Biodiversity Assessment - Carnarvon
Carnarvon
Introduction
Quaternary alluvial, aeolian and marine sediments overlying Cretaceous strata. A mosaic of saline alluvial plains with samphire and saltbush low shrublands, Bowgada low woodland on sandy ridges and plains, Snakewood scrubs on clay flats, and tree to shrub steppe over hummock grasslands on and between red sand dune fields. Limestone strata with Acacia startii / bivenosa shrublands outcrop in the north, where extensive tidal flats in sheltered embayments support extensive mangroves. Climate is arid to sub-tropical, with variable summer and winter rainfall. Cyclonic activity can be significant, and cyclonic systems may affect the coast and hinterland annually. The bioregion contains two subregions, Cape Range (CAR1) and Wooramel (CAR2).
Summary of overall condition and trend
Most pastoral landscapes in the region are poor or degraded with widespread loss of soil litter layers and mineral A-horizon. Even the main river channels are occluded with sand. The trend is to decline, as goats continue replace sheep and cattle as the main source of income for the pastoral industry. Nearly 50% of the region's original non-volant mammal fauna is now extinct. Continental landscape stress class is 3 as assessed by the Landscape Health report (1 is most stressed, 6 is least stressed). It would be rated as worse than this except for three factors: the loss of native vegetation biomass and soil has not been measured, several large reserves occur in the region, and the extensive areas of sandplain and dunefield are mostly in good condition because they provide poor grazing for stock and feral herbivores.
Summary of conservation priorities
The coverage of the reserve system needs to be improved. The islands need to be protected from disturbances. Feral animal, fire and weed control is a priority across all lands. Management of pastoral lands needs to be re-emphasised towards protecting biodiversity values, including soil profile conservation.
Natural values
Special values include the islands of Shark Bay, Exmouth Gulf, the Muiron group, the Lowendal group, the Barrow group and the Montebello group. All are important for sea turtle breeding, seabirds and endangered mammal species some of which are no longer found on the mainland. The karst system of Cape Range has a large troglobitic fauna of international significance, with Bundera Sinkhole having the only known example of Remipede (Lasionectes exleyi) community in southern hemisphere, and Camerons Cave supporting a unique assemblage of terrestrial and aquatic troglofauna. Extensive mangal communities occurs along the southern and entire eastern coast of Exmouth Gulf. The extensive and diverse wetland system of Lake MacLeod is rich in aquatic invertebrates and waterbirds. The lizard genus Lersita has a centre of evolutionary radiation in the region and includes a variety of local endemics.
Click here to link to a table of natural values within each subregion
Wetlands
Eight nationally listed wetlands including subterranean karst systems, brackish to saline lagoons, intertidal flats, marshes and swamps, ephemeral freshwater lakes and swamps, salt pans and beaches. Four of these are in good condition and are static in their trend, two are in a fair condition with one of these declining and the other declining rapidly (McNeill Claypan). The condition and trend of two is unknown. Threatening processes are pollution, grazing by feral animals (goats), increased salinity, weeds, mining fragmentation, inappropriate tourism and fishing.
There are three wetlands of subregional significance comprising major rivers with some permanent pools and riparian vegetation of river gums (Wooramel, Gascoyne and Manilya). They are important in being the principal drainage, regional alluvial process-control, biological refuge and riverine ecosystems. All are degraded and are declining. Threatening processes include changed hydrology from massive sediment loads, weeds (buffel grass and Athel pine), grazing pressure from cattle and feral animals (foxes, cats, rabbits and goats).
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
The bioregion includes the western (lower) reaches of the Wooramel, Gascoyne, Manilya, Lyndon and Ashburton Rivers. Their catchments have the same name, but are almost entirely in the Murchison and Gascoyne bioregions, to the east. All riparian zones are degraded with buffel grass very common, permanent and semi-permanent pools affected by cattle, sheep and goats and are declining in condition. Threatening processes are grazing pressure, feral animals (cattle, sheep horse, goats and rabbits) and weeds.
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
Two threatened ecological communities have been declared as Critically Endangered by WA. However, more than 20 other ecosystems are known to be at risk: stygofauna, coastal marine, ephemeral creeklines, permanent soaks, plant, invertebrate and reptile assemblages, mangrove, floodplain and samphire. Most of these degraded ecosystems are declining in condition. The main threatening processes are feral animals (fox, cat, goats and rabbits) and grazing pressure.
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
Under WA state legislation, 3 invertebrates are listed as Critically Endangered, 1 mammal, 1 bird, 1 reptiles and 5 invertebrates are Endangered, and 1 plant, 12 mammals, 4 birds, 4 reptiles, 2 fish and 14 invertebrates are declared as Vulnerable.
A further four millipede species, 11 crustaceans, four arachnids and two birds are listed as rare at the State level. The threatening processes for most vertebrate species are poorly known. For two species of mammal, habitat changes in combination with fox and cat predation are the main threats, with fragmentation of habitat and grazing pressure also threatening the birds species. The main threatening process for invertebrate species is pollution.
