Biodiversity Assessment - Yalgoo
Yalgoo
Introduction
Yalgoo extends westwards to the boundary of the South-west Botanical Province and includes the Toolonga Plateau of the southern Carnarvon Basin. This region is an interzone between South-western Bioregions and the Murchison. It is characterised by Callitris-E. salubris, Mulga, and Bowgada open woodlands and scrubs on earth to sandy-earth plains in the western Yilgarn Craton and southern Carnarvon Basin. The latter has a basement of Phanerozoic sediments. Climate is Mediterranean, semi-arid to arid and warm. Rich in ephemerals. Arid to semi-arid warm Mediterranean.
Summary of overall condition and trend
Continental landscape stress class is 4 as assessed by the Landscape Health report (1 is most stressed, 6 is least stressed) even though much of the region is visibly degraded by past agricultural practices (primarily sheep grazing) and feral herbivores. Stress class calculations have been distorted by one large reserve (Toolonga Nature Reserve) located on the northern periphery of the Region. The stress class should actually be 3. The condition of wetlands and riparian systems in the bioregion is fair to good but declining or for some wetlands the trend is unknown. Many ecosystems and species are considered to be under threat from vegetation clearing and fragmentation, grazing pressure, feral animals, changed fire regimes, weeds, salinity and mining.
Summary of conservation priorities
Reserves system is biassed both in its geographical dispersl and coverage of vegetations. Access and management is limited on most reserves. Feral herbivores, feral predators, weeds need to be controlled throughout the region. There are considerable contraints on off-park conservation in the region (rank = 2), while its NRM priority is high (rank = 1).
Natural values
The dominant land use in the region is grazing, with smaller areas of conservation estate, unoccupied Crown Land/Crown Reserves and mining. The special values include Tallering Peak Ironstone and jaspilite range (unique landform and vegetation complexes), banded ironstone Mt Gibson Ranges (contains a significant number of endangered flora), Warradagga Rock (granite outcrop with endangered flora and invertebrates in ephemeral ponds) and the Mt Singelton Ranges (number of endangered flora with some unusual vegetation types). A number of rare vertebrate animals (Egernia stokesii badia, Calyptorynchus latirostris and Acanthiza iredalei iredalei), plants (Acacia vassalii, Darwinia masonii and Eucalyptus crucis subsp. praecipua) and ecosystems (particularly shrublands and succulent steppe) exist within the region. The region is also rich and diverse in flora and fauna however most species are wide ranging and usually occur in at least one, adjoining regions. Freshwater pools are refugia for species requiring mesic conditions.
Click here to link to a table of natural values within each subregion
Wetlands
Two wetlands of national sugnificance are present, Thundelarra Lignum Swamp (currently in good condition) and Wagga Wagga Salt Lake (currently in fair conditon). Their trend is unknown. The threatening processes that affect wetlands are grazing and feral animals (goats, foxes, cats and rabbits). Lake Moore and Lake Monger are both significant for maintenance of ecological processes at a regional scales. Both are currently in good condition but the trend is unknown. Threatening processes include grazing (goats and sheep) and hydrological changes due to degradation of surrounding vegetation types, increasing runoff and siltation.
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 principal streams are the Murchison and the Grenough Rivers, and Yalgoo region incorporates the Murchison/Gascoyne, Yarra Yarra and Ninghan Catchment areas. The river systems are in fair condition and are forecast to decline. The threatening processes are grazing pressure and feral animals (goats, foxes and rabbits).
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
There are no Threatened Ecological Communities in this subregion, however 12 ecosystems are considered to be 'at risk', mainly wetlands and riparian zones, but some are outcrop communities. All are in fair to poor condition and 'declining', except for Tallering Peak vegetation complexes ('static') and Critical Weight Range mammals ('decling rapidly'). Threatening processes include feral animals (goats, rabbits, cats and foxes), mining, grazing, changed fire regimes, and increased siltation of granite rock pools.
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 (Eremophila viscida) have been declared as Critically Endangered, two plants as endangered (Eucalyptus beardiana and Eucalyptus crucis subsp. praecipua) and one plant (Eucalyptus synandra), one bird (Cereopsis novaehollandiae grisea) and one skink (Egernia stokesii badia) as Vulnerable under WA State legislation. A further 18 species of plants and animals are thought to be at risk. Threatening processes include vegetation clearing and fragmentation, grazing pressure, feral animals (goats, foxes and cats), changed fire regimes, weeds, salinity, mining and poaching of nests (birds species). Populations are believed to be declining.
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.
