The survey

Methodology (PA Waddell)

Geomorphology (PA Waddell)

Soils (P Hennig)

Vegetation (AK Gardner)

Habitat type ecology (PA Waddell and AK Gardner)

Land systems (PA Waddell)

Resource condition (PA Waddell)

Resource management (PA Waddell)

69 70 Methodology also be clearly mapped at a 1:250 000 or 1:500 000 scale for regional uses. PA Waddell The minimum-sized area of land considered The rangeland resource survey of the Western mappable at these scales is approximately one Australian part of the Nullarbor region was square kilometre (1 km2) in extent. Narrower jointly undertaken by the Department of areas, for example 500 m, can be mapped Agriculture and Food (DAFWA) and Landgate provided they are 1.5 km long. This allows long (formerly the Department of Land Information). sinuous features such as Ponton Creek and the This survey is the thirteenth of its type in a clay depressions of the Woorlba land system to program of rangeland classification, mapping be mapped. and resource evaluation in the State. Rangeland surveys have been conducted in Reconnaissance field work Western Australia since the 1950s when they Black and white aerial photographs at a scale of were commenced by the Commonwealth 1:50 000 were taken between 1997 and 1998, Scientific and Industrial Research Organisation though in some western parts for areas affected (CSIRO). Rangeland surveys have been widely by bushfire, aerial photos from 1980 were used. used in Western Australia by CSIRO (Speck et Aerial photographs were used to identify land al. 1960; Mabbutt et al. 1963; Speck et al. system boundaries and to plan navigation 1964; Stewart et al. 1970) and in joint throughout the survey area. Department of Agriculture, Western Australia (now Department of Agriculture and Food, WA) Reconnaissance trips were initially carried out and Department of Lands and Surveys (now between April 2000 and September 2001. This Landgate) rangeland surveys which are included visiting areas mapped during the 1974 commissioned by the Pastoral Lands Board of Western Australian Nullarbor Plain survey Western Australia (Wilcox & McKinnon 1972; (Mitchell, McCarthy & Hacker 1979). During Payne et al. 1979; Mitchell, McCarthy & Hacker these trips initial descriptions of the soil and 1979; Payne, Curry, & Spencer 1987; Payne, vegetation were collected from 108 inventory Mitchell & Holman 1988; Payne & Tille 1992; sites. The Nullarbor survey was delayed when Curry et al. 1994; Pringle, Van Vreeswyk & higher priorities required field work. The survey Gilligan 1994; Payne et al. 1998; Van Vreeswyk recommenced in 2005, though due to staffing et al. 2004; Cotching 2005; Hennig 2009). changes two further reconnaissance trips were required; in May the southern areas were visited The land system approach to mapping different and in July northern areas. country types has been used in all of the pre- vious regional rangeland surveys in Western To help define land system boundaries other Australia. The concept of land systems was sources of information on the biophysical first used by Christian and Stewart in 1953. resources of the survey area were reviewed, They define a land system as ‘an area with a including Lowry’s geology of the Western recurring pattern of topography, soils and Australian part of the Eucla Basin (1970) in vegetation’. These recurring patterns can be conjunction with the 1:250 000 geological map seen using aerial photography or other series produced by Geological Survey of remotely sensed images. It is assumed areas Western Australia and Beard’s vegetation with a similar pattern represent the same land survey of the Nullarbor (1975). system. The land systems are ground-truthed The aim of the reconnaissance trips was to during field work. familiarise survey team members with eastern Land system boundaries are mapped from land systems identified in the 1974 survey 1:50 000 scale aerial photographs and can be (Mitchell, McCarthy & Hacker 1979), major land reproduced onto topographical maps or types and vegetation communities, and to trial pastoral plans at any required scale. Maps at and finalise field methods to be used during the 1:100 000 scale have been found useful for survey. Plant species not identified in the field both paddock and whole station applications were collected and their locations recorded. (Curry et al. 1994); 1:50 000 scale plans are These specimens were later identified with the better suited to the preparation of environ- assistance of staff from the Western Australian mental reviews for mining and engineering Herbarium. Due to the large area to be covered projects (e.g. Pringle 1995). Land systems can in a relatively short period the team mainly

71 travelled along major tracks, moving through The area was surveyed on a station by station the area relatively quickly and camping in a basis. Prior to each trip traverse routes were different location each night. planned for the pastoral leases to be visited. Between three and five days were spent on At Cocklebiddy Roadhouse in June 2005 the each lease depending on size. Pastoralists Nullarbor Land Conservation District held a were notified when the team would be in their meeting where the survey team delivered a area and encouraged to spend at least one day session for pastoralists explaining the proce- with the team while they were surveying their dures and intended outcomes for the Nullarbor property. survey. This provided an opportunity for the team to meet with present day pastoralists and Land system identification in previous surveys to gain some local knowledge. To assist in the involved mapping provisional land system preliminary mapping of land systems boundaries onto aerial photography using a pastoralists provided maps of their leases with stereoscope prior to each field trip. Once in the the land systems they recognised marked out field ground-truthing determined the accuracy on their properties. Pastoralists’ opinions were of provisional boundaries, with amendments also sought on such topics as the palatability of made as required. In the land zones other than major plant species, stocking rates of different the Nullarbor Plain proper such as the pasture types and the susceptibility of different Hampton Tableland, Mardabilla Plain, Nyanga pasture types to fire and grazing. During the Plain and the Roe Plains this method was reconnaissance period former Nullarbor successfully applied, primarily in the west and pastoralists and rangeland practitioners were south of the survey area. The 1:250 000 also sought for advice and opinion. geological map series produced by the Geological Survey of Western Australia was also used to help determine provisional land system boundaries. This method, however, proved impractical for the vast and featureless areas of the Nullarbor Plain. Land systems occur over a much broader scale than in previous rangeland surveys and have poorly defined boundaries, tending to transition into adjoining systems over a distance of kilometres. The land systems on the Nullarbor Plain are difficult to distinguish because of the lack of relief in the landform and the similarity in vegetation communities across the same geology. As Participants at the Cocklebiddy meeting held by the Mitchell, McCarthy and Hacker (1979) found in Nullarbor Land Conservation District in June 2005. the 1974 survey many land systems on the Nullarbor Plain are defined and differentiated by the arrangement of jointing patterns. Main field work Differential weathering along these jointing Between September 2005 and November 2007 patterns has led to the development of eleven trips lasting two to three weeks were drainage floors of variable form (Lowry 1970). made to the survey area. The survey team Where jointing patterns differentiate land comprised two rangeland advisers and a soil systems, in most cases no distinct boundary surveyor from the Department of Agriculture can be discerned, a transitional zone occurs and Food and a navigator from Landgate. The where characteristics from both land systems staff involved was: are evident, sometimes for up to 5 km. Rangeland advisers PA Waddell, AK Gardner In determining these broad land systems Navigator KA Leighton traditional stereoscopic photograph interpreta- Soil surveyor P Hennig tion was supplemented by LANDSAT satellite imagery printed onto A0 sheets at 1:50 000 to correspond with the aerial photographs. This assisted in identifying the vast land systems of

72 the Nullarbor Plain. Land system boundaries of range condition was made. The range drawn by pastoralists during the Cocklebiddy condition was recorded as a rating of workshop also provided a valuable method for vegetation condition and the extent of determining provisional land system bounda- accelerated erosion at the site. The ‘site’ was ries. Aerial photography was still used in the considered to be an area within a 50 m radius field for these areas and observations regard- of the vehicle at the kilometre interval point. ing the landscape were marked onto the The ratings of vegetation condition were sub- photos to assist in the final determination of a jective visual assessments. They are based on land system boundary. the assessor knowing what type of vegetation Problems in navigating through this featureless is supported on the particular landform/soil terrain were largely overcome through the use association being assessed and an under- of LANDSAT imagery and software linked to a standing of the natural range in attributes such Global Positioning System (GPS) unit. This as species composition, density and cover and was viewed on a laptop computer in real time the effect unnatural and natural disturbances and allowed the team to accurately determine have on the landscape. A rating of very good, its position on the satellite imagery in the field. good, fair, poor or very poor was given, based on the extent of induced changes from the During field work the navigator recorded the ‘natural’ state of the landscape (Table 6). location of all station infrastructure both on the Pastoralism is the most extensive land use in aerial photographs and into a geo-referenced the survey area, and the changes observed computer program. Names of bores, dams and from the ‘natural’ state are mostly attributed to paddocks were checked with the pastoralist, the development of artificial water points and and the positions of new watering points, tracks grazing by introduced stock, native herbivores and fences were recorded. This ensured land and feral animals, particularly rabbits. resource information could later be supplied to land managers on an accurate base map. In conjunction with grazing, fire has a major role in extensively altering much of the Traverses Nullarbor landscape. Some vegetation com- munities have undergone ecological changes The navigator followed the predetermined so dramatic the original perennial species traverse on the aerial photographs and composition has been replaced by an annual LANDSAT imagery. This allowed land system component. Some areas are now considered to boundaries to be marked, verified or amended be in a state of irreversible transition and as necessary. At 1 km intervals along the therefore were assessed on their present form traverse the land system, land unit and habitat rather than speculating on their former state. type were recorded. In addition, an assessment

Table 6 Criteria for assessment of vegetation condition

Rating Condition indicators 1 Excellent or very good For the land unit-vegetation type, the composition and cover of shrubs, perennial herbs and grasses is near optimal; free of obvious reductions in palatable species or increases in unpalatable species, or the habitat type supports vegetation which supports vegetation which is predominantly unattractive to herbivores and is thus largely unaltered by grazing. 2 Good Perennials present include all or most of the palatable species expected; some less palatable or unpalatable species may have increased, but the total perennial cover is not very different from the optimal. 3 Fair Moderate losses of palatable perennials and/or increases in unpalatable shrubs or grasses, but most palatable species and stability desirables still present; foliar cover is less than on comparable sites rated 1 or 2 unless unpalatable species have increased. 4 Poor Conspicuous losses of palatable perennials; foliar cover is either decreased through general loss of perennials or is increased by the invasion of unpalatable species. 5 Very poor Few palatable perennials remain; cover is either greatly reduced, with much bare ground arising from loss of stability desirables, or has become dominated by a proliferation of unpalatable species.

73 In assessing range condition past surveys have water points, it is increasingly difficult away rated vegetation condition alongside an assess- from water points to differentiate natural ment of accelerated erosion when present. The erosion cells, a feature of the karst, against lack of surface drainage means the Nullarbor pastoral-induced erosion cells (Gillieson, has not developed the large scale accelerated Cochrane & Murray 1994). Forms of erosion water-induced erosion features seen in other away from water points were assessed on their southern rangeland regions, particularly those origin, anthropogenic or karst-induced, and this with exoreic drainage now displaying wide- was taken into account when determining a spread catchment dysfunction (Pringle, Watson condition rating. Where erosion was attributed & Tinley 2006). The Nullarbor land surface, to pastoral activities this contributed to down- especially the Nullarbor Plain with its shallow grading a site’s rating. The criteria for assess- soils, has been extensively shaped through ment of accelerated erosion are provided in wind erosion (Lowry 1970), as well as by Table 7. localised natural erosion cells driven by karst To aid in assessment of each site the presence processes. and abundance of the dominant vegetation Reconnaissance trips and early traverse ratings species was recorded. As an indicator of the recognised a high level of erosion across many grazing pressure such features as the habitat types and the dilemma faced in attribut- abundance of stock pads and browse lines was ing the cause of the erosion. Whilst acknowl- also recorded. If an assessment point was less edging pastoral activities have contributing to than 100 m from an area of human-induced overgrazing leading to accelerated erosion at disturbance such as a quarry, road works or some locations, especially the large piospheres building then no assessment of range condition (zones of attenuated impact) radiating out from was made.

Table 7 Criteria for assessment of accelerated erosion at sites

Type – intensity combination No accelerated erosion present Slight erosion (< 10% of site affected) Slight accumulation of wind-blown soil around plant bases and other obstacles and/or Removal of finer soil particles evident but soil crust is largely intact and/or Occasional rills (< 300 mm deep evident) and/or A few scalds present, usually < 2 m in diameter Minor erosion (10–25% of site affected) Accumulation of soil around plant bases with plant mounds noticeably enlarged and/or Evidence of pedestalling but soil loss minor and plant bases not greatly elevated and/or Breaking of surface crust with small erosion faces and some redistribution of soil and/or Rilling evident but no gully development and/or Scalding evident but scalds relatively small and discontinuous Moderate erosion (25–50%) of site affected Soil piling around plant bases and other obstacles is common but no plants completely covered and/or Pedestalling apparent with plant bases distinctly raised and with obvious soil loss and/or Rilling common or gullying present of parts of site and/or Surface sheeting with erosion faces (and/or microterracing) and active redistribution of soil and/or Wind scalds common Severe erosion (50–75% of site affected) Extreme hummocking around plants and other obstacles; some plants completely covered and/or Severe pedestalling with plant bases greatly elevated and major soil loss and/or Widespread rilling or major gullying and/or Scalding extensive, smaller scalds have coalesced to form large, more or less continuous scalded areas and/or Surface sheeting with extensive exposure of subsoil or parent material; erosion faces (and/or microterracing) and active redistribution of soil and/or Much of surface generally unstable with ripple mark formation Extreme erosion (75–100% of site affected) General surface movement, total surface area bare with formation of shifting dunes and/or Surface shifting and or scalding complete with exposure of subsoil or parent material and/or Extensive gullying

74 Ninety traverse routes, with an average length In conjunction with inventory sites, at locations of 80 km, were completed in the survey area. representative of major habitat type groups These are shown in Figure 22. Some 6997 condition sites were sampled determined by traverse points were recorded in the survey distances from permanent water points (0.5, 1, area, 6276 of which had a range condition 2, 4 or > 5 km). This allowed investigation of assessment within pastoral lease boundaries. various site attributes which could be used to The geographical locations of the traverse determine key variables of ecological points were stored using a GPS navigation unit disturbance and to characterise the patterns of linked to a geo-referenced computer program. condition states within major habitats.

Inventory and condition sites Inventory sites were selected to ensure each major land unit within each land system was adequately sampled and to assist in interpreting land system patterns as identified on aerial photos and LANDSAT imagery. Occasionally, when a different land unit/vegetation/soil association was encountered in the field additional sites were selected. The aim of inventory sites is to collect information at the land unit scale. The site is considered to be an area within a 50 m radius of the survey vehicle. If the land unit was smaller, the assessor would only record information for the area within the selected unit. Inventory site within a gilgai depression on the Nullarbor Plain.

BALLADONIA

Figure 22 Traverse and reconnaissance routes in the survey area

75 Condition sites provided a means of calibrating • basal cover class for perennial grasses visual resource condition assessments. • height class of tree stratum Sampling techniques to interpret perennial • height class of tall shrub stratum plant species density were undertaken using • list of perennial plant species different size classes of quadrats depending on • list of annual species. the vegetation type. For bindii–grassland communities the frequency of perennial grass Soil and shrub species was assessed using 0.5 m2 quadrats. For chenopod shrubland sites • Australian Soil Classification class (Isbell perennial species were counted within 100 m2 1996) quadrats. • total soil depth • substrate At each site information on the landform, • soil surface condition vegetation and soil was recorded onto a standard record sheet similar to those used by • type and structure of pans Curry et al. (1994) in the Murchison regional • soil reaction trend survey. The attributes recorded at sites were: • observation method • details of soil horizon; horizon designation, General depth, texture and texture group, moist • site number colour, soil moisture status, consistence, • land system porosity, fabric, structure, ped shape, boundary distinctness, abundance, shape, • land unit size and type of coarse fragments and • pastoral station segregations, effervescence with concen- • GPS location trated hydrochloric acid and field pH. • 1:250 000 map sheet name Notes and landscape sketches were also made • aerial photograph year, run and number on an ad hoc basis. At each site a standardised • date method was used to photograph the site. The • compass bearing of the site photograph. photo was taken from the top of the survey vehicle with a board identifying the survey and Physical environment site number placed about 10 m away. • slope (in percentage) It usually took between 30 and 60 minutes to • unit relief complete the description of an inventory and/or • geology (according to the 1:250 000 a condition site. Over the course of the survey Geological Survey series) 392 inventory sites were sampled, though eight • site geology—if different to the mapped registered outside the survey area. Figure 23 geology shows the location of inventory sites, including • surface mantle abundance, shape, size and those sampled from the 1974 survey. type • outcrop, abundance and type Table 8 Foliar cover classes for tree and shrub strata (Curry, Payne & Wilcox 1983) • type and intensity of accelerated erosion features Foliar cover Projected foliar cover Foliar cover • vegetation condition rating class (%) • extent and type of surface crusting 1 0–2.5 Isolated • evidence of fire. 2 2.5–5 Very scattered 3 5–10 Very scattered Vegetation 4 10–15 Scattered • habitat type 5 15–20 Scattered • projected foliar cover (PFC) class of 6 20–25 Moderately close perennial shrubs (Table 8, Curry, Payne & 7 25–30 Moderately close Wilcox 1983) 8 30–50 Close • the dominant species in each stratum 9 > 50 Closed • the relative dominance of each stratum

76 Figure 23 The distribution of inventory sites in the survey area

Water point sampling Inventory and condition site data Information was also gathered on all artificial The inventory and condition site data was also watering points located adjacent to traverse entered into a database, sorted and analysed routes. The water point name, map co- to develop detailed descriptions of land ordinates, type of water body, field pH and systems, land units, soil, vegetation and condi- salinity were recorded. Whether the watering tion trends. These are presented in the main point was operational and its position in the chapters of this report. The data was then landscape was also noted. linked to the resource maps, allowing spatial interrogation. Inventory site data from the 1974 Analysis of data survey was also used to provide information to assist with this report. Traverse records Traverse assessment data was recorded in a Map production database. As the assessment points had been In the southern, western and northern parts of recorded using GPS, the points could be the Nullarbor survey area land system bound- referenced on the land system resource maps. aries are well defined and could be readily This allowed traverse information recorded in mapped within the confines of 1:50 000 scale the field such as the pastoral lease, paddock aerial photography. For the Nullarbor Plain, name and land system to be cross-referenced through the central and eastern parts of the with the location of each traverse point on the survey area, the broadscale land systems were map and amended if necessary. mapped onto A0 sheets showing LANDSAT Summaries of the traverse assessments were imagery at 1:50 000 to correspond with the made by sorting the data on the attributes for aerial photography. Land system boundaries which information was required. For example: were finalised using the knowledge gained summaries of the land units and habitat types during field work to reinterpret and confirm within each land system which assisted in boundaries drawn on aerial photographs and developing land system descriptions; and A0 sheets. The aerial photographs and A0 summaries of the condition of pastoral leases, sheets were scanned and computer software land systems, land units and habitat types in was used to digitise land system boundaries. the survey area. Land system area and condition statements for individual pastoral stations were also prepared.

77 First order or discernible land system bound- References aries were identified by solid lines. On the Nullarbor Plain land systems commonly lack Beard, JS 1975, Vegetation survey of Western obvious boundaries, tending to have a transi- Australia – Nullarbor, Sheet 4, University of tional zone of up to 5 km where characteristics Western Australia Press, Nedlands, Western from both land systems are likely to occur. On Australia. the map where there is no distinct land system Christian, CS & Stewart, GA 1953, Summary of boundary dashed lines indicate an approximate general report on survey of Katherine– boundary occurring through the transitional Darwin Region 1946, CSIRO Land Research zone between the land systems. Series 1, p. 24. With improved aerial photography and the Cotching, WE 2005, An inventory of rangelands benefit of LANDSAT imagery the land systems in part of the Broome Shire, Western identified in the eastern part of the Western Australia, Department of Agriculture, Australian Nullarbor Plain during the 1974 Western Australia, Technical Bulletin No. 93. survey (Mitchell, McCarthy & Hacker 1979) Curry, PJ, Payne, AL, Leighton, KA, Hennig, P have been reassessed and in some cases & Blood, DA 1994, An inventory and boundaries have been modified. Four land condition survey of the Murchison River systems from the 1974 survey were extensively catchment and surrounds, Western modified resulting in one system being re- Australia, Department of Agriculture, named and three systems incorporated into Western Australia, Technical Bulletin No. 84. others. Topographical and cultural information covering Curry, PJ, Payne, AL & Wilcox, DG 1983, the survey area was loaded onto the computer ‘Suggested descriptive terms for classes of system and updated with information collected foliar cover in arid zone shrublands’, Range during the field work. Land system boundaries Management Newsletter, 83(3), 12–13. were overlain on this background information. Geological Survey 1:250 000 scale geological Maps were edited to make all features and text map sheets and explanatory notes (various clear and legends were added. authors and dates), Balladonia, Culver, Resource information has been presented on a Cundeelee, Eucla–Noonaera, Forrest, land system map which accompanies this Loongana, Madura–Burnabbie, Naretha, report. If clients require more detail, maps can Seemore and Zanthus. be provided at a smaller scale. Special purpose Gillieson, DS, Cochrane, JA & Murray, A 1994, maps can be produced displaying any com- ‘Surface hydrology and soil movement in an bination of information presented on the arid karst: the Nullarbor Plain, Australia’, accompanying map, as data have been Environmental Geology, 23, 125–133. captured in a multilayered geographically Hennig, P 2009, An inventory and condition referenced digital format. Not all the data survey of the lower Murchison River area, collected during the field work is presented in Western Australia, Department of Agriculture this report or on the accompanying map. More and Food, Western Australia, Technical detailed information is available from the Bulletin No. 96. Department of Agriculture and Food on request. Isbell, RF 1996, The Australian Soil Classification, Australian soil and land survey Station plans at a scale of 1:100 000 have also handbook series, vol. 4, CSIRO Publishing, been produced for each of the pastoral leases Collingwood, Australia. within the survey area. These are available to lease holders as full colour maps from the Lowry, DC 1970, Geology of the Western Department of Agriculture and Food. Australian part of the Eucla Basin, Geological Survey of Western Australia, Bulletin 122.

78 Mabbutt, JA, Litchfield, WH, Speck, NH, Pringle, HJR, Van Vreeswyk, AME & Gilligan, Sofoulis, J, Wilcox, DG, Arnold, JA, SA 1994, An inventory and condition survey Brookfield, M & Wright, RL 1963, General of the north-eastern Goldfields, Western report on the lands of the Wiluna– Australia, Department of Agriculture, Meekatharra area, Western Australia, 1958, Western Australia, Technical Bulletin No. 87. CSIRO Land Research Series No. 7. Pringle, HJR, Watson, IW & Tinley, KL 2006, Mitchell, AA, McCarthy, RC & Hacker, RB 1979, ‘Landscape improvement, or ongoing A range inventory and condition survey of degradation – reconciling apparent part of the Western Australian Nullarbor contradictions from the arid rangelands of Plain, 1974, Western Australian Department Western Australia’, Landscape Ecology, of Agriculture, Technical Bulletin No. 47. 21, 1267–1279. Munsell Color Co. 1954, Soil color charts, Speck, NH, Bradley, J, Lazarides, M, Munsell Color Co., Baltimore, USA. Patterson, RA, Slayter, RO, Stewart, GA & Twidale, CR 1960, The lands and pastoral Payne, AL, Kubicki, A, Wilcox, DG & Short, LC resources of the North Kimberley area, 1979, A report on erosion and range Western Australia, CSIRO Land Research condition in the West Kimberley area of Series No. 4. Western Australia, Western Australian Department of Agriculture, Technical Bulletin Speck, NH, Wright, RL, Rutherford, GF, No. 42. Fitzgerald, K, Thomas, F, Arnold, JA, Basinski, JJ, Fitzpatrick, EA, Lazarides, M, & Payne, AL, Curry, PJ & Spencer, GF 1987, An Perry, RA 1964, General report on the lands inventory and condition survey of rangelands of the West Kimberley area, Western in the Carnarvon Basin, Western Australia, Australia, CSIRO Land Research Series Western Australian Department of No. 9. Agriculture, Technical Bulletin No. 73. Stewart, GA, Perry, RA, Paterson, SJ, Payne, AL, Mitchell, AA & Holman, WF 1988, Traves, DM, Wright, RL, Slayter, RO, An inventory and condition survey of Dunn, PR, Jones, PJ & Sleeman, JR 1970, rangelands in the Ashburton River Lands of the Ord–Victoria area, Western catchment, Western Australia, revised Australia and Northern Territory, CSIRO edition, Western Australian Department of Land Research Series No. 28. Agriculture, Technical Bulletin No. 62. Van Vreeswyk, AME, Payne, AL, Leighton, KA & Payne, AL & Tille, PJ 1992, An inventory and Hennig, P 2004, An inventory and condition condition survey of the Roebourne Plains survey of the Pilbara region, Western and surrounds, Western Australia, Western Australia. Department of Agriculture Western Australian Department of Agriculture, Australia, Technical Bulletin No. 92. Technical Bulletin No. 83. Wilcox, DG & McKinnon, EA 1972, A report on Payne, AL, Van Vreeswyk, AME, Pringle, HJR, the condition of the Gascoyne catchment, Leighton, KA & Hennig, P 1998, An inventory Western Australian Department of and condition survey of the Sandstone- Agriculture, Technical Report No. 2. Yalgoo-Paynes Find area, Western Australia, Agriculture Western Australia, Technical Bulletin No. 90. Pringle, HJR 1995, Environmental considerations for the proposed Goldfields gas pipeline route through Wanjarri Nature Reserve, Department of Agriculture, Western Australia, Resource Management Technical Report 148.

