Biodiversity Assessment - Central Kimberley
Central Kimberley
Introduction
Hilly to mountainous country with parallel siliceous ranges of Proterozoic sedimentary rocks with skeletal sandy soils supporting Triodia spp. hummock grasses with scattered trees, and with earths on Proterozoic volcanics in valleys supporting ribbon grass (Chrysopogon spp.) with scattered trees. Open forests of river red gum (Eucalyptus camaldulensis) and Pandanus spp. occur along drainage lines. The climate is dry hot tropical, sub-humid to semi-arid, with summer rainfall. Three subregions are recognised. The Pentecost subregion is the true central Kimberley. It is mostly underlain by middle Pentecost sandstone strata, with King Leopold and Warton sandstone ranges along its southern peripheries. Large areas are mantled by Cainozoic soils and there is moderate dissection by several rivers (Durack, Chamberlain and Fitzroy). The Hart subregion is dominated by Hart dolerite exposed along the eastern edge of the Kimberley Craton where basement is folded and exposed. It is the driest subregion, has a rugged topography, and is the headwaters of the Ord, Dunham and Fitzroy Rivers. The Mount Eliza subregion is the south-western periphery of Kimberley Craton. It is very rugged with intense folding and exposure of basement strata.
Summary of overall condition and trend
The Mt Eliza subregion is continental landscape stress class 6, while the other two are 5 as assessed by the Landscape Health report (1 is most stressed, 6 is least stressed). However, the effects of late dry-season fires, feral animals and stock are equally evident in all three subregions, and substantial, changes to vegetation structure are ubiquitous. Trend is for continued decline.
Summary of conservation priorities
Change in current fire management, feral animal and stock control practices across the entire landscape, including conservation reserves. A foraml region-wide assessment of species and ecosystem status and of the impact of fire, grazing and weeds is essential. Substantial reservation effort is required to fill gaps in the reserve system.
Natural values
The Fitzroy and Ord, two of the Kimberley's major rivers, originate in this bioregion. It is fox and rabbit free and essentially uninhabited. The exposed folding of the rock strata within the King Leopold Ranges is of particular note. The Declared Rare Flora Eucalyptus mooreana is found within this bioregion.
Click here to link to a table of natural values within each subregion
Wetlands
One permanent freshwater lake (Lake Gladstone) is listed as nationally important for the maintenance of ecological processes, migratory species, and as a drought refuge, breeding and feeding ground for a diversity of taxa. Its condition is good but declining with the primary threatening process being the grazing pressure from cattle.
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 condition of riparian zones within the bioregion is good but declining. Threatening processes, acting independently or conjointly, include changed fire regimes, grazing pressure from feral herbivores, weeds and changed hydrology in the catchments as a result decreasing perennial vegetation cover and loss of top soil in the savanna.
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 have been declared in the region, although nine ecosystems are considered to be at risk. They include tropical and sub-tropical rainforest (NVIS 2), tropical forests and woodlands (NVIS 9 and11), paperbark forests and woodlands (NVIS 15.), herbland, sedgeland and rushland (NVIS 38) and freshwater lakes (NVIS 42). The rainforests are in fair condition and declining rapidly; the other ecosystems are fair-to-good with undocumented trend. The main threatening processes are grazing pressure, weeds and changed fire regimes. More work is required in this bioregion to define ecosystems at risk and threatening processes.
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 bird and 2 mammals are listed as Endangered, 2 birds declared as Vulnerable, one mammal and one plant are declared rare and 16 plants as either priority one or priority two under WA State legislation. One bird is listed as endangered and three birds vulnerable by the Commonwealth. The threatening processes for individual vertebrates are poorly understood or unknown, although changed fire regime is considered to be the main threatening process for the Gouldian finch. The trend in the condition of all species is mostly unknown, as are threatening processes for the plants.
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
Central Kimberley has not been well surveyed. It is known to support small populations of several Kimberley endemics that have limited ranges, and is moderately important for two threatened species. This list would undoubtedly be extended by greater survey effort; currently the bioregion would not rank highly in terms of avian biodiversity. However, overall the avifauna would appear to be healthy on the basis of trends in guilds and the lack of introduced species.
Status: Moderately diverse tropical woodland avifauna, some Kimberley endemics.
Rare and threatened: No major populations.
Increasers: None indicative of landscape health.
Indicators: Emu, Australian Bustard, Varied Lorikeet, Black-tailed Treecreeper, Purple-crowned Fairy-wren, Jacky Winter.
Trend: Generally stable.
Scenario: Possible long-term loss of fire sensitive species.
Actions: Reimpose mosaic burning, at least in representative habitats.
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 37 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 .459. (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 .07. (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 .09. (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 .63. (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 5. (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 1. (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
The only conservation reserve within the bioregion is part of the large King Leopold Range Conservation Park. This reserve comprises 4.4 % of the bioregion, and includes examples of only 12 of the region's 82 vegetation associations. Thus it has a reservation class of 2. The bioregion is ranked at poor to fair in terms of reserve management. Apart from a donkey control program and presence of a full time ranger, there are no feral animal control programs, only limited aerial burning prescribed, and no formal understanding of threatening processes such as weeds. Due to uncontrolled stock access, soil profile and vegetation changes are occurring within the park. The presence of pigs is a serious concern.
Seventy-seven of the region's 82 vegetation associations and four 'at risk' ecosystems have a high priority for reservation. The associations include grassland, grassland with associated woodland, hummock grasslands, various mosaic communities, shrublands, woodlands, mangroves and bare areas. Ecosystems include rainforests, riparian zones, swamps and paperbark forests.
Constraints include competing land-uses such as pastoral production, land purchase costs and the poor resolution of available data on biodiversity patterns.
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
Recovery actions for mammal, bird and plant species 'at risk' require data on status, population trends and mechanisms of threatening processes, as well as locations of remaining populations. For 'at risk' ecosystems, frequent, broad scale, hot, late dry-season burning in savanna needs to be avoided, feral stock needs to be removed from conservation estate, stock on other lands need close-order management, and donkeys and pigs need to be eradicated. Savanna fire regimes and grazing are the main causes of decline in biodiversity values throughout the region, including its rainforests and riparian zones. To address this issue, coordination between Government agencies, the pastoral grazing industry, traditional owners and the broader community will need to be improved. A large off-park effort is needed and there are resource constraints and limited community capacity.
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
There are no region-wide 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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