Biodiversity Assessment - Nsw South Western Slopes
Nsw South Western Slopes
Introduction
The New South Wales South Western Slopes Bioregion covers an area of approximately 8,674,100 Hectares immediately west of the Great Dividing Range from central NSW near Dubbo, south, just past the NSW Victorian border. It consists of only two subregions*, Northern Inland Slopes subregion (NSS1) and Lower Slopes subregion (NSS2).
NSS1: Northern Inland Slopes subregion consists of Ordovician to Devonian folded and faulted sedimentary sequences with inter-bedded volcanic rocks and large areas of intrusive granites. Landforms are composed of steep, hilly and undulating ranges and granite basins. Occasional basalt caps and confined river valleys with terrace remnants also occur. Shallow stony soils occur on steep slopes, texture contrast soils grading from red subsoils are present on upper slopes to yellow subsoils on lower slopes. Alluvial sands, loams and clays also occur. Open forests and woodlands occur. Red stringybark is present on upper slopes with black cypress pine, kurrajong, red ironbark, white gum, white box, yellow box and Blakely's red gum on lower slopes, merging west to yellow box, grey box and white cypress pine. Rough-barked apple on flats with river oak occurs on upper tributaries and river red gum occurs on lower and larger streams.
NSS2: Lower Slopes subregion is similar to the Upper Slopes subregion, consisting of Ordovician to Devonian folded and faulted sedimentary sequences with inter-bedded volcanic rocks and large areas of intrusive granites. It also contains larger areas of Tertiary and Quaternary alluvium. Characteristic landforms of the subregion are undulating and hilly ranges and isolated peaks set in wide valleys at the apices of the Riverina alluvial fans. Soils are similar to those of the Upper Slopes with shallow stony soils on steep slopes, and red and yellow subsoils with alluvial sands, loams and clays also occurring. This subregion has more extensive red-brown earths on undulating plains and more extensive grey clays on alluvium. Dwyer's gum occur on granite, with red ironbark on sedimentary rocks and Hill red gum, white cypress pine and red stringybark in the ranges. Grey box woodlands occur with yellow box, white cypress pine and belah on lower areas. Poplar box, kurrajong, wilga and red box are present in the north, with limited areas of bull mallee, blue mallee, green mallee and congoo mallee in the central west. Myall, rosewood and yarran occur on grey clays, with yellow box, polar box, and belah on alluvial loams. River red gum occurs on all streams with black box in the west with some lignum and river cooba.
(* Subregional boundaries in NSW are an interim product in draft format for use exclusively in the Audit terrestrial biodiversity assessment.)
Summary of overall condition and trend
The South western Slopes of NSW are some of the most highly cleared and altered lands in the state, with most of the remaining areas of native vegetation in the more heavily fragmented areas remaining only in small, isolated patches. Substantial clearing is continuing within the bioregion and the rates have been increasing in some parts, with increased clearing of particular concern along the western margin of the bioregion.
As a result of habitat loss resulting from clearing, major declines and collapse of faunal groups are occurring, including ground mammals, aquatic assemblages (particularly frogs) and woodland birds. Concomitant with direct loss of biodiversity values, there has also been significant loss of ecosystem services, including breakdown of soil structure and declining water quality. Dryland salinity now affects significant areas in the bioregion and at current rates is predicted to increase dramatically over the next two decades affecting up to a quarter of the NSW South Western Slopes bioregion.
Summary of conservation priorities
Unfortunately, very little opportunity exists for reserve consolidation in the South Western Slopes. The priority areas for conservation are in the areas of landholder stewardship practices and conversion of various crown reserves, such as travelling stock routes, into conservation oriented reserves. To encourage these landholder stewardship agreements, legislation and other incentives are required to ensure that acceptable conservation outcomes are met.
Natural values
Click here to link to a table of natural values within each subregion
Wetlands
There are nine wetlands listed in the Directory of Important Wetlands in Australia in the South Western Slopes and all are mostly considered in a fair condition although their trend is variable. Threats such as feral animals and exotic weeds are a problem associated with all wetlands in the bioregion. Flood mitigation and other alterations to the water flows interfere with the environmental flows of many of the wetland systems. Salinity is a further problem as is on the increase in this region.
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 vegetation of the bioregion is largely degraded and is declining. Threatening processes include feral animals and exotic weeds, grazing pressure, clearing and fragmentation. Changed hydrology plays a major role in the decline of riparian ecosystems both water abstraction, damming of creeks and rivers and salinity affected waterways.
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
A total of 124 ecosystems have been identified as threatened in this bioregion. This includes 105 ecosystems in NSW and 19 in Victoria. Clearing, grazing, agriculture, and salinity are the most concerning threats to the biodiversity of this area.
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
Of the one hundred and two species identified as at risk, the major threats to their survival are increasing fragmentation and loss of remnants and grazing pressure. Salinity and feral animals also a major role in the survival of many species, cats and foxes are especially problematic because they prey on many birds and smaller mammals.
Those species identified as threatened or vulnerable within the bioregion are listed in the table below
| State | Commonwealth | |||||
|---|---|---|---|---|---|---|
| Endangered | Vulnerable | Extinct | Endangered | Vulnerable | Extinct | |
| Bird | 6 | 25 | 0 | 2 | 4 | 0 |
| Mammal | 0 | 9 | 0 | 0 | 2 | 0 |
| Plant | 10 | 25 | 0 | 13 | 34 | 0 |
| Amphibian | 3 | 0 | 0 | 1 | 1 | 0 |
| Fish | 0 | 0 | 0 | 1 | 0 | 0 |
| Reptile | 1 | 3 | 0 | 0 | 3 | 0 |
| Insect | 0 | 0 | 0 | 0 | 1 | 0 |
| Total | 20 | 62 | 0 | 17 | 45 | 0 |
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.
Eucalypts and Acacias
Endemism
Four Eucalypt species have been identified as being endemic to the South Western Slopes, Eucalyptus cadens, E. irrorata, E. miscella and E. affinis. One acacia species, Acacia paucijuga, has also been identified as being endemic to the bioregion
Richness
The NSW South Western Slopes Bioregion has not been identified as having significant species richness of its acacia and eucalypt species.
Birds
The western slopes are one of the most intensively cleared and cultivated parts of the country, and have been for many decades. Vegetation that remains is fragmented, so declines might be expected. Woodland fragments are particularly important for the Vulnerable Superb Parrot and the Endangered Regent Honeyeater and non-breeding Swift Parrots. Perhaps surprisingly the reporting rate of all three was at least as high in the two atlases. This was also true of most bird guilds. Two possible reasons for this are a greater emphasis on searching fragments during the second Atlas period, since the status of the woodland birds was much publicised, and the change in rainfall from drier than average in the first Atlas period to wetter than average in the second. However, while many trends were stable and positive, the taxa for which there were lower reporting rates were those that have declined elsewhere in the south-east: Southern Whiteface, Hooded, Scarlet and Flame Robins, Restless Flycatcher, most woodswallows, Diamond Firetail and White-winged Chough. The exotic species load is moderate and probably increasing.
Status: Remnant populations of woodland birds in an agricultural landscape, moderate exotic species load.
Rare and threatened: Superb Parrot, Swift Parrot and Regent Honeyeater in woodland fragments.
Increasers: Little Corella, Common Blackbird, Common Myna.
Indicators: Emu, Australian Bustard, Banded Lapwing, Gang-Gang Cockatoo, Superb Parrot, Blue Bonnet, Brown Treecreeper, Regent Honeyeater, Scarlet Robin, Flame Robin, Hooded Robin, Jacky Winter, Grey-crowned Babbler, Varied Sittella, Crested Shrike-tit, Restless Flycatcher, Diamond Firetail .
Trend: Ground-feeding insectivores reported less frequently; temperate forest birds more often.
Scenario: Continued loss of woodland birds likely during next dry period.
Actions: Protect, enhance and link woodland fragments. No grazing in representative areas and the adoption of reduced, conservative grazing rates in key habitat across the bioregion. Maintain an on-going supply of hollows within riparian forests. Protect or rehabilitate catchments of major wetlands retaining values for freshwater birds. See also Action Plan for Australian Birds 2000 Coordinated Conservation Plan: Temperate Woodlands.
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 48 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 .396. (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 .25. (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 .15. (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 .6. (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 .5. (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 13. (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).
Click here to link to a list of extinct mammal species for this bioregion.
Management responses
Reserve consolidation
Less than 2% of the bioregion is reserved, however opportunities for further significant additions to the reserve system are limited.
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
Catchment Management Blueprints and Regional Vegetation Management Plans play an important part of identifying threats and recovery options for species, species groups and ecosystems.
Integrated NRM
Incentives, Threat abatement plans, Legislation (both state and federal), Landcare, landholder stewardship schemes and recovery plans are all important mechanisms that can be introduced or expanded to facilitate better NRM in the bioregion. Significant gains in biodiversity will need to involve conservation on all land tenures, including other crown land and private lands. Establishing and maintaining partnerships with local land-owners and managers is vital, including Rural Lands Protection Boards. Two critical issues in establishing these partnerships are that they will need to be well resourced in the long term, and the need for effective incentive schemes that extend beyond the local or particular themes.
Map: IBRA map showing frequency of recovery actions (species).
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
The ecological detail available for both threatened flora and fauna species was insufficient to provide specific threatening process/ recovery actions on a subregional scale. Ecosystem mapping currently being completed (NPWS state biodiversity project funding). This data will ultimately identify threatened ecosystems, and assist in identifying RA's. As such, no comment on ecosystem reservation priority has been made at a bioregion level. Herbarium records and NPWS Wildlife Atlas data have bias towards roadside and development site records. There are also very low record numbers for Western NSW. A comprehensive, uniform vegetation layer derived from structural and floristic data needs to be developed for Western NSW. Eucalyptus experts are currently unavailable to comment on condition, trend and threatening process for subregions that are species rich or with endemic eucalypts.
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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