79 Geomorphology Physiographic regions of the PA Waddell Nullarbor Plain Province Physiographically most of the survey area Introduction occurs within the Nullarbor Plain Province of The geomorphology of the survey area is Jennings and Mabbutt (1977). The western- described in terms of its morphotectonic setting most margin of the survey area extends into at a continental and regional scale. Land the Coonana–Ragged Plateau section of the surface types are described with reference to Yilgarn Plateau Province (Figure 24). Within their component land systems. Landscape the Nullarbor Plain Province the survey area evolution is discussed in terms of Cainozoic occupies all or parts of the following component alteration of the morphotectonic setting and the sections of the Province – the Carlisle Plain, interactions between land use and landscape the Bunda Plateau, the Israelite Plain, the Roe processes are considered. Plains and supports a low chenopod shrub and Austrostipa scabra (speargrass cover over its greater part. The sections occupied by the survey area are described in Table 9.

Table 9 Brief description of the physiographic regions in the survey area (Jennings & Mabbutt 1977)

Province Sections Nullarbor Plain Carlisle Plain—sandstone plain with shallow closed depressions Bunda Plateau—covered karst plain of flat-lying limestone with closed depressions and caves; continuous cliff margin on south coast *Israelite Plain—narrow coastal plain with extensive dunes Roe Plains—coastal plain with extensive dunes Yilgarn Plateau *Coonana–Ragged Plateau—sandplain and stripped gneissic plains with low hills of granite and metamorphic rocks; calcrete and scattered small salt lakes along shallow valleys

* Only very small parts of these sections fall within the survey area.

Figure 24 Physiographic regions of the Nullarbor (after Jennings & Mabbutt 1977)

80 Lowry (1970) identified five main physiographic Cliffs and Hampton Range to the south. The units within the Eucla Basin: a plateau (the region is characterised by undulating ridge- Bunda Plateau), a scarp (known in different corridor topography with an average relief places as the Hampton Range, Baxter Cliffs greater than elsewhere on the Bunda and Wylie Scarp), two coastal plains (Roe Plateau. Plains and Israelite Plain), and a continental • Nyanga Plain – in the west of the Bunda shelf (the Eucla Shelf). Plateau to the north and west of the Lowry (1970) further divided the Bunda Plateau Nullarbor Plain and the Hampton Tableland. into physiographic regions based on differ- Broad flat plains of variably thick and con- ences in geological history, topography, soil, tinuous residual clay loam and calcrete vegetation and climate (Figure 25). overlying Nullarbor Limestone characterise this region. • Nullarbor Plain – restricted to the treeless part of the limestone karst in the centre of • Mardabilla Plain – in the south-western part the Bunda Plateau. The landscape is of the Bunda Plateau and is bordered by the generally of low relief, generally less than Wylie Scarp to the south and the Nyanga 4 m, and is characterised by different forms Plain to the north-east. The surface of the of karst depressions which form corridors of plain is covered with clay and calcrete. linear depressions and ‘dongas’ (locally Numerous inliers of crystalline basement named rounded depressions or claypans) rock protrude through the plateau surface. separated by low rocky limestone ridges or • Carlisle Plain – north of the Nyanga Plain. rises. The Carlisle Plain is developed on the • Hampton Tableland – in the south of the Colville Sandstone and consists of plains Bunda Plateau between the Nullarbor Plain with sparsely vegetated sandy soil. to the north and bordered by the Baxter

Figure 25 Physiographic divisions of the Eucla Basin from Lowry and Jennings (1974)

81 The regional geology is characterised by near- Lowry (1970) described the surface terrain as horizontal sequences of Cainozoic sediments, having formed as a result of a virtual absence predominantly limestones and calcrete, over- of tectonism and an extreme regularity of karst lying Cretaceous sedimentary rocks of the weathering due in combination to the low Eucla Basin on an irregular basement of rainfall, high permeability and surface solution Precambrian granite and metamorphic rocks. of limestones forming the plateau surface. The survey area may be divided into two However Webb and James (2006) propose that distinct geological regions within which a climate only had a minor role in restricting karst number of land zones have been defined. The development; it is more likely the relative lack major geological regions are the Bunda of surface and underground karst features are Plateau and the coastal Roe and Israelite due to the particular characteristics of the plains. The major feature is the Bunda Plateau limestones (primary porosity, lack of jointing which also includes Quaternary sandplains on and inception horizons) in combination with the the margins of the Eucla Basin. Nullarbor Plain’s flat geomorphology and hardening of surface limestones by calcrete, The survey area is situated largely within the which has increased resistance to solutional Western Australian portion of the Eucla Basin and erosional processes. (Jutson 1950), the margins corresponding with the limit of the present distribution of the Eucla Group. Lowry (1970), expanding on from Morphotectonic setting of the Eucla Singleton (1954), described the Eucla Group Basin as all sedimentary rocks deposited in the Eucla By the close of the Late Precambrian the Basin between the Middle Eocene and the morphotectonic structures largely responsible Lower Miocene comprising the Hampton for determining the future evolution of Western Sandstone, Wilson Bluff Limestone, Toolinna Australian geology were essentially in place Limestone, Abrakurrie Limestone, Nullarbor (Wyrwoll & Glover 1988). The Western Limestone and Colville Sandstone. The upper Australian Shield composed of the Yilgarn and formations of the Eucla Basin are exposed on Pilbara Blocks, associated orogenic belts and cliffs and in caves, but the lower formations are sedimentary basins has essentially remained obscured and known only from bores. The the dominant morphotectonic element Western Australian margins of the Eucla Basin controlling the relative stability of large parts of correspond with the limit of the Colville present day land surfaces. Sandstone and Plumridge Formation in the north and the Nullarbor Limestone and Toolinna In the Palaeozoic Australia was part of the Limestone in the west and south-west. The super continent Gondwanaland and the area southern extremity of the basin is marked by where the Eucla Basin occurs was a stable the 200 m isobath of the continental shelf in the land mass (Lowry 1970; Wyrwoll & Glover Great Australian Bight. 1988). The basement rocks beneath the Eucla

Toolinna Cove: In the south marine erosion of the The centre of the Bunda Plateau is dominated by the Bunda Plateau has formed cliffs exposing limestone vast, level to gently undulating Nullarbor Plain. beds with uniform structure and lithology.

82 Basin comprise Precambrian granite, gneiss, arid mid-latitudes between the temperate and schist and quartzite in the south-west; with tropical latitudes (Jennings 1967; Lowry 1970; folded Proterozoic sedimentary rocks in some Beard 1975; Wasson 1982; Wyrwoll & Glover northern and eastern areas. When the Eucla 1988; Benbow 1990a; Gillieson & Spate 1992). Basin developed these Precambrian basement During the Middle Eocene (45 Ma) downwarp- rocks in the south-western part had a high ing of the Eucla Basin recommenced and was relief and were exposed to erosion (Lowry accompanied by marine invasion. Deposition 1970). started in the basin’s centre with lenticular By the Late Jurassic a divergence rift zone sandstone (Hampton Sandstone) followed by parallel to the present south coast had marl (the lower part of the Wilson Bluff developed as the Gondwanaland sections of Limestone) until a brief pause in downwarping Australia and Antarctica began to separate (Lowry 1970). In the Late Eocene downwarping through continental extension (Veevers, Jones resumed with the deposition of chalky, & Powell 1982). Active Mesozoic drainage bryozoan limestone (the upper part of the systems of easterly trend were precursors of Wilson Bluff Limestone) occurring across the modern drainage basins (Beard 1975). It is basin in areas of calmer water and well sorted likely these drainage systems were responsible bryozoan limestone (Toolinna Limestone) in the for reducing the topography of the western south-west under higher energy conditions Precambrian rocks to the low irregular relief (Lowry 1970). These processes continued until similar to the present day condition. Such the end of the Late Eocene when downwarping erosion also stripped the extensive covering of ceased and the sea regressed past the present tillite sediments deposited in the southern shoreline, resulting in weathering and erosion portions of the Eucla Basin during the Lower across the surface of the Wilson Bluff Permian (Lowry & Jennings 1974). Limestone for over 10 million years (Webb & James 2006). In the Early Cretaceous downwarping commenced in the Eucla Basin towards the In the Late Oligocene to Early Miocene (25 Ma) southern rift (Wyrwoll & Glover 1988). the sea returned resulting in the deposition of Terrigenous conglomeratic sandstone bryozoan calcarenite and calcirudite (Loongana Sandstone) and siltstone and shale (Abrakurrie Limestone) over the centre of the (the basal part of the Madura Formation) basin. By the Early to Middle Miocene the accumulated over the basins basement rocks marine transgression had expanded to cover (Lowry 1970). In the Early to Middle the entire Eucla Basin (Lowry 1970; Hocking Cretaceous 120 to 125 million years ago (Ma) 1990). Widespread deposition of foraminiferal the break-up commenced between Australia and algal calcarenite followed (Nullarbor and Antarctica (Hocking 1990). As subsidence Limestone and its basal unit, the Mullamullang continued the sea entered the Eucla Basin Limestone Member). The Nullarbor Limestone from the south or south-west. Marine deposi- extensively overlies most of the basin except tion occurred across the basin and continued where it laterally merges, at its northern through to the Late Cretaceous. Marine sedi- margins, into calcareous sandstone (Colville ments during this period continued to form the Sandstone) (Lowry 1970) and its equivalents Madura Formation and the overlaying Toondi further east (Benbow 1990b). The Colville Formation. In the Late Cretaceous the central Sandstone grades northwards into fine-grained area of the basin was overlain with glauconitic sandstone and siltstone with lesser claystone sandstone and sandy siltstone (Nurina and conglomerate (Plumridge Formation) Formation) (Hocking 1990). Towards the end of (Hocking 1990). The limit of the Miocene the Cretaceous the Officer Basin was uplifted shoreline is marked by the western and to become land, deposition ceased in the Eucla northern margins of the Nullarbor Limestone Basin and did not recommence until the Middle and Colville Sandstone respectively, a Permian Eocene (Lowry 1970). sandstone scarp in the far north and Eocene dunes of the Ooldea Range in the north- The Australian continent began its northerly eastern margin of the Bunda Plateau, in South drift away from Antarctica in the Middle Australia (Lowry & Jennings 1974; Benbow Eocene. Stratigraphic and palaeontologic 1989, 1990a). Lowry (1970) stated that as evidence indicates Australia has become there is no evidence that other areas of increasingly drier as it drifts northward into the

83 southern Western Australia were submerged in whilst the open depressions have clay loam the Miocene, the transgression was probably soils. These undulations are straight and due to downwarping of the Eucla Basin. parallel but the trend changes throughout the plain reflecting the systematic tectonic control Evolution of landforms in the through joint directions (Jennings 1967a, Cainozoic 1967b). In some locations where joint patterns of equal importance converge, the relief pattern In the Middle to Late Miocene (about 15–12 Ma) develops into a lattice arrangement. Here, the Australian continent was uplifted. Uplift of shortened ridges occur as compact low rises the Eucla Basin combined with global eustatic (limestone hummocks) and are surrounded by lowering of sea level resulted in the sea finally smaller depressions. receding, exposing the Miocene sea floor. From Further inland there are also circular closed the extent of the uplift and the vast, exposed karstic depressions locally termed ‘dongas’, surface of the Nullarbor Limestone, brought 400–1600 m or more across and a metre or two about by the lengthy duration of erosion, Lowry deep, commonly clay-floored with or without (1970) concluded the Eucla Basin had stopped gilgai micro-relief. In some areas these subsiding. Karst features characteristic of the depressions are arranged in lines parallel with Bunda Plateau have since developed on and the regular wave pattern of the ridges and below this surface. corridors, but elsewhere they are randomly Since the Miocene uplift there has been scattered (Jennings 1967a). Dongas are con- extensive coastline recession of the carbonate sidered solution dolines rather than collapsed geology where the more durable Precambrian caves, formed through water ponding in depres- rocks are absent, forming the Great Australian sions in the limestone plain with solution further Bight. Aside from the Israelite and Roe coastal dissolving the limestone and deflation later plains the land begins at the top of the lime- exposing them (Jennings 1963; Lowry 1970). stone cliffs forming the southern edge of the Erosion features normally associated with Bunda Plateau, 60–100 m above sea level. limestone country, such as solution sculptured West of Point Malcolm, in the Esperance pits and rock-holes in outcrop, sinkholes, District, Precambrian outcrop has reduced the dolines, underground drainage and caverns, effects of marine erosion along the southern are scarce in proportion to the regions area coastline. (Jennings 1967a, 1967b; Lowry & Jennings Sloping upwards from the southern sea-cliffs, to 1974; Webb & James 2006). The majority of about 250 m above sea level at the northern solution features occur in the south of the perimeters, the majority of the Bunda Plateau’s Plateau where rainfall has presumably always surface is a vast and featureless limestone plain been higher than further inland. Despite having with only minimal evidence of coordinated a long history this karst is considered to have drainage systems that became inactive during remained immature and retarded, due to a lack the Pleistocene. The perpetuation of the flat- of water available to initiate greater solution ness of this uplifted sea floor is the result of sculpturing (Jennings 1967a, 1967b). Both extreme regularity in weathering and minimal Jennings (1967b) and Lowry (1970) state that tectonic activity (Lowry 1970). the climate has never been much more humid On the Bunda Plateau there are primarily two than at present for long periods since it kinds of surface relief. Both features can be emerged from the Miocene sea. described in terms of minor differential surface In the Pliocene marine erosion carved sea-cliffs solution of limestones directed by joint patterns. into the uplifted limestones (James et al. 2006). Of widespread occurrence is the undulating During the Late Pliocene the underlying relief of parallel, low ridges separated most calcarenite geology for the two coastal plains of often by open depressions, though closed the Western Australian portion of the Eucla depressions are common in some systems. The Basin was deposited (Hocking 1990; James et wavelength between undulations is commonly al. 2006). Several sea level changes associated 400–1600 m, though it can be greater, with an with Pleistocene climatic fluctuations are amplitude of 1.5–3 m, though nearer the coast it marked today by old strand-lines on the Roe can be up to 10 m. The ridges form regular Plains. During this period the maximum high limestone rises scattered with rocky outcrop sea level stand was about 36 m above the

84 present sea level (Lowry 1970). The coastal against the cliffs. Sand transported up climbing dunes overlying these plains are primarily dunes formed dune ramps to the top of the calcareous and on the basis of calcrete plateau. Subsequent rises in sea level eroded development three significant stages of dune the ramps re-exposing the cliff face (Jennings building can be identified (Jennings 1968; 1968). Whilst the wave-cut cliffs and escarp- Lowry 1970). ments of the plateau’s southern margin were From the Late Pliocene through the formed during past interglacial stages, wave Pleistocene alternating glacial and interglacial action today continues to erode the sea-cliffs periods influenced and controlled the develop- since the last post-glacial rise in sea level ment of geomorphic features. In the Early (Davey et al. 1992; James et al. 2006). Pleistocene, following the onset of arid condi- The Bunda Plateau is Australia’s largest karst tions, erosional periods were responsible for area and the world’s largest arid karst region significant deflation of the soils of the central (~250 000 km2). Arid climatic conditions, the Nullarbor Plain (Jessup 1961; Lowry 1970). high permeability of the plateau surface Lowry (1970) proposed that the combination of limestones, concretisation and the geomorphol- low rainfall and the high permeability of the ogy of the plain have been the major factors plateau surface limestones had resulted in the responsible for the evolution of the present day regularity of weathering across the plateau, relief; a landscape shaped by extreme with up to 100 m of the surface limestone regularity of weathering and minimal tectonic removed. The extent of deflation that occurred activity. Since the emergence of the plateau during this period exposed the subsurface relief from the Miocene sea karst development has of the joint controlled depression and ridge remained restricted, most likely due to the topography. However Webb and James (2006) particular characteristics of the limestone and state that the combination of the flatness of the the flatness of the plain. The vast, uniform land plain and the hardening of the surface by surfaces of the Bunda Plateau, and the calcrete are the features most likely respon- associated Quaternary coastal plains, have sible for the uniform denudation and relative evolved by processes of erosion, weathering lack of surface karst features; climate having and deposition. only a minor role. The Roe Plains are backed by the Hampton Land surface types (groups of land Range and the Israelite Plain is backed by the systems) Wylie Scarp (Figure 25). The exposed scarp Eight land surface types were defined within section of the Hampton Range displays the survey area and grouped primarily on Nullarbor Limestone over Abrakurrie Limestone geology, relief and landform, and secondly on and the Wylie Scarp displays calcrete over genesis and soil (Table 10). Land surfaces Toolinna Limestone (Lowry & Jennings 1974). have been further subdivided according to Both scarps are only slightly degraded by vegetation and drainage patterns into 15 land erosion. Alluvial fans have developed below types which provide information at a more fluvial gullies along the scarp face aligned with regional level than that at the land system structurally controlled joints. The bases of the scale (refer to land systems chapter). Hampton Range and Wylie Scarp are overlain by a concave apron of colluvium, consisting (i) Calcrete plains mostly of clay with fragments of limestone and calcrete debris washed off the tops of the These surfaces are level to gently undulating scarps (Lowry 1970). plains of very low relief formed of cemented calcium carbonate developed as part of the There are two sections of presently active sea- subsoil of an original soil profile. These cliffs along the southern margin of the Bunda surfaces are generally underlain by various Plateau: the 160 km long Baxter Cliffs in limestones of the Eucla Group, except in rare Western Australia and the 200 km long Bunda instances in the south-west where granite Cliffs in South Australia. Along the top of the outcrop protrudes through the surface. Pre- Baxter Cliffs there are sections of weathered dominantly consisting as relict land surfaces sand dunes. These clifftop dunes are wind- with deposits of uncertain origin, some land blown Pleistocene sand deposits formed when systems represent stages of transition with substantial quantities of drift sand accumulated

85 Table 10 Land surface types of the Western Australian Nullarbor survey area

Predominant Survey location Land surface type Land system surface Characteristic landform(s) Dominant vegetation type and distribution geology (i) Calcrete Caiguna Calcrete Gently undulating plains with Low eucalypt woodland South-west, plains residual calcareous low rises common Carlisle Calcrete Gently undulating partially Bindii grassland with sparse North-east, deflated stony plains myall uncommon Colville Calcrete Very gently undulating plains Myall woodland over bindii North-east, rare overlain by sandy loam grassland Culver Calcrete Gently undulating stony plains Low mallee woodland over South, common sedges and hummock grasses Gumbelt Calcrete Very gently undulating plains Eucalypt woodland with West, common overlain by sandy loam mixed scrub understorey Haig Calcrete Level loamy plains Chenopod shrubland or Central, rare bindii grassland Jubilee Calcrete Undulating and dissected plains Bindii grassland with very North-east, scattered myall uncommon Kyarra Calcrete Level loamy plains Bindii grassland with sparse Central and myall north, common Moodini Calcrete Level to gently undulating Eucalypt or myall woodland South-east, rare sandy loam plains Moopina Calcrete Level sandy clay plains Eucalypt and melaleuca South-east, rare woodland; false bluebush shrubland in drainage foci Nyanga Calcrete Level loamy plains Myall or casuarina West and north, woodland over chenopod very common understorey Rabbit Calcrete Level loamy plains Bindii grassland North-east, rare Zanthus Calcrete Level sandy loam plains Mallee woodland over West, rare spinifex (ii) Depressions Koonjarra Calcrete Low breakaways and Chenopod shrubland or West, within depressions grassland uncommon calcrete Woorlba Calcrete Closed depressions Chenopod shrubland or South-west, plains grassland uncommon (iii) Granite Balladonia Granite Low granite outcrop Bare granite outcrop with South-west, rare outcrop in fringing acacia–dodonaea– calcrete eremophila shrubland plains (iv) Limestone Kanandah Recrystallised Gently undulating plains Myall woodland over pearl North-west, plains [with Limestone bluebush shrubland or common deeper soil bindii grassland than (v)] Lowry Recrystallised Undulating rise overlain by Pearl bluebush shrubland Central, rare Limestone sandy loam Thampanna Abrakurrie Undulating joint controlled stony Eucalypt and myall South-east, Limestone, ridges and rises woodland on ridges; common Mullamullang chenopod shrubland and Member grassland mosaics on Limestone, drainage floors Nullarbor Limestone Toolinna Toolinna Undulating stony plains Low mallee woodland, South, common Limestone, coastal heath and scrub Abrakurrie Limestone Virginia Recrystallised Gently undulating plains Myall woodland on low West, common Limestone ridges; halophytic shrubland on saline drainage floors Weebubbie Nullarbor Gently undulating stony plains Eucalypt and melaleuca South-east, Limestone woodland on rises; uncommon grassland on drainage floors and claypans

