Biodiversity Assessment - Dampierland
Dampierland
Introduction
There are two sub-regions. The Fitzroy Trough (DL1) is the semi-arid northern periphery of Canning Basin and contains the middle and lower catchment of the Fitzroy River. Extensive coastal mud flats are associated with its delta. Devonian limestone barrier reef structures are preserved along the Trough's northern and eastern peripheries. The Pindanland subregion (DL2) is the coastal, semi-arid, northwestern margin of the Canning Basin. The region has a semi-arid, hot, tropical climate with summer rainfall. Quaternary sandplains mantle Jurassic and Mesozoic sandstones and support Pindan vegetation on the plains and hummock grasslands on hills. Quaternary marine deposits on coastal plains support mangal, samphire, Sporobolus grasslands, Melaleuca acacioides low forests, and Spinifex-Crotalaria strand communities. Quaternary alluvial plains associated with the Permian and Mesozoic sediments of the Fitzroy Trough support Eucalyptus microtheca and Lysiphyllum cunninghamii tree-savannas over Chrysopogon-Dichanthium grasslands with scattered forests of River Gum and Cadjeput along drainage lines. Devonian limestones in the north and east of the Trough support tree steppes with understoreys of Triodia intermedia and T. wiseana hummock-grass.
Summary of overall condition and trend
Fitzroy Trough subregion is continental landscape stress class 4 as assessed by the Landscape Health report (1 is most stressed, 6 is least stressed), which is appropriate given the threatening processes operating at the landscape scale (grazing pressure and changed fire regime). Pindanland was incorrectly rated as having a stress class of 6, but this should be reviewed because fire and grazing have degraded the Pindan. Vegetation cover throughout the region has declined due to an inappropriate fire regime in combination with pastoral use.
Summary of conservation priorities
The reserve system is biased; many ecosystems of both the Fitzroy Trough and Pindanland are not represented in the system. Improved control of fire, feral herbivores and weeds are the other priorities.
Natural values
Special values include the stranded remnants of a Devonian barrier reef system with Windjana and Geikie Gorges, Minbi Caves and Tunnel Creek. The gorges are world-class tourist destinations and Tunnel Creek is the only known example in WA of a river passing through a range via a cave. The Tunnel supports colonies of Ghost Bat, Yellow-lipped Cave Bat and Orange Horseshoe Bat. Rainforests and paperbark swamps are associated with organic profiles of mound springs on coastal mudflats and with primary coastal sand dunes on Dampier Peninsula. Camballin Floodplain is one of the few large floodplains of the Kimberley region while vast grasslands occur on black soils of the Roebuck Plains. Enormous numbers of migratory birds are found at Roebuck Bay and Eighty Mile Beach, where palaeoriver systems have produced extensive coastal mudflats. Keraudrenia exastia and Pandanus spiralis var. flammeus are both declared rare species.
Click here to link to a table of natural values within each subregion
Wetlands
Ten wetlands are listed nationally, including mound springs supporting diverse flora, a cave watercourse, limestone river gorges, a riverine floodplain, a coastal creek system, and palaeoriver systems important for migratory waders. The paleoriver systems comprise a large bay, extensive coastal wetland plains, an inland wetland complex and a coastal dune and mudflat system. All the palaeoriver systems are Ramsar listed. Most are in a fair or good condition but declining, but two are near pristine and of unknown trend. Main threatening processes include grazing and trampling by stock, tourist-use, changed hydrology with siltation and altered flows, feral animals, changed fire regimes and impacts due to the proximity of the town of Broome to two sites. The Fitzroy River and tow other wetlands are important for the maintenance of ecological processes at a subregional scales (a claypan and Tunnel Creek). The condition of the claypan is fair and the subterranean system is near pristine. Threatening processes are weeds, grazing by stock and tourism.
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 zones are in good but declining condition across the bioregion. Threatening processes include changed fire regimes, grazing pressure from stock and feral herbivores, weeds changed hydrology and, in some places, tourism.
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
One Threatened Ecological Community has been declared Vulnerable in WA (coastal vine thickets of the Dampier Peninsula), but 19 others ecosystems are thought to be at risk. These include tropical rainforest (NVIS 2), tropical forests and woodlands (NVIS 11), paperbark forests and woodlands (NVIS 15), grasslands (NVIS 37), herbland, sedgeland and rushland (NVIS 38), mangroves (NVIS 40) and freshwater lakes (NVIS 42). There is not enough information available at present to determine the trend in the condition of most of the ecosystems at risk, although five are definitely in decline. Main threatening processes include grazing pressure, weeds and changed fire regimes. Several are threatened by human disturbance and 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
One plant species have been declared as Critically Endangered, 1 plant, 1 mammal, 1 bird and 1 reptile are listed as Endangered, and 4 mammals, 1 bird, and 4 reptiles are declared as Vulnerable under WA state legislation. Some of these are marine turtles. The threatening processes for individual vertebrate species are mostly poorly understood or unknown. For terrestrial species, the main process is changed fire regimes and grazing pressure operating at the landscape scale.
