Biodiversity Assessment - Great Victoria Desert
Great Victoria Desert
Introduction
Arid active sand-ridge desert of deep Quaternary aeolian sands. Mostly overlying Permian and Devonian strata of the Gunbarrel Basin. Tree steppe of Eucalyptus gongylocarpa, Mulga and E. youngiana over hummock grassland dominated by Triodia basedowii. The climate is arid, with summer and winter rain averaging 150 -190mm per annum. Landforms consists of red sand plains with patches of aeolian dunefields, salt lakes and major valley floors with lake derived dunes, and out-cropping and silcrete-capped mesas and plateaus (breakaways). Climate is arid with summer and winter rain. Three subregions are recognised in WA: GVD1 - The western end is underlain by Yilgarn Craton. There is a higher proportion of sandplains in comparison to the entire bioregion. GVD2 - is arid active sand-ridge desert with extensive dune fields of deep Quaternary aeolian sands overlying Permian strata of the Gunbarrel Basin. GVD3 - Eastern is underlain by Devonian sediments of the Gunbarrel Basin, with extensive sandplains of deep Quaternary aeolian sands.
Vegetation is primarily a Tree steppe of Eucalyptus gongylocarpa, Spinifex (Triodia spp) and mallee (Eucalyptus kingsmilli, E. youngiana ) over hummock grassland dominated by Triodia basedowii on the aeolian sands, Acacia and Mulga occur on the colluvial soils with Eremophila and Santalum spp.
Scattered marble gum (E gongylocarpa) and native pine (Callistris spp) occur on the deeper sands of the sand plains. Halophytes such as salt bush (Atriplex), Bluebush (Kochia), and samphire (Arthrocnemum) occur marginal to the salt lakes and in saline drainage areas.
Summary of overall condition and trend
Condition is good, apart from the western fringes of GVD1 which have been degraded by grazing from stock. CWR species have declined or become extinct. Feral herbivoures (camels and rabbits) and . lLarge, intense summer wildfires have reduced vegetation biomass throughout the region, although the grazing effects are more pronounced in wetlands. Continental landscape stress class is between 5 and 6 (GVD1 and 3 =6, GVD2 =5) as assessed by the Landscape Health report (1 is most stressed, 6 is least stressed).
Summary of conservation priorities:
Control feral herbivores and carnivores, introduction of fire management regimes to reduce the size and impact of summer wildfires, and ecological surveys to gain more knowledge of the bioregion are the management priorities. Resourcing and isolation are major constraints to management activities. Increasing interests in mineral prospects and the possibility of mine development will require management. Region has a medium priority for reserve consolidation with 9.4% in IUCN I-IV reserves, and minimal sub-regional bias.
Natural values
Rare species include the Princess Parrot, Samphire Thornbill, Sandhill Dunnart, Marsupial Mole, Mulgara, Rock Wallaby, Lerista puncticauda, Egernia kintorei Conospermum toddii, Calytrix warburtonensis, Dampiera ramosa, Dicrastylis nicholsii, Eremophila aureivisca, E. undulata Eucalyptus articulata, Labichea deserticola, Micromyrtus helmsii, Olearia arida, Ptilotus stipitatus, Thruptomene wittweri, Threatened Ecological Communities include the Yellow sandplain communities of the Great Victorian Desert, Assemblages of Queen Victoria Spring and the Mirramiratjarra dune field. One hummock grassland vegetation-type (444) is confined entirely to GVD1 and two vegetation-types (2245 and 4621) have greater than 85% confined to GVD2.
Click here to link to a table of natural values within each subregion
Wetlands
Two wetland of national significance are listed: Yeo Lake and Lake Throssell (WA044) are both in good condition with recovery expected in the short term with minimal intervention. Both were old pastoral leases. Yeo Lake is now a Nature Reserve and Lake Throssell was never taken up or developed as a pastoral lease and is a proposed reserve. The trend is condition improving with the removal of stock aiding in the recovery. The threatening process is mainly feral animals, including rabbits, goats, foxes, cats and stray stock.
There are two wetlands of regional significance: Lake Minigwal and Lake Rason. Both are significant for the maintenance of ecological processes. Lake Minigwal is a seasonal intermittent saline lake with a static trend and in good condition. Threatening processes include feral animals and a changed hydrology due to de-watering of mine sites and discharge of hypersaline water into lake beds. Lake Rason is also a seasonal intermittent saline lake with a static trend, but it is in near-pristine condition with mineral exploration and feral animals as threatening processes.