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.
Birds
In the first Atlas period, Yalgoo was much drier than average, in the second, much wetter. This may explain why, in comparison to the first Atlas period, there were more records of breeding birds per survey in the second, but also why freshwater birds were recorded more frequently, contrary the national trend. Otherwise the bioregion is notable only for the proportion of Australian endemics among the resident bird species. The few occurrences of threatened, limited range and introduced species are of minor importance, and the composition broadly resembles that of other semi-arid bioregions; the bioregion is of major importance for no bird species.
Status: Low diversity avifauna, typical of semi-arid Australia, 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, Grey-crowned Babbler.
Trend: Increase in freshwater species associated with wetter conditions.
Scenario: Probably little change but gradual declines of some grazing-sensitive species may continue.
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 32 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 .594. (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 .5. (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 .47. (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 .62. (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 unknown. (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 16. (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
Toolonga Nature Reserve is a large reserve to the north of the bioregion and accounts for more than 80% of CALM estate. Management actions are limited and access is extremely limited to the majority of reserves. No fire beaks or fire access tracks are installed and no feral animal control program are in place. Management action is also limited at Kadji Kadji Timber Reserve. Again no fire beaks or fire access tracks installed, no feral animal control programs are in place (there is no knowledge of extent of the problem) and a grazing lease is held over part of area. All other areas under CALM control are recently purchased pastoral lands (held as pastoral leases or Unallocated Crown Land ) and management actions vary widely. Fire control measures have usually been put in place and numbers of feral herbivores and stock have been reduced. No feral predator control programs are in place.
Twenty-five of the region's 80 vegetation associations, and five 'at risk' ecosystems, are not represented in conservation reserves, even though they are high reservation priority. Even so, Yalgoo was rated as having a reservation class of 4, an artifact of the sheer size of Toolinna Nature Reserve. Clearly, the region's current reserve system is highly biased in terms of CAR criteria, even in terms of comprehensiveness. The region should be no more than reservation class 3. Constraints on consolidating the reserve system include competing land uses (pastoralism occupies more than 76% of the region and mining also has considerable interests, the cost of land purchase and subsequent management, and difficulty in locating biodiversity values in most areas given the level of land degradation.
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
The priority groups for off-park conservation include birds (Leiopoa ocellata, Cacatua leadbeateri mollis, Calyptorynchus latirostris, and Acanthiza iredalei iredalei), reptiles (Egernia stokesii badia) and plants (Acacia cerastes, A. unguicula, A. vassalii, Darwinia masonii, Hyalosperma stoveae, Lepidium merrallii, Melaleuca oldfieldii, Micromyrtus sp. Ninghan (MG Corrick 9332), Persoonia pentasticha, Sauropus sp. Woolgorong (M Officer s.n. 10/8/94), Stenanthemum poicilum, and Eucalyptus crucis subsp. praecipua). Recovery plans have been written for these birds, reptiles and mammals, but not for any plants in the bioregion.
A number of actions need to be taken to prevent further decline of species and ecosystems, including: landscape-wide habitat retention, control of foxes and cats, reduction in grazing pressure (fencing of sensitive areas, especially where there are large goat populations), further research on habitat requirements for many species, weed control, investigation of optimal fire regimes and the reintroduction of some species to previous areas of habitat.. Significant off park effort is required, despite resource constraints, limited community capacity.
Integrated NRM
Existing initiatives: institutional reform through the Gascoyne Murshison Strategy (purchase of leases for conservation estate), threat abatement planning (vegetation management plans, pest management), industry codes of practice relating to pastoral, mining and exploration activities, environmental management systems and ecological sustainable product marketing, integration with property management planning, catchment planning and Landcare through Land Care District committees.
Opportunities include: duty of care legislation for leasehold and other lands, institutional reform (rural reconstruction, industry reconstruction, new tenure and management arrangements), planning opportunities with local government and National Action Plan for water quality and salinity, and supporting pastoralists as they identify and implement ecologically sustainable practices.
Constraints are substantial (rank = 1). Under Land Administration legislation, pastoral leases can be required to maintain stocking levels that may degrade conservation values. Gazetting of new reserves is limited by mining leases and tenements.
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
The highest priority data gaps in the bioregion are the lack of environmental maps at better than 1: 250 000 scale, survey data on the region's flora and fauna distributions and population sizes, and information on the habitat requirements for many organisms. Quantitative data is also required on the effects of feral animals and weeds, hydrological changes and the current fire regimes, particularly on wetland systems and other ecosystems low in the landscape.
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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