86 Table 10 continued

Predominant Survey location Land surface type Land system surface Characteristic landform(s) Dominant vegetation type and distribution geology (v) Deflated Arubiddy Nullarbor Gently undulating stony plains Pearl bluebush shrubland; South-central, limestone Limestone with irregular joint patterns halophytic shrubland on common plains drainage floors Balgair Nullarbor Gently undulating stony plains Pearl bluebush shrubland Central, Limestone with irregular joint patterns on broad ridges; bladder common saltbush shrubland and grassland mosaics on drainage floors Bullseye Nullarbor Very gently undulating stony Bindii grassland; donga Central north, Limestone plains, dongas common groves very common Chowilla Nullarbor Gently undulating stony plains Myall woodland and pearl South-east, Limestone with irregular joint patterns bluebush shrubland; common grassland and halophytic shrubland mosaics on drainage floors Gafa Nullarbor Very gently undulating stony Pearl bluebush shrubland Central, very Limestone plains with irregular joint or bindii grassland; bladder common patterns saltbush and grassland shrubland mosaics on drainage floors Kinclaven Nullarbor Level stony plains, dongas Mixed shrubs and bindii Central north, Limestone common grassland; donga groves common Kitchener Nullarbor Gently undulating stony plains Mixed acacia shrubs and North-west, Limestone bindii grassland with sparse uncommon black oak Kybo Nullarbor Undulating stony plains Pearl bluebush shrubland; Central, Limestone grassland and herbland on common drainage floors Moonera Nullarbor Very gently undulating stony Pearl bluebush shrubland; Central, very Limestone plains defined by north-east to bladder saltbush shrubland common south-west trending joint on drainage floors patterns Morris Nullarbor Level to very gently undulating Pearl bluebush shrubland; South-east, Limestone stony plains with irregular joint bladder saltbush shrubland common patterns and grassland on drainage floors Nanambinia Nullarbor Level to gently undulating stony Sugarwood over chenopod South-west, Limestone plains shrubland or grassland uncommon Naretha Nullarbor Gently undulating stony plains Mixed acacia and pearl Central west, Limestone bluebush shrubland; bindii uncommon grassland Nightshade Nullarbor Gently undulating stony plains Tussock grassland; South, common Limestone halophytic shrubs in drainage foci Nurina Nullarbor Stony plains commonly with Grassland or bladder Central, Limestone gilgai patches saltbush shrubland uncommon Oasis Nullarbor Level stony plains, dongas Bindii grassland; dongas North-east, Limestone common groves common Pondana Nullarbor Gently undulating stony plains Pearl bluebush shrubland; Central west, Limestone with large rounded claypan bladder saltbush shrubland common depressions or annual herbland in claypan depressions Reid Nullarbor Level to very gently undulating Pearl bluebush shrubland; East, common Limestone stony plains defined by north- bladder saltbush shrubland west to south-east trending joint on drainage floors patterns Seemore Nullarbor Level stony plains Pearl bluebush shrubland North-east, Limestone with sparse myall and black uncommon oak Shakehole Nullarbor Gently undulating stony plains Pearl bluebush shrubland South-east, Limestone along regular joint patterns with sparse myall; common trending north-east to south- grassland and bladder west saltbush shrubland mosaics on drainage floors

87 Table 10 continued

Predominant Survey location Land surface type Land system surface Characteristic landform(s) Dominant vegetation type and distribution geology Skink Nullarbor Level to very gently undulating Pearl bluebush shrubland; Central south- Limestone stony plains defined by north- bladder saltbush shrubland east, common east to south-west trending joint on drainage floors patterns Vanesk Nullarbor Gently undulating stony plains Pearl bluebush shrubland Central west, Limestone defined by north-south trending and scattered myall uncommon joint patterns woodland on low ridges; halophytic shrubland on drainage floors (vi) Calcarenite Mundrabilla Colluvium, Level loamy plains Myall woodland over false South, plains Roe bluebush; open chenopod Uncommon Calcarenite shrubland and nitre bush Roe Colluvium, Level plains overlain by sandy Eucalyptus and melaleuca South, Roe loam woodland Uncommon Calcarenite (vii) Coastal Baxter Sand, calcrete Clifftop dunes Banksia coastal heath and South-west, rare plains and scrubland dunes Bilbunya Sand Coastal dunes, beach Coastal shrubland South-west, rare foredunes, dunefields Delisser Sand Coastal dunes, beach Coastal shrubland South, rare foredunes Wurrengoodyea Sand, calcrete Coastal dunes Eucalypt coastal heath South, rare woodland Wylie Sand, calcrete Coastal dunes Banksia coastal heath and South-west, rare scrubland (viii) Salt lakes Boonderoo Alluvium, Lake bed, saline alluvial plains, Halophytic and non- North-west, rare sand, gypsum sandy banks halophytic shrubland Damper Alluvium, clay, Lagoonal saline clay flats Halophytic shrubland South, rare gypsum Lefroy Alluvium, Lake beds, saline alluvial Halophytic shrubland South-west, rare sand, gypsum plains, sandy plains Ponton Alluvium, silt, Concentrated drainage Halophytic and non- North-west, rare sand channels halophytic shrubland erosional processes dominant as indurated supporting myall woodland over bindii calcrete surfaces become exposed through grassland; dongas and claypans exhibit denudation. This surface type occupies the centripetal drainage. second largest part of the survey area, occupy- Culver—Level to gently undulating stony plains ing almost 29 per cent. The land systems of this of residual and aeolian loam containing surface type are: sheet and nodular calcrete, irregularly Caiguna—Level to gently undulating plains of dissected by differential weathering along residual and aeolian loam containing sheet joint patterns to form closed drainage foci and nodular calcrete, with occasional and low rises. Supports low mallee wood- residual calcareous rises, supporting low land over sedges and hummock grasses. eucalypt woodland. Gumbelt—Level to very gently undulating Carlisle—Gently undulating plains of residual plains of shallow aeolian sand over residual clay loam containing sheet and nodular loam containing sheet and nodular calcrete calcrete dissected to expose Nullarbor supporting eucalypt woodland with mixed Limestone supporting bindii grassland with scrub understorey. sparse myall; differential surface weathering Haig—Level to gently undulating plains of has formed dongas and drainage floors. residual clay loam containing sheet and Colville—Very gently undulating plains of nodular calcrete supporting chenopod residual sandy loam containing sheet and shrubland or bindii grassland; weakly nodular calcrete at or near the surface dissected by relic ancient river courses.

88 Jubilee—Undulating plains of residual clay Depression floors are almost level with drain- loam containing sheet and nodular calcrete, age foci in the lowest positions with various dissected by differential weathering along limestones of the Eucla Group exposed at the joints and relic ancient river courses to surface either through deflation or gilgai expose Nullarbor Limestone. Supports bindii processes. Solution of the underlying limestone grassland with very scattered myall. This and deflation of clay is believed to be the system is intermediate in form between process responsible for depression formation intact residual loamy calcrete plains of the (Lowry 1970). This surface occupies almost Nyanga and Rabbit land systems and the 1.4 per cent of the survey area. The land completely deflated stony limestone plains systems of this surface type are: of the Bullseye and Oasis land systems. Koonjarra—Low breakaways form plateau Kyarra—Level plains of residual clay loam edges to calcrete plains enclosing large, containing sheet and nodular calcrete depressions, supporting chenopod shrub- partially dissected to expose Nullarbor land or grassland, with centripetal drainage Limestone, supporting bindii grassland with patterns to drainage foci with gilgai micro- sparse myall. This system is intermediate in relief. form between intact residual loamy calcrete plains of the Kyarra and Nyanga land Woorlba—Level to gently inclined depressions, systems and the completely deflated stony supporting chenopod shrubland or grass- limestone plains of the Bullseye and Oasis land, forming drainage foci for surrounding land systems. plains. Moodini—Level to gently undulating plains of (iii) Granite outcrop in calcrete plains undissected residual sandy loam and calcrete, derived from weathered residual In the south-west part of the Bunda Plateau aeolian deposits. Supports eucalypt or myall inliers of Proterozoic granite protrude through woodland. the calcrete plains of the Mardabilla Plain. Fringing surfaces are characterised by gritty- Moopina—Level plains of undissected residual sandy surfaces or moat-like depressions where sandy clay and calcrete, derived from water run-off is concentrated leading to weathered residual aeolian deposits, dissolution of calcareous surroundings. This supporting dense eucalypt and melaleuca surface type is a rare occurrence occupying woodland. about 0.1 per cent of the survey area. The land Nyanga—Level plains of residual clay loam system of this surface type is: containing sheet and nodular calcrete, Balladonia—Granite low rises and domes supporting myall or casuarina woodland protruding through calcrete plains, fringed over chenopod understorey. by gritty, sandy surfaces supporting acacia– Rabbit—Level plains of residual clay loam dodonaea–eremophila shrubland. containing sheet and nodular calcrete, with infrequent small, shallow claypans. (iv) Limestone plains [with deeper Dominated by bindii grassland. soils than (v)] Zanthus—Level plains of residual sandy loam These limestone plains differ from the deflated containing nodular calcrete near the limestone plains primarily by the amount of soil surface, overlain by shallow deposits of development brought about by weathering. aeolian sand. Supports mallee woodland These surfaces are capable of supporting over spinifex hummock grassland. woodland and occupy about 9.3 per cent of the (ii) Depressions within calcrete survey area. This surface type can be further subdivided into two groups based on post- plains depositional limestone weathering processes. Within the calcrete plateau forming the Nyanga Along the south of the Bunda Plateau surface and Mardabilla plains karstic depressions of weathering has created greater land unit relief variable size occur. Ranging from 5 to 15 m in the Hampton Tableland than in land units of deep, these depressions are bounded by low the Nullarbor Plain. This is considered largely a breakaways or gently inclined slopes. factor of higher rainfall in southern areas

89 causing greater solution of the limestones (v) Deflated stony limestone plains along joint patterns. The plains of the Hampton Tableland consist of undulating stony rises and These surfaces form the Nullarbor Plain and ridges separated by karstic depressions of occur in the centre of the Bunda Plateau. This various form and length. The land systems of erosional surface is the largest in the survey this surface type are: area occupying approximately 53.2 per cent of the area. Wind erosion in combination with Thampanna—Undulating irregular low stony weathering dissolution is the process most rises (limestone hummocks) and ridges responsible for the regularity of weathering supporting eucalypt and myall low open across the plain. Extensive deflation over the woodland separated by open depressions plateau surface has exposed a level to gently formed by differential weathering of lime- undulating surface with thin soil on the rises and stones along predominantly north-east to clay to clay loam in the depressions. Deflated south-west trending joint patterns which stony limestone plains can be further sub- support a mosaic of chenopod shrubland divided into two groups based on the genesis of and grassland. karst landforms. Toolinna—Undulating stony plains with In the south of the Nullarbor Plain the surface irregular low rises (limestone hummocks) has a gently undulating relief of parallel, low separated by stony marginal slopes and rocky ridges and rises separated by depres- irregular drainage foci in-filled with sions controlled by structural joints in the colluvium. Supports low mallee woodland underlying limestones. The land systems of this grading seaward into coastal heath and surface type are: scrub along clifftops. Arubiddy—Gently undulating stony plains Weebubbie—Gently undulating low ridges and supporting pearl bluebush shrubland, stony plains enclosing small drainage foci. differentially weathered along irregular joint Supports eucalypt and melaleuca woodland patterns to form closed drainage depres- on rises and grassland on the lower slopes, sions, supporting halophytic shrubland. closed drainage floors and claypans. Balgair—Gently undulating low stony rises with Along the west of the Nullarbor Plain broad stony marginal slopes, supporting weathering of Nullarbor Limestone has resulted pearl bluebush shrubland, separated by in recrystallisation from a hard (indurated) drainage floors, containing a mosaic of limestone to a soft, porous, rubbly limestone. bladder saltbush shrubland and grassland, The land systems of this surface type are: along irregular joint patterns with infrequent Kanandah—Gently undulating plains of large claypans and dongas; occasional relic partially deflated residual loam over ancient river courses form sinuous, narrow recrystallised Nullarbor Limestone, support- drainage tracts terminating indistinctly into ing myall woodland over pearl bluebush the surrounding plains. shrubland or bindii grassland; differential Chowilla—Gently undulating stony plains, weathering of the surface has formed small supporting scattered myall woodland and dongas and gilgaied depressions. pearl bluebush shrubland, separated by open Lowry—Undulating low rise composed of depressions, supporting grassland and recrystallised Nullarbor Limestone halophytic shrubland, along irregular joint supporting pearl bluebush shrubland. patterns forming narrow drainage floors often terminating in oval claypans or as small Virginia—Gently undulating plains formed closed drainage foci randomly distributed through differential weathering of recrystal- throughout the stony plains. lised Nullarbor Limestone along north-south trending joint patterns have formed parallel, Gafa—Very gently undulating stony plains, low stony ridges, supporting myall woodland, supporting pearl bluebush shrubland or bindii separated by narrow, saline drainage floors grassland, with large claypans, infrequent up to 10 km long, dominated by halophytic dongas, lignum swamps and wide drainage shrubland. floors, supporting a mosaic of grassland and bladder saltbush shrubland; drainage patterns restricted to the ancient river tracts.

90 Kitchener—Gently undulating stony plains of Infrequent relic ancient river courses form residual calcareous loam and sheet calcrete sinuous, narrow drainage tracts terminating dissected to expose Nullarbor Limestone; indistinctly into the surrounding plains. differential weathering of the surface has Nightshade—Gently undulating stony plains formed infrequent dongas. Plains support differentially weathered along irregular joint mixed shrubs and bindii grassland. This patterns to form closed drainage depres- system is intermediate in form between the sions or open drainage floors; saline intact residual loamy calcrete plains of the drainage foci supporting halophytic shrubs Nyanga land system, the weathered lime- occur irregularly throughout the plains. stone plains of the Kanandah land system Plains are dominated by tussock grassland. and the deflated stony limestone plains of the Naretha land system. Pondana—Gently undulating stony plains differentially weathered to form large, closed Kybo—A deflated fault scarp, supporting pearl depressions with level claypan floors bluebush shrubland, trending north-south for characterise this system. Elsewhere the nearly 40 km characterises this system. plains are superficially weathered to form Elongated clay drainage floors lie to the west dongas or drainage floors along north-south of the low scarp, elsewhere superficial trending joint patterns. Drainage is restricted weathering of the limestone plain along to relic ancient river courses. Plains support north-east to south-west trending joint pearl bluebush shrubland; depressions patterns has formed undulating stony ridges support bladder saltbush shrubland or separated by broad, level drainage floors, up annual herbland. to 8 km long and < 1 km wide, with infrequent claypans and dongas forming Reid—Level to very gently undulating stony large drainage foci in the lower-lying areas. plains differentially weathered along Drainage floors support grassland and predominantly north-west to south-east herbland. trending joint patterns to form linked, circular drainage foci along narrow drainage floors, Moonera—Very gently undulating stony plains. extending up to 5 km. Stony plains support Defined by north-east to south-west trending pearl bluebush shrubland; drainage floors joint patterns, which have formed wide drain- support bladder saltbush shrubland. age floors supporting bladder saltbush shrub- land, separated by very gently undulating Seemore—Level plains of partially deflated broad, stony low rises and ridges, supporting residual loam exposing Nullarbor Limestone pearl bluebush shrubland; large infrequent support pearl bluebush shrubland with irregular claypans, < 1 km in extent. sparse myall and black oak. Differential weathering of the surface has formed small Morris—Level to very gently undulating stony dongas and gilgaied depressions. This plains, supporting pearl bluebush shrubland, system is intermediate in form between the separated by sinuous drainage floors along intact residual loamy calcrete plains of the irregular joint patterns, up to 3 km long, and Nyanga land system, the recrystallised large, irregular claypans in drainage foci, up limestone plains of the Kanandah land to 1.5 km in extent. Drainage floors support system and the deflated stony limestone bladder saltbush shrubland and grassland. plains of the Kinclaven land system. Nanambinia—Level to gently undulating stony Shakehole—Gently undulating stony plains plains and gently inclined depressions differentially weathered along north-east to subject to very diffuse sheet flow. Supports south-west trending joint patterns form a scattered sugarwood over chenopod shrub- series of long, narrow drainage floors, up to land or grassland. 10 km long. Large drainage foci within Naretha—Gently undulating stony plains drainage floors consist of closed, round partially overlain by shallow sandy loams, claypans < 1 km in diameter or open, support mixed acacia and pearl bluebush irregular clay plains up to 3 km in extent. shrubland over bindii grassland. Differential Stony plains support pearl bluebush weathering of the surface has formed long, shrubland with sparse myall on rises and a narrow drainage tracts, occasional dongas mosaic of grassland and bladder saltbush and very shallow clay depressions. shrubland in drainage floors.

91 Skink—Level to very gently undulating stony surfaces subject to pedogenesis; clay loams plains differentially weathered along and calcrete dominate the soil profile. This predominantly north-east to south-west surface occupies almost 4 per cent of the trending joint patterns to form long, narrow survey area. The land systems of this surface drainage floors, generally up to 10 km long, type are: and large oval claypans in drainage foci, Mundrabilla—Landward section of coastal < 1 km in extent. Stony plains support pearl plain, backed by marine eroded scarp, bluebush shrubland; drainage floors support covered by shallow clay loam containing bladder saltbush shrubland. sheet and nodular calcrete; supporting myall Vanesk—Gently undulating stony plains woodland over false bluebush and open defined by north-south trending joint shrubland dominated by chenopods and patterns forming marginal slopes to nitre bush. drainage floors, with saline drainage foci. Roe—Coastal plain, in sections backed by Stony plains and low ridges support pearl marine eroded scarp, covered by shallow bluebush shrubland and scattered myall clay loam, with superficial sands, containing woodland; saline drainage floors support calcrete nodules; supporting eucalyptus and halophytic shrubland. melaleuca woodland. In the north of the Nullarbor Plain the surface of the level plain is interrupted by many, (vii) Coastal plains and dunes rounded shallow, closed karstic depressions These depositional surfaces form the coastal locally called ‘dongas’. Dongas can be either areas in the south of the survey area. They randomly scattered or aligned parallel with joint consist of beaches, foredunes, interdunal patterns in the underlying limestone. The land swales and saline depressions, partially systems of this surface type are: consolidated to unconsolidated dunefields and Bullseye—Very gently undulating stony lime- colluvial sand ramps against the escarpment of stone plains supporting bindii grassland and the Bunda Plateau. These coastal surface drainage floors with frequent large dongas, types occupy about 2.5 per cent of the survey occasional swamps and small claypans. area. The land systems of this surface type Kinclaven—Level stony plains, supporting are: mixed shrubs and bindii grassland, with Baxter—Clifftop transverse sand dunes frequent dongas, occasional swamps and trending west-north-west separated by small gilgai patches randomly distributed interdunal corridors of indurated calcrete; through stony plains. supporting banksia coastal heath and Nurina—Stony plains dissected by broad scrubland. drainage floors, occasional dongas and Bilbunya—Beaches, foredunes, interdunal infrequent relic ancient river courses. Gilgai swales and coastal dunefields with largely patches characterise this system. Plains unconsolidated parabolic dunes trending support grassland or bladder saltbush approximately north-south, frequently shrubland. becoming reticulate, occasionally forming Oasis—Level stony plains supporting bindii star dunes; dune relief up to 90 m. Sparsely grassland, with numerous small dongas; vegetated by coastal shrubland. drainage is restricted to relic ancient river Delisser—Beaches, unconsolidated to partially courses. consolidated foredunes, dunefields of unconsolidated parabolic dunes trending (vi) Calcarenite plains approximately north-south, swales and interdunal saline depressions. Sparsely These surfaces occur on the Roe Plains below vegetated by coastal shrubland. the Bunda Plateau. The coastal plain is under- lain by calcarenite deposited after Late Wurrengoodyea—Coastal parabolic sand Pliocene marine erosion removed the earlier dunes and swales supporting eucalypt limestones of the Eucla Group and formed the coastal heath woodland. Sand dunes escarpment and cliffs of the Bunda Plateau. partially consolidated by a thin layer of sheet They are predominantly level, depositional land or nodular calcrete close to the surface.

92 Wylie—Interdunal saline depressions between occur on the margins of the Nullarbor Plain, partially consolidated coastal dunes backed whilst the majority of the plain is dominated by to the escarpment by colluvial sand ramps deflated surfaces. The extent of deflation has supporting banksia coastal heath woodland. exposed the subsurface relief of the joint controlled depression and ridge topography. (viii) Salt lakes Stony limestone plains and infrequent low rises are the predominant features across the Salt lakes and their fringing tributary plains Nullarbor Plain’s surface, separated by open or have developed as a result of past drainage closed drainage floors, claypans and dongas. systems becoming infilled by alluvial deposition Less common are traditional karst features and choked by aeolian sediments. They are such as caves, dolines and sinkholes. The capable of holding water for extended periods limestone plains generally have an abundant after heavy rainfall. These surface types are the mantle of limestone and calcrete fragments, lowest depositional surfaces and occupy about with outcrop more common on the tops of rises 0.5 per cent of the survey area. The land and undulations. systems of this surface type are: Some areas of the Nyanga Plain also exhibit Boonderoo—Lake beds and fringing plains on erosional surfaces. Calcrete plains on the saline alluvium surrounded by sandy banks, margins of the Nullarbor Plain are commonly gypsiferous and kopi dunes, supporting dissected and the soil surface is shallow with halophytic and non-halophytic shrubland. extensive limestone outcrop. These surfaces Damper—Lagoonal surfaces of saline, are considered intermediate in form between gypsiferous calcareous clay with aeolian intact residual loamy calcrete plains of the deposits forming minor low dunes; Nyanga Plain and the deflated stony limestone supporting halophytic shrubland. Nullarbor Plain. Erosion is the dominant Lefroy—Lake beds and fringing plains on process rather than the formation of soil and saline alluvium with drainage foci and calcrete. Similarly some calcrete surfaces claypans surrounded by sandy banks, low within the Hampton Tableland are also sand dunes and kopi dunes, supporting dominated by erosional processes. Within the halophytic shrubland; only occurs in the far Nyanga Plain the large karstic depressions south-west of the survey area. forming the Koonjarra land system are also considered erosional land surfaces. Ponton—Channels with narrow flanking alluvial plains and sandy banks supporting halo- The southern edge of the Bunda Plateau phytic and non-halophytic shrubland; only represents a major erosional surface. The sea- occurs in the far north-west of the survey cliffs and escarpments carved by marine area. erosion into the uplifted limestones are active zones of erosion with cliff retreat a prominent Erosional landforms and processes feature of the present day coastline. Scree and colluvial development against the escarpment Erosional land surfaces dominate the survey on the coastal plains is less dramatic but still area, occurring extensively across the Nullarbor an active process. Plain and where the calcrete plains of the Of rare occurrence in the south-west of the Nyanga Plain are solution weathered, dissected survey area are the protrusions of granite and deflated exposing the underlying Nullarbor outcrop through the calcareous plains. The Limestone. exfoliation observed on low granite domes and The surface of the Nullarbor Plain has been rises, as well as the surrounding gritty surface formed through solution, concretisation and margins, indicate erosional processes. deflation by wind erosion resulting in uniform Depressions, 3–10 m deep and 50–150 m regularity across the plateau. The karst wide, characteristically ring most granite out- features characteristic of the Bunda Plateau crop. These moat-like depressions are caused have since developed on and below this by water run-off from the granite concentrating surface. The limestone plains can be sub- solutional processes on the surrounding divided into two surface types distinguished by calcareous sediments (Lowry & Jennings the amount of soil development. Limestone 1974). plains with calcareous soils of variable depth

93 Relict land surfaces and processes Depression evolution can be described in terms of differential surface solution of limestones. Relict land surfaces are the second most Though their genesis is solutional, depression common surfaces in the survey area. Negligible landforms such as drainage floors and dongas soil development is the predominant process. are locally depositional settings accumulating The term ‘relict’ as defined by Hocking et al. colluvium from the surrounding stony plains and (2007) refers to landforms where deposits are of aeolian sediments from further afield. Within uncertain origin, being either transported or depressions soil depth is variable, determined weathered in situ. On such relict land surfaces by the degree of limestone solution. However, the processes of denudation operate with surfaces can display stony fragments exposed minimum intensity and the rate of weathering is through deflation or brought to the surface often equal to or exceeds the pace of surface through gilgai processes. Within the land erosion (Thomas 1974). The majority of these system hierarchy they are part of the greater surface types occur on the Nyanga Plain to the erosional process active on the limestone west and north of the Nullarbor Plain. Small plains. isolated areas also exist on the southern edge of the Bunda Plateau on the top of the Hampton Within the Nyanga and Mardabilla plains clay Range. floored depressions form drainage foci for surrounding systems. These depressions form The level to gently undulating surface of the the base unit of the Woorlba land system and Nyanga Plain is underlain by about 4.5 m of clay are enclosed by gentle slopes draining down loam and calcrete, developed as part of the from neighbouring land systems. Fine colluvial subsoil of an original soil profile. In most sediments eroded via sheet flow from locations the plains support open myall wood- surrounding plains accumulate in the land. The calcrete has formed as part of the soil depressions. profile through the cementation of calcium carbonate. The thick surfaces of clay loam have On the Roe Plains colluvial deposits grade into developed over an extensive time period with distal sheetwash deposits in areas proximally calcrete formation possibly commencing as associated to the Hampton Range. The majority early as the Pliocene (Lowry 1970). of the Roe Plains, not overlain by coastal dunes, consist of clay loam underlain by Roe Residual Late Pleistocene dunes are situated on Calcarenite. These surfaces support either the top of the Hampton Range. Formerly highly open myall woodland and open shrubland or calcareous these have been reduced to sandy melaleuca and eucalyptus mallee woodland. clay loams. Calcrete exists at or near the surface as a well developed horizon. Elsewhere coastal dunes have developed on land surfaces adjacent to the coast. Dunes Depositional landforms and fringe the Roe and Israelite coastal plains as well as locations on top of the Baxter Cliffs. On processes the coastal plains dune deposition is an Depositional landforms are less common in the ongoing process forming the present day Nullarbor region than in other Western beaches, foredunes and interdunal swales Australian physiographic regions. They are the bordering the Southern Ocean. These recent least common surface types in the survey area, deposits are backed by large dunefields of largely due to the areic, self-draining nature of unconsolidated, mobile dunes forming the the Bunda Plateau. The lack of surface drain- Bilbunya Dunes on the Israelite Plain and the age, particularly across the Nullarbor Plain, Wurrengoodyea Hills and Delisser Sandhills on means the volume of sediment dispersed by the Roe Plains. Older, consolidated dunes exist alluvial processes is greatly reduced. Aside from on the landward side of the younger dunes and deposition processes associated with coastal on top of the Baxter Cliffs. Considered to be of environments, on the Bunda Plateau areas of Late Pleistocene age these older dunes have deposition are largely restricted to depressions calcrete development close to the surface and evolved through karst solution processes. are vegetated. At specific locations sand ramps link the Bunda Plateau and the coastal plains. On the Nullarbor Plain karstic depressions These wind-built ramps formed at the base of within the limestone plains are controlled by the escarpment when the sea exposed coastal structural joints in the underlying limestones. areas during a past sea regression.

