The Bioregional Landscape
The Natural Capital of the Landscape
Land Management Themes
Biodiversity Condition
Management Responses
Tables and Charts for the Victorian Mallee

The Bioregional Landscape
The Victorian Mallee extends north and north-west from the Victorian Highlands to the New South Wales and South Australian borders. Annual rainfall ranges from 500 mm in the south to less than 250 mm in the north. It is part of the much larger Murray-Darling Depression IBRA region which extends into New South Wales and South Australia. The area is characteristically of low elevation and three bioregions are recognised. The Wimmera bioregion corresponds to the flat to gently undulating Wimmera plains of the southern part of the area. The Lowan Mallee bioregion extends in three lobes eastwards from the South Australian border, in part dividing the Wimmera plains. These three lobes correspond broadly to: the southern section of the Murray-Sunset National Park; the Big Desert including Wyperfeld National Park; and the Little Desert National Park. The Lowan Mallee bioregion is typified by a complex array of jumbled dunes and east-west trending dunes with intervening plains of deep white siliceous sand. The Murray Mallee bioregion is typified by an extensive, undulating sandy plain that is often overlain by linear, east-west aligned, stabilised sand dunes with intervening heavier textured swales. It occurs over much of the eastern portion of the area but extends to the South Australian border in the north. The Lowan Mallee and Murray Mallee soils in particular are exceptionally prone to wind erosion when cleared.

The Victorian Mallee characteristically has few surface water bodies because its soils are highly permeable and its climate promotes high evaporative losses. The Murray River flows along the northern edge of the bioregion and the northerly flowing Avoca River more or less defines the eastern edge. Anabranches of the Murray River form the Hattah Lakes complex and define the southern edges of Wallpolla, Mulcra and Lindsay islands. The Wimmera River/Outlet Creek and the Yarriambiack, Tyrrell and Lalbert creeks are northward-flowing intermittent creeks that originate beyond the southern edge of the area. They all fail to reach the Murray River, terminating in freshwater or saline lake systems. The Hattah Lakes, which are a declared wetland of international significance under the Ramsar Convention, are contained within the Hattah-Kulkyne National Park, which is itself a designated Biosphere Reserve under the UNESCO ‘Man and the Biosphere’ program. The Wimmera River north of Lochiel is listed as a Heritage River, reflecting its important biodiversity values. The terminal lakes of this system include Lake Hindmarsh, which is a Ramsar-declared wetland, and the often dry Lake Albacutya. Also of major significance for geological, archaeological and nature conservation reasons is the Lake Tyrrell Wildlife Reserve, which is the terminal lake for the Tyrrell Creek. Lake Buloke in the south supports large numbers of waterbirds when full and is the most popular duck hunting area in the State.

The most significant of the conservation reserves in the Wimmera bioregion support remnants of Plains Grassy Woodlands, particularly at Glenlee, Barrett and Gerang Gerung. Highly significant remnants also occur in the Brynterion and Barrabool State forests.

Prior to European settlement, the Mallee and Wimmera were occupied by Aboriginal people of eight language groups. The bulk of the area was occupied by the Wergaia, who were found in the southern and central Mallee and the Wimmera as far east as Lake Tyrrell and almost to the Loddon River. In the north the people were concentrated along the main watercourses, the Wimmera/Outlet Creek system and the Murray. Further south, where conditions were somewhat less harsh the population was probably slightly more dispersed. However the freshwater lakes and swamps such as Lake Buloke and Lake Hindmarsh were undoubtedly focal points, offering both water and abundant food supplies which permitted gatherings of large groups from several tribes.

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The Natural Capital of the Landscape
The Victorian Mallee is a large area and has a correspondingly complex and diverse array of vegetation communities occurring as complex mosaics in the landscape. Many individual species of fauna utilise a range of ecosystems and consequently are widely distributed across the area. Characteristic of the Lowan Mallee and Murray Mallee bioregions are multi-stemmed mallee eucalypts, which dominate several communities. These are interspersed with small to large stands of Slender Cypress-pine, Buloke and Belah woodlands, grasslands and Savannah Mallee on high ground, while halophytic shrublands occur on lower ground close to or intersecting the water table. The river and creek systems allow the persistence of significant stands of River Red Gum and Black Box Woodland as well as lake-bed communities. Desert Stringybark communities are found in and around the Little Desert and the southern Big Desert. The Wimmera plains were originally covered by woodlands variously dominated or co-dominated by Yellow Gum, Buloke, Black Box and Grey Box with large areas of native grassland occurring between the woodlands.

