes in place to responsibly protect these assets. Traditionally, the mallee is burned with large-scale fires every 10 to 20 years. The terrain of the mallee, steep dunes, soft sand, isolated regions and minimally available response teams means that once fires start they are quick-moving and difficult to fight.
Flora and fauna species colonise and capitalise on regenerating bush areas after fires. Bearded and Painted dragons take advantage of the open areas. Invertebrates utilise the germination and re-emergence of lush undergrowth and saplings. Insectivorous birds are drawn to the surge in prey numbers.
In their entirety, invertebrates are well represented in the mallee. The leaf litter and hummock grass house communities of ants, centipedes and grasshoppers that feed on the grasses. There are scorpions and spiders that are usually adapted to arid areas or have a widespread distribution.
In the mallee, reptiles have adapted to the temperature extremes. The survival of hummock grass is substantial for them, as they live inside hummock grass. Night-shift reptiles such as Burton’s Legless lizards (Lialis burtonis), bardicks (Echiopsis curta) and Spiny-tailed geckos (Strophurus spinigerus) can be seen moving about the triodia or adjacent areas. Day-shift lizards such as Striped skinks (ctenotus spp., morenthia spp.) and dragons, especially Painted or Mallee, rapidly move about feeding on ants.
Other large and well-known species of reptiles forage around these habitats, including the Shingleback Lizard (Tiliqua rugosa), Western Blue-tongued Lizard (Tiliqua occipitalis), Sand Goanna or Gould’s Monitor (Varanus gouldii gouldii) and Bearded dragons (Pogona spp.). Smaller snakes, especially blind snakes (ramphotyphlops sp.) emerge only after dark, during showers and local storms, leaving from their subterranean ant nests. Large snakes are rarely seen, other than the widespread Eastern Brown Snake (Pseudonaja textilis), which is more prevalent in rural regions, chasing the more favourable house mouse rather than lizards, which are its normal diet.
Desert Skinks (Liopholis inornata) are often seen near their burrows at the base of triodia plants. Often they build one to three entrances and emerge at dusk, but also may be seen during thunderstorms in the afternoon. They can also be seen at night just outside of their burrow as they ambush passing prey, especially invertebrates.
Some types of mallee habitats are hummock grasslands, heathland, mallee woodlands and shrublands. Storm clouds over the mallee. A beaded gecko emerging at night to catch invertebrates.
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