94 Along the coast on the Roe and Israelite plains Payne, Curry & Spencer 1987; Payne et al. small lagoons have developed in interdunal 1998; Curry et al. 1994; Pringle, Van Vreeswyk depressions containing sand, silt, clay and & Gilligan 1994) document lands on which occasionally gypsiferous sediments. On the natural erosion processes have been acceler- Roe Plains two larger areas of lagoonal ated by inappropriate land uses. More recently deposits represent Pleistocene lagoons barred participatory research and extension projects in from the sea by advancing dunes. the southern rangelands of Western Australia have begun to look at rangeland landscapes Salt lakes are rare in the survey area occurring across a variety of scales and in doing so are in the west at the end of Ponton Creek forming identifying geomorphic determinants responsi- Lake Boonderoo and in the far south-west. ble for landscape change (Pringle & Tinley Lake sediments consist of recent aeolian and 2001, 2003; Pringle, Watson & Tinley 2006). lacustrine deposits of quartz sand, silt and clay, sometimes with halite and gypsum. Lake Boonderoo is intermittently filled by infrequent Calcrete plains cyclonic summer rains when Ponton Creek These surfaces are level to gently undulating flows after being fed by salt lakes to the west of plains of very low relief generally with clay loam the Eucla Basin. Due to saline headwaters soils of variable depth (e.g. Nyanga land Lake Boonderoo can be highly saline. system). When in good condition the moderate In summary, the majority of the present land- covering of vegetation in combination with the forms in the survey area occur on the Bunda flat topography means these surfaces are Plateau comprising extensive level to gently generally resistant to erosion. However the undulating limestone plains, distinguished by friable nature of the soil surface makes these soil development and karst landforms, plains susceptible to degradation and erosion bordered in the north and west by calcrete following disturbance, particularly after plains. In the south the Western Australian preferential grazing fragments vegetation portion of the Bunda Plateau is bordered by communities or fire completely exposes the sea-cliffs and the Roe and Israelite coastal ground surface. plains fringed by beach and coastal dunes. Where calcrete plains border the Nullarbor Relief is greatly subdued and surface drainage Plain the surfaces are even more susceptible is generally absent except in the west where to erosion (e.g. Jubilee and Kyarra land there are rare salt lakes. The areic drainage system). Due to landform dissection and slight surface above the Eucla Group limestones gradient differences between the calcrete results in surface waters permeating through plains over the underlying limestone, soil depth karst landforms into underground drainage becomes shallower in these intermediate systems. Landform patterns are best surface types as they merge onto the Nullarbor appreciated in terms of the morphotectonic Plain. The decrease in soil depth reduces the setting with uplift of the Eucla Basin leading to capacity for vegetation formations to offer the exposure of the Miocene sea floor. Minimal significant soil surface protection as their tectonic activity since uplift, in combination with coverage is generally scattered. When vegeta- the onset of arid conditions, the highly tion is further reduced through disturbance, permeable nature of the surface limestones, such as by overgrazing, storm damage and hardening through concretisation and plain fire, soil loss is further exacerbated. geomorphology has resulted in the regularity of weathering across the plateau surface. Karst Depressions within calcrete plains features have since developed on and below this surface. Low breakaway scarps in the calcrete plain occupy a very small area of the survey (e.g. Land use impacts on landscape Koonjarra land system). These land units are inherently unstable and have tributary rills, processes guttering, gullies and exhibit soil loss down- Until recently there had been little research on slope. They exhibit some of the most active the impacts of land use on landscape proces- natural erosion within the survey area as they ses in Western Australian rangelands. Similar represent erosional fronts between the topo- surveys to this one (Wilcox & McKinnon 1972; graphically higher calcrete plains and the

95 underlying limestones. Naturally eroding Deflated stony limestone plains through solution of the underlying limestone and deflation of clay; the degradation of the Deflated limestone plains are dominated by breakaway scarps is accelerated through loss level to gently undulating stony surfaces with of perennial shrubs by overgrazing and vehicle regular outcrop. Soils on the stony surfaces are tracks. To reduce the track impact on break- shallow and vegetation cover is commonly low away slopes and to protect associated fragile and scattered (usually less than 15 per cent vegetation communities bunds should be projected foliar cover). The stony mantle offers constructed to reduce the volume and erosive some protection but where loss of perennial potential of water flow channelled by the tracks. shrubs has occurred wind erosion is accelerated. Granite outcrop in calcrete plains The lack of surface drainage on the Nullarbor Plain results in water sheet flow having only a The nature of this surface type results in very restricted and localised role in transporting little infiltration and run-off is concentrated to sediment from the stony plains to surrounding the margins of the protruding rock outcrop. karstic depressions. Wind is also responsible Erosion of these surfaces is generally not a for supplying depression deposits. Deposits concern as the surfaces are commonly bare, form level surfaces in the depressions except exposed granite outcrop fringed by gritty-sandy where gilgai cause irregular, hummocky surfaces. patches. The fine clay soil crust of depression Limestone plains [with deeper soils] floors is readily erodible and any form of disturbance will inevitably lead to accelerated These limestone plains are level to gently deflation through wind erosion. Installing water undulating and are capable of supporting open points on such fragile landforms has resulted in woodland primarily due to the amount of soil the extensive piospheres scarring the land- development improving infiltration. These scape through the Nullarbor pastoral areas. plains are generally covered by a variable soil The reduction in perennial vegetation to trap layer with a stony mantle. They are generally wind-blown material exacerbates the extent of not susceptible to erosion except when plant piospheres, zones of attenuated impact. cover is reduced and cryptogamic crusts Through deflation such areas are losing their become fragmented through disturbance. ability to provide suitable conditions for germination and establishment of perennial On the Hampton Tableland in the south, where plants. Dust storms on the Nullarbor are a surface weathering has resulted in greater land common occurrence, especially during unit relief, undulating stony rises and ridges are prolonged dry periods. active sites of erosion as sediments are transported to surrounding depressions (e.g. Thampanna land system). Vegetation loss through overgrazing or fire can result in erosion leaving rises (limestone hummocks) completely bare and exposed. In such landforms, particularly when affected by fire, total grazing pressure should be restricted for a period of time set by seasonal conditions which will determine the effectiveness of recovery. Continuous grazing pressure immediately after fire and/or through extended dry periods can result in continual erosion stripping these surfaces to such as extent they become incapable of supporting perennial vegetation communities. A piosphere caused by overgrazing at a water point located on the fragile soils of a drainage floor between stony plains.

96 Deflated surface within a piosphere. Overgrazing Older weathered limestone surfaces commonly has removed perennial shrubs and trampling by display pitting, whereas recently exposed surfaces stock has disrupted protective soil crusts, exposing lack weathered features indicating the extent of soil the soil to wind erosion. loss.

Calcarenite plains likely causes of disturbance responsible for reducing vegetation cover and initiating These surfaces occur on the Roe Plains below erosion. the Bunda Plateau (e.g. Mundrabilla and Roe land systems). Underlain by calcarenite these Salt lakes and lagoonal flats surfaces form level plains subject to pedo- genesis with clay loams and calcrete through Level to very gently inclined saline alluvial the soil profile. The flat topography and plains are found adjacent to salt lakes (e.g. moderately dense surface cover of vegetation Boonderoo and Lefroy land systems). Soils are comprising either open myall woodland and duplex types with a sandy surface horizon open shrubland or melaleuca and eucalyptus commonly over gypsiferous sediments. Water mallee woodland means the plains are infiltration is often enhanced and there are generally resistant to erosion. Disturbance widespread cryptogamic crusts. On the coastal through overgrazing and fire can expose plains lagoonal clay flats occur in interdunal surfaces making them susceptible to erosion. swales or as Pleistocene lagoons (e.g. Damper The colluvial footslopes of the Hampton Range land system). Generally, lack of slope renders are naturally erodible due to steep gradients. these systems not susceptible to water Grazing activity should be minimised on these erosion, though they are subject to inundation. slopes. Regularly spaced bunds and spoon If vegetation cover is reduced and cryptogamic drains should be constructed on scarp tracks to crusts are disturbed (e.g. by overgrazing and reduce the volume and erosive potential of trampling) wind erosion can result in scalding. water flow channelled by tracks. In summary, the Western Australian part of the Nullarbor region has a number of natural Coastal plains and dunes characteristics which help protect the land- Unconsolidated coastal beach dunes (e.g. scape from the impacts of inappropriate land Bilbunya and Delisser land systems) and use. The factor most responsible for offering partially consolidated coastal sand dunes (e.g. protection to the Nullarbor landscape is its flat Baxter, Wurrengoodyea and Wylie land topography and calcrete capping of surface systems) are subject to strong sea breezes and limestones in conjunction with prolonged arid are susceptible to wind erosion if vegetation is to semi-arid climatic conditions, resulting in the lost. Aside from beach dunes and mobile dune- nearly level, areic terrain. The lack of distinct fields, most coastal dunes are stabilised with coordinated surface drainage means the coastal scrubland and partially consolidated Nullarbor has not developed the large scale with thin calcrete horizons near or at the accelerated water-induced erosion features surface. Fire and vehicle traffic are the most initiated by overgrazing, as seen in other

97 southern rangeland regions, particularly those Benbow, MC 1990b, The Yarle Sandstone: a with exoreic drainage. Other protective Miocene coastal terrigenous sequence of the characteristics include the stony surfaces and Eucla Platform. South Australia, Department cryptogamic soil crusts. On the calcrete and of Mines and Energy, Quarterly Geological coastal plains moderately dense vegetation Notes, 113, 2–6. communities comprising species which are Curry, PJ, Payne, AL, Leighton, KA, Hennig, P largely unaffected by grazing have also & Blood, DA 1994, An inventory and contributed to protecting the landscape. condition survey of the Murchison River Fire is a natural feature of the Nullarbor catchment and surrounds, Western environment spontaneously occurring as a Australia, Department of Agriculture, result of lightning strikes during summer Western Australia, Technical Bulletin No. 84. thunderstorms. Good seasonal conditions Davey, AG, Gray, MR, Grimes, KG, promote an abundance of annual growth and Hamilton-Smith, E, James, JM & Spate, AP expansion of Austrostipa scabra (speargrass). 1992, World Heritage significance of karst Following dry conditions the potential fuel load and other landforms in the Nullarbor region, from this growth will readily carry fire. Since Applied Ecology Research Group, Report to European settlement the frequency of fires in DASET, Canberra, University of Canberra. the Nullarbor region has increased particularly during the period when steam trains used the Gillieson, D & Spate, A 1992, ‘The Nullarbor Trans-Australian Railway and sparks ignited karst’, in Geology, climate, hydrology and fires adjacent to the railway line. karst formation: field symposium in Australia: guidebook, Special Publication No. 4, The areas in which the landscape is most Department of Geography and susceptible to inappropriate land use are the Oceanography, University College, Bunda Plateau escarpment footslopes and low Australian Defence Force Academy, breakaway scarps of the calcrete plains which Canberra. are subject to sheet flow; various forms of karstic depressions (e.g. drainage floors, Hocking, RM 1990, ‘Eucla Basin’, in Geology claypans and dongas) where disturbance and mineral resources of Western Australia, accelerates deflation; sand dunes along coastal Western Australia, Geological Survey, areas; and sites supporting vegetation which is Memoir 3, pp. 548–561. highly preferred by herbivores. The impact of Hocking, RM, Langford, RL, Thorne, AM, land use in these areas has not been quantified Saunders, AJ, Morris, PA, Strong, CA, in terms of soil loss rates, sediment yields, Gozzard, JR & Riganti, A 2007, A vegetation cover thresholds and other such classification system for regolith in Western variables inherently reflective of landscape Australia, Western Australia Geological processes and ecosystem health. Survey, Record 2007/8. References Jennings, JN 1963, ‘Some geomorphological problems of the Nullarbor Plain’, Beard, JS 1975, Vegetation survey of Western Transactions of the Royal Society of South Australia: Nullarbor, 1:1 000 000 Vegetation Australia, 87, 41–62. Series, Explanatory notes to sheet 4, University of Western Australia Press, Perth. James, JM, Bone, Y, Carter, RM & Murray-Wallace, CV 2006, ‘Origin of the Late Benbow, MC 1989, History of recognition and Neogene Roe Plains and their calcarenite delineation of coastal aeolian landforms of veneer: implications for sedimentology and the Eucla Basin, South Australia, Geological tectonics in the Great Australian Bight’, Survey of South Australia, Quarterly Australian Journal of Earth Sciences, Geological Notes, 109, 9–14. 53, 407–419. Benbow, MC 1990a, ‘Tertiary coastal dunes of the Eucla Basin, Australia’, Geomorphology, 3(1), 9–29.

98 Jennings, JN 1967a, The Surface and Pringle, H & Tinley, K 2001, ‘Ecological Underground Geomorphology. Caves of the sustainability for pastoral management’, Nullarbor – a review of speleological Journal of Agriculture, Western Australia, investigations in the Nullarbor Plain, South 42, 30–35. Australia, JR Dunkley & TML Wigley (eds), Pringle, HJR & Tinley, KL 2003, ‘Are we Speleological Research Council, Sydney, overlooking critical geomorphic determinants 13–31. of landscape change in Australian Jennings, JN 1967b, Some Karst areas of rangelands?’ Ecological Management and Australia. Landform Studies from Australia Restoration, 4, 180–186. and New Guinea, JN Jennings & JA Mabbutt Pringle, HJR, Watson, IW & Tinley, KL 2006, (eds), Australian National University Press, ‘Landscape improvement, or ongoing Canberra, 1971, 256–292. degradation – reconciling apparent Jennings, JN 1968 The Nullarbor Plain, contradictions from the arid rangelands of Australia: A dryland karst region, New Western Australia’, Landscape Ecology, Zealand Geographical Society, 45, 17–19. 21, 1267–1279. Jennings, JN & Mabbutt, JA 1977, Singleton, OP 1954, ‘The Tertiary stratigraphy Physiographic Outlines and Regions. of Western Australia, a review’, Pan-Indian Australia – A Geography, DN Jeans, Sydney Ocean Science Congress, Perth, University Press, 1977, 38–52. Proceedings Section C, pp. 59–65. Jessup, RW 1961, ‘A Tertiary-Quaternary Thomas, MF 1974, Tropical Geomorphology: A pedological chronology for the south-eastern study of weathering and landform portion of the Australian arid zone’, Journal development in warm climates, Macmillan of Soil Science, 12, 199–213. Press, London. Jutson, JT 1950, The physiography Veevers, JJ, Jones, JG & Powell, CMcA 1982, (geomorphology) of Western Australia, ‘Tectonic Framework of Australia’s Geological Survey of Western Australia, Sedimentary Basins’, APEA (Australian Bulletin 95 (Third edition of Bulletin 61, Petroleum Exploration Association) Journal, 1914). 22(1), 283–300. Lowry, DC 1970, Geology of the Western Wasson, RJ 1982, ‘Landform development in Australian part of the Eucla Basin, Australia’, in Evolution of the Flora and Geological Survey of Western Australia, Fauna of Arid Australia, WR Barker & PJM Bulletin 122. Greenslade (eds), Peacock Publications, South Australia. Lowry, DC & Jennings, JN 1974, ‘The Nullarbor karst Australia’, Zeitschrift für Webb, JA & James, JM 2006, ‘Karst evolution Geomorphologie NF, 18, 35–81. of the Nullarbor Plain, Australia’, in Perspectives on Karst geomorphology, Payne, AL, Curry, PJ & Spencer, GF 1987, An hydrology and geochemistry, RS Harmon, inventory and condition survey of rangelands CM Wicks, DC Ford & WB White (eds), in the Carnarvon Basin, Western Australia, Geological Society of America, Special Western Australian Department of Paper 404. Agriculture, Technical Bulletin No. 73. Wilcox, DG & McKinnon, EA 1972, A report on Payne, AL, Van Vreeswyk, AME, Pringle, HJR, the condition of the Gascoyne catchment, Leighton, KA & Hennig, P 1998, An inventory Western Australian Department of and condition survey of the Sandstone- Agriculture, Technical Report No. 2. Yalgoo-Paynes Find area, Western Australia, Agriculture Western Australia, Technical Wyrwoll, KH & Glover, JE 1988, Physical Bulletin No. 90. features and geology: The Geological and Geomorphological Framework of Western Pringle, HJR, Van Vreeswyk, AME & Gilligan, Australia, Western Australian Year Book, SA 1994, An inventory and condition survey 1988, Australian Bureau of Statistics. of the north-eastern Goldfields, Western Australia, Department of Agriculture, Western Australia, Technical Bulletin No. 87.

99 Soils The basic concept of describing and identifying soils is through the examination of soil layers or P Hennig horizons. The soil layers have identifiable properties and are described through the con- Summary cept of pedologic organisation (pedology being The soils of the study area are dominated by the study of soils). Using the principle of soil reddish shallow calcareous loams and sands layering or organisation, soils are described as derived from calcareous parent materials. belonging to three main texture groups: soil with uniform texture throughout the profile, soils that White, grey and brown deep sands, predomi- gradually change in texture down the profile; and nantly calcareous, are associated with coastal soils with a texture or permeability contrast margins of the survey area. (often termed duplex) within the profile. Red/brown clayey soils occur sporadically Soils with uniform textures include sands (e.g. throughout in clay plains and clay, gilgai or deep sandplains inland from the coast or donga depressions. spinifex sandplains in the Zanthus area), loams Red sands and red sandy earths are associ- (e.g. plains of the southern Nullarbor) and clays ated with sand banks near Lake Boonderoo in (e.g. deep clays in dongas). Gradational soils the north-west. are common on donga margins and areas of common water accumulation. Texture contrast Small areas of saline and gypsiferous soils (duplex) soils are uncommon. In many cases occur around Lake Boonderoo and variable the soils are shallow with hardpans or rock stony soils, gritty shallow red sands and bare within 1 m of the soil surface. rock are associated with occasional granite outcrop in the south-west. Field sampling methods Previous surveys Three hundred and twenty soils were described using the criteria of the Australian Soil and Land The Nullarbor Plain soils were broadly Survey Field Handbook (McDonald et al. 1990). described and mapped at a scale of 1:2 000 000 by Northcote et al. (1960–68) as Sampling was via shallow soil pits and a 50 mm part of The Atlas of Australian Soils, providing a diameter soil auger, to retrieve soil to a depth of general overview of soil distribution. Laut et al. 1 m or to the level of the impermeable (1977), Mitchell et al. (1979) and McKenzie et al. underlying rock. Samples were laid out on (1987) provided more detailed soils information. groundsheets to determine different soil layers. Soil textures were determined for the sieved fine Soil classification and description earth fraction (< 2 mm) through moistening the The Australian Soil Classification (Isbell 2002) is sample and noting the behaviour of the kneaded the national system for classifying soils. It soil. Field textures provided an indication of the replaces previous systems by Stace et al. proportions of sand, silt and clay. Soil textures (1968) and Northcote (1979). The Australian Soil range from sand (< 5 per cent clay) to heavy Classification system uses scientific, soil-based clay (> 50 per cent clay). nomenclature similar to other classification Textures were determined down the profile to systems in the world. separate the major soil layers into A, B, C or K In Western Australia a simple system for horizons where, the ‘A’ horizon is the topsoil, the describing the main soil types—the Soil groups ‘B’ horizon is the subsoil, the ‘C’ horizon is of Western Australia is also used (Schoknecht weathered rock and the ‘K’ horizon is limestone 2002). Soil groups are a simple method of or calcrete. describing and naming the soils in Western Soil colour was determined in the field using a Australia using easily recognisable soil moistened fresh soil aggregate and compared morphological features. In this chapter, the soil to standard soil colour charts (Munsell 1954). types of the Nullarbor are categorised by WA Consistence (a measure of soil particle Soil groups with reference to typical Australian bonding) was determined by compressing a Soil Classifications provided within each 20 mm unit of undisturbed soil. Soil structure category. and fabric were determined using a hand lens.