Seventy-eight per cent of Victoria’s mammal extinctions have occurred in this area, with at least 11 species in the small to medium size range lost. Many extant species are found nowhere else in Victoria (e.g. Red Kangaroo, Paucident Planigale, Mallee Ningaui, Mitchell’s Hopping-mouse). The Silky Mouse and Western Pygmy-possum are restricted to the Big and Little Deserts. The avifauna is distinctive, with raptors, parrots and honeyeaters the dominant groups. Victoria’s only megapode, the Malleefowl, occurs here. Clearing and subsequent habitat fragmentation has led to the decline of many species including the Black-eared Miner, Malleefowl, Australian Bustard and Western Whipbird. In Victoria, the Malleefowl is restricted to Mallee Eucalypt Shrublands with a preference for habitat that has not been burnt for at least 40 years. The White-browed Treecreeper is significantly affected by clearing of its habitat of Slender Cypress-pine, Buloke and Belah woodlands. The reptile fauna is especially well developed, with a greater diversity in the Victorian Mallee than in any other area of the State. Fire and past clearance of native vegetation may play the major role in the restricted range of some cryptic species such as the Mallee Worm-lizard, whereas human interference still has a detrimental effect on others such as the Carpet Python. Two threatened amphibians, 11 threatened fish and at least five threatened invertebrates occur or used to occur in the Victorian Mallee.

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Land Management Themes
Small rural towns occur across the whole of the area, but the major regional centres are Mildura, Horsham and Swan Hill. Cereal and coarse grain cropping and livestock industries dominate the dryland areas while irrigated horticulture along the Murray and Wimmera rivers makes a significant economic contribution. The area falls wholly or in part within the jurisdiction of three municipalities and seven shires.

The national parks of the western side of the area make up 40 per cent of Victoria’s national park estate and include representation of all local BVTs. As the Lowan Mallee bioregion dominates these major blocks of public land, the heathy vegetation communities are best represented. Vegetation communities associated with the region’s better agricultural soils in the Murray Mallee and Wimmera bioregions, especially Grassland, Plains Grassy Woodland, Wimmera Mallee Woodland, Slender Cypress-pine, and Buloke and Belah woodlands have been extensively cleared for agriculture. Therefore the Grassland and Plains Grassy Woodland BVTs and many significant vegetation communities below the BVT level of resolution are under-represented, especially in the Murray Mallee and Wimmera bioregions. East of the Calder Highway to Swan Hill and south to Donald and Warracknabeal, public land is largely confined to scattered small blocks, streamside reserves and lakes. Freehold land retains only about three per cent of its original native vegetation as remnants. Therefore roadsides and unused road reserves are particularly important in preserving remnant stands of native vegetation and providing corridors for the movement of wildlife. Their role in connecting with other larger remnants should not be underestimated. Off-reserve conservation in the Victorian Mallee is vital to the achievement of Victoria’s conservation objectives.

Overall, approximately 70 per cent of Victoria’s mallee vegetation has been cleared. As a direct consequence of farming practices, the 1930s saw a part of the Victorian Mallee become one of the worst wind eroded areas in Australia, resulting in the passing of soil conservation legislation in Victoria. The area also gained notoriety for rabbit populations of plague proportions exacerbating the effects of stock grazing on leased land and severely affecting particularly grassy and woodland communities on reserved land. Many mallee species require fire to regenerate. Heath of the Lowan Mallee appears to be affected by fire intensity, whereas timing appears to be the critical factor in mallee shrublands and grasslands of the Murray Mallee.

Riverine communities require intermittent flooding. River regulation has altered not only the timing of floods but also the size and frequency of flooding. Creeks that formerly ran dry for extended periods continue flowing while others that were more often wet now remain dry except for exceptionally high floods. These changes affect not only adjacent floodplain vegetation but also aquatic fauna that may be dependent upon certain flooding regimes.

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Biodiversity Condition
A relatively high proportion of public land occurs in the north-west of the area. The best represented and least modified BVT in this area is Heathland. Pest plants and animals have made least incursion on this BVT largely due to lack of water and its undisturbed nature. Here the fire regime is the single most important factor in maintaining biodiversity. Other BVTs reserved for conservation purposes have been modified through past management practices. Prior to reservation, parts of the Murray-Sunset and Hattah-Kulkyne national parks had long pastoral histories. Timber from woodland communities was utilised for fencing, horticultural trellising and firewood. Grazing pressure exerted by stock, rabbits and feral animals such as goats modified the landscape, converting woodlands to grasslands with a high proportion of weed species. Remnant dams support artificially high populations of native grazers in their hinterlands. Routine kangaroo culling has taken place within a section of Hattah-Kulkyne National Park since 1990, with evidence that a subsequent increase in some plant species can be directly attributable to a reduction in grazing pressure. Modified flooding regimes have a significant impact on each bioregion’s waterways, notably the Outlet Creek system, which together with the terminal lakes and Lake Albacutya forms part of the Wimmera Heritage River system. River Red Gum and Black Box communities associated with this system provide important habitat for a range of species, notably the Regent Parrot. Regulation of the Wimmera River has resulted in a drastic reduction in the frequency of flows, with some areas not receiving any since the 1920s.

