Grassland (excluding the alps)
Grassland ecosystems in Victoria are found in flat to gently undulating country at low altitudes (generally below 700 m) in low to medium rainfall areas (400-1000 mm a year) on relatively nutrient-rich loam, clay-loam and alluvial soils. Slightly less than 10% of the area once supporting Grassland in Victoria falls on public land while a little under 5% is represented in conservation parks and reserves. About 85% of Grassland has been removed or substantially altered for agriculture and urban development. Grassland may be bordered by a range of other ecosystems including Red Gum, Black Box Woodland, Heathland, Dry Sclerophyll Forest and Box-Ironbark Forest.
The Grassland ecosystem varies considerably over its large climatic and geographic range, from the volcanic plains to the south-west, to the calcareous flats of the Wimmera in the west, the alluvial plains of the north and South Gippsland, the high-altitude hillsides of East Gippsland and the low country around Port Phillip Bay and Westernport. In most areas of Grassland there is a sparse tree canopy over at least small portions of the landscape. In the west the most common tree is Eucalyptus camaldulensis (River Red Gum) which is sometimes associated with Eucalyptus melliodora (Yellow Box), Eucalyptus leucoxylon (Yellow Gum) or small populations of Allocasuarina luehmannii (Buloke) or Allocasuarina littoralis (Black Sheoak) . Further north and east Eucalyptus microcarpa (Grey Box) is more abundant and may be associated with or replaced by stands of Eucalyptus albens (White Box), while in South Gippsland Eucalyptus tereticornis (Forest Red Gum) occupies a similar environment to Eucalyptus camaldulensis elsewhere.
The understorey doesn't support a typical shrub layer, although there
are often scattered shrubs in on deeper soils, in drainage lines or near rocky outcrops.
The ground layer is dominated by perennial, mostly tufted or
tussock-forming grasses (Kangaroo Grass,
Tussock Grass, Spear Grass, Wallaby Grass, Windmill Grass) with
some rhizomatous or stoloniferous species (Weeping
Grass) and a few annuals (Blown
Grass). In most areas the grasses are accompanied by a wide
range of perennial and annual herbs (wood-sorrel,
bindweed, sundew, woodruff, everlasting, bidgee-widgee, lobelia, trigger
plant, blue devil), sedges (Carex,
Schoenus), lilies (mat-rush,
chocolate lily, milkmaids, early nancy) and small shrubs (rice-flower,
sida, astroloma, peas).
The pre-European composition of Grassland is, in most areas, impossible to determine due to the substantial changes that took place throughout the ecosystem before any systematic ecological assessments were undertaken. Livestock, mostly sheep, were released onto Grassland almost immediately after settlement and as a result the most palatable species, and those that are sensitive to trampling by hard-hoofed animals, will have been substantially reduced in number by the time the first European botanist examined the vegetation. It wasn't long before graziers discovered that the productivity of native grasslands was beginning to decline because, unlike their European counterparts, the Victorian grasses, and herbs, were poorly adapted to sheep and cattle grazing. One of the obvious changes was that Kangaroo Grass, Tussock Grass and Wallaby Grass decreased in numbers, while the abundance of Spear Grass increased. Graziers noticed that the long-awned seeds of Spear Grass would work their way into the flesh of sheep and became a regular contaminant of mutton. Early settlers would jokingly refer to the seeds as a natural seasoning which they called 'native caraway', but there was no doubt that these grasses were considered to be undesirable in pasture.
As a result, northern hemisphere pasture grasses and clovers were sown over great areas to improve both the quality of the fodder and increase the nitrogen availability in the soil. The first and most commonly sown grass was (and remains) Perennial Rye-grass (Lolium perenne) and the most abundant clover was Subterranean Clover (Trifolium subterraneum) but other grasses and clovers soon followed. In later years artificial fertilisers, particularly superphosphate, were applied liberally to pastures of all kinds and the composition of Grassland changed forever. The increase in soil nutrients, the heavy grazing by sheep and cattle and the introduction of rabbits, all worked to the advantage the non-native plant species, and by the late 1800s most of the plains once dominated by Kangaroo Grass and brightly flowered herbs (in summer the Grassland west of Melbourne used to be referred to as the 'wildflower plains') were gone.
