Biodiversity Assessment - Geraldton Sandplains
Geraldton Sandplains
Introduction
Comprises the central and northern Perth Basin, the Pinjarra Orogen, and the south end of the Carnarvon Basin. Extensive proteaceous heaths and scrub-heaths rich in endemics, often with emergent mallees, Banksia and Actinostrobus, on an undulating, lateritic sandplain mantling Permian to Cretaceous strata. Outcrops of Jurassic siltstones and sandstones can be heavily lateralized. Sandplains are most extensive in the north and southeast where the region overlaps the edges of the Carnarvon Basin and Yilgarn Craton, respectively. Extensive York Gum and acacia woodlands occur on alluvial outwash plains associated with drainage and valleys in hill country. Areas of coastal aeolian sands and limestone support proteaceous heath and Acacia scrubs. Includes the Houtman Abrolhos and Dirk Hartog Islands. Semi-arid (Dry) warm Mediterranean climate. Three subregions: Edel (GS1), Geraldton Hills (GS2) and Lesueur Sandplain (GS3).
Summary of overall condition and trend
Two subregions are continental landscape stress class 4 and 3 as assessed by the Landscape Health report (1 is most stressed, 6 is least stressed). The regional stress class should be between 2 and 3 because reserves are on its coastal or inland margins or generally small and threatened by salinity. In many aspects its condition and trend resemble the Avon Wheatbelt bioregion, and reserves are mainly on agriculturally unproductive lands.
Summary of conservation priorities
Numerous vegetation associations and 'at risk' ecosystems need to be reserved. This is also applies to populations of a wide variety of threatened species. Feral animal control is a priority across all lands.
Natural values
A high percentage of rare and endemic plants with over 250 plants endemic to GS3 alone, and 16 taxa within the Genus Scholtzia endemic to GS2. Moresby Ranges communities with rare plants such as the mallee species Eucalyptus blaxelli, Mallee Box (Eucalyptus cuprea), heath, Moresby Range Drummondita (Drummondita ericoides) and orchid Caladenia hoffmanii hoffmanii. Mount Lesueur supports a large number of distinct, species rich and geographically restricted communities. Houtman Abrolhos islands are refugia with Tammar (Macropus eugenii) population, rare breeding seabirds and sealion (Neophoca cinerea) colonies. Largest Western Australian nesting site of Loggerhead Turtles (Caretta caretta) and major nesting site for Green Turtles (Chelonia mydas) are on Dirk Hartog Island. Reptile endemism is high, especially in Lerista, Ctenotus and other genera of small lizards. Endemic animals include the Sandhill Frog (Arenophryne rotunda).
Main land-uses, ordered in terms of their extent, are: cultivation (dry land agriculture), conservation lands, grazing of native pastures, and other Crown lands.
Click here to link to a table of natural values within each subregion
Wetlands
Four wetlands are listed as important nationally, including a coastal intermittent saline lake, a river and estuarine system and a seasonal freshwater to permanent saline lake system. All but one are in only fair condition and static; the Logue-Indoon System is rapidly declining. All are affected by weeds, changing hydrology (rising watertable, increasing sediment load and salinity, respectively), and grazing by goats, rabbits and/or stock. Aquaculture and mining are also threats. There are two wetlands of subregional significance: Deep, freshwater pools in the bed of the Greenough River, and freshwater springs in the Northampton area. They support a significant number of taxa and contain rare or threatened species/ecosystems. The deep pools are degraded and rapidly declining in condition whereas the springs are generally in good condition and static. Threatening processes include salinity, pools filling with sand, grazing pressure and exotic weeds such as glossy nightshade, saffron thistle, soursob, lupin and wild oats.
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
Riparian zones in the the catchments of , and along, the Greenough, Chapman Irwin, Hill and Moore Rivers are degraded, those along the Murchison River system are only fair. All are declining. Threatening processes are salinity, increased flow, ferals (foxes, cats, rabbits and goats) and weeds (caster oil bush, box thorn, wild oats, soursob and, lupins).