100 The presence or absence, size and shape of soil aggregates (particle clusters held together by forces of inter-particle bonds) were recorded. The parent material, substrate or underlying rock was determined either from examination of material retrieved via soil auger or from geological maps. Soil pH was measured using a portable pH meter or less commonly a paste calorimetric method described by Raupach and Tucker (1959). Carbonates were detected via drops of hydrochloric acid, effervescence indicating presence of calcium carbonate. The electrical conductivity (EC) of soil horizons was obtained in the field using a portable EC meter using 10 g of soil in 50 mL of distilled water. This was used to indicate the total soluble salts expressed in milliSiemens per metre (1 mS/m equates to about 5 parts per million). The soil salinity classes are:

Topsoil Low (non-saline) 1–40 mS/m Moderate (saline) 41–80 mS/m High (highly saline) > 80 mS/m Describing a soil profile at an inventory site. Subsoil Low (non-saline) 0–120 mS/m High (saline) > 120 mS/m Other recordings were the shape, size and abundance of coarse fragments, soft segregations or crystals within a profile plus surface features such as mantle, outcrop and cryptogam crusting. Cryptogams (microbiotic assemblages of mosses, fungi, lichen and liverworts) form thin surface crusts covering many soil surfaces. The soils were classified using the Australian Soil Classification system in which the soil depth classes are: < 25 cm very shallow 25–50 cm shallow 50–100 cm moderately deep > 100 cm deep

101 Soil groups recognisable soil morphological features. A summary table lists the dominant features of Eighteen soil groups (Schoknecht 2002) were each soil group. Soil types occupying greater identified in the survey area and are summa- than 25 per cent of a land system are listed as rised in Table 11. The soil group concept seeks major soils. Soils occupying 10–25 per cent of a to summarise and standardise the naming of land system are listed as minor soils. soils across Western Australia based on easily

Table 11 Soil groups in the survey area

Soil group (code) Description Landscape location Salt lake soil (102) Gypsiferous deposits Lake Boonderoo, lacustrine plains Bare rock (201) Rock outcrop with very shallow Granitic outcrop Stony soil (203) skeletal soils Red deep sandy duplex soils (405) Red deep sandy surfaced soils Floors of depressions with calcrete overlying clay subsoils plain Calcareous shallow sands (421) Shallow sands overlying limestone Hampton and Wylie scarps Pale shallow sands (422) Pale shallow sands overlying Interdunal swale calcrete Red shallow sands (423) Red shallow red sands overlying In the west of the survey area near granite or occasionally calcrete granitic outcrop Deep sands (440) Grey and brown deep sands Beach foredunes and swales Calcareous deep sands (442) Calcareous sands over 1 m deep Beach and foredunes; coastal dunefields and dune ramps Red deep sands (445) Red sands over 1 m deep Sandy banks around Lake Boonderoo Red sandy earths (463) Red soils with a sandy surface Sandy banks around Lake grading to loam or clay by 80 cm Boonderoo; Nyanga Plain Calcareous shallow loams (521) Shallow calcareous loam overlying Limestone, calcrete and calcarenite incorporating Calcareous stony soil (202) calcareous rock types plains Red shallow loams (522) Shallow red loam overlying calcrete Calcrete plains Calcareous loamy earths (542) Loamy surfaced soils grading to clay Limestone, calcrete and calcarenite loam subsoils; calcareous plains throughout Red loamy earths (544) Deep red loamy surfaced soils often Calcrete plains grading to clay loam Cracking clays (600) Cracking clays exhibiting surfaces Dongas, swamps and drainage foci cracks or gilgai mounding Red/brown non-cracking clays (622) Red to brown clays (mostly deep) Dongas, drainage foci and lacustrine sometimes with cracking clays depressions; calcrete plains

102 Soil group 102—Salt lake soils gypsum deposits support samphire and other (Gypsiferous deposits) highly salt tolerant plant species. Surface exposures of gypsum are protected from This soil type is uncommon and was recorded erosion via a thin firm surface crust. around the lake bed and saline plains of Lake Boonderoo. These soils also occur on the saline plains, gypsiferous plains and lagoonal low dunes of the Damper land system, or kopi dunes of the Lefroy land system. Gypsum (calcium sulphate) deposits form from saline groundwater or lacustrine accumulations. When dry these deposits are redistributed by wind erosion, often forming dunes on lake or saline plain margins. An accumula- tion of pure gypsum deposits is in one sense, not a true soil, but rather a growth medium for very specific plants. Gypsum deposits are highly saline and alkaline, providing a harsh growing environment, and as such, support little or no vegetation. When masked by thin layers of sand or clay, Gypsum deposits forming around margins of Lake Boonderoo.

Gypsiferous deposits summary

Australian Soil Classification Gypsic Hypersalic Hydrosol Soil textures Fine crystals of gypsum throughout the profile or occasionally overlain by thin layers of fine sand or light clay Land systems Major soil of the Boonderoo land system, minor with the Damper and Lefroy systems Land units Lake bed, saline plain, gypsiferous plain or lagoonal low dunes Soil colour Greyish brown (2.5Y 5/2) topsoil to brownish yellow (10YR 6/8) subsoil Soil depth Deep (> 100 cm) Pedality/Fabric/Structure Apedal, earthy and massive Soil surface condition No rock outcrop or mantle Topsoil slaking Complete Subsoil slaking Complete Topsoil/subsoil dispersion Nil Topsoil/subsoil pH range Alkaline (9.5) topsoil and subsoil Topsoil EC range Highly saline (> 1500 mS/m) Subsoil EC range Highly saline (> 200 mS/m) Soil permeability Highly permeable Available water storage Moderate to high Unrestricted rooting depth High Wind/water erosion hazard High Inundation/flooding risk High

103 Soil group 201—Bare rock and Soil classified as Rudosols. Soil depths range from group 203—Stony soil just a few millimetres to about 30–40 cm in (Rocky granite soils) localised accumulation zones. As the soil consists of very coarse quartz grains, nutrients These soil groups are uncommon and occur in and organic matter are leached from the profile the south-west of the survey area on exposed relatively quickly resulting in soil with excellent domes of granite. In terms of development, drainage, but with few nutrients and a low these soils are little more than roughly sorted water-holding capacity. These soils display an coarse gritty sands lying on or at the base of acidic soil reaction trend. These soils have granite rock. Granite rock is mainly composed linkages to the red shallow sands (soil group of feldspar, mica and quartz. Feldspar and mica 423). The soil is reddish brown and the surface decompose relatively quickly during weathering may have an infrequent to common mantle of leaving mainly coarse quartz. In displaying little granite with abundant rock outcrop. or no true soil development these soils are

Rocky granite soils summary

Australian Soil Classification Paralithic, Lithic, Leptic or Arenic Rudosol Soil texture Very coarse sand Land system Balladonia land system Land unit Low granite rise Soil colour Dark reddish brown (2.5YR 3/4 to 5YR 3/4) Soil depth Very shallow (< 25 cm) Pedality/Fabric/Structure Apedal, sandy and single grain Soil surface condition Loose with a common (10–50%) stony mantle of granite and abundant rock outcrop (> 50%) Substrate Granite Topsoil/subsoil pH range Acidic (5.5–6.0) Topsoil EC range Negligible Subsoil EC range Negligible Soil permeability Highly permeable Available water storage Very low Unrestricted rooting depth Low Wind/water erosion hazard Minor Inundation/flooding risk Nil

104 Soil group 405—Red deep sandy duplex grading to light clay. The topsoil was non-saline, soils with a neutral soil reaction, and non-dispersive, but did slake. The subsoil was saline with an This soil type was only recorded once as a alkaline soil reaction. The soil surface was minor occurrence on the marginal slopes to stone-free and displayed abundant cryptogams. depression floors in the Koonjarra land system. Soil colour ranged from dark red in the topsoil to The soil profile comprised thin fine sandy topsoil red in the subsoil. overlying a deep subsoil of silty clay loam

Red deep sandy duplex soil summary

Australian Soil Classification Red Chromosol Soil textures Fine sand overlying silty clay grading to light clay Land system Minor soil within the Koonjarra land system Land units Marginal slope to drainage floor Soil colour Dark red (2.5YR 3/6) topsoil to red (2.5YR 5/6) subsoil Soil depth Deep (> 100 cm) Pedality/Fabric/Structure Apedal, earthy and massive Soil surface condition No rock outcrop or mantle; abundant (70%) cryptogam crusting Substrate Calcrete Topsoil slaking Complete Subsoil slaking Nil Topsoil/subsoil dispersion Nil Topsoil/subsoil pH range Neutral (7.0) topsoil and alkaline (9.5) subsoil Topsoil EC range Non-saline (< 5 mS/m) Subsoil EC range Saline (200 mS/m) Soil permeability Moderately permeable Available water storage Moderate to high Unrestricted rooting depth Moderate Wind/water erosion hazard Low Inundation/flooding risk Nil

105 Soil group 421—Calcareous shallow are abundant. The soil textures are fine sand sands with a topsoil colour of light brownish grey overlying dark greyish brown subsurface sand. Calcareous shallow sands are restricted to the These soils are highly calcareous, non-saline scarp face land unit of the Wurrengoodyea land and have an alkaline soil reaction trend. This system. These sands are very shallow and soil type is uncommon. overlie limestone. Biological surface crusts are infrequent, but limestone mantles and outcrop

Calcareous shallow sand summary

Australian Soil Classification Hypercalcic Calcarosol Soil textures Fine sand over sand Land system Minor soil within Wurrengoodyea land system Land unit Scarp face Soil colour Topsoil of light brownish grey (10YR 6/2) over subsoil of dark greyish brown (10YR 4/2) Soil depth Very shallow (< 25 cm) Pedality/Fabric/Structure Apedal, sandy and single grained Soil surface condition Infrequent (< 10%) biological surface crusting with an abundant (> 50%) limestone mantle and outcrop Substrate Limestone Topsoil/subsoil slaking Nil Topsoil/subsoil dispersion Nil Topsoil pH range Alkaline (9.0) Subsoil pH range Alkaline (9.0) Topsoil EC range Non-saline (< 5 mS/m) Subsoil EC range Non-saline (< 5 mS/m) Soil permeability Highly permeable Available water storage Very low Unrestricted rooting depth Low Wind erosion hazard Moderate (due to landscape position) Water erosion hazard Low Inundation/flooding risk Nil

106 Soil group 422—Pale shallow sands soil reaction trend. Soil colour ranges from light grey at the surface to dark yellowish brown in These soils are uniform textured fine sands the subsoil. This soil type is uncommon and overlying calcrete or calcarenite at very shallow was recorded only once on the interdunal swale depth. Soil surfaces are soft with no biological land unit of the Wurrengoodyea land system. surface crusts and have no mantle. The soil is non-calcareous and non-saline with a neutral

Pale shallow sand summary

Australian Soil Classification Leptic Rudosol Soil texture Fine sand Land system Minor soil within the Wurrengoodyea land system Land unit Interdunal swale Soil colour Topsoils of light grey (10YR 7/1) and subsoils of dark yellowish brown (10YR 4/4) Soil depth Very shallow (< 25 cm) Pedality/Fabric/Structure Apedal sandy and single grained Soil surface condition Soft surface with infrequent (< 10%) cryptogam crusting and no mantle Substrate Calcarenite Topsoil/subsoil slaking Nil Topsoil dispersion Nil Subsoil dispersion Nil Topsoil pH range Neutral (6.0) Subsoil pH range Neutral (7.0) Topsoil EC range Non-saline (< 5 mS/m) Subsoil EC range Non-saline (< 5 mS/m) Soil permeability Highly permeable Available water storage Very low Unrestricted rooting depth Low Wind erosion hazard Low to moderate dependant Water erosion hazard Nil Inundation/flooding risk Nil

107 Soil group 423—Red shallow sands granitic land systems tend to be marginally coarse in texture, as the sands are generally These soils are very shallow to shallow, uniform developed in situ and are not transported long textured loamy sands overlying calcrete. The distances though wind or water erosion. soils are dark red in colour, non-calcareous and have a neutral to weakly alkaline soil reaction Within the Zanthus land system red shallow trend. This soil type is uncommon in the survey sands occur on the calcareous plains. The area and was found in the Balladonia and sands are also shallow and overlie calcrete and Zanthus land systems. some of these sands contain calcrete nodules. Soil textures tend to be marginally finer than Within the gritty-surfaced plains of the those of the granitic (Balladonia) land system as Balladonia land system the shallow substrate is the Zanthus sands tend to be of aeolian origin. granite with an occasional veneer of calcrete. These sands generally lack surface crusting or Biological surface crusts are common and a a mantle. mantle of calcrete/limestone fragments is frequent. The loamy sands associated with

Red shallow sand summary

Australian Soil Classification Arenic or Leptic Rudosol Soil textures Medium grained loamy sand (occasionally medium to coarse) in the Balladonia land system and medium to fine-grained loamy sand in the Zanthus land system Land systems Major soil Balladonia and Zanthus land systems Land units Gritty-surfaced plains (Balladonia land system) and calcareous plains (Zanthus land system) Soil colour Dark red (2.5YR 3/6) Soil depth Very shallow to shallow (< 25–50 cm) Pedality/Fabric/Structure Apedal, sandy and single grained or apedal, earthy and massive Soil surface condition Common (10–50%) cryptogam crusts with frequent (10–50%) limestone mantle or infrequent mantle and crusting Substrate Granite (with or without a calcrete veneer or calcrete) Topsoil/subsoil slaking Nil Topsoil/subsoil dispersion Nil Topsoil pH range Neutral (7.5) to alkaline (8.2) Subsoil pH range Mostly alkaline (8.0–8.5) Topsoil EC range Non-saline (< 5 mS/m) Subsoil EC range Non-saline (< 5 mS/m) Soil permeability Highly permeable Available water storage Very low Unrestricted rooting depth Low Wind erosion hazard Low Water erosion hazard Low for granitic areas, otherwise nil Inundation/flooding risk Nil

108 Soil group 440—Deep (grey and brown) or no carbonates. These soils trend from grey sands near the coast progressively showing brown and yellow colours further inland. Sand dune These sands occur inland from the calcareous soils have colour ranges from grey-brown in the deep sands (soil group 442) associated with the topsoils to yellowish brown in the deep subsoil. beaches. They are more developed than the In the swales soil colour ranges from grey to beach sands and occur as sand dunes and dark yellowish brown. sand sheet swales. Soil textures comprise fine sand and the soils are non-saline. Soil reaction is neutral to alkaline and these soils contain little

Deep (brown) sand soil summary

Australian Soil Classification Arenic Rudosol Soil textures Fine sand sometimes grading to weak clayey sand Land system Major soil of the Wurrengoodyea land system Land units Dunes and swales Soil colour Grey (10YR 5/1) to greyish brown (10YR 4/2, 10YR 5/2) grading to dark yellowish brown (10YR 4/6) or yellowish brown (10YR 5/4, 10YR 6/4) Soil depth Deep (> 100 cm) Pedality/Fabric/Structure Apedal, sandy and single grained Soil surface condition Soft with common (30–40%) cryptogam crusting Topsoil/subsoil slaking Complete Topsoil/subsoil dispersion Nil Topsoil pH range Neutral (7.5) to alkaline (8.0) Subsoil pH range Alkaline (9.0–9.5) Topsoil EC range Non-saline (< 5 mS/m) Subsoil EC range Non-saline (< 5 mS/m) Soil permeability Highly permeable Available water storage Very low Unrestricted rooting depth High Wind erosion hazard Moderate Water erosion hazard Low Inundation/flooding risk Nil

109 Soil group 442—Calcareous deep sands beach sands show no organisation in a soil development sense. They are fine sands This soil group comprises deep white, grey and continually rearranged by the forces of wind and brown calcareous sands of the sandy coastal the ocean. As such they are structureless and margins of the survey area. The sands tend to support little or no vegetation because of the be white to light grey on the beach and foredune harsh environment in which they occur. zones, trending to brown inland. Soil textures Although faced with regular erosion (and are fine sand and soil colour depends on the reformation), occasional inundation and vegetative cover. As such, beach sands with influenced by strong salt laden sea breezes, little or no vegetation are mostly white or grey. these soils contain very low levels of salt due to Inland from the beaches, shrubs and stunted their highly porous nature. The colour of the trees contribute organic matter to the soil, beach sands is white to light grey. Adjoining the resulting in different coloured and more stable beach sands are the beach foredunes, soils. Calcareous deep sands occur within four somewhat mobile dunes due to the influence of land systems: Baxter, Bilbunya, Delisser and wind erosion. These foredunes are similar in Wurrengoodyea. The Bilbunya and Delisser texture to the beach sands, but are commonly systems front the ocean and consists of stabilised with pioneer plant species. beaches, foredunes and inland dunes. The

Calcareous deep sand soils summary

Australian Soil Classification Shelly, Arenic or Hypersalic Rudosol Soil texture Fine sand Land systems Major soil of the Bilbunya, Delisser and Wurrengoodyea land systems Land units Beach, inter-dune swale, sand dune Soil colour Beaches of white or light grey (10YR 7/1), dunes of light grey to very pale brown (10YR 8/3) to brown (10YR 5/3) or brown (10YR 5/3) to white (10YR 8/2) Soil depth Deep (> 100 cm) Pedality/Fabric/Structure Apedal, sandy and single grained Soil surface condition Loose (on the beach and dunes), otherwise soft to firm with infrequent to common (< 50%) cryptogam crusting Substrate Occasionally coastal limestone Topsoil slaking Complete Subsoil slaking Complete Topsoil/subsoil dispersion Nil Topsoil pH range Alkaline (> 8.9) Subsoil pH range Alkaline (> 8.5) Topsoil EC range Non-saline (1–25 mS/m) Subsoil EC range Mostly non-saline (1–18 mS/m), some weakly saline (60–135 mS/m) Soil permeability Highly permeable Available water storage Very low Unrestricted rooting depth High Wind erosion hazard High Water erosion hazard Low (beach and dune land units high) Inundation/flooding risk Low (tidal beach land unit high)

110 Soil group 445—Red deep sands These soils may occur adjacent to and among red sandy earths (soil group 463). There may This soil type is uncommon and occurs on the be some intergrading of these soil groups. In sandy banks of the Boonderoo land system. many instances the red deep sands and the red These soils are deep and have thin to medium sandy earths share similar types of topsoils. topsoil textures of loamy sand overlying thick Red sandy earths are more clayey with depth. subsoils of clayey sand. The soils are red in colour and have an alkaline soil reaction trend The red deep sands are very common in the due to the association with gypsic elements desert areas north of the Bunda Plateau, but from Lake Boonderoo. The profiles are free of have neutral to weakly acidic soil reaction coarse fragments and the soil surfaces are soft. trends.

Red deep sand soils summary

Australian Soil Classification Arenic Rudosol Soil textures Loamy sand to clayey sand Land system Minor soil of the Boonderoo land system Land unit Sand bank Soil colour Red (7.5YR 4/6) to reddish brown (5YR 4/4) and yellowish red (5YR 5/6) subsoils Soil depth Deep (> 100 cm) Pedality/Fabric/Structure Apedal, sandy, single grained Soil surface condition Soft with infrequent (< 10%) cryptogam crusts Topsoil/subsoil slaking Nil Topsoil/subsoil dispersion Nil Topsoil pH range Alkaline (8.5) Subsoil pH range Alkaline (9.0) Topsoil EC range Non-saline (< 2 mS/m) Subsoil EC range Non-saline (< 2 mS/m) Soil permeability Highly permeable Available water storage Low Unrestricted rooting depth High Wind erosion hazard Moderate to high Water erosion hazard Low Inundation/flooding risk Nil

111 Soil group 463—Red sandy earths alkaline and colour is red throughout. Red sandy earths are uncommon and occur with red deep These soils exhibit thin to medium topsoils of sands (soil group 445) on the sand bank land loamy sand to sandy loam graduating to unit of the Boonderoo land system. Within the medium to thick subsoils of loam or sandy clay Nyanga land system this soil was recorded loam or clay loam. They are deep soils and may infrequently in areas where shallow aeolian contain calcareous nodules in the lower subsoil sands overlay the calcareous loams. or be weakly saline at depth. Soil reaction is

Red sandy earth soils summary

Australian Soil Classification Red Kandosol Soil textures Loamy sand to sandy loam overlying sandy loam or sandy clay loam; calcareous nodules occasionally present Land systems Major soil of the Colville and Zanthus land systems; minor soil of the Nyanga, Ponton and Boonderoo land systems Land units Calcareous loamy plain overlain with shallow aeolian sands or sandy banks Soil colour Dark reddish brown (2.5YR 3/3) or dark red (2.5YR 4/6) grading to yellowish red (5YR 4/6 and 5/6) to reddish yellow (5YR 6/6) Soil depth Deep (> 1 m) Pedality/Fabric/Structure Apedal, sandy or earthy (with intergrades); single grain to massive Soil surface condition Soft to firm Substrate Occasional calcareous nodules in lower subsoil Topsoil slaking Complete Subsoil slaking Complete Topsoil dispersion Nil Subsoil dispersion Partial Topsoil pH range Alkaline (8.5) Subsoil pH range Alkaline (9.0–9.5) Topsoil EC range Non-saline (1–5 mS/m) Subsoil EC range Non-saline to weakly saline (5–90 mS/m) Soil permeability Highly permeable Available water storage Moderate Unrestricted rooting depth Moderate to high Wind erosion hazard Moderate Water erosion hazard Low Inundation risk/flooding risk Low

112 Soil group 521—Calcareous shallow Sandy loams are uncommon and have either loams (incorporating soil group 202— uniform textures of fine sandy loam overlying Calcareous stony soil) calcrete at very shallow depth or weak grada- tional textures of sandy loam grading to loam at Calcareous shallow loams are common on all shallow depth. The fine sandy loam type has but coastal and sub-coastal land systems. only one major horizon whereas the gradational These soils are divided into three subgroups: soil type has two primary layers. Soil colour is sandy loams, loams, and clay loams all over principally red for the fine sandy loams and calcareous rock types (i.e. limestone, calcrete, reddish brown to brown for the gradational calcarenite). Profiles with more than 50 per cent loams. The fine sandy loams are non-saline of rock fragments or calcrete are classified as while the gradational loams may be either non- Calcareous stony soil. saline or weakly saline. All of these soils are non-dispersive and do not slake.

Calcareous shallow (sandy) loam soils summary

Australian Soil Classification Lithocalcic Calcarosol Soil textures Fine sandy loam to sandy loam Land systems Minor soils of the Lowry, Naretha, Nyanga, Roe and Virginia land systems Land units Calcrete plain overlain by loam (KPL), Limestone hummock (low rise) (LHR), Calcareous plain with shallow sands (PKE), Stony limestone plain (SLP) Soil colour Mainly dark red (2.5YR 3/6) for fine sand loams and reddish brown (5YR 4/4) to yellowish red (5YR 4/6) or brown (7.5YR 3/4) to strong brown (10YR 5/4) for gradational types Soil depth Very shallow (< 25 cm) for fine sandy loams and shallow (25–50 cm) for deeper gradational sandy loam to loam soils Pedality/Fabric/Structure Apedal, earthy and massive Soil surface condition Mostly to abundant (50–90%) stony mantle of calcareous geology or where below 50% abundant biological (cryptogam) crusting (50–60%) Substrate Limestone, calcrete, calcarenite Topsoil/subsoil slaking Nil Topsoil/subsoil dispersion Nil Topsoil pH range Alkaline (9.0) Subsoil pH range Alkaline (9.0) Topsoil EC range Low (1–5 mS/m) for fine sandy loams, weakly saline (30 mS/m) for some gradational loams Subsoil EC range Low (1–10 mS/m) for fine sandy loams, weakly saline (60 mS/m) for some gradational loams Soil permeability Highly permeable Available water storage Low Unrestricted rooting depth Shallow Wind erosion hazard Low Water erosion hazard Low Inundation/flooding risk Low

113 The loam soil subgroup is very common and slightly deeper soils have reddish brown top- consists of mainly one or two loam-textured soils overlying strong brown or dark yellowish horizons overlying limestone at very shallow or brown subsoils. The deeper soils tend to show shallow depth. Soil colour is mainly reddish slightly more saline subsoils than the more brown to yellowish red with occasional stronger shallow types. Soil reaction is alkaline. hues of brown for the more shallow types. The

Calcareous shallow loam soils summary

Australian Soil Classification Lithocalcic Calcarosol Soil texture Loam Land systems Soils of the Balgair, Caiguna, Culver, Haig, Nanambinia, Naretha, Nightshade, Nurina, Nyanga, Thampanna, Roe, Shakehole and Weebubbie land systems Land units Calcrete plain overlain by loam (KPL), Calcrete stony plain (KSP), Limestone hummock (low rise) (LHR), Calcareous plain with shallow sands (PKE), Stony limestone plain (SLP) Soil colour Mainly dark red (2.5YR 3/6) or brown (7.5YR 3/4) to strong brown (10YR 5/4) Soil depth Very shallow (< 25 cm) to shallow (25–50 cm) Pedality/Fabric/Structure Apedal, earthy and massive Soil surface condition Mostly an abundant (50–90%) stony mantle of calcareous geology, abundant biological (cryptogam) crusting (50–60%) Substrate Limestone, calcrete, calcarenite Topsoil/subsoil slaking Nil Topsoil/subsoil dispersion Nil Topsoil pH range Alkaline (9.0) Subsoil pH range Alkaline (9.0) Topsoil EC range Low (1–30 mS/m) Subsoil EC range Low (1–30 mS/m), weakly saline (60 mS/m) for some gradational loams Soil permeability Highly permeable Available water storage Low Unrestricted rooting depth Shallow Wind erosion hazard Low Water erosion hazard Low Inundation/flooding risk Low

A calcareous shallow loam with only 15–20 cm of soil This shallow soil supports speargrass (Austrostipa scabra) and overlying limestone. Soils wallaby grass (Austrodanthonia caespitosa), some shrubs and a like this are common few trees. The shrub and tree roots follow fissures in the lime- throughout much of the stone in search of soil moisture. This is from an area west of Nullarbor Plain proper. Rawlinna Station homestead.

