Native grasses are once again being given the respect they
deserve! Two hundred years of a 'remove and replace' attitude towards native
grass-dominated habitats has now changed. Promote and enhance them at all
costs is the new imperative! Native grasses also have emerged as the plants of choice for revegetating degraded habitats and for establishing an exciting new landscape style based on mass plantings of native grasses. The new Melbourne Freeways are a fine example. Home gardeners can now be rewarded for growing their own native grass-dominated landscapes, With colourful dainty herbs, lilies and bush peas juggling for position amongst domineering tufty, native grasses. More importantly, within a growing season, they yield a menagerie of fascinating insects, birds and wildlife.
Their chequered history of use and abuse
Traditionally, grass-dominated habitats were an integral part of the aboriginal hunting and gathering life style. The sweet stem bases of Spear Grass could be eaten like sugar cane. The Kangaroo, Spear and Tussock Grass seeds could be ground into flour. With open palms, the aboriginal women rolled the tough fibrous leaves along their thighs to form a fine thread. A string could be plied from two or three threads and used to make dillies, mats and nets.
To attract kangaroo and to harvest bush tucker easily, aborigines patch-burnt these grassy swards with hot fires to provide succulent 'green pick'. Only enough 'roos were killed to ensure that the many shrub and tree seedlings, which germinated after the hot fires, remained heavily grazed. This guaranteed that forest did not encroach across their valued grasslands, which now presents a deep problem for grassland managers.
In contrast to the aborigines, unaware farmers had little appreciation of the ecosystem value of native grasses. For 200 years, native grasses suffered the onslaught of weed invasion, grazing, ploughing, fertilising, exotic pasture over-seeding and five-acre sub-division. Frequent cool burning to force lush green shoots on Kangaroo grass paddocks proved clever at first, but finally degraded them. Weeds or spine-tipped, wiry awned seeded Spear grasses, which ruined fleeces and pierced eyes and skin have replaced them. Only a few remnants now remain, located in unexpected sanctuaries such as cemeteries, road and rail reserves.
| Introducing Native grasses and their
roles The palette of native grasses available for revegetation include Kangaroo Grass (Themeda triandra), Wallaby grasses (Austrodanthonia sp.), Spear grasses (Austrostipa sp.), Plume Grasses (Dichelachne sp.), Common Wheat-grass (Elymus scabrous), Blown grasses (Agrostis sp.), Tussock grasses (Poa sp.), Weeping Grass (Microlaena stipoides) and Forest Wire Grass (Tetrarrhena distichophylla), as well as the coastal sand-binding grasses of Hairy Spinifex (Spinifex sericeus), Salt-grass (Distichlis distichophylla) and Coastal Fescue (Austrofestuca littoralis). Silver Tussock Grass |
|
They not only command respect for their role in sustaining the intricate web of native fauna and flora, but they also play a filtering role for our watersheds by soaking up the rainfall so it can infiltrate slowly down into the depleted underground aquifers. Otherwise, the rains drain across and erode precious soil. Within the urban landscape, native grass landscapes are popular due to their natural beauty, drought tolerance, resistance to vandalism and ease of maintenance. They now embellish many prestigious city landscapes and roadside plantings. Florists are warming to the beauty of their unique flower heads, using them in floral displays.
Habitat for Marsupials, Reptiles and Frogs
Kangaroos, Wallabies, Wombats and Pademelons feed on the aptly named Kangaroo and Wallaby Grasses and their suites of inter-tussock herbs. Our small fry hop-alongs such as the Bettong, Southern Brown Bandicoot and Ringtail Possum all build nests for breeding, incorporating native grasses. It is a privilege to see a Bettong with a tail coiled around a bundle of native grasses scurrying to build its nest! The Eastern Barred Bandicoot prefers the shelter of native grass tussocks to scratch for seeds and insects. They leave distinctive conical shaped holes in native grass patches after feeding on grubs that munch on the grass roots. Echidnas gorge on the insect treats inhabiting the native grasses. A torchlight safari may reward the keen observer! Native grasses are also a favoured habitat for reptiles such as the Grass Skink and the Copperhead, White Lipped and Tiger snakes, that feed on the smaller prey and insects living amongst the native grasses.
The Southern Toadlet and Smooth Froglet breed in low lying grassy patches, laying their eggs on the expectation that the area will be flooded in autumn. Since they walk rather than hop and do not lay their eggs in water, they are radically different to most frogs. However, for the snakes and echidnas they are just as tasty as the other frogs!
Birds thrive amongst native grass tussocks
Native birds and even the nocturnal Greater and Lesser Long-Eared Bats scavenge grassy forest understoreys for plump seed heads and insects. Pardalotes, Thornbills, Honeyeaters, Robins, Whistlers, Fantails, Wrens and Welcome Swallows all line their nests with dried grasses interwoven with spider webs. Many of these birds busily collect 'beak fulls of nothing'. Closer inspection reveals a fine spider's silk being harvested. These birds, along with the mid to upper-canopy feeding species, provide the key to preventing tree dieback. They are known to eat up to 70% of the leaf-feeding insects attacking stressed trees. Remove or degrade the native grass understorey and this ecosystem rapidly declines as we see from the Midlands Highway.
Native grasses are ideal sites for web-producing spiders including the Wheel-web Spider. It spins its flimsy wheel-like web in an unusual horizontal position supported by the grass tussocks' intricate 3D architecture, and hangs upside down under the web's hub. Lacking poison glands, they use their disproportionately-long front legs-they cannot walk on flat surfaces-to wrap and subdued their prey. By injecting digestive enzymes they liquefy and suck out the prey's flesh. Of course, birds pick them off like liquorice allsorts.
Habitats for Bees, Ants, Butterflies and Moths
Our small solitary native bees exploit the hollow grass flower stalks. They construct a series of pollen and honey filled cells, into which they lay their eggs. Each cell is sealed with waxy secretions and frass.
Many butterflies and moths have evolved to feed voraciously on native grasses. The White Grassdart lays its eggs on the leaves of the Danthonia sp. and Poa sp. which then hatch into pale green larva. These form a shelter by joining several leaves together. Here they pupate into butterflies that characteristically rest with their forewings held up over the body while the hind wings are held flat. The night feeding Dominula and Tasmanian Skipper butterfly larvae also use silk to form a tubular shelter amongst Poa sp. The butterflies feed on a range of native daisies in the inter-tussock spaces. The Common Brown butterfly larvae feed on Kangaroo Grass, whilst in summer, the adults frequent the flowers of the Native Box Bursaria spinosa.
Interestingly, the Ptunarra Brown butterfly relies totally on Poa tussock grasses for their larval food, adult habitat and sunning spots. After mating they drop their eggs, like a low flying bomber, on the tussocks. The larvae hatch to feed on the tussock tips. In early autumn, they pupate from the tussock's base into weak-flying gregarious adults.
Conclusion
Grassy woodland communities are diverse systems of checks and balances. To remove any part (roos, wrens, spiders etc) or to add foreign components (sheep, fertilizers, weeds, cool burns etc) will cause a dramatic alteration to the rules under which they function. Finally do not manage a small grassy remnant under the illusion that it functions like a miniature, extensive grassy woodland; it responds to a distinctly different set of rules.