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
Three Threatened Ecological Communities have been declared in the region by WA ('Acacia rostellifera low forest on Greenough River flats' and 'Lesueur-Coomaloo floristic community D1' are listed as Critically Endangered while 'Lesueur-Coomaloo floristic community A1.2' is listed as endangered), but 34 other ecosystems are considered to be at risk. These ecosystems are broadly described as shrublands (NVIS 28, 29, 31, 32), Acacia and Eucalypts forests and woodlands (NVIS 8, 9, 14), a mixture of woodlands and shrublands (NVIS 21, 30), mixed chenopod, samphire and forblands (NVIS 39), mangroves, tidal mudflat and coastal samphire (NVIS 40), undescribed vegetation associations in the Lesueur area, cave invertebrates, spring communities and gypsum dune associations. Most are either declining or static with the trend in the condition of many being unknown. Two ecosystems are rapidly declining. The main threatening processes are feral animals, primarily the rabbit but also goats and pigs, grazing pressure, changed fire regimes, increasing fragmentation of the landscape, exotic weeds and to a lesser extent various forms of changed hydrology.
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, 21 plant species have been declared as critically endangered, 26 plants and 1 bird as endangered and 19 plants, 4 birds and 4 reptiles as vulnerable. The plants comprise ephemerals and perennials, including a wide variety of eucalypts, acacias and grevilleas. Reptiles include small skinks and marine turtles, while birds include a quail, a cockatoo and small passerines such as wrens. The mammal is a macropod. Most taxa are declining as a result of broad-scale vegetation clearing and ongoing loss of remnants, grazing pressure by stock, feral pigs, goats and rabbits, competition from exotic weeds, and changed fire regimes. Vertebrate populations are under additional pressure from fox and cat predation (the marine turtles and Carnaby's Cockatoo through increased predation on their eggs and hatchlings). Two pythons are especially protected under State legislation.
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
Although it has a typical semi-arid avifauna in many ways, the Geraldton Sandplains bioregion has several distinctive taxa associated with islands protecting Shark Bay. Dirk Hartog, Bernier and Dorre Islands support between them five Vulnerable subspecies: two Rufous Fieldwrens, a Variegated and White-winged Fairy-wren and a Southern Emu-wren. Out to sea, the Houtman Abrolhos support Vulnerable subspecies of Painted Button-quail and Lesser Noddy. The sandplains themselves support important populations of Carnaby's Black-Cockatoo, though reporting rates of this species were lower during the second Atlas period than during the first. There were few introduced birds recorded, most being urban taxa, although they included a substantial proportion of the Laughing Turtle-Dove population. Ground-nesting birds and marine and coastal species had reduced reporting rates, though the reasons for this are unclear.
Status: Typical semi-arid avifauna in heavily cleared and degraded inland regions, but high endemicity on coast and islands.
Rare and threatened: Rufous Fieldwren subspecies, Variegated and Superb Parrot, Southern Emu-wren on Shark Bay islands; Lesser Noddy and Painted Button-quail on Houtman Abrolhos; Carnaby's Black-Cockatoo in heaths.
Increasers: Laughing Turtledove.
Indicators: Emu, Australian Shelduck, Australian Bustard, Banded Lapwing, Carnaby's Black-Cockatoo, Yellow-plumed Honeyeater, Tawny-crowned Honeyeater, Hooded Robin, Grey-crowned Babbler, Varied Sittella, Crested Bellbird.
Trend: Increase in ground seed-eaters; decrease in freshwater guild.
Scenario: Loss and salinisation of wetlands will continue freshwater bird decline.
Actions: Maximise or increase the size of and integrity of woodland fragments. Provide connectivity between seasonally variable resources. Rehabilitate catchments of major wetlands, retaining values for freshwater birds. See also Action Plan for Australian Birds 2000 Coordinated Conservation Plan: Shark Bay.
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 44 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 .523. (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 .47. (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 .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 .7. (The maximum new endemism index value recorded in a bioregion is 0.93 and the minimum is 0.5).
Click here to link to a list translocated species that has/have been successfully translocated into this 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
The 745 000 hectare conservation estate comprises 16.4 % of the bioregion and encompasses 78 of 106 vegetation associations. There are five large national parks (Lesueur, Alexander Morrison, Kalbarri, Badgingarra and Nambung), six large nature reserves (Pinjarega, Beekeepers, Southern Beekeepers, Wandana, Toolonga and Zuytdorp), a single conservation park: (Coalseam) and in excess of 200 smaller reserves. Management standard overall is classed as poor with many reserves becoming saline or encountering rising water tables. Wildfire management facilities are limited by resources, except for fire breaks and fire-access tracks which are installed and maintained except on areas of Beekeepers nature reserve and nature reserves smaller than 200ha. Feral herbivore grazing activities are widespread and feral predator control systems are in place on only three large national parks. The reservation system is strongly biased. For instance, 88 % of the conservation estate in the Geraldton Hills subregion is confined to agriculturally unproductive surface-types on its northern periphery.
