Natural Temperate Grasslands of Southern Volcanic Plain

Images ©:
©Nicholas Williams

The Southern Volcanic Plain was created by volcanic activity that began 4.5 million years ago and continued until 10 000 years ago. On average, an eruption took place every 10 000 years and over 400 eruption points have been identified. Although there were some explosive eruptions that produced circular craters (maars), which now contain lakes and swamps, most were small volcanoes, active for a few years or decades. These deposited thin broad shields or long lava flows of basalt 2–10 m deep, creating broad plains, but other flows up to 100 m thick filled existing valleys. Native grasslands occur in areas where these flows have experienced long periods of weathering, producing heavy grey, red or black cracking clay soils, which are generally fertile but poorly drained. In contrast, the youngest relatively unweathered lava flows are known as stony rises and have thin soils and support woodland vegetation dominated by genera such as Banksia (Banksias), Acacia (Wattles) and Allocasuarina (She-oaks and Bull-oaks).

The dominant native grass of the Victorian Volcanic Plain grasslands is Themeda triandra (Kangaroo Grass) which is a summer growing tussock forming species. A range of winter growing grasses – including Rytidosperma spp. (Wallaby Grasses), Dichelachne spp. (Plume Grasses) and Austrostipa spp. (Spear Grasses) – occur as minor components in most grasslands, but increase in abundance where soils are shallow (soil moisture stress reduces Kangaroo Grass productivity) and where past heavy stock grazing has occurred. Poa labillardierei (Common Tussock-grass) occurs in wetter areas, such as drainage lines. A variety of perennial forbs occupy the spaces between grass tussocks. Intertussock species that occur throughout the range of the community include Eryngium ovinum (Blue Devil), Acaena echinata (Sheep’s Burr), Leptorhynchos squamatus (Scaly Buttons), Convolvulus angustissimus (Pink Bindweed) and Schoenus apogon (Common Bog-rush). In areas of higher rainfall to the west of the bioregion, other species that frequently occur include Microtis unifolia (Common Onion-orchid) and Drosera peltata (Pale Sundew). In lower rainfall areas, Chrysocephalum apiculatum (Common Everlasting) and Calocephalus citreus (Lemon Beauty-heads) become more prevalent.

Conservation Status (EPBC Act) 
Critically Endangered
Percent of former extent remaining 
< 2%
Bioregions the community occurs in