114 Calcareous shallow clay loams are very from non-saline to highly saline in the deeper common and have textures ranging from heavy subsoils. These soils are non-dispersive and do loams at the surface grading into clay loams not slake. Mantles of calcareous rock types are above the calcareous substrate. The soils may mostly abundant and surface biological crusting have one to three, mostly thin, horizons. Soil is conversely abundant (i.e. where the mantle is colour ranges from yellowish red in the topsoil highly abundant, crust abundance is low). Soil to yellowish red and dark brown in the subsoil. reaction is alkaline. Salinity is very low in the topsoil and may range

Calcareous shallow clay loam soils summary

Australian Soil Classification Calcarosol Soil textures Heavy loam throughout or grading to clay loam where soil depth is over 30 cm Land systems Major soils of the Balladonia, Caiguna, Culver, Damper, Gafa, Gumbelt, Kybo, Mundrabilla, Nanambinia, Nightshade, Nurina, Nyanga, Roe, Thampanna, Toolinna and Zanthus land systems Land units Calcrete plain overlain by loam (KPL), Calcrete stony plain (KSP), Low granite rise (LGR), Limestone hummock (low rise) (LHR), Stony limestone plain (SLP) Soil colour Mainly yellowish red (5YR 4/6) or brown (7.5YR 4/4) to dark brown (10YR 3/3) for gradational types Soil depth Shallow (25–50 cm) Pedality/Fabric/Structure Apedal, earthy and massive Soil surface condition Mostly abundant (50–90%) stony mantles of limestone or where below 50%, common to abundant biological (cryptogam) crusting (30–50%) Substrate Limestone Topsoil/subsoil slaking Nil Topsoil/subsoil dispersion Nil Topsoil pH range Alkaline (8.5–9.0) Subsoil pH range Alkaline (9.0) Topsoil EC range Low (1–30 mS/m) Subsoil EC range Low (1–30 mS/m) to high (50–200 mS/m) for deeper clay loams Soil permeability Highly permeable Available water storage Low Unrestricted rooting depth Shallow Wind erosion hazard Low Water erosion hazard Low Inundation/flooding risk Low

115 Soil group 522—Red shallow loams Generally soil reactions are neutral to weakly alkaline and no coarse or soft calcareous Red shallow loams are uncommon in the fragments occur through the profile. Soil colour survey area. They mostly consist of sandy is dark reddish brown to red or dark brown. loams, rarely grading to sandy clay loams and Soils with sandy veneers have stone-free overlie limestone, nodules of limestone or surfaces. Elsewhere the surfaces have occasionally calcrete. Some soils have a thin infrequent to common mantles of calcareous veneer of sand on the surface. When overlying fragments commonly with biological crusts. granite, soil textures are sandy clay loams.

Red shallow loam soils summary

Australian Soil Classification Petrocalcic, Lithic or Leptic Rudosol Soil textures Sandy loam occasionally grading to sandy clay loam; sandy clay loams when over granite Land systems Soils within the Balladonia, Gumbelt, Naretha, Nyanga, and Zanthus land systems Land units Drainage floor (DFL), calcrete plain overlain by calcareous loam (KPL), low granite rise (LGR), plain calcareous loam with aeolian sand covering (PKE), stony limestone plain (SLP) Soil colour Mainly dark reddish brown (2.5YR 3/4) and red (2.5YR 4/6) to red or dark brown (7.5YR 3/3) Soil depth Very shallow (< 25 cm) to shallow (25–50 cm) Pedality/Fabric/Structure Apedal, earthy and massive Soil surface condition No stony mantle for soils with a thin sand veneer, otherwise few to common (2–50%) stony mantles of limestone and common to abundant biological (cryptogam) crusting (40–80%) Substrate Limestone or limestone nodules, occasionally calcrete or granite Topsoil/subsoil slaking Nil Topsoil/subsoil dispersion Nil Topsoil pH range Weakly alkaline to alkaline (7.9–8.6), except where it is neutral (6.5–7.0) in granite areas Subsoil pH range Alkaline (8.5–9.0), except in granite areas where it is neutral to weakly alkaline (7.0–8.0) Topsoil EC range Low (1–5 mS/m) Subsoil EC range Low (1–10 mS/m) Soil permeability Highly permeable Available water storage Low Unrestricted rooting depth Shallow Wind erosion hazard Low Water erosion hazard Low Inundation/flooding risk Low

116 Soil group 542—Calcareous loamy these moderate depth soils. Limestone gravels earths occur within 30 cm of the soil surface and generally increase in abundance and size with This group is comprised of soils with textures of depth. Saline subsoils mostly occur in low-lying loam throughout the profile. It is a complex of areas supporting salt tolerant vegetation or various soil types. where gypsum occurs within the soil. Similarly The lightest expression of this Soil group soils with clayey subsoils are almost always displays topsoils of fine sandy loam or sandy weakly to strongly saline. In lighter textured soils loam overlying subsoils of loam. This soil phase salinity is variable. Soil reaction is alkaline. is relatively uncommon, occurring mainly in the Soil colour is generally dark reddish brown to Nyanga land system. Most soils within the reddish brown near the surface to yellowish red calcareous loamy earth soil group consist of in the subsoil. Within the Thampanna land loam to heavy loam topsoils overlying subsoils system the loamy soils tend to be browner in of heavy loam to clay loam. This soil phase colour. The soil surfaces are generally covered occurs on almost every land system. A less with an abundant mantle of limestone or common soil phase is the heavier textured loam calcrete with infrequent to common cryptogam soils being clay loam topsoils grading to light crusting. clay subsoils. Most of the soils within this soil group have thin to medium topsoils overlying moderate to deep subsoils. Limestone or calcrete often underlie

Calcareous loamy earth summary

Australian Soil Classification Calcarosol Soil textures Fine sandy loam to sandy loam over loam; loam grading to clay loam or clay loam grading to light clay Land systems Major soils of the Arubiddy, Caiguna, Damper, Kyarra, Kybo, Mundrabilla, Moonera, Nanambinia, Nightshade, Nyanga, Thampanna, Shakehole and Roe land systems. Minor soils of the Lowry, Naretha, Virginia and Zanthus land systems Land units Calcrete plain overlain by loam (KPL), calcrete stony plain (KSP), calcrete rise overlain by calcareous loam (KRL), stony limestone plain (SLP), plain calcareous loam (PKL), Limestone hummock (low rise) (LHR) Soil colour Mainly dark red (2.5YR 3/6) and reddish brown (5YR 4/4) to yellowish red (5YR 4/6) or brown (7.5YR 3/4) to strong brown (10YR 5/4) Soil depth Moderate to deep (> 80 cm) Pedality/Fabric/Structure Apedal, earthy and massive Soil surface condition Mostly to abundant (50–90%) stony mantles of limestone, common to abundant biological (cryptogam) crusting (10–50%) Substrate Limestone Topsoil/subsoil slaking Nil Topsoil/subsoil dispersion Nil Topsoil pH range Alkaline (9.0) Subsoil pH range Alkaline (9.0) Topsoil EC range Low (1–10 mS/m) for sandy loams and some loams Subsoil EC range Low (1–10 mS/m) for sandy loam and some loams, moderately to highly saline (100–400 mS/m) clay loam or light clay subsoils Soil permeability Loamy soils—highly permeable, loams grading to clays moderately permeable Available water storage Moderate to high Unrestricted rooting depth Moderate to deep Wind erosion hazard Low Water erosion hazard Low Inundation/flooding risk Low

117 A typical calcareous loamy earth with limestone gravels. Note the ability of Calcareous loamy earths support several different types of vegetation. tree roots to penetrate This area is towards the north of Noondoonia Station. deep into the subsoil to get moisture.

Soil group 544—Red loamy earths mantle of stone. The soils are non-saline and only rarely have calcareous deep subsoils. Soil Red loamy earths are infrequent. They occur as reaction is neutral or occasionally alkaline and deep soils with sandy clay loam or clay loam the topsoils do not slake or disperse. The soil topsoils graduating to clay loam or light clay colour ranges from dark reddish brown to dark subsoils. The soil surfaces may have a thin brown. sandy veneer or occasionally support a light

Red loamy earth soils summary

Australian Soil Classification Red Kandosol Soil textures Sandy clay loam to clay loam overlying light clay loam Land systems Minor soils of the Gumbelt and Naretha land systems Land units Clay depression (CLD) and plain with calcareous loam and thin sand veneer (PKS) Soil colour Mainly dark reddish brown (2.5YR 3/6) to dark red (2.5YR 4/6) Soil depth Deep (> 100 cm) or moderately deep (> 80 cm) Pedality/Fabric/Structure Apedal, earthy and massive Soil surface condition Thin sandy veneer on surface or infrequent to common biological (cryptogam) crusting (0–40%) Substrate Limestone Topsoil/subsoil slaking Nil for topsoil, nil to partial for subsoil Topsoil/subsoil dispersion Nil for topsoil, nil to complete for subsoil Topsoil pH range Neutral (7.0) Subsoil pH range Neutral to alkaline (7.0–8.5) Topsoil EC range Low (1–5 mS/m) Subsoil EC range Low (5–20 mS/m) Soil permeability Highly permeable Available water storage Moderate Unrestricted rooting depth Deep Wind erosion hazard Low Water erosion hazard Low Inundation/flooding risk Low

118 Soil group 600—cracking clays varying amounts of surface cracking. Soil colour is mainly dark reddish brown to red, soil Cracking clay soils are deep with thin to reaction is alkaline and many soils contain medium light clay (occasionally medium clay) some carbonates within at least part of the topsoils. Occasionally the topsoils may include profile. The soil surfaces are generally non- a thin layer of clay loam. The thick to very thick saline with deep subsoils being either non- subsoils have textures of light or medium to saline or partially saline. These soils occur in heavy clay. The uppermost layers display large dongas, swamps or areas of surface water surface cracks or have crumbly (self-mulching) accumulation. Cracking clay soils often occur surfaces when dry and often show rough with or adjacent to, red/brown non-cracking clay mounded (gilgai) surfaces. Large areas of soils (Soil group 622). cracking clays tend to show zonations of

Cracking clay soils summary

Australian Soil Classification Red Vertosol Soil textures Light clay grading to medium or heavy clay Land systems Soils of the Haig, Koonjarra, Nurina and Nyanga land systems Land units Clay plain (CLP), Gilgai depression (GIL), Calcrete plain overlain by loam (KPL) Soil colour Mainly yellowish red (5YR 4/6) or strong brown (7.5YR 4/6 to 7.5YR 5/6) Soil depth Deep (> 100 cm) Pedality/Fabric/Structure Pedal, moderate to strong polyhedral ped structure Soil surface condition Occasional infrequent to common (10–30%) limestone with some soil surface cracks or mounded gilgais Topsoil/subsoil slaking Nil, sometimes partial Topsoil/subsoil dispersion Nil, sometimes partial or complete Topsoil pH range Alkaline (9.0) Subsoil pH range Alkaline (9.0) Topsoil EC range Low (1–20 mS/m) occasionally high (90 mS/m) Subsoil EC range Low (10–20 mS/m) occasionally high (390 mS/m) Soil permeability Moderately permeable Available water storage High Unrestricted rooting depth Moderate to deep Wind erosion hazard Low Water erosion hazard Low Inundation/flooding risk Low

119 Soil group 622—Red/brown non- Deep red/brown non-cracking clays often occur cracking clays with cracking clay soils and some soils show juvenile features of cracking clays such as Red/brown non-cracking clays are mostly deep weakly developed self-mulching surfaces or soils. Shallow clays occur sporadically through- minor soil surface cracking. Soil colour is out the area but rarely dominate. mainly dark reddish brown to dark red or strong The deep clays are generally composed of light brown. The soils are alkaline throughout and clay, occasionally grading to medium or heavy may contain calcareous segregations of clay. Deep clays are mostly non-saline, but weathered limestone fragments in the lower saline types tend to occur in areas accumulat- subsoils. The topsoils generally do not slake or ing overland water flow like clay plains, clay disperse (unless highly saline) but subsoils depressions, saline plains and areas with commonly partially or completely slake and gypsum in the subsoil. Shallow clays overlie disperse. The soil surfaces generally have an limestone. infrequent mantle of limestone, but display abundant biological cryptogam crusting.

Red/brown non-cracking clay soils summary

Australian Soil Classification Red Kandosol Soil textures Light clay grading to light medium or sometimes heavy clay Land systems Commonly found on the Damper, Lefroy, Koonjarra, Kybo, Pondana, Thampanna, Shakehole and Vanesk land systems. Minor soils of the Caiguna, Gafa, Haig, Jubilee, Kanandah, Kitchener, Moonera, Nurina, Skink and Woorbla land systems Land units Clay depression (CLA), clay plain (CLP), donga depression (DON), Gilgai depression (GIL), Calcrete plain overlain by loam (KPL) Soil colour Mainly dark reddish brown (2.5YR 4/6) to yellowish red (5YR 4/6)or strong brown (7.5YR 5/6) Soil depth Deep (> 100 cm), minor shallow soils (50 cm) over limestone Pedality/Fabric/Structure Mostly apedal, earthy and massive, or moderately structured with polyhedral ped when occurring among cracking clay soils Soil surface condition Hardsetting with mostly abundant biological (cryptogam) crusting (50–90%) and infrequent (< 10%) mantles of limestone Substrate Limestone for shallow soils Topsoil/subsoil slaking Nil unless saline, then partial Topsoil/subsoil dispersion Mostly partial to complete Topsoil pH range Alkaline (8.5–9.0) Subsoil pH range Alkaline (9.0) Topsoil EC range Low for non-saline soils (1–30 mS/m), high for saline soils (100–160 mS/m) Subsoil EC range Low for non-saline soils (30–50 mS/m), high for saline soils (200–600 mS/m) Soil permeability Highly permeable Available water storage High for deep soils, low for shallow soils Unrestricted rooting depth Deep, low for shallow soils Wind erosion hazard Low Water erosion hazard Low Inundation/flooding risk Low, but high in clay or gilgai depressions

120 Biological soil crusts • Undulating plains with isolated or scattered eucalyptus trees also support low to tall Most soil surfaces of the Nullarbor have some shrubs. Tree and shrub canopies protect the form of protection from wind and water erosion. soil surface. Under many trees leaf litter also This can be in the form of stone, plant or leaf provides soil protection. Vegetation canopies litter cover. Where there is none of this cover, may cover up to 40 per cent of the soil soil crusting mostly exists. Biological soil crusts surface and stone cover may be infrequent make up a vital component of the arid or semi- to common. The soils are generally free arid ecosystem. Collectively known as crypto- draining with light textured topsoils. Generally gams (from two Greek words ‘kryptos’ meaning cryptogam crust cover ranges from 10 to hidden and ‘gamos’ meaning marriage), they 20 per cent in these environments. are made up of various lichens, mosses, liverworts, fungi and blue-green algae. The • Drainage foci on open plains act as local lichen and larger mosses are visible while the drainage termination zones. Water percola- microflora of the algae and fungi are difficult to tion through the soil profile is slow (weeks distinguish without the aid of magnification. The rather than days). These foci are mostly lack of soil crusts around some permanent stone-free and may support either (non- livestock watering points in the Nullarbor saline) gilgai soils with grasses or claypans pastoral area is notable. Soil surface crusting with salt-tolerant vegetation. Soil salinity falls into four scenarios: influences the amount of crusting (in a down- ward trend) and the surface crust rarely • Stone (mantle) free, open low plains exceeds 70 per cent. surrounded by low rises. The low plains act as micro-sumps collecting some run-off Biological soil crusts often appear somewhat water from the surrounding rises. These low brittle and hard in the dry state, but with the plains primarily have deep clay-based soils slightest amount of rainfall become soft, pliable and water percolation through the soil is not and spongy. Soil crusts have not evolved to rapid, taking days rather than hours. The withstand continuous trampling by hard-hoofed primary vegetation is bladder saltbush animals and regular vehicle impact. Once (Atriplex vesicaria) and may make up to 20 broken the crusts re-establish relatively quickly per cent of the soil cover. Plants provide provided they are no longer disturbed. Constant protection to the soil through intercepting trampling or traffic will destroy the crusts and rainfall and creating protection from wind re-establishment may take many years. erosion. As such biological soil crusting does not grow under the plant canopies. The remaining soil cover is mostly soil crusting. • Stony open low rises or level to gently undu- lating plains with a moderate to abundant mantle of limestone rocks and outcrop have shallow soils and water percolation is rela- tively rapid, within hours. These plains and rises support pearl bluebush (Maireana sedifolia) with or without bladder saltbush. In the north, mulga (Acacia aneura), tall shrubs or occasional trees provide overstorey. The stony rises and plains have up to 20 per cent vegetation cover protecting the soil surface. The stony mantle may provide up to another A section of healthy biological soil crust. Note the 50 per cent of the surface leaving the different colours and types of cryptogams. During dry remaining 30 per cent covered with biological times much of the crust will appear black and surface crusts. lifeless. Some cryptogams, especially certain mosses, ‘green-up’ almost immediately after wetting.

121 McDonald, RC, Isbell, RF, Speight, JG, Walker, J & Hopkins, MS 1990, Australian soil and land survey field handbook, 2nd edn, Inkata Press, Melbourne and Sydney. McKenzie, NL & Robinson, AC 1987, A biological survey of the Nullarbor Region South and Western Australia in 1984, South Australian Department of Environment and Planning, Western Australian Department of Conservation and Land Management and Australian National Parks and Wildlife Service. Mitchell, AA, McCarthy, R & Hacker, RB 1979, A A section of scalded soil surface. In this highly range inventory and condition survey of part degraded state the soil surface has been removed by of the Western Australian Nullarbor Plain, water and/or wind exposing the clayey subsoil which 1974, Agriculture Western Australia, is relatively impervious to water. In this state water Technical Bulletin No. 47. flow is rapid and its erosive capacity significantly increased compared to areas where water flow is Munsell 1954, Munsell Soil Colour Charts, obstructed by a rough cryptogam surface. Munsell Color Co. Inc. Baltimore 18 Maryland 21218, USA. Northcote, KH 1979, A factual key for the Biological soil crusts not only protect the under- recognition of Australian soils, 4th edn. lying soil surface from forces above the ground, Rellim, Adelaide, South Australia. but also provide a mulch-effect reducing soil desiccation rates through solar evaporation. Northcote, KH with Beckmann, GG, Bettenay, E, There is also anecdotal evidence soil crusts Churchward, HM, Van Dijk, DC, Dimmock, influence surface salinity. In some random GM, Hubble, GD, Isbell, RF, McArthur, WM, tests, salinity levels were measured on the Murtha, GG, Nicholls, KD, Paton, TR, surface of the ruts of vehicle station tracks and Thompson, CH, Webb, AA & Wright, MJ healthy intact soil surfaces less than one metre 1960–68, Atlas of Australian Soils, Sheets 1 away from the tracks. Soil salinity levels just to 10 with explanatory data, CSIRO and below the surface of healthy crusted surfaces Melbourne University Press, Melbourne. were so low the salinity could not be measured Raupach, M & Tucker, BM 1959, ‘The field with a field electrical conductivity (EC) meter. determination of soil reaction’, Journal of the However the salinity of the soil surface (and just Australian Institute of Agricultural Science, below) in the active vehicle tracks was high 25, 129–33. because there were no binding crusts. Schoknecht, N 2002, Soil groups of Western References Australia—A simple guide to the main soils of Western Australia, 3rd edn, Agriculture Isbell, RF 2002, The Australian Soil Western Australia, Resource Management Classification, Revised edition, Australian soil Technical Report 246. and land survey handbook series, vol. 4, CSIRO Publishing, Collingwood, Australia. Stace, HCT, Hubble, GD, Brewer, R, Northcote, KH, Sleeman, JR, Mulchahy, MJ & Laut, P, Heligers, P, Kieg, G, Loffler, E, Margules, Hallsworth, EG 1968, A handbook of G, Scott, R & Sullivan, M 1977, Environments Australian soils, Rellim, Glenside, South of South Australia, Province 7, Western Australia. Pastoral, CSIRO, Canberra.

122 Vegetation This chapter focuses on plants and the communities they comprise. The habitat type AK Gardner ecology chapter looks in more detail at the This chapter describes aspects of the vegeta- ecology of vegetation communities. tion. The first part provides a review of the regional vegetation within the survey area based Regional overview on the Interim Biogeographical Regionalisation Most of the survey area lies in the Nullarbor of Australia (Environment Australia 2000) and Biogeographic Region of the Interim Beard’s (1975) vegetation survey of the Biogeographic Regionalisation of Australia. In Nullarbor. The remainder presents the findings the south-east is the Hampton Biogeographic of the current survey. A summary of the major Region, and in the south-west some of the taxa recorded during the survey is presented in survey area is classified within the Coolgardie the second section. Following this the vegeta- and Mallee Biogeographic Regions. A small tion of the survey area is discussed firstly in portion in the north-west includes the Great terms of plant form and secondly as vegetation Victoria Desert Biogeographic Region. All of formations. Regional patterns of distribution at a these biogeographic regions are within the plant community and species level are then Eremaean Botanical Province apart from the presented to provide a broader biogeographic Mallee Biogeographic region which is within the perspective. Finally flora conservation is South-west Botanical Province (Figure 26). addressed.

