Biodiversity Assessment - Coolgardie
Coolgardie
Introduction
Granite strata of Yilgarn Craton with Archaean Greenstone intrusions in parallel belts. Drainage is occluded. Diverse woodlands, rich in endemic eucalypts, occur on low greenstone hills, on alluvial soils on the valley floors, around the saline playas of the region's occluded drainage system, and on broad plains of calcareous earths. The granite basement outcrops at mid-levels in the landscape and supports swards of 'granite grass', wattle shrublands and Yotk Gum. The playa lakes support dwarf shrublands of samphire. Sand lunettes are associated with playas along the broad valley floors, and sand sheets surround the granite outcrops. Upper levels in the landscape are the eroded remnants of a Tertiary lateritic duricrust, with yellow (COO2) or red (COO3) sandplains, gravel and laterite breakaways. These support scrubs and mallees. In the west, these scrubs are rich in endemic Proteaceae, in the east they are rich in endemic acacias. Arid to Semi-arid Warm Mediterranean with 250-300mm of mainly winter rainfall. Three subregions are defined:
COO1: Eocene marine limestone plain, on a granite basement in its western parts. Red-brown loams and aeolian sands over sheet and nodular kankar. Eucalyptus woodland over broomebush/greybush, bluebush and saltbush.
COO2 gently undulating uplands on granite strata dissected by broad vallys with bands of low greenstone hills.
COO3 gently undulating plains interrupted in the west with low hills and ridges of Archaean greenstones and in the east by a horst of Proterozoic basic granulite. The underlying strata are eroded flat and covered with Tertiary sand and gravel soils, scattered exposures of bedrock, and plains of calcareous earths.
Summary of overall condition and trend
COO1, COO3 and NE part of COO2 are extensively degraded by pastoral activities. Western third of COO2 is cleared for dry-land agriculture, with salinity problems emerging. Whole region has been affected by mining activities and has weed and feral pest problems resulting in CWR extinctions. Too frequent fires are a problem, especially in scrubs and mallees on duplex, sandy and laterite surfaces. Trend is static, except weed problems are increasing. Continental landscape stress class is between 4 and 5 as assessed by the Landscape Health report (1 is most stressed, 6 is least stressed).
Summary of priority management / conservation priorities
Control of weeds, feral herbivores and carnivores, and more ecologically sustainable development of rangelands is priority. Region has medium priority for reserve consolidation, but system is highly biased with COO3 having only 4.3% of its area reserved.
Natural values
Rare species include Malleefowl, Slender-billed Thornbill, Samphire Thornbill, Carpet Python, Western Quoll, Tetratheca harperi, T. aphylla, T. paynteri, Gastrolobium graniticum, Ermophila virens, Myriophyllum lapidicola, Pityrodia scabra, Daviesia microcarpa, Eucalyptus platydisca. Rare features include Rowles Lagoon, Fraser Range, Woodline Hills, Swan Lake, banded ironstone hill flora. Arid-zone eucalypt woodlands reflect a regional radiation of eucalypts (170 species in the region and many are endemic e.g. E. dundasii), acacias and myrtaceae. Other endemics include Ctenotus xenopleura, banded-ironstone hill communities, 21 eucalypt woodland associations, three succulent steppe associations, and two acacia associations. Region is itself a major biogeographic interzone. communities of acacia on sandplains and valley floors, and of ephemeral plants on Tertiary sandplains and in valley floor woodlands, are exceptionally rich.
Click here to link to a table of natural values within each subregion
Wetlands
One wetland of national significance is listed. Rowles Lagoon System (WA015) is only in fair condition (recovery requires significant management intervention), but its trend is static. Threatening processes include feral rabbits, goats, foxes, cats, stray stock, exotic weeds (Saffron Thistle, Bathurst Burr, Brom Grass, Southern Liquorice), uncontrolled recreational use.
Three types of regionally significant wetland are identified. Swan Lake, one of very few freshwater wetlands that are usually inundated. It is important for migratory species and as a drought refuge for waterbirds, but degraded (being in the centre of a sheep paddock) and declining. TPs are grazing, feral predators and weeds.Wallangine Soak, an artificial wetland at foot of large granite tor; entire regional bat fauna recorded at dam which is surrounded by uncleared vegetation and static. The other six are salt lake systems with sampire and peripheral lunettes, kopi dunes & woodlands. All are in fair condition and static. Threatening processes include feral predators, wildfires and rabbits.