With 70 per cent of the area cleared, habitat loss is the single most important factor affecting biodiversity. In addition to the widespread loss of communities, clearing has resulted in increased recharge and subsequent rising saline ground water. The Victorian Mallee contains some of the worst salt-affected land in the State, with large areas affected by dryland salinity and more concentrated effects in irrigated horticultural areas. Low-lying areas such as the Hattah Lakes are at threat from a further rise in ground water while floodplains of the Murray River may have yet to experience the full effect of increased salinity.

Native vegetation in the largely cleared areas is in many cases retained as isolated reserves or remnant patches on private land. Road and other linear reserves are the sole means of linking many of these patches. While remnant grasslands are relatively well represented in the north they are susceptible to high grazing pressure and weed invasion. Elsewhere grasslands occur only as small remnants where edge effects and continued clearing for agriculture pose the greatest threat.

In the Wimmera bioregion the main threats to remnants are invasion by introduced grasses and clearing. Other threats include inappropriate tree planting into remnants, drift from aerial spraying, expansion of irrigation and stock grazing without replacement of senescent trees.

Of the 223 known threatened species and undetermined number of threatened ecological communities in this suite of bioregions there are:

• 102 listed vertebrates and plants, of which 21 have Action Statements;
• six listed invertebrates, of which three have Action Statements;
• one listed community, which does not yet have an Action Statement.

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Management Responses
The range of management responses in the Victorian Mallee reflects the three broad themes: maintenance of largely natural landscapes of the Lowan Mallee; rehabilitation of previously grazed landscapes in the Sunset and Hattah-Kulkyne areas; and protection of remnants in a rural landscape.

In mallee heaths and heathlands that are well represented in the national parks, the need for greater understanding of fire ecology is particularly important. The large remote areas typical of the Lowan Mallee provide an opportunity for management of fire for biodiversity objectives to be undertaken at a broad scale.

In large areas of native vegetation efforts are directed at restoring the ecological balance after past uses. Proactive management of total grazing pressure, hydrological regimes, pest plants and animals, and salinity is critical for the protection of biodiversity. The relationship between these factors and biodiversity is in some cases poorly understood and requires an ongoing commitment to research and monitoring. Control of introduced species continues to be a high priority in many areas and the Hattah-Kulkyne National Park is a part of the national monitoring program to gauge the impact of the calicivirus release on the biodiversity assets affected by rabbits. Grazing pressures from over-population of kangaroos have now been monitored for nearly a decade and routine culling will continue to be undertaken where demonstrable benefits to ecosystem health and threatened flora conservation can be realised.

Areas outside the major reserves rely on sympathetic management of remnant vegetation on private land, linear reserves and isolated small blocks of public land. Intrinsic to this is a high level of community education and incentives in the form of assistance in identifying sites of significance and their management requirements. Regional Vegetation Plans will provide strategic direction for these activities and will recognise the inherent importance of remnants on roadsides and unused road reserves and their role in providing wildlife corridors. The requirement for continuing assistance through conservation programs for works such as fencing remnant vegetation or undertaking pest plant and animal control is significant in areas that have been extensively cleared. Conservation covenants and land purchase may be the only options for poorly represented remnant communities such as the Plains Grassy Woodlands of the Wimmera plains. Raising community awareness of the nature and significance of these communities will prevent inappropriate tree planting.

Together with the state-wide key directions outlined earlier, land and water managers and planners in each bioregion should consider the following priorities.

• Target Land for Wildlife and land protection grants to owners protecting and enhancing Northern Plains Grassland, Buloke, Belah or Sandalwood Woodlands and riparian vegetation.
• Manage kangaroo populations in parks and reserves as part of a program to restore threatened vegetation communities.
• Protect and enhance aquatic environments, floodplain wetlands and riparian vegetation by managing environmental flows and grazing on the banks of the Murray and Wimmera rivers and terminal, northward flowing streams.
• Determine and implement ecologically based fire regimes, particularly in the Lowan Mallee, as part of integrated processes outlined in the Code of Practice for Fire Management
• Protect roadside habitat from soil drift due to wind erosion.
• Manage and protect floodplain wetlands and other low lying areas of natural habitat from the effects of rising salinity.
• Complete Ecological Vegetation Class mapping of the Little Desest and the Wimmera and facilitate identification of all sites of biological significance in the rural landscape in conjunction with local government, and encourage appropriate use of this information in local planning schemes.