The loss of native plants from Grassland was followed, and in some cases preceded, by the local extinction of native animals. Grassland species that were once common, such as the Plains Wanderer, Australian Bustard, Eastern Barred Bandicoot, Bush Stone-curlew and Striped Legless Lizard, have become rare since European settlement. Some species, recorded only from early expeditions and with poor location information, may have vanished so quickly that we are not sure of their original status in Grassland or even if they used the ecosystem at all (for example, White-footed Rabbit Rat, Brush-tailed Bettong, Eastern Bettong). Clearly the success of Red Fox in Victoria also played a big role in the reduction of these species as did competition with the European Rabbit.
Today, Victoria's most widespread ecosystem is also its most disturbed, most commonly converted to grain and other monoculture crops, and least well represented in conservation parks and reserves. Nevertheless, the majority of the main components of Grassland are still present, some are quite common, and there is reason to believe that there is considerable value in maintaining a substantial proportion of the original elements for long-term sustainability of modern pastures.
Some of the most valuable areas of native and near-native vegetation in Victoria (in a monetary as well as ecological sense) are small pockets of Grassland on the western and northern outskirts of the Melbourne Metropolitan Area. All of them are essentially disused paddocks, with a grazing history dating back 100 years or more, which had, by the 1980s, become surrounded by urban and light-industrial development. Once the stock were removed local botanists began to notice the distinctive bronze of Kangaroo Grass (Themeda triandra) which was beginning to cover the landscape. Closer examination revealed many other native grasses and herbs, typical of a mature Grassland ecosystem, were appearing in the paddocks and that the non-native plants, while still common, were not always the most abundant species. Arguments were put to the state government that such areas of Grassland should be purchased from the private landowners and put into the state's reserve system. While there was sympathy for this it was not a straightforward process as the land prices were very high due to the potential for subdivision for the rapid urban expansion of Melbourne. The result was that only a few properties were purchased at a cost that some observers noted would have allowed the repatriation of 100 times the area in places such as the Mallee and Wimmera.
The lesson learnt from this was that not all Victorian graziers and farmers were as diligent and thorough in their conversion of native pasture into European-style grazing land as was once thought. While livestock were present it was difficult to tell how far the conversion had gone - one cropped bit of grass looks like most others from a distance - and it was only after grazing was stopped that the native plants, when present, were able to show through. In addition it was discovered that many farmers had purposely left some paddocks unaltered, except for grazing, as they had found native pasture survived hot summers and periods of drought much better than 'improved pasture'. One of the reasons for this is that some native grasses, (Kangaroo Grass, Windmill Grass) employ chemical and morphological mechanisms for photosynthesis that are very efficient under hot, dry conditions and low nitrogen availability - the so-called C4 carbon fixation process in which an intermediate molecule with four carbon atoms is created before sugars are made. This method of capturing carbon and converting it to sugar requires more energy than the C3 pathway (which creates an intermediate molecule with three carbon atoms) utilised by most other species (Perennial Rye-Grass, Wallaby Grass, Spear Grass) but releases far less water into the atmosphere. Consequently a mixture of plants using the two photosynthetic pathways provides the Grassland ecosystem with options for growth under conditions of drought and of plentiful water availability - it just isn't as productive as traditional European pastures.
It is doubtful that large areas of truly pre-European Grassland will ever be a reality in Victoria, apart from our lack of knowledge about the original botanical composition and the primarily private ownership of the land, we don't know exactly how the Koori's fire management programs in Grassland worked. There is, however, some hope that many, near-native patches of the ecosystem may exist on private land across the state, where pasture improvement has not been engineered. The fact that in some areas the simple measure of removing stock for few years can reveal a wide range of native species (as was true when cattle were removed from the Alpine areas of Victoria) suggests that management of these patches for conservation purposes may not necessitate the complete removal of domestic stock from all areas. There is clearly some room for encouraging farmers to lower the grazing regime on the best Grassland on their properties in return for management assistance and other cooperative arrangements with the state government.
© Paul Gullan, Viridans Biological Databases