Nationally important wetlands
Map: IBRA map showing DIWA locations, towns, subregions, major roads and reserves and most common threatening processes.
Click here to link to a table of Australia's Important Wetlands (Directory of Important Wetlands of Australia): their type, condition, trend and threatening processes within each subregion.
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
Riparian systems comprise only the headwaters of the now occluded regional drainage system. They are in good condition, static, and would recover if feral herbivores and stock, exotic weeds, changed fire regimes, feral predators and firewood collection could be controlled.
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
No Threatened Ecological Communities are listed for this region, but a variety of ecosystems are currently proposed for listing as vulnerable, and need significant management intervention if they are to recover:
- Ephemeral wetland communities (saline, brackish and fresh-water - NVIS 39, 42 and 43) are threatened by exotic herbivores and mining but static at present.
- Succulent steppe (bluebush, saltbush, samphire) communities on calcareous plains are threatened by grazing, weeds and feral predators (Veg associations 122, 214, 221 and 241; NVIS 8 and 31) and declining as wards weed spreads.,
- Granite outcrops, including apron woodlands, herbfields, moss sheet communities, Jam-Sheoak thickets, ephemeral pools aquatics (NVIS 15, 41 and 43) are declining under pressures from human recreation, and rabbits),
- Twelve flora complexes of banded ironstone, greenstone and other isolated ranges (NVIS 21, 26, 28 and 32) are static, but small, isolated, grazed by rabbits and subject to mining.
- Valley-floor woodlands of species such as York and Salmon Gum (467, 500; NVIS 8) are 97% alienated across their WA ranges and the remainder are threatened by fire and feral predators.
- Melaleuca scrubs (NVIS 28) are 70% alienated but static.
- Three mallee formations (514, 515 & 925) are threatened by fire and feral predators.
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
One plant species have been declared as Critically Endangered, one bird (Carnaby's Cockatoo, but edge of range only) and three plants are listed as Endangered, and one bird, one mammal (Western Quoll) and fifteen plants are listed as Vulnerable under State legislation. Except for the vertebrates (static), their populations are all declining due to pastoral practices (grazing by stock and changed fire regimes) and feral herbivores. The vertebrate populations are threatened by fire regimes, fragmentation and feral predators.
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 arid shrublands of the inland southwestern Australian bioregion Coolgardie share much of their avian biodiversity with other regions to the east and north. The bioregion is distinctive, however, for the proportion of Australian endemic species that occur in the bioregion, the avifauna being more typically Australian than in most other bioregions. There are no evident trends in reporting rate of the guilds, except for the decline in grassland birds that has been reported across much of the south of the country.
Status: Low diversity, semi-arid; high proportion of Australian endemics.
Rare and threatened: No major populations.
Increasers: None indicative of landscape health.
Indicators: Emu, Australian Bustard, Banded Lapwing, White-browed Treecreeper, Hooded Robin, Jacky Winter.
Trend: Decline of some grassland species.
Scenario: Most species continue to fluctuate within normal range, possible long term decline in some ground-feeding insectivores.
Actions: No grazing in representative areas and the adoption of reduced, conservative grazing rates in key habitat across the bioregion.
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 49 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 .469. (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 .42. (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 .39. (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 .67. (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 .86. (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 9. (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 20. (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
Reserve system comprises 44 reserves, including some of the largest in Western Australia, with three levels of protection (A-class: three national parks, 11 nature reserves, one conservation park and one state forest. B-class: one nature reserve. C-class: 14 nature reserves, one conservation park, "8 five-G" and 4 timber reserves). In addition, two pastoral leases were recently acquired for conservation. A total of 1.8 million hectares (56 of the regions 106 vegetation associations) is in this conservation estate, 13.7% of the region's area. In general reserves biased towards sandplains, gravel surfaces, granite outcrops and erosional surfaces high in the landscapes underlain by granitic basement of Yilgarn Craton, although saltlake systems and calcareous plains are represented in eastern areas. Vegetations include scrubs, mallees, mallets, a variety of eucalypt woodlands, samphire and communities with a Greybush understorey.