Figure 26 Biogeographic regions in the survey area (after Environment Australia 2000)

123 Beard (1975) mapped the major vegetation or grassland of Austrostipa scabra and communities within Western Australia at a scale Austrodanthonia caespitosa. of 1:1 000 000. The survey area occurs within To the north, large circular depressions or Beard’s (1975) Nullarbor map sheet 4. Most is dongas become prominent. The dongas located within the Eucla Botanical District of the support open grassy groves dominated by Eremaean Botanical Province, with smaller Acacia tetragonophylla, Eremophila longifolia, areas within the Nanambinia System of the Grevillea nematophylla and/or Pittosporum South-Western Interzone and the Culver angustifolium. System of the South-west Botanical Province. Generalised vegetation formations modified Further to the north and west calcrete plains from Beard (1975) are displayed in Figure 27. support open woodlands of Acacia papyrocarpa (myall) with an understorey of chenopod shrubs Eremaean Botanical Province (Chapman 2005). The calcrete plains become progressively more wooded towards the Nullarbor Biogeographic Region northern and western periphery of the Nullarbor province, with myall replaced by Acacia aneura, Broad plains of gently undulating limestone Casuarina pauper, Myoporum platycarpum and dominate this region. The plains consist of low eucalypts (Beard 1975). Eucalypts and spinifex rises, marginal run-off areas, drainage tracts become increasingly dominant at the perimeter and claypans. The low rises predominantly of the north and west of the region, indicative of support a low shrubland of Maireana sedifolia, the transition into the Coolgardie and Great the marginal slopes support Atriplex vesicaria Victoria Biogeographic Regions. and the drainage tracts and claypans support either a low shrubland of Atriplex vesicaria and/

Figure 27 Generalised vegetation formations within the survey area (modified from Beard 1975)

124 Hampton Biogeographic Region South-west Botanical Province The Hampton tableland supports tall shrubland Mallee Biogeographic Region of eucalypts and melaleucas, with an under- storey of sclerophyll and succulent shrubs. The Most of this region comprises mallee woodland scree slopes of the Hampton Scarp are with an understorey of scattered mixed shrubs, dominated by open mallee woodland including Melaleuca, Eremophila and Senna. A (Chapman 2005). sparse layer of low shrubs including Atriplex vesicaria, Cratystylis conocephala and Below the Hampton Scarp the extensive Maireana sedifolia is also present. The calcarenite Roe Plains overlies marine understorey becomes increasingly dominated limestone. The northern portion of the Roe by heath species including Adenanthos, Plains supports open myall woodland with Beaufortia, Callitris and Grevillea towards the Melaleuca lanceolata and Myoporum coast and the vegetation becomes platycarpum with an understorey of Atriplex progressively wind-pruned (Beard 1975). Soils species, Cratystylis conocephala and Nitraria are primarily calcareous loams and sands billardierei. This vegetation association overlying Eocene and Oligocene marine alternates with open saltbush plains and limestone. occasional patches of mallee. The vegetation grades eastwards into mallee woodland with an Where sand dunes occur at Point Culver, understorey of Cratystylis conocephala (Beard Toolinna, and Twilight Cove the vegetation is 1975). Soils are calcareous shallow loams and similar to that of the sandplains of Esperance calcareous loamy earths. due to the siliceous nature of the sands. Banksias, grevilleas and casuarinas dominate The southern portion of the Roe Plains supports the understorey of sparse mallee woodland stony plains covered with mallee woodland with (Beard 1975). an understorey of heath and sedge species including Beaufortia, Callitris, Spyridium, Taxonomic summary Dianella, Lepidosperma and Schoenus. Along the coast is a belt of partially consolidated The plant taxonomy adopted in this survey is dunes, poorly vegetated with open mallee based on the Census of Western Australia woodland with an understorey of coastal Plants but also adopts changes on the advice of species and sedges including Carpobrotus spp. the Western Australian Herbarium. Scientific and Dianella revoluta (Beard 1975). Soils are names are used with colloquial names of calcareous shallow loams, loamy earths and common species provided in the appendices. deep sands. Four-hundred-and-twenty-six species of vascu- Coolgardie Biogeographic Region lar plants representing 198 genera in 61 families were collected during the survey, including 328 Unique to this biogeographic region is scattered perennials and 98 annual species (Appendix 2i). granite outcrop. The outcrop is often sparsely A small number of botanical families contain a vegetated and surrounded by dense stands of large proportion of the species (Table 12). Dodonaea lobulata and Eremophila alternifolia. The largest family is the Chenopodiaceae; the This region predominantly supports mallee species in this family dominate the survey area, woodland on calcrete plains of Eocene and particularly the limestone plains of the treeless Oligocene marine limestone of the Eucla Basin. portion of the Nullarbor land zone. The The understorey is composed of a variety of Asteraceae family contained the second mixed shrubs including Atriplex, Cratystylis, greatest number of species; species within this Dodonaea, Eremophila, Maireana and Senna family are found in many different landscapes. (Beard 1975). Soils are calcareous shallow The Myrtaceae family is predominantly growing loams, calcareous loamy earths and at the perimeters of the Nullarbor land zone to occasionally red loamy earths. the north, south and west, with melaleucas preferring the coastal areas. The grasses of the Poaceae family are found in a wide variety of environments.

125 Table 12 Major families and dominant genera in the survey area

Family No. of species Dominant genera Asteraceae 49 Cratystylis, Olearia, Rhodanthe, Senecio Chenopodiaceae 47 Atriplex, Chenopodium, Maireana, Rhagodia, Sclerolaena Poaceae 37 Austrodanthonia, Austrostipa, Enneapogon, Eragrostis Myrtaceae 35 Eucalyptus, Melaleuca Mimosaceae 25 Acacia Myoporaceae 23 Eremophila, Myoporum Proteaceae 15 Adenanthos, Banksia, Grevillea, Hakea Brassicaceae 13 Carrichtera, Lepidium, Sisymbrium Papilionaceae 13 Pultenaea, Swainsona, Templetonia Solanaceae 12 Lycium, Nicotiana, Solanum

Plant forms E. diversifolia, E. sp. Fraser Range, E. incrassata, E. melanoxylon, E. rigida, The major plant forms observed within the E. socialis and E. surgens. survey area were trees, mallees, tall shrubs (> 2 m), mid shrubs (1–2 m), low shrubs Tall shrubs (< 1 m), subshrubs or perennial herbs (< 0.5 m), perennial grasses, annual herbs and Acacias and melaleucas dominate the tall grasses, creepers, sedges, fern and soil shrubs (> 2 m) throughout the survey area. The cryptogams. These are briefly described below. most common acacias are Acacia burkittii, A. oswaldii and A. tetragonophylla and the most Trees common melaleucas are Melaleuca lanceolata and M. quadrifaria. Other tall shrubs common Trees are very scattered throughout the survey within the survey area include Dodonaea area, becoming increasingly abundant away lobulata, Eremophila dempsteri, Exocarpos from the Nullarbor land zone. The most aphyllus, Geijera linearifolia and Myoporum common species are Acacia papyrocarpa, platycarpum. Myoporum platycarpum and Pittosporum angustifolium. Also common are Alectryon Mid shrubs oleifolius, Casuarina pauper and Eremophila longifolia. Other trees which occur occasionally The most common mid shrub (1–2 m) within include Acacia aneura and Grevillea the survey area is Atriplex nummularia. nematophylla. Most common eucalypts Eremophila and Senna are also commonly recorded in tree form were in the west and represented within this group. Common north-west of the survey area. Eucalyptus Eremophila include E. alternifolia, E. decipiens, concinna, E. eremophila, E. fraseri subsp. E. dempsteri, E. deserti and E. scoparia. fraseri, E. fraseri subsp. melanobasis, Common Senna includes S. artemisioides E. gracilis, E. melanoxylon, E. salubris and subsp. x artemisioides and S. artemisioides E. urna occur in tree form, though some subsp. x coriacea. Other common mid shrubs species also occur in mallee form. include Dodonaea lobulata, D. stenozyga, Exocarpos aphyllus and Nitraria billardierei. Mallees Low shrubs Mallees are common towards the west and south of the survey area. Mallees are usually The most common growth form is low shrubs found as open multi-stemmed plants rarely (< 1 m). Most are succulent low shrubs belong- exceeding 6 m high. The most common ing to the Chenopodiaceae family. The most mallees recorded were the Eucalyptus oleosa common members of this family are Atriplex (group) and E. yalatensis. Other mallees vesicaria and Maireana sedifolia. Other recorded include Eucalyptus brachycalyx, common low shrubs from this family include E. conglobata, E. cooperiana, E. discreta, Chenopodium curvispicatum, Enchylaena

126 tomentosa, Maireana erioclada, M. trichoptera, Creepers M. turbinata, Rhagodia crassifolia and Tecticornia spp. Five creepers were recorded within the survey area. The most common was Marsdenia Common low shrubs not in the australis that produces edible fruits. Others Chenopodiaceae family include Cratystylis included Billardiera fusiformis, Cassytha conocephala, Lawrencia squamata, Lycium melantha, Comesperma volubile, Glycine australe, Olearia calcarea, Ptilotus obovatus, rubiginosa and Marianthus bicolor var. bicolor. Solanum nummularium and Westringia rigida. Sedges Subshrubs or perennial herbs Seven species of the sedge family Cyperaceae Subshrubs are seasonally dependent, weakly occur. The most common of these was Gahnia facultative perennial, generally less than 0.5 m lanigera and Tetraria capillaris. Other sedges (50 cm) in height. Common subshrubs are included Ficinia nodosa, Isolepis congrua, Atriplex acutibractea, Euphorbia drummondii, Lepidosperma sp. A2 Island Flat, Mesomelaena Sclerolaena diacantha, S. obliquicuspis, S. stygia, M. stygia subsp. stygia, Schoenus patenticuspis and Sida spodochroma. caespititius, S. lanatus and S. subflavus subsp. hispid culms. Sedges are predominantly found Perennial grasses along the south coast. The most common perennial grasses are the tussock grasses Austrodanthonia caespitosa Ferns and Austrostipa scabra. Tussock grasses vary Four species of fern were recorded. from dense, well developed plants to open Cheilanthes austrotenuifolia and C. lasiophylla almost herbaceous forms. Other common were found in the crevices of granite outcrop. tussock grasses include Austrostipa Marsilea hirsuta and Pleurosorus rutifolius were platychaeta, Enneapogon caerulescens, also recorded. E. cylindricus, Eragrostis dielsii and E. setifolia. Hummock grasses are a uniquely Australian Soil cryptogams form of grass in which rigid, pungent involute Soil cryptogams consist of unicellular algae, leaves form large rounded ‘hummocks’. Only liverworts, and foliose and crustose lichens. one species of hummock grass, Triodia They have an important role in soil ecology in scariosa (spinifex) is found in the survey area arid zones as they fix nitrogen and stabilise and is restricted to the woodland in the north- naturally dispersive soils. Particularly in the western, west and south-western extent where Nullarbor land zone cryptogams have an aeolian sand begins to accumulate over especially important role in protecting the soil calcrete. from wind erosion. Where cryptogams are absent or scarce, generally due to soil Annual herbs and grasses disturbance, wind erosion is severe leading to The survey was conducted in dry seasonal the prominent piospheres seen in satellite conditions, however, following localised heavy imagery around water points. Cryptogams also rains that fell predominantly on Kybo Station in provide forage for microscopic herbivores, the south-east the presence of annuals contributing both directly and indirectly to recorded increased within that localised rainfall biological activity at the soil surface. zone. The most commonly recorded annuals were Aristida sp., Eriochiton sclerolaenoides, Vegetation formations and their Salsola tragus and the introduced weed floristic components Carrichtera annua. Other common annuals The vegetation formations described below include Atriplex acutibractea, Rhodanthe have been developed from inventory site data. floribunda and Zygophyllum iodocarpum. The dominant stratum at each habitat type was recorded. The vegetation formations are defined as:

127 Woodland Woodland dominant stratum is trees or mallees (trees have a single stem to 1.3 m high above Woodland habitats where trees are the ground level and mallees are multi-stemmed dominant stratum generally had a canopy height plants to 6 m) of 2–6 m and a canopy cover of 2–20 per cent. These habitats are categorised as ‘Open Low Tall shrubland Woodland B’ or ‘Low Woodland B’ (Muir 1977). dominant stratum is shrubs over 2 m tall Woodland habitats where mallees are the Mid shrubland dominant stratum generally had a canopy height dominant stratum is shrubs 1 to 2 m tall of 2–12 m and a canopy cover of 15–25 per Low shrubland cent. These habitats are categorised as ‘Open dominant stratum is shrubs less than 1 m tall Tree Mallee’ (Muir 1977). Tussock grassland Of the 20 woodland sites dominated by trees, dominant stratum is tussock grasses Acacia papyrocarpa dominated six sites, Hummock grassland followed by Eremophila longifolia and dominant stratum is hummock grasses Myoporum platycarpum which each dominated three sites. The remaining 52 woodland sites Herbland were dominated by 15 species of mallee-form dominant stratum is herbs or subshrubs less eucalypts. Eucalyptus gracilis dominated 22 than 0.5 m tall (herbs may be annual or sites, E. yalatensis dominated 16 sites and perennial plants). E. oleosa dominated 13 sites. These vegetation formations are a simplification Sites on calcrete plains in the north-west and of traditional methods of describing vegetation. west of the survey area were commonly Muir’s (1977) method of classification is dominated by tree and mallee woodland. Acacia referred to in each of the formations described papyrocarpa was commonly the dominant below. species of tree at woodland habitats directly Vegetation was described at 392 inventory sites. above and below the Hampton Scarp in the Twenty-five had co-dominant strata and one site south-east, as well as along the northern had no vegetation. The dominant stratum at the perimeter. Woodland habitats located on remaining 366 sites is shown in Table 13. limestone hummocks (low rises), the scree Low shrubs were the dominant stratum at the slopes of the Hampton Scarp and along the majority of inventory sites, followed by trees, south coast were primarily dominated by tussock grasses, mid shrubs, tall shrubs, herbs eucalypts. Myall, eucalypt and occasional and lastly hummock grasses. casuarina woodland alternatively dominated the western perimeter. Table 13 The floristic variability of dominant strata Most (66 per cent) of the woodland sites were in No. of dominant very good condition, with 26 per cent in good Dominant stratum No. of sites species condition, 5 per cent in fair condition and 3 per Tree 73 24 cent in poor condition. Tall shrub 31 21 Mid shrub 30 15 Tall shrubland Low shrub 160 26 The projected foliar cover (PFC) of tall shrub- Tussock grass 42 8 land habitats ranged from 5 to 50 per cent, with Hummock grass 3 1 over a quarter of the sites having a PFC of Herb/subshrub 27 13 30–50 per cent. The height of the shrubs ranged Total 366 108 from 2 to 6 m. According to Muir (1977) tall shrubland with a canopy cover of 10–30 per cent is considered ‘Scrub’, and those with a Low shrubland had the least floristic variability in cover of greater then 30 per cent are the dominant strata, considering the large categorised as ‘Thickets’. number of sites sampled. In comparison, sites that had a dominant stratum of tall shrubs, mid shrubs and herbs had greater floristic variability.

128 Acacias and melaleucas were the dominant Low shrubland species at over two-thirds of the 31 tall shrub- land sites. Both Melaleuca lanceolata and The PFC for low shrubland sites varied from M. quadrifaria were the dominant species at six 5 to 50 per cent. They are categorised as ‘Low sites, predominantly located along the south Heath C’ where the PFC is between 30 and coast. Acacia burkittii was the most common 50 per cent, ‘Dwarf scrub C’ where the PFC is acacia to dominate tall shrub sites (three sites); between 10 and 30 per cent and ‘Open Dwarf these sites were located in the central west of Scrub C’ where the PFC is lower than 10 per the survey area. However, Acacia cent (Muir 1977). tetragonophylla and Acacia oswaldii were the Of the 160 low shrubland sites, 19 were most common tall shrubs, occurring as very co-dominated by two species of low shrubs and scattered to isolated shrubs, featuring in 30 and one site by three species. Of the 140 sites 34 inventory sites respectively, especially in the dominated by a single species of low shrub, Nullarbor land zone. over 75 per cent were dominated by species of Tall shrubland sites on plains overlain by the Chenopodiaceae family. Atriplex vesicaria shallow aeolian sands and land units associ- dominated 48 of these sites and Maireana ated with granite outcrops were dominated by sedifolia 39 of these sites. Eight other species of Dodonaea and Eremophila. Chenopodiaceae dominated the 14 other sites. Nearly half (49 per cent) of tall shrubland sites Sixteen species of low shrubs not within the were in good condition, 30 per cent in very good Chenopodiaceae family dominated the remain- condition, 8 per cent in fair condition and 13 per ing 32 sites. Cratystylis conocephala dominated cent in poor condition. nine of these sites, Lawrencia squamata five sites and Lycium australe four sites. Sites Mid shrubland dominated by Lawrencia squamata commonly occurred on the breakaway slope to drainage The majority of mid shrubland sampled had a floor within the Koonjarra land system. Ptilotus PFC of 5 to 20 per cent, which according to obovatus and Westringia rigida each occurred Muir’s (1977) system of classification are ‘Low at three sites. An overstorey of scattered trees Scrub A or B’ where the PFC is between and mallees is often associated with low shrub- 10 and 30 per cent and ‘Open Low Scrub A or B’ land dominated by non-chenopodiaceous where the PFC is less than 10 per cent. species. These sites are commonly found Cratystylis conocephala and Maireana sedifolia towards the northern and western perimeters of which dominated the most sites, reach a the survey area. maximum height of 1.5 m and fall within group Over half (57 per cent) of the sites were in good B, whilst species such as Atriplex nummularia condition, 21 per cent were in very good condi- and Geijera linearifolia grow to 2 m and are in tion, 17 per cent in fair condition, 4 per cent in group A. Where the PFC was greater than poor condition and 1 per cent in very poor 30 per cent such sites were classified as condition. heathland. Nine of the 30 mid shrubland sites were Tussock grassland dominated by Maireana sedifolia. These sites were located throughout the survey area, The basal cover of tussock grasses is most excluding the coastal region to the south. commonly 5 to 10 per cent. The PFC was Cratystylis conocephala was the dominant estimated to be between 30 to 70 per cent. The shrub at three sites, a scattered overstorey of height of grasses that dominate this stratum is Acacia papyrocarpa or eucalypts was present predominantly less than 0.5 m. Tussock grass- at these sites. Geijera linearifolia and Nitraria land is classified as ‘Low Grasslands’ (Muir billardierei each dominated two sites in the 1977). south of the survey area and Atriplex Eight dominant species were recorded at the 42 nummularia dominated two sites in the west. tussock grassland sites. Austrostipa scabra The majority (64 per cent) of mid shrubland was the dominant species at most grassland sites were in good condition, 18 per cent were sites. Austrodanthonia caespitosa, Eragrostis in very good condition and 18 per cent were in dielsii and Eragrostis setifolia were each fair condition. dominant at three sites.

129 Grassland sites dominated by Austrostipa three sites located within areas of drainage scabra and Austrodanthonia caespitosa often focus in the north-east. Herb species that represented a transition from degraded shrub- dominated two sites included Carrichtera land sites. It is likely the shrubs were lost or annua, Cullen cinereum and Zygophyllum reduced by fire and overgrazing by rabbits, and iodocarpum. These species commonly secondarily through overgrazing by domestic dominate sites in dongas in the north. stock. These sites predominantly occur on Nearly half (52 per cent) of herbland sites were limestone plains, with Austrostipa scabra considered to be in fair condition, 15 per cent dominating sites across the survey area and were very good, 26 per cent were good and Austrodanthonia caespitosa sites in the north- 7 per cent were poor. east. Grassland dominated by Eragrostis dielsii and Eragrostis setifolia is found in areas where Regional distribution of plant surface drainage accumulates, commonly claypans, dongas and gilgai. communities Tussock grassland is difficult to rate as it often There is a noticeable geographic variation in the dominated an altered vegetation community. As dominant strata at sampling sites across the it is assumed that the altered transition is survey area. Low shrubland is the most permanent, vegetation communities were rated common vegetation formation on all 1:250 000 as found rather than as was perceived to have scale map sheets except Burnabbie where been once. Over half (56 per cent) of the woodland dominates. The Cundeelee, Forrest grassland sites were considered to be in good and Noonaera map sheets had too few sites condition, with 15 per cent in very good recorded to allow any analysis. condition, 27 per cent in fair condition and 2 per Low shrubland is most common on the Eucla, cent in poor condition. Madura and Naretha map sheets that fall pre- dominantly within the Nullarbor Plain proper. Hummock grasslands Woodland is more common on the Balladonia Three hummock grassland sites were and Burnabbie map sheets that border the recorded; the sites had a PFC of 10 to 40 per survey area in the south-west and south. The cent. According to Muir (1977), a site with a majority of woodland on these map sheets is PFC of less than 30 per cent is classified as mallee woodland. Tussock grassland grading ‘Hummock Grass’ and a site with a PFC of southwards into tall shrubland is most common greater than 30 per cent, ‘Mid Dense Hummock on the Culver map sheet. On the Zanthus map Grass’. Only one species of hummock grass, sheet mallee woodland and mid shrubland is Triodia scariosa was found. Hummock grass- most common. Herbland is common through land occurs in the north-west, west and south- the Loongana map sheet, though myall wood- west of the survey area on calcareous aeolian land is common along the western border. sandplains. Similarly herbland is common in the south-east of the Seemore map sheet with woodland in the All sites were rated as being in good condition. north-western portion. Herbland Atriplex vesicaria was the most commonly recorded species on the Balladonia, Eucla, The PFC for herbland sites was mostly Madura and Zanthus map sheets recorded at between 2 and 15 per cent. Herbland sites are nearly 90 per cent of the sites on these map therefore classified as ‘Very Open Herbs’ where sheets, except the Zanthus map sheet where it the PFC is less than 10 per cent and ‘Open occurred at 77 per cent of the sites. In the north Herbs’ where the PFC is greater than 10 per on the Loongana, Naretha and Seemore map cent (Muir 1977). sheets, Austrostipa scabra was the most Thirteen species of herb were recorded at 27 common species recorded at over 70 per cent herbland sites. Sclerolaena obliquicuspis of the sites. dominated four sites and Sclerolaena In the south of the survey area on the Burnabbie patenticuspis dominated seven sites. These and Culver map sheets vegetation associations sites were commonly located on limestone have more defined boundaries and are confined plains in the north-east of the survey area. to smaller areas than further north. This is due Salsola tragus was the dominant species at to the close coastal proximity and its effect on

130 Table 14 The proportion (%) of the plant form of the dominant strata recorded at 366 inventory sites on the 1:250 000 map sheets of the Nullarbor

Tall Mid Low Tussock Hummock No. of Map sheet Tree Herb shrub shrub Shrub grass grass sites Balladonia 28 9 9 47 7 0 0 32 Burnabbie 47 8 11 24 10 0 0 37 Culver 15 21 9 29 24 2 0 34 *Cundeelee 50 0 0 17 0 0 33 6 Eucla 21 9 3 58 9 0 0 43 Loongana 7 0 7 36 14 0 36 14 *Forrest 0 0 0 67 0 0 33 4 Madura 19 0 1 51 19 0 10 70 Naretha 7 14 9 53 7 0 10 58 *Noonaera 0 50 0 50 0 0 0 2 Seemore 11 8 16 35 14 0 16 37 Zanthus 24 7 21 42 3 3 0 29

* Too few sites recorded to allow for analysis. the geophysical development of landforms and map sheets. The understorey of myall woodland local weather conditions. As a result, no one is primarily composed of Cratystylis species was recorded at more than 55 per cent conocephala and Chenopodiaceae. In the north, of the sites on these two map sheets. Maireana dense population recruitment of juvenile myall is erioclada (54 per cent) and Melaleuca occurring. In dry periods myall trees are lanceolata (50 per cent) were the most browsed, whilst sheep and rabbits favour myall commonly recorded plants on the Burnabbie seedlings. It is likely the germination is most map sheet and Austrostipa scabra (48 per cent) noticeable in these northern areas as these on the Culver map sheet. areas are not stocked with sheep and rabbit numbers have been substantially reduced by The most noticeable geographic variation in rabbit calicivirus. The reduction in the total individual species is the distribution of trees. grazing pressure is providing the opportunity for The distribution is largely dependent on myall seedlings to survive beyond germination. geomorphology, geology, soils and rainfall gradients across the landscape. The distribution Casuarina pauper (black oak) is most common across map sheets of five tree species in the south-west, on the Naretha and Zanthus common on the Nullarbor is shown in Table 15. map sheets. It is commonly found on calcrete plains or residual calcrete rises and is often Acacia papyrocarpa (myall) is found on all map associated with an understorey of Acacia, sheets within the survey area, though is most Eremophila and Chenopodiaceae. common on the Eucla, Seemore and Zanthus

Table 15 The number of sites that tree species were recorded at on the 1:250 000 map sheets of the Nullarbor

Acacia Casuarina Eucalyptus Eucalyptus Myoporum No. of Map sheet papyrocarpa pauper gracilis yalatensis platycarpum sites Balladonia 6 3 23 0 48 32 Burnabbie 5 0 3 16 11 37 Culver 9 3 9 15 15 34 Eucla 28 0 35 26 12 43 Loongana 21 0 0 0 21 14 Madura 21 0 7 11 13 70 Naretha 21 21 0 0 14 58 Seemore 38 11 0 0 30 37 Zanthus 30 27 3 0 33 29