Fifteen vegetation associations and 14 of the 'at risk' ecosystems are not on reserves and have a high priority for acquisition. A further 10 vegetation associations and 7 'at risk' ecosystems, whilst present in reserves, have a high priority for further acquisition. The associations include shrublands of Melaleuca, Acacia, Banksia, Allocasuarina, York gum, wandoo, mallee, low and medium woodlands of York gum and salmon gum and low forest of Acacia . The 'at risk' ecosystems comprise Moresby Range thicket, Eucalyptus macrocarpa sandplain community, Irwin River assemblages, Hutt Lagoon assemblages, Moresby Range Verticordia dominated heath, Moresby Range Allocasuarina/Melaleuca thicket, Acacia/Eucalyptus scrub, Burma Road sandplain, Leseuer-Coomallo area, chert hill heaths, coastal lakes, 3 island communities, herbaceous plant of lake beds, spring communities and cave communities. Priority acquisitions are remnants of ecosystems on agriculturally productive alluvial soils in Lesueur Sandplan and Geraldton Hills subregions, springs and soaks, succulent steppe and hill-top communities. Competing land-use is the primary issue because cleared farming land occupies 49% of the bioregion. Economic constraints include the purchase price of land and the cost of subsequent management. There are difficulties in identifying biodiversity values in some areas because biodiversity data lacks resolution and the level of degradation due to agricultural practices and the impacts of feral herbivores is high.
Despite the overall area reserved, a reservation priority class of 4 is appropriate given the biassed nature of the region's reserve system and the array of threatening processes.
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
For most of the threatened species, the main recovery actions are habitat protection, feral animal control, translocations, then fire management and monitoring of populations. The first two actions are relevant to birds and turtles. Habitat protection is best achieved through reservation and protection on other State lands. Protection on private lands may be essential in some cases. Similar actions are required for ecosystem recovery, along with fencing of sensitive areas where there are heavy goat and/or rabbit numbers, and weed control.
A large off-park effort is required in both Edel and Geraldton Hills subregions, where agriculturally productive ecosystems are now fragmented and alienated, and salinity is a problem. Remaining vegetation fragments are few, small, and mostly degraded.
Integrated NRM
Existing actions: Legislation through soil conservation and land clearing legislation exist but are not always effective. Institutional reform through the Gascoyne Murchison Strategy and purchase of leases for conservation estate are effective in the northern part of the region. A variety of planning programs are in place, including threat abatement planning (vegetation management plans, pest management), pastoral and mining industry codes of practice, capacity building through the Bushcare Program, property and catchment planning via a number of Land Conservation District Committees and the Northern Agricultural Integrated Management Strategy, and other planning opportunities such as the Batavia Coast Regional Strategy and local government strategies for controlling development and assessing proposals.
Opportunities include: Legislation for more rigorous control of planning ideals, tradeable rights through carbon credits to provide impetus for new revegetation efforts, local government and National Action Plan planning the for water quality and salinity, increasing the role of NRM in agricultural management, catchment planning and Landcare.
Constraints: The current role of Government Departments in NRM and policing of activities such as land clearing is fragmented and unclear. Departments that have responsibility for resource exploitation may also have resource protection roles. Penalties for undertaking activities such as land clearing are comparatively minor and do not have the support of the greater rural community. Lack of awareness of biodiversity benefits. Land Administration Act needs to be reviewed to ensure requirements on pastoral leases operations are optimised for ecologically sustainable development.
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 region-wide vegetation, environmental geology or soils mapping is available at better than 1:250 000 scale. Systematic survey data are confined to flora, vertebrates and selected invertebrate taxa, is sparse and patchy. Most reserves don't have long-term survey data on species present, even for vertebrates. Currently little data are available on habitat requirements of most plants, uncommon vertebrates and virtually all invertebrate species. There are no data to provide a regional context on life-history (including population-trend) of most species, including rabbits, cat and fox.
There are no quantitative data on the effects of exotic predators, weed colonisation, fragmentation, farm clean-up, fire and mineral-extraction on gypsum and lime surfaces.
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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