Twenty-eight vegetation associations, and many of the 'at risk' communities described above, are not on reserves and have a high priority for acquisition. Gaps include:
- Ephemeral wetland communities (saline, brackish and fresh-water).
- Succulent steppe (bluebush, saltbush, samphire) communities on calcareous plains and broad valley floors.
- Granite outcrops, including apron woodlands, herbfields, moss sheet communities, Jam-Sheoak thickets, ephemeral pools aquatics.
- Flora complexes of banded ironstone, greenstone and other isolated ranges, including various Allocasuarina cristata, blackbutt, gimlet and Salmon Gum woodlands, and a variety of shrubland complexes.
- Valley-floor and lower-slope woodlands of species such as York and Salmon Gum, Gimlet and Morrel.
- Melaleuca scrubs and mallee comunities on dunes peripheral to salt lakes.
- Red Mallee and Acacia shrublands
The main constraints on filling gaps in the reserve system are economic -- the ironstone and greenstone ranges are mining tenements or exploration leases, and the succulant steppes and wetlands are highly productive for stock. This region is Reservation Class 3 (11.3 % of its area reserved in IUCN I-IV reserves). Overall, ephemeral fresh water wetland communities, succulent steppe, ironstone and greenstone range and valley-floor woddland communities have priority, especially in COO3 with only 4.35% of its area in reserves and a strong bias in the comprehensiveness of its reserve system.
Reserve management standard is ranked as 'fair' because there are no feral predator programs are in place yet; wildfire management facilities are limited by resources. Even so, fire breaks and fire-access tracks are installed and maintained, mining activities (exploration) are supervised (except for old exploration drill holes which often remain open), and feral herbivore grazing activities now minimal (e.g. rabbit-Callicivirus, goats are few). In addition, vegetation and soils are probably stable or regenerating from grazing (now light) and from timber removal early in the 20th century.
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 (ephemeral wetlands, succulent steppe, isolated greenstone/ironstone hill complexes etc) and species (discussed earlier) include habitat retention by reservation or by agreements with landholders. Methods include excluding stock from sensitive areas (e.g. Rowles Lagoon, Swan Lake, Fraser Range, Woodline Hills, examples of succulent steppe), weed and feral animal control (Wards Weed, rabbits, cats, foxes, stock). Particularly in GOO3, capacity building required with industry. Regionally extinct and declined CWR mammals need to be re-introduced through translocation programmes. Better inventory and life history data are needed for nearly all of these species, and an understanding of ecological interactions between grazing, fire regime and ecosystem biodiversity.
Limited off-park measures for the various species and ecosystem conservation/recovery efforts listed above are needed in all three sub-regions, but are equally constrained by limited funding, equipment, knowledge-base and community capacity.
Integrated NRM
Existing NRM initiativees 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 are 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 mitigate damage. Opportunities include reviews of the Wildlife Conservation, Pastoral and Mining Acts to strengthen protection of biodiversity, and duty-of-care in relation to mining, pastoral or other activities. Grazing of arid woodlands and savannas provide only marginal benefits when related to economic, social and environmental costs; initiatives to restructure the pastoral industry under the Gascoyne-Murchison Strategy are better integrating the activities of conservation, pastoral and mining agencies and industries, minimising environmental costs. However, the region's remoteness and absence of infrastructure adds to the costs of implementing NRM. Other impedements 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 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.
Click here to link to a table of contribution of integrated Natural Resource Management to the protection of biodiversity in each subregion: feasible opportunities and comments.
Further Information & Gaps
Data gaps and research priorities
No regolith mapping available. Veg map and surfacial lithology resolution is 1:250 000 at best. Data on biodiversity is sparse. Systematic biodiversity survey data is confined to vertebrates and plants at 200 quadrats (400 for plants) across region. Quadrats only positioned on widespread surface-types, and only 3 - 4 quadrats per surface-type. Few quadrats have been sampled on more than three occasions. Additional flora quadrats have been sampled on some localised substrates of particular interest. There few data on habitat requirements of virtually all invertebrate species, most ephemeral 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, weed colonisation, fire on biodiversity, and effect of mineral-extraction on greenstone communities.
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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