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
Much of the avian biodiversity of Carnarvon occurs along the coast, including all four restricted range species, which, here, are on the southern edge of their range. Two threatened species also occur in Carnarvon along the margins of their range, and the bioregion is of marginal importance for them. There are a few introduced species, although it is not known whether the Ostrich has formed a new feral population or the birds seen had escaped from farms. Several cyclones made Carnarvon much wetter during the second Atlas period than during the first, but there was no consistent trend in reporting rate. The reporting rate of Emu, for instance, was much lower, even though nearby regions in Western Australia had both higher rainfall and higher reporting rates. Reporting rates of freshwater birds actually declined more than the national average.
Status: Moderately diverse, typical semi-arid avifauna.
Rare and threatened: No major populations.
Increasers: None indicative of landscape change.
Indicators: Emu, Australian Bustard, Banded Lapwing, Hooded Robin, Grey-crowned Babbler.
Trend: Increase in obligate granivorous birds.
Scenario: Probably relatively stable for most species.
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 61 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 .541. (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 .39. (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 .38. (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 11. (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 19. (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
Regional conservation lands include three national parks (Cape Range, Francois Peron and Kennedy Ranges National Parks), one marine park (Ningaloo), two conservation parks (Bundegi and Jurabi), four large nature reserve (Toolonga, Bernier Island, Dorre Island and Barrow Island) and many smaller island nature reserves (Gulf islands, Muiron Island, and Lowendal, Barrow and Montebellos groups). The 762866 hectares of conservation estate occupies 8.3% of the bioregion with 46 of the 100 vegetation types reserved, but it should be Reservation Class 2 because the reserve system is strongly biassed.
The management of reserves is ranked as fair because, although foxes are baited effectively on one national park, there is usually poor access for management vehicles, only a minimal goat control program even though grazing by both goats and rabbits is widespread, virtually no fire management and considerable public use of islands and coastal reserves. Significant conservation work is being undertaken on some islands.
Fifty-nine vegetation units, including 17 'at risk' communities, have a high priority for acquisition. They include: mosaic grassland, sedgeland with low trees, hummock grasslands, hummock grasslands with shrubs and low trees, shrublands, mosaic shrublands, woodlands, succulent steppe, mangroves and bare areas
There are constraints in terms of the cost of land and in terms of implementing management. Competing land uses include prospective mining interests (limestone and oil) over karst, and pastoral production. Inappropriate recreation developments (marina resorts) are also proposed.
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 main recovery actions for species include monitoring populations, feral animal control, translocation efforts, and habitat protection and retention through reservation and conservation on other land tenures. The control of human disturbance for turtle species is considered important. All species need research on their distribution and habitat requirements. This is also the case for plant species along with habitat retention and protection, feral animal control (primarily goats) and fire management.
The main recovery actions required for ecosystems at risk include habitat retention through reserves or on other estate; weed control on islands, fencing of sensitive areas where there are heavy goat numbers, feral animal control and fire management. A significant off park effort is needed for the bioregion however there are resource constraints and limited community capacity.
Integrated NRM
Institutional reform through the Gascoyne Murshison Strategy represents major initiatives to purchase pastoral leases for conservation estate. Threat abatement planning as part of NRM includes limited management of feral animals on the pastoral estate, vegetation management plans and pest management. The mining (and oil) industry has various codes of practice. Integration with property management planning, catchment planning and Landcare through Land Care District committees are these delivering biodiversity benefits.
Opportunities include: tighter legislative control over pastoral management to control feral animals; structual reform of the grazing industry on State lands so that a range of natural resource benefits are emphasised, including the protection of biodiversity, noting that some pastoral areas are already attempting to implement ecologically sustainable practices through processes developed by the Rangelands Environmental Management Program of the Gascoyne-Murchison Strategy; specific management of islands is a NRM priority including the control of goat, fox and weeds; the 'Code of Practice' for the oil industry should include specific measures to protect troglofauna and sea turtles (lighting);.
Constraints include the Land Administration Act and operations of the Pastoral Land Board which both require Pastoral Leases to operate in ways that may be inconsistent with conservation. There is a need to increase awareness of conservation values through education of major industries (mining, agricultural) and the public in general.
Map: IBRA map showing frequency of recovery actions (ecosystems).
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
There is an urgent need for substrate mapping at better than 1:250 000. Quadrat-based biodiversity survey data is sparse and confined to CAR2 and Cape Range. As a result, there are few data to provide a regional context on population-trends for ecologically significant species such as native rodents, dasyurids, spinifex reptile communities, termites, ants, weeds such as buffel grass, kapok bush and ruby dock. There are few detailed data on species ecological requirements, life histories and effect of disturbing processes. This applies to virtually all invertebrate species (including troglabitic species), plants, persisting CWR mammals, uncommon vertebrate and plant species, and even to ecologically dominant plant communities such as hummock grasslands.
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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