Threatened flora of the Western Volcanic Victorian Plains

The Western Volcanic Plains in Victoria is approximately 2.3 million hectares in area and lies south of the Western Uplands, stretching from the Otways in the south-east, to the South-Australian border in the south-west. It encompasses part of the broader Victorian Volcanic Plains (VVP) bioregion, characterised by relatively fertile basalt sediments formed by volcanic lava flows dating from 5 million years ago. Endangered vegetation communities such as Plains Grasslands and Plains Grassy Woodland are iconic to this bioregion, notably for their spectacular and colourful spring and summer flowering displays, as well as for their rarity. Since European Settlement, more than 99% of grasslands in the VVP has been lost or substantially modified through clearance and conversion for pasture, grazing, and settlement, as well as through the lack of important disturbance regimes such as fire, which are critical to maintaining an open vegetation structure and promoting recruitment of native flora species.

Flowering ground cover of remnant grassland in the Western Volcanic Plains (photo: L.Kivisalu)

In the Western Volcanic Plains, it is estimated that less than 0.1% of native grasslands, and less than 5% of grassy woodlands remain. As a result, there is a high number of threatened and endemic flora and fauna species within these remnant vegetation communities. Their associated habitat areas are therefore highly significant for biodiversity conservation.

Nature Glenelg Trust, through the funding support of the Victorian Government – Department of Environment and Primary Industries’ (DEPI) Victorian Environmental Partnerships Program (VEPP), is delivering a number of flora conservation projects within the Western Volcanic Plains. These activities will aim to restore and enhance habitat values at three unique public reserves to promote the persistence of endemic flora populations.

Nature Glenelg Trust will also support key working partners and community groups in establishing long term management visions for the reserves, to ensure conservation values at the site are secured into the future.

Maam Water Reserve

Wetland communities of the Maam Water Reserve, Allansford (photo: J.Tuck)

The Maam Water Reserve, is a small 7 hectare public land area in Allansford, just  6km north-east of Warrnambool. The reserve encompasses a number of vegetation communities, including the endangered Plains Grassy Woodland and Swamp Scrub, as well as a number of wetland communities including Plains Grassy Wetland, Plains Sedgy Wetland, and Aquatic Herbland. These wetland communities are likely to be fed by groundwater emerging from a freshwater spring.

There are a number of significant flora populations within the reserve, including the  Basalt Leek-orchid (Prasophyllum viretrum) which is endemic to the Western Volcanic Plains, only known to a handful of grassland sites. The ongoing management of woody weeds present Maam reserve such as Gorse (Ulex europeaus) and non-indigenous Coast Wattle (Acacia longifolia spp.) will be important in providing an open ground cover structure to promote the growth and recruitment of this rare orchid, as well as many other native grassland species present.

Prasophyllum viretrum in flower (photo: D.Pitts)

The Warrnmabool Society of Growing Native Plants (SGAP) group have played a key role in promoting conservation management at the reserve, already being successful in sourcing funding through government agencies for the completion of comprehensive vegetation surveys and development of management recommendations, undertaken by Ecology Australia. Nature Glenelg Trust will continue to work collaboratively with the Warrnambool SGAP group in the current conservation project.

Mortlake Common Flora Reserve

Old seed heads of native Kangaroo Grass, which dominates areas of grassland within the Mortlake reserve (photo: L.Kivisalu)

The Mortlake Common Flora Reserve represents one of the largest and most herb-rich grasslands within the Western Volcanic Plains region, approximately 300 hecatares in size. The reserve encompasses Plains Grassland/Plains Grassy wetland mosaics, and formerly Grassy Woodland, as indicated by the presence of scattered River Red Gums (Eucalyptus camaldulensis)  and Tree Everlasting (Ozothamnus ferrugineus).

A number of Leek-orchid populations occur within the reserve, including the Basalt Leek-orchid, as well as the undescribed Western Gaping Leek-orchid (Prasophyllum sp. aff. correctum), with the latter known only to this site. The management of invasive species such as Gorse, as well as Phalaris (Phalaris aquatica) will be undertaken to promote an open and functioning grassland system, and increase the habitat condition for these rare flora species.

Western Gaping Leek-orchids flowering in the Mortlake Common (photo: A.Pritchard)

Lake Linlithgow and Lake Bulrush Lake Reserve

Birdlife at Lake Linlithgow, with Grampians in background (photo: Tracey Kruger)

Lake Linlithgow and Lake Bulrush Lake Reserve (L.R) encompasses a number of volcanic lakes, formed by the moulding and weathering of basalt lava flows. These formations are very unique rare landforms in the western district, and create  habitats critical to waterbirds of the region. Lake Linlithgow, most significant in size (over 1400Ha), is comprised of a number of vegetation communities including Plains Grassland, Brackish Wetland and saltmarsh communities.

The Vunerable (EPBC Act 1999) Salt Lake Tussock-grass (Poa sallacustris) occurs within the reserve, in a distinct littoral zone around the lake fringes. This small, spreading grass only reaches 30cm when in flower, and is thought to have the ability to spread rhizomatously in response to inundation and soil property changes around the lake. Invasive weeds such as the Spiny Rush (Juncus acutus), Tall Wheat Grass (Thinopyrum ponticum), and Phalaris are encroaching into the habitat of the Salt Lake Tussock-grass along the lake shores, competing with and shading out the low lying native vegetation.

The Hamilton Field Naturalists Club (HFNC) have been actively promoting restoration and conservation of the lake reserve over a number of decades, including the removal of grazing which has seen impressive recovery of the native vegetation. Nature Glenelg Trust will be working with the HFNC, as well as land managers Parks Victoria and the Southern Grampians Shire Council to undertake strategic management of the threatening weeds, and promote conservation of the site to the wider community.

Salt Lake Tussock-grass in flower (photo: L.Kivisalu)



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