Acacia melvillei Shrubland in the Riverina and Murray-Darling Depression bioregions - profile

Conservation status in NSW: Endangered Ecological Community

Description

Acacia melvillei Shrubland in the Riverina and Murray-Darling Depression bioregions is the name given to the ecological community that is dominated by Acacia melvillei. Acacia melvillei Shrubland typically has an open canopy of shrubs or small trees, sometimes with scattered mid-stratum shrubs, and with a sometimes sparse, but highly variable ground layer dominated by grasses, chenopods and herbs. The structure and species composition of the community varies depending on disturbance history and temporal variability in rainfall. The open stratum of large shrubs or small trees may be reduced to isolated individuals or may be absent as a result of past clearing. The shrub/tree layer is dominated by Acacia melvillei (Yarran), either in pure stands or with a range of other less abundant trees or tall shrubs. These may include Acacia loderi (Nelia), Alectryon oleifolius subsp. canescens (Rosewood), Casuarina pauper (Belah) and Myoporum platycarpum (Sugarwood).

Acacia melvillei Shrubland shares a number of species with Acacia loderi Shrublands, another endangered ecological community. These two ecological communities inhabit similar soils and landforms and have some overlap in their distributions, but Acacia loderi Shrublands are more common in the northern part of the Riverina and Murray-Darling Depression bioregions and extend further north into several other bioregions. They may be distinguished on the basis of the relative abundance of their tree species (with A. melvillei generally uncommon within A. loderi shrublands) and differences in composition of their understories.

Location and habitat

Distribution
Acacia melvillei Shrubland is currently recorded from south-western portion of NSW in the Riverina and Murray-Darling Depression bioregions in the local government areas of Balranald, Carrathool, Central Darling, Conargo, Wakool and Wentworth. Acacia melvillei Shrubland is scattered over a relatively large distribution, with an estimated extent of occurrence in the order of 50000km2. However, throughout this distribution, Acacia melvillei Shrubland occurs in relatively small patches.

Habitat and ecology

Acacia melvillei typically occupies sandhills and undulating sand plains in south-western NSW.
The community occurs on red-brown, sandy loam soils as scattered patches grading into surrounding woodlands of Belah and Rosewood, White Cypress Pine or sandplain mallee.

Regional information
This species is found in the following catchment management authority regions. Click on a region name to see more details about the distribution, vegetation types and habitat preference of the species in that region.

Threats

Most of the remaining stands of Acacia melvillei Shrubland are heavily degraded by overgrazing, which has resulted in simplification of community structure, changes in species composition, invasion of weeds and soil erosion.
Some stands of the community are threatened by clearing for cropping, particularly in the east of its range.
Fragmentation, grazing and small-scale physical disturbance have resulted in weed invasion throughout the distribution of Acacia melvillei Shrubland, which continues to threaten the ecological function of the community.
Overgrazing by domestic livestock and feral herbivores, including rabbits and goats, has resulted in a scarcity of woody understorey plants and a lack of regeneration of palatable trees and shrubs in the community. Consequently, senescent trees are not replaced with new individuals and there is a prolonged trend of stand degeneration, which is difficult to reverse, even under active conservation management. Overgrazing also reduces the habitat suitability for vertebrate fauna that occur in the community.

What needs to be done to recover this species?

Reduce agricultural grazing pressures through the adoption of suitable grazing regimes which allow for regeneration.
Control feral rabbit and goat populations to reduce erosion and grazing pressure.
Create wildlife corridors between remnant vegetation patches were possible to reduce the ecological impact associated with environmental fragmentation.
Rehabilitate the understorey of remnants via weed control.
Protect all known habitat from clearing or disturbance.
Monitor status of all known remnants.
Involve stakeholders in the management of remnants, and distribute information about this EEC to the community.
Ensure that the fire sensitivity of the community is considered when planning hazard reduction and asset management burning.
Protect sites from inappropriate burning.
Ensure that this species is considered in the land use planning process, particularly development consents, rezonings and regional planning.

References

Batty AL, Parsons RF (1992) Regeneration of Acacia melvillei in part of semi-arid south-east Australia. Proceedings of the Royal Society of Victoria 104, 89-97.
Eldridge DJ (1998). Trampling of microphytic crusts on calcareous soils and its impact on erosion under rain-impacted flow. Catena 33, 221-239.
Eldridge DJ, Greene RSB (1994). Assessment of sediment yield from a semi-arid red earth with varying cover of cryptogams. Journal of Arid Environments 26, 221-232.
Kodela PG (2001) Identification and review of Acacia melvillei specimens in New South Wales. Report to the NSW Scientific Committee, Sydney.
NSW Scientific Committee (2008). Acacia melvillei Shrubland in the Riverina and Murray-Darling Depression bioregions- endangered ecological community. Final determination DEC (NSW), Sydney.
Porteners MF (1993) Natural vegetation of the Hay Plain: Booligal-Hay and Deniliquin-Bendigo 1:250 000 maps. Cunninghamia 3, 1-122.
Westbrooke ME, Miller JD (1995) Vegetation of Mungo National Park, western NSW. Cunninghamia 4, 63-81