Nationally important wetlands
Map: IBRA map showing DIWA locations, towns, subregions, major roads and reserves and most common threatening processes.
Table: Australia's Important Wetlands (Directory of Important Wetlands of Australia): their type, condition, trend and threatening processes within each subregion.
There is no data available for this table within the bioregion.
Regionally important wetlands
Click here to link to a table of provisional identification of wetlands of regional significance: their type and special values within each subregion. The reliability of the overall subregional assessment is indicated.
Click here to link to a table of provisional identification of wetlands of regional significance: their condition, trend and threatening processes within each subregion.
Riparian Zones
The is no external drainage. Riparian vegetation is confined to major creek systems that only flow intermittently, and is of limited extent. On pastoral leases on western edge of region, its condition is degraded. But it is in near-pristine in remaining areas. The trend is declining on pastoral leases and static for the remainder. Threatening processes include grazing pressure on pastoral lease areas in western section, feral animals, changed fire regimes, and changed hydrology from de watering of mines and lowering of water tables.
Map: Riparian threatening processes.
Click here to link to a table of riparian zones: their average condition, trend and threatening processes for each subregion. The reliability of this overall assessment is indicated.
Ecosystems at risk
The following ecosystems are considered vulnerable: Yellow sandplain communities of the Great Victoria Desert have a very diverse mammal and reptile faunas (NVIS 24) and their distinctive plant communities are threatened by grazing, feral animals, mining and changed fire regimes; assemblages of Queen Victoria Spring (NVIS 25) are threatened by grazing, feral animals and changed fire regimes; Mirramiratjarra dune field is an unique dune formation with a vegetation and drainage system threatened by grazing pressures and feral animals.
Map: IBRA map showing frequency of threatening processes for ecosystems.
Click here to link to a table of provisional list of threatened ecosystems in Australia: their broad vegetation type (National Vegetation Information System - Major Vegetation Subgroup), recommended status, current legislative protection as a threatened ecosystem, trend and bioregional distribution. These ecosystems are arranged in the bioregion of their principal occurrence. The reliability of the recommended status is indicated.
Click here to link to a table of provisional list of threatened ecosystems in each subregion: their threatening processes.
Click here to link to a table of provisional list of threatened ecosystems in each subregion: their recommended recovery actions
Species at risk
The Marsupial Mole and two plants (Eucalyptus articulata, Conospermum toddii), are considered endangered. One bird, one skink, three mammals and one plant are considered vulnerable, while a further 19 are listed either priority 1 or 2 under WA State legislation. Threatening processes to both fauna and flora include carnivorous and herbivorous feral animals, changed fire regimes, and grazing pressures.
Map: IBRA map showing frequency of threatening processes for species.
Click here to link to a table of species at risk in each subregion: their status, trend and subregional distribution. The reliability of the assessment of trend is indicated and whether recovery plans have been prepared.
Click here to link to a table of species at risk in each subregion: their threatening processes.
Click here to link to a table of species at risk in each subregion: their status recommended recovery actions.
Birds
The Great Victoria Desert was much wetter during the second Atlas than the first, thanks to a series of cyclones, which may explain some apparent increases in species like the Emu. A handful of limited range, threatened and introduced species do occur in the bioregion, but apparently only in small numbers. With only a small number of surveys over an enormous area, trends must be interpreted with extra caution. None were detected statistically.
Status: Semi-arid avifauna that responds primarily to rainfall change and has the highest level of Australian endemism.
Rare and threatened: No major populations.
Increasers: None indicative of landscape health.
Indicators: Emu, Australian Bustard, Banded Lapwing, Scarlet-chested Parrot, White-browed Treecreeper, Hooded Robin, Jacky Winter, Varied Sittella, Crested Bellbird, Restless Flycatcher.
Trend: No trends detected.
Scenario: Possible decline of some ground-feeding birds as a result of changes in fire regime, grazing or predators.
Actions: No grazing in representative areas and the adoption of reduced, conservative grazing rates in key habitat across the bioregion, along with appropriate fire regime to maintain diversity.