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
Dampier Land is first landfall for many wader species, and also supports small populations of several Kimberley endemics and two threatened taxa. There are small numbers of introduced birds around the town. During the first Atlas period, Broome was a place to stop on the long dirt trip around Australia. In the intervening years, not only has the road been sealed, but a bird observatory has been established on the shores of Roebuck Bay. Energetic wardens and wader watchers have thus transformed the reporting for the second Atlas. Not surprisingly, most guilds, particularly those associated with water, were reported more frequently. Ground nesting species, however, had lower reporting rates, possibly a result of degradation along the Fitzroy River valley.
Status: Highly significant for migratory waders and offshore seabirds, moderate diversity of tropical woodland birds.
Rare and threatened: No major populations.
Increasers: Rock Dove.
Indicators: Emu, Australian Bustard, Flock Bronzewing, Black-tailed Treecreeper, Hooded Robin, Jacky Winter.
Trend: Most wetland and coastal guilds reported more frequently, ground nesters reported less frequently.
Scenario: Shifts in species composition of wader flocks as a result of offshore processes, elsewhere declines in woodland taxa from change in fire management.
Actions: Continue protection of coastal systems. Re-establish fire mosaics in woodland.
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 50 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 .49. (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 .17. (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 .18. (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 .64. (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).
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 7. (The maximum number of extinct mammal species in a bioregion is 29 and the minimum is 0).
Table: Extinct Species
There is no data available for this table within the bioregion.
Management responses
Reserve consolidation
Regional conservation lands include three small national parks (Windjana Gorge, Geikie Gorge and Tunnel Creek), one large and one small conservation park (Devonian Reef and Brooking Gorge) and one small nature reserve (Point Coulomb). These reserves comprise 1 % of the bioregion and include examples of only 17 of the region's 86 vegetation associations. The reserve system is highly biased with significant gaps. The management standard is ii) fair for the Devonial Reef national parks (Wandjina and Geikie Gorges) where there is a ranger presence, however the impact of weeds, fire and feral animals on these parks is poorly documented. The management standard for all other reserves is i) poor because the effect of threatening processes is not documented and management is limited to occasional visits.
Fifty-two of the unreserved vegetation associations, 12 partially-reserves associations, and 13 of the 'at risk' ecosystems have a high priority for acquisition. They include grasslands, grasslands with associated woodlands, hummock grasslands, shrublands, woodlands, mosaic communities, bare areas, succulent steppe and mangroves.
Constraints on reserve acquisition are mainly pastoral land-use and the cost of purchasing pastoral leases.
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
A number of recovery actions are required for threatened mammal, bird, turtle and plant species: Research on the overall condition, trend and impact of threatening processes; avoiding frequent, broad-scale, hot, late dry-season burning in savannah; removing feral stock from conservation estate and close-order management of stock on other lands; eradication of feral animals especially cattle, donkeys and pigs. For all plant species there is a need for the systematic survey of each of the plant species to better determine.
The effects of fire and grazing are major issues in tropical savanna ecosystems generally. Better co-ordination between the pastoral grazing industry, traditional owners and the broader community, in the context of management research, is essential for action. A large off park effort is needed over much of the bioregion, yet resources and community capacity are limited. State and regional weed strategies need define priorities in both an agricultural sense and an environmental context. Resources required for already identified.
Integrated NRM
Existing NRM actions include legislation for pastoral lease condition inspections by the Department of Agriculture. Pastoralists are notified of any problems and, ultimately, the Commissioner for Soil Conservation can resume the lease. In practice, this process does not appear to be very effective. Other actions include threat abatement planning as part of NRM, co-ordinated efforts by the Department of Agriculture to control donkeys, Land Conservation District Committees that provide a venue for discussing conservation matters and integrating property and catchment planning. There are a range of opportunities for NRM. Duty-of-care for biodiversity on pastoral lands needs to be tightened. Environmental management systems for controlling weeds, fire and feral animals should be co-ordinated across a variety of land tenures through Land Conservation District Committees, supported by research into the mechanism and impacts of these threatening processes and cost/effective solutions. Shire planning should incorporate biodiversity objectives and acknowledge the worth of the natural environment to tourism and the cost of managing bioodiversity and making national parks accessible. Catchment and regional plans should developed collaboratively by all stakeholders. Constraints include financial resources, the small number of people available to implement strategies and that few people recognise biodiversity benefits.
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
Regional vegetation, soil and environmental geology maps at better than 1:250 000 scale for planning. No quadrat based fauna and flora survey of region for assessing species and ecosystem status, condition, trend and effects of threatening processes such as cats, cattle, donkeys, pigs, fire and weeds.
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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