131 Myoporum platycarpum (sugarwood) is mostly evidence of the impact sheep have had on found on the Balladonia, Seemore and Zanthus suppressing myall populations. map sheets. Sugarwood often dominates the Two key factors affect the susceptibility of plant stony calcrete plains of the Nanambinia land communities to grazing: first the distance from system and the clay depressions of the water and second the palatability of plant Woorbla land system. Dense recruitment of species. Cridland and Stafford Smith (1993) sugarwood is often found in these areas, which demonstrated that the impact of grazing is considered to be in response to the reduction increases as the distance from water in rabbit numbers due to rabbit calicivirus. decreases. Closer to watering points the A variety of eucalypt species is found in the concentration of stock is greatest, as all stock western and southern perimeters of the survey from within a paddock congregate in the small area coinciding with greatest rainfall. area surrounding watering points to drink. This Eucalyptus gracilis, E. oleosa and E. yalatensis results in increased grazing and trampling of the were the most common eucalypts recorded. vegetation and padding of the soil in close Eucalyptus gracilis and E. oleosa can survive proximity to watering points. with less water than Eucalyptus yalatensis The intensity of the piosphere effect surrounding (Parsons 1970) and therefore have a greater water points depends on the volume of water range, being most common on the Balladonia, stock need; this varies depending on the salt Zanthus and southern portion of the Eucla map content of feed and water, temperature and sheets. Eucalyptus yalatensis is restricted to seasonal conditions. When stock are grazing the narrow strip along the coast from Balladonia on saline feed and drinking saline water, as is into South Australia. Within the survey area often the case on the Nullarbor, the volume of Eucalyptus yalatensis is most common on the water required per day is greatly increased. Balladonia and southern portion of the Eucla High temperatures also increase the volume map sheets. that stock must drink to replace that lost through evaporative cooling mechanisms (Macfarlane & Flora conservation Howard 1974). The greater the volume of water Flora conservation involves maintaining biologi- required, the longer stock will spend near cal diversity at a variety of scales, from genetic watering points and the less distance they will diversity within single populations to continental be able to travel away from watering points and global species richness. In this section the before needing to return. This increases the threats to plant species and communities, and level of deterioration of the soil and vegetation threatened species are discussed. surrounding watering points. Following periods of rainfall, stock are able to Threats to native flora graze further from water points due to the increased volume of water ingested as a Pastoralism component of newly germinated herbage. Pastoralism has extensively modified native During these times sheep can often fulfil their plant communities in the rangelands. Where daily requirements from the water within feed, grazing has been excessive, plant species that cattle however will always need access to are palatable to domestic stock, feral animals sources of ‘free’ water (Burnside, Williams & and kangaroos have been substantially reduced Curry 1990). or removed. The vacated niches are then Vegetation communities that are highly palatable replaced by suites of less palatable plants, with and accessible to stock are at the greatest risk the resulting species richness, density and from overgrazing. Livestock are known to cover rarely equal to that of the previous actively seek more desirable plants from vegetation community (Payne et al. 1998). No pasture, and will range, if necessary, beyond plants are known to have become extinct in the their expected grazing radius to select these survey area since pastoralism was introduced, plants even when there is abundant feed along though palatable plant species such as the way (Eckersley 1988). Within the Nullarbor, Maireana georgei are likely to have been the most palatable feed is often the grasses and reduced. The prolific germination of Acacia herbage that grow between the perennial papyrocarpa (myall) in areas absent of sheep, shrubs. In dry seasons when grasses and coinciding with reduced rabbit numbers, is

132 herbage are scarce, the preferred vegetation is flora increasing in specific localised areas often chenopod shrubs, particularly Atriplex included Salvia verbenaca (wild sage), Schinus vesicaria, and browse from Acacia molle var. areira (pepper tree) and Tamarix papyrocarpa, Alectryon oleifolius, Cratystylis aphylla (tamarisk). conocephala, Eremophila longifolia and Pittosporum angustifolium. These perennial Feral herbivores shrubs and trees may be killed by overgrazing, Historically, rabbits have had a large impact on leading to loss of plant cover and increased the Nullarbor. During the 1940s their number exposure of soil which increases the was so great it enabled a substantial com- susceptibility to all forms of erosion. mercial trade, with 20 000 rabbits a week A more even distribution of grazing can be trapped in the Cocklebiddy area alone (Parsons achieved if paddocks enclose similar land types 1970). Rabbit plagues have had a devastating (Pringle 1994). All areas within a paddock will be effect on the landscape. They have reduced the similarly preferred by stock, and so stock will recruitment of trees such as Acacia not selectively graze out the most palatable papyrocarpa by grazing on seedlings and areas. Small areas such as dongas and juveniles, and ringbarking older trees. Rabbit drainage foci often contain vegetation of high densities must remain very low in some arid palatability, but also support unique vegetation areas to enable plant regeneration. The regen- communities which are important contributors eration of Acacia papyrocarpa was found to be to the heterogeneity of the Nullarbor ecosystem. affected by rabbit grazing at densities of less Excluding dongas and drainage foci from than 0.5 rabbits per kilometre (Lange & Graham grazing systems is unfeasible, however such 1983). Rabbits have also overgrazed palatable areas would benefit from not having water herbs and grasses, leading to a reduction in points located directly in them to reduce the ground cover so that the rate of erosion is degradation that such positioning inevitably increased (Gilfillan 1999). The reduction in causes. This would also encourage more even perennial plants as well as the soil disturbance grazing of the surrounding dominant vegetation caused by burrowing has also led to an types. increase in populations of unpalatable, short- lived annuals. The release of the viruses Introduced flora species (myxomatosis in 1954 and 1966, rabbit calicivirus in 1995) has greatly reduced rabbit Forty-three introduced flora species were numbers across the Nullarbor (Gilfillan 1999). recorded within the survey area (Table 16). Of the 6997 traverse ratings where range condition Feral camels occur in medium to high numbers was assessed, introduced flora was recorded throughout the pastoral areas, with larger at 3.3 per cent of traverse points. The most numbers in the Unallocated Crown Land in the common species was Carrichtera annua north and east of the survey area (Woolnough (Ward’s weed) recorded at 3 per cent of et al. 2005), feral horses are also present traverse points. though in lower numbers. Horses and camels graze on the fruits, leaves and stems of trees. Many introduced flora species were commonly They are able to browse higher trees than other recorded in degraded dongas and along the animals within the area. The repeated browsing Trans-Australian Railway line and Eyre Highway. of foliage and bark, breaking of branches and Whilst many of the introduced flora species eventually the central trunk can lead to the death tend to remain restricted to depressions some of trees. The mustering of feral horses and the species have the potential to cause significant shooting of both feral camels and horses is ecological problems to Nullarbor communities. considered the most practical form of control for Asphodelus fistulosus (onion weed) has these animals. Control programs are carried out become established in a number of locations by pastoralists. through its ability to dominate disturbed or degraded areas. Another species with the potential to spread on the Nullarbor is Cenchrus ciliaris (buffel grass). At the time of the survey buffel grass was observed in the vicinity of the Trans-Australian Railway line, occurring in small but established populations. Other introduced

133 Table 16 Introduced flora species recorded in the survey area

No. of inventory Taxon Common name Growth form sites Anagallis arvensis Pimpernel Annual herb 1 Arctotheca populifolia Dune arctotheca Perennial herb - Asphodelus fistulosus Onion weed Annual herb 1 Brassica tournefortii Wild turnip Annual herb - Cakile maritima Sea rocket Annual herb 1 Carduus nutans Nodding thistle Annual herb 1 Carrichtera annua Ward’s weed Annual herb 111 Carthamus lanatus Saffron thistle Annual herb 1 Cenchrus ciliaris Buffel grass Perennial grass - Centaurea melitensis Maltese cockspur Annual herb 2 Centaurium erythraea Common centaury Annual herb 1 Chenopodium murale Nettle-leaf goosefoot Annual herb 2 Chloris gayana Rhodes grass Annual herb - Citrullus lanatus Pie melon Perennial herb 6 Cucumis myriocarpus Prickly paddy melon Annual herb - Emex australis Doublegee Annual herb 1 Erodium aureum - Annual herb 21 Erodium cicutarium Common storksbill Annual herb 4 Euphorbia paralias Sea spurge Perennial herb 2 Heliotropium europaeum Common heliotrope Annual herb - Gomphocarpus fruticosus Narrowleaf cottonbush Perennial herb - Hordeum glaucum Northern barley grass Annual grass - Lepidium africanum Rubble peppercress Annual herb - Lythrum hyssopifolia Lesser loosestrife Annual herb - Malva parviflora Marshmallow Annual herb - Malvastrum americanum Spiked malvastrum Perennial herb 6 Marrubium vulgare Horehound Perennial herb - Mesembryanthemum crystallinum Iceplant Annual herb 35 Mesembryanthemum nodiflorum Slender iceplant Annual herb 3 Nicotiana glauca Tree tobacco Tree - Oncosiphon suffruticosum - Annual herb 1 Oxalis corniculata Yellow wood sorrel Annual herb 5 Pentaschistis airoides False hairgrass Annual herb - Rostraria pumila - Annual herb 1 Salvia verbenaca Wild sage Perennial herb 4 Schinus molle var. areira Pepper tree Tree - Schismus barbatus Kelch grass Annual grass - Sisymbrium erysimoides Smooth mustard Perennial herb 10 Sisymbrium irio London rocket Annual herb - Solanum nigrum Blackberry nightshade Perennial herb 2 Sonchus oleraceus Common sowthistle Annual herb 17 Tamarix aphylla Tamarisk Tree 1 Xanthium spinosum Bathurst burr Annual herb 7

134 Kangaroos Many of the areas now supporting extensive grasslands once supported a mosaic of cheno- Kangaroo numbers are unnaturally high in pod shrubland and grassland. In years of good pastoral country due to permanent water at annual growth these areas have sufficient fuel artificial watering points (Oliver 1986; Norbury to burn readily. In combination with increased 1992). This results in additional grazing fire regimes, plague proportions of rabbits pressure on native plants. Kangaroo grazing is grazed on post-fire regrowth limiting the regen- largely uncontrolled due to the ineffectiveness of eration of chenopod shrubland. The expansion conventional stock fences in prohibiting of grassland at the expense of chenopod kangaroo movement. It has been demonstrated species has further increased the susceptibility that kangaroos hinder regeneration programs in of the area to fire. The increased frequency of areas where stock have been excluded to burning in combination with grazing of juvenile encourage the recovery of native plants plants by rabbits has adversely affected the (Gardiner 1986a, 1986b; Norbury & Norbury vegetation composition. 1991). Commercial shooting is the main method of control of kangaroos. Threatened species Fire The Department of Environment and Bushfires are a natural feature of the Nullarbor. Conservation maintains a declared rare and In years following prolific annual growth the priority flora list (Atkins 2005) under the pro- abundant dry matter has the potential to readily visions of the Wildlife Conservation Act. Fifteen catch fire as a result of lightening strikes during species from the declared rare and priority flora thunderstorms. Since European settlement the list occur within the survey area (Table 17). No frequency of fires has increased in the Nullarbor threatened ecological communities have been district. Sparks from steam trains on the Trans- identified. Australian Railway are considered responsible for Table 17 Declared rare and priority flora listings for the survey area many fires on land adjacent (Atkins 2005) to the railway (Mitchell, No. of McCarthy & Hacker 1979). Taxon Priority code1 inventory sites The Chenopodiaceae are the Eremophila attenuata 1 - most dominant flora type in Grevillea phillipsiana 1 - the survey area. Chenopod Lepidium fasciculatum 1 1 shrubland is not adapted to a Thysanotus baueri 1 3 regular fire regime (Graetz & Chthonocephalus multiceps 2 - Wilson 1984). Maireana Eucalyptus fraseri subsp. melanobasis 2 1 sedifolia (pearl bluebush) can tolerate moderate intensity Eucalyptus surgens 2 - fires though may be substan- Goodenia varia 2 - tially thinned out, whilst Harperia eyreana 2 1 Atriplex vesicaria (bladder Opercularia loganioides 2 1 saltbush) may be completely Phlegmatospermum eremaeum 2 - eliminated. Hodgkinson and Allocasuarina eriochlamys 3 - Griffin (1982) state that as Eremophila dendritica 3 - chenopod regeneration after Eucalyptus histophylla 3 - fire is by seed alone, there is Eucalyptus pimpiniana 3 - a risk of completely exhaust- Galium migrans 3 - ing the seed bank if grazing Eremophila hillii 4 - pressure is not relaxed post- fire. Eremophila parviflora subsp. parviflora 4 - Myriophyllum balladoniense 4 -

Priority codes: 1 Taxa with few poorly known populations on threatened lands. 2 Taxa with few poorly known populations on conservation lands. 3 Taxa with several poorly known populations, some on conservation lands. 4 Rare taxa, not currently threatened, but require monitoring.

135 Of the declared rare and priority species which Conclusion are known to exist in the Nullarbor area only eight were collected during the survey: The vegetation of the Nullarbor is primarily Eremophila dendritica, Eucalyptus fraseri Eremaean; it is adapted to a desert climate subsp. melanobasis, E. surgens, Harperia without an assured growing season. The eyreana, Lepidium fasciculatum, Myriophyllum majority of the survey area is covered by low balladoniense, Opercularia loganioides and shrubland dominated by bluebush and saltbush. Thysanotus baueri. Low open myall woodland over chenopod shrubland is present around the perimeter of the Eremophila dendritica was collected during Nullarbor Plain. In the west diverse woodland of traversing through the Nyanga Plain on the eucalyptus and sugarwood is also present. Zanthus map sheet. Soils consisted of calcareous loamy soils that contained sheet or The south-east of the survey area includes the nodular calcrete at varying depth. Hampton Range which is dominated by mallee woodland. The calcareous Roe Plains below Eucalyptus fraseri subsp. melanobasis was the Hampton Range supports myall and collected on three occasions: at one inventory eucalypt open woodland trending towards site and at two traverse locations. All locations coastal heath in the south. The south-west occurred in the eucalyptus woodland of the supports mixed eucalypt woodlands trending Caiguna and Gumbelt land systems on the towards coastal heath in the south before Balladonia map sheet. These areas had terminating at the Baxter Cliffs. calcareous loamy soils with sheet or nodular calcrete at varying depths. The effect of European settlement in the Nullarbor has impacted both directly and Eucalyptus surgens was collected once during indirectly on the vegetation communities. The a reconnaissance trip on the Culver map sheet. increased fire frequency in combination with The area consisted of scattered limestone and plague proportions of rabbits has substantially calcrete outcrop with shallow calcareous loamy altered the vegetation. The vegetation has been soils. further modified by the introduction of domestic Harperia eyreana was also collected on a stock and the development of water points. reconnaissance trip on the Burnabbie map These have led to an increase in the presence sheet. It occurred on a calcareous dune and associated impacts of feral animals and overlying a calcarenite plain. kangaroos. Lepidium fasciculatum was collected at one The vegetation associations dominated by inventory site. It was collected from a donga in chenopods that cover vast areas of the the Kybo land system on the Madura map Nullarbor are relatively resistant to managed sheet. The soil was moderately light clay. grazing. The areas of greatest degradation are those surrounding water points. This is a result Myriophyllum balladoniense was collected of the high salt content of feed and water and during traversing from an ephemeral rock pool the arid climatic conditions that compel stock to on a granite outcrop. It occurs as an aquatic, drink frequently. Away from the piosphere emergent perennial herb. effects that surround water points, the Opercularia loganioides was collected at one vegetation is generally considered to be in good inventory site. It occurred in drainage foci of the condition. However, natural areas of water Toolinna land system not far inland from the accumulation such as dongas and drainage Baxter Cliffs on the Culver map sheet. The area areas are prone to degradation due to their often had calcareous loamy soils. close proximity to water points and because they contain highly palatable vegetation. These The rating of Thysanotus baueri as Priority 1, areas often support unique flora and fauna taxa with few poorly known populations on communities that are crucial to the health and threatened lands, is likely due to a lack of productivity of the Nullarbor ecosystem. sampling in the areas in which it commonly occurs. Thysanotus baueri was found within the Land managers have a major contribution to Balladonia and Culver map sheets in open make to regional conservation through the woodland where the overstorey was dominated integration of nature conservation and primary by eucalypts and the soil was calcareous loam production objectives. Pastoralists can make overlying calcrete. substantial progress towards ecological

136 sustainability by adopting strategies to manage Gardiner, HG 1986b, ‘Dynamics of perennial the total grazing pressure of domestic, feral and plants in the mulga (Acacia aneura F. Muell.) native stock and by improved control of stock zone of Western Australia. II. Survival of movement, including the development of perennial shrubs and grasses’, Australian infrastructure away from ecologically fragile Rangeland Journal, 8, 28–36. locations. Gilfillan, S 1999, Monitoring the impacts of reduced rabbit numbers due to Rabbit References Calicivirus Disease on native fauna and Atkins, K 2005, Declared rare and priority flora vegetation in the Nullarbor Region, Western list for Western Australia, Department of Australia, Department of Conservation and Conservation and Land Management, Land Management, Western Australia. Western Australia. Graetz, RD & Wilson, AD 1984, ‘Saltbush and Beard, JS 1975, Vegetation survey of Western Bluebush’, in Management of Australia’s Australia: Nullarbor, 1:1 000 000 Vegetation rangelands, GN Harrington, AD Wilson & Series, Explanatory notes to sheet 4, MD Young (eds), CSIRO, Melbourne, pp. University of Western Australia Press, Perth. 209–222. Burnside, D, William, A & Curry, P 1990, Hodgkinson, KC & Griffin, GF 1982, ‘Adaptation Spacing water points in the southern pastoral of shrub species to fires in the arid zone’, in areas of Western Australia, Western Evolution of the Flora and Fauna of Arid Australian Department of Agriculture, Bulletin Australia, WR Barker and PJM Greenslade 4162. (eds), Peacock Publications, South Australia. Chapman, A 2005, Interim Biogeographic Lange, RT & Graham, CR 1983, ‘Rabbits and Regionalisation of Australia (IBRA), used with the failure of regeneration in Australian arid the permission of the Western Australian zone Acacia’, Australian Journal of Ecology, Herbarium, Department of Environment and 8, 377–381. Conservation, Macfarlane, WV & Howard, B 1974, ‘Ruminant www.florabase.dec.wa.gov.au/help/ibra. water metabolism in arid areas’ in Studies of Cridland, S & Stafford Smith, M 1993, the Australian Arid Zone. II. Animal Development and dissemination of design Production, AD Wilson (ed.), CSIRO, methods for rangeland paddocks which Australia. maximise animal production and minimise Mitchell, AA, McCarthy, R & Hacker, RB 1979, A land degradation, Department of Agriculture, range inventory and condition survey of part Western Australia, Miscellaneous Publication of the Western Australian Nullarbor Plain, 42/1993. 1974, Agriculture Western Australia, Eckersley, T 1988, ‘The effect of salinity of feed Technical Bulletin No. 47. and water on the grazing behaviour of sheep Muir, BG 1977, Biological Survey of the Western and cattle’, in Animal production in the Australian Wheatbelt Part 2. Vegetation and spinifex and shrubland regions of Western habit of Bendering Reserve, Records of the Australia, Western Australian Department of Western Australian Museum Supplement 3. Agriculture, Miscellaneous Publication 23/87. Norbury, GL 1992, ‘An electrified watering trough Environment Australia 2000, Revision of the that selectively excludes kangaroos’, The Interim Biogeographic Regionalisation of Rangeland Journal, 14(1), 3–8. Australia (IBRA) and the Development of Version 5.1 – Summary Report, Department Norbury, GL & Norbury, DC 1991, ‘The impact of of Environment and Heritage, Canberra. red kangaroos on rangeland regeneration in Western Australia: preliminary observations’, Gardiner, HG 1986a, ‘Dynamics of perennial Proceedings of the Australian Vertebrate Pest plants in the mulga (Acacia aneura F. Muell.) Control Conference, Adelaide, South zone of Western Australia. I. Rates of Australia, pp. 322–327. population change’, Australian Rangeland Journal, 8, 18–27.

137 Oliver, AJ 1986, ‘Social organisation and dispersal in the red kangaroo’, PhD thesis (unpublished), Murdoch University, Western Australia. Parsons, RF 1970, ‘Mallee vegetation of the southern Nullarbor and Roe Plains, Australia’, Transactions of the Royal Society of South Australia, 94, 227–242. Payne, AL, Van Vreeswyk, AME, Pringle, HJR, Leighton, KA & Hennig, P 1998, An inventory and condition survey of the Sandstone- Yalgoo-Paynes Find area, Western Australia, Agriculture Western Australia, Technical Bulletin No. 90. Pringle, HJR 1994, Pastoral resources and their management in the north-eastern Goldfields, Western Australia, Department of Agriculture, Western Australia, Miscellaneous Publication 22/94. Woolnough, AP, Gray, GS, Lowe, TJ, Kirkpatrick, WE, Rose, K & Martin, GR 2005, Distribution and abundance of pest animals in Western Australia: a survey of institutional knowledge, Department of Agriculture, Western Australia, Miscellaneous Publication 30/2005.

138 Habitat type ecology of the land system; and as minor where it occurs on < 20 per cent of the land system). PA Waddell and AK Gardner Terminology used in describing Habitats as ecological units habitat composition The interrelationships between the physical environment and the plant communities it Vegetation formations supports can be described by classifying The following definitions were used to describe sampling points (inventory sites) into habitat the vegetation formations: types. Habitat types are classified in terms of combinations of landforms, soil types and plant Woodland—dominant stratum is trees or communities. They closely resemble the mallees (trees have a single stem to a height ‘ecological site’ of the Society for Range of 1.3 m above ground level and mallees are Management (1991) and the habitat of Tinley multi-stemmed plants to a height of 6 m) (1991). In previous rangeland surveys of Grove—dominant stratum is trees and tall pastoral areas in Western Australia, habitat shrubs confined to small areas types have been referred to as ‘pasture lands’ (Payne, Mitchell & Holman 1988), ‘pasture Shrubland—dominant stratum is shrubs; shrub types’ (Payne, Curry & Spencer 1987), referring to a perennial woody multi- ‘vegetation types’ (Curry et al. 1994), ‘site types’ stemmed plant which branches from below (Pringle, Van Vreeswyk & Gilligan 1994) and or near ground level ‘habitat types’ (Payne et al. 1998). ‘Habitat type’ Scrub—dominant stratum is collectively was chosen as it most accurately fits the composed of stunted trees and shrubs of ecological classification below and is relevant to variable height (< 5 – < 0.5 m), where plants those not familiar with rangeland survey. generally have a distinguishable single stem Habitat types are generally referred to by their or trunk land surface, dominant taxon and dominant Heathland—dominant stratum is perennial low vegetation stratum and given an appropriate shrubs four letter code (e.g. PXCS—Plain with mixed chenopod shrubland). Many of the habitat types Grassland—dominant stratum is tussock identified on the Nullarbor are distinguished by grasses vegetation, as so much of the survey area Herbland—dominant stratum is subshrubs and occurred on limestone and calcrete plains of annual herbs. similar geomorphic origin. Where a habitat type is described as a shrub- Habitats types are described within broader land or woodland the dominant stratum for habitat groups so as to aggregate ecologically locations supporting this habitat type may occur similar habitat types. Habitat types within a as either shrubs or trees, respectively. habitat type group are generally located in the same position in the landscape as well as Number of plant species having similar vegetation and soils. The broader habitat type groups are categorised in terms of: The survey average is the average number of plant species recorded at each of the 392 • general information (physical environment, inventory sites sampled. This was calculated as distribution patterns, general ecology) 11 perennial species and three annual species. • vegetation physiognomy (Projected Foliar Cover—PFC) and composition (by stratum) Dominant and common plant species • patterns of variation (including the impact of The following definitions have been used to grazing and fire) categorise the structure of the dominant and common plant species for each habitat type: • gradational associations, and Tree—a plant over 2 m high with a single trunk • land system representation (a habitat is to at least 1.3 m, including single trunk defined as being a major type if it occurs on eucalyptus 30 per cent or more of the land system; as common where it occurs on 20–29 per cent Mallee—a multi-stemmed eucalypt

139 Tall shrub—a perennial woody plant over 2 m lands. Such taxa are under consideration for tall with more than one trunk below 