Click hereto download a summary report including the physical characteristics of the bioregion, a species list, and summary statistics [Excel file]. The file may open on your screen. To save it to your system 'Save as' under the File menu.
Mammals
Number of species and status
There are 52 mammal species within this bioregion. (The maximum number of species recorded in a bioregion is 86 and the minimum is 25).
Click here to link to a table of number of species in each status class for this bioregion.
Click here to link to a list of mammal species and their status for this bioregion.
Critical weight range
The critical weight range (35 - 5500 g) of mammals is the size range of Australian mammals that have been most affected by environmental changes following European settlement. In this bioregion, the proportion of mammal fauna within the critical weight range is .5. (The maximum proportion of fauna within the critical weight range recorded in a bioregion is 0.632 and the minimum is 0.222).
Faunal Attrition Index
Faunal attrition is a measure of contraction or loss of species richness with a region. A high index value means many species have declined or are extinct in the bioregion. The index can be used to compare the status of mammal fauna to regional attributes such as changes since European settlement and average annual rainfall. The Faunal Attrition Index for mammals in this bioregion is .41. (The maximum faunal attrition index value recorded in a bioregion is 0.66 and the minimum is 0).
Click here to link to a table of Faunal Attrition Index for groups of mammals shows the contributions of each group to overall patterns of faunal decline.
Faunal Contraction Index
A range contraction index is a measure of the extent to which the range inhabited by a particular species has contracted. A high index value means that many of the species comprising the region's original mammal fauna have contracted from a high proportion of the regions they originally occurred in. The faunal contraction index for the mammal fauna in this bioregion is .43. (The maximum faunal contraction index value recorded in a bioregion is 0.51 and the minimum is 0.07).
Faunal Endemism Index
Endemic species are those restricted to certain regions. Regions containing endemic species are considered to have high biodiversity conservation values because opportunities to conserve those species do not exist elsewhere. A high index value means that the species comprising the original mammal fauna typically occurred in few bioregions. The faunal endemism index value for the mammal fauna in this bioregion is .66. (The maximum faunal endemism index value recorded in a bioregion is 0.79 and the minimum is 0.52).
New Endemism Index
Extant (still surviving) species that have undergone major range contractions can be considered 'new endemics'. Bioregions that contain new endemic species are often important refugia for threatened species. The new endemism index for the mammal fauna in this bioregion is .6. (The maximum new endemism index value recorded in a bioregion is 0.93 and the minimum is 0.5).
Table: Translocated Species
There is no data available for this table within the bioregion.
Exotic Mammals
The number of introduced exotic mammal species that occur within this bioregion is 7. (The maximum number of introduced exotic mammal species in a bioregion is 16 and the minimum is 5).
Click here to link to a list of introduced exotic mammal species for this bioregion.
Extinct mammal species
The number of extinct mammal species that previously occurred within this bioregion is 21. (The maximum number of extinct mammal species in a bioregion is 29 and the minimum is 0).
Click here to link to a list of extinct mammal species for this bioregion.
Management responses
Reserve consolidation
The existing system comprises seven reserves and includes the Great Victoria Desert Nature Reserve, the largest reserve in Western Australia. There are five A-class Nature Reserves and one C-class Nature Reserve in WA with a total area of 1.9 million hectares. They include examples of 17 of the region's 39 vegetation associations: hummock grass, mallee, mulga and various eucalypt communities as well as communities of the Queen Victoria Springs yellow sandplain.
In addition to the 'at risk' communities described above, eight vegetation associations have a high priority for reservation: mallee scrub shrublands, low Mulga woodlands between sandridges, low Allocasuarina cristata woodlands, Mulga and Marble Gum over hard spinifex, succulent steppe with an open low woodland comprising of Mulga over saltbush, grassland and shrub steppe of mulga and mallee over soft spinifex, succulent steppe of saltbush and bluebush, and the Mirramiratjarra dune field complex which is a unique dune formation, vegetation and drainage system.
The main constraints on filling these gaps are resource related in terms of management and research, although competing landuses (pastoral industry) and prospective mineral exploration and mining leases are also factors. Aboriginal Land Agreements will probably enhance biodiversity conservation.
Overall 9.4% of the bioregion is reserved in IUCN I-IV reserves and the bioregion is IBRA reservation Class 5. However GVD3 is considered Class 4. The sub-regions have the following percentages within IUCN I-IV reservations: GVD1=7.8%, GVD2=10.3%, GVD3=8.4%.
Reserve management standard is ranked 'fair' as biodiversity values and management issues are poorly identified and some resource degradation is occurring, although retrievable. Predator control through aerial dog baiting programs has occurred in pastoral areas, and the impact of feral herbivores is unknown. Wildfire management is non-existent although mining exploration activities are supervised.
Click here to link to a table of comprehensiveness, adequacy and representativeness (CAR) of the National Reserve System in terms of ecosystems and area sampled and a ranking of reserve management. The bioregional priority for consolidating the National Reserve System is based on this CAR analysis and threat.
Table: Bioregional and subregional priorities and ecosystem priorities to consolidate the National Reserve System and associated ecosystem constraints.
There is no data available for this table within the bioregion.
Off-park conservation for species and ecosystem recovery
Main recovery actions required for 'at risk' ecosystems and species include habitat retention, if not by reservation then by by agreements with landholders. Fire management is a high priority to reduce the effect of large intense, summer wildfires on biota. Feral animal control is also a required action, as it will assist in the recovery of CWR species. Futher research is needed to determine species status and distribution, which will help to increase knowledge of the biodiversity values and conservation issues in the region.
Limited off-park measures for the various species and ecosystem conservation/recovery efforts listed above are needed in all three sub-regions. There are few major conflicting land uses, as much of desert is Unallocated Crown Land, Aboriginal Reserve or Conservation Reserve. Pastoral industry, mineral exploration and possible mine establishment are considered the main conflicting land use, but localised. Once the 'Spinifex Agreement' with indigenous peoples is implemented, extensive areas of the desert will be managed for conservation.
Integrated NRM
Existing NRM initiatives include the Wildlife Conservation, Pastoral and Mining Acts. The last two include clauses related to protection of land and natural vegetation. Pest management including feral animal control is a priority in 'threat abatement planning'. There are industry 'Codes of Practice' guidelines on the extent of vegetation that should be removed during mineral exploration and restorative actions to mitigate damage.
Opportunities include reviews of industry codes of practice to strengthen protection of biodiversity, and duty of care for leasehold and other lands. Threat abatement planning in relation to vegetation and threaten species management plans, pest management and fire management plans. Capacity building with the community, landholders, industry and institutions is another opportunity for NRM.
However the region's remoteness and absence of infrastructure adds to the costs of implementing NRM. Other impediments include the Land Administration Act, the extent of mining leases and tenements, and limited financial and staff resources. These NRM priorities apply equally to all GVD subregions.
Map: IBRA map showing frequency of recovery actions (species).
Map: IBRA map showing frequency of recovery actions (ecosystems).
Map: IBRA map showing existing projects part of NRM.
Click here to link to a table of contribution of integrated Natural Resource Management to the protection of biodiversity in each subregion: existing measures and effectiveness.
Table: The contribution of integrated Natural Resource Management to the protection of biodiversity in each subregion: feasible opportunities and comments.
There is no data available for this table within the bioregion.
Further Information & Gaps
Data gaps and research priorities
Regolith mapping is unavailable at better than 1:250 000 resolution. No systematic biological survey has been made of the region, although these has been some assessment of biota on proposed and current reserves and a number of localised studies have occurred. There is little fine scale floristic data available for the sub-region. There are few data on habitat requirements of virtually all invertebrate species, most emphemeral plants, persisting CWR mammals and uncommon vertebrate and plant species. There are no data to provide a regional context on life-history (including population trend) of any species, even rabbits, and no quantitative data on the affect of exotic predators, introduced herbivores or weed colonisation.
References
Environment Australia 2000. Revision of the Interim Biogeographic Regionalisation of Australia (IBRA) and the Development of Version 5.1. - Summary Report. Department of Environment and Heritage, Canberra.
A complete list of references is available by clicking here.
Further information
View the Landscape Health in Australia report.
View the Terrestrial Biodiversity Assessment 2002 report.
Download the Terrestrial Biodiversity Assessment 2002 Database - Biodiversity Audit Data Entry System (BADES), and specifications
Click here to link to a table of some major data gaps in each subregion in terms of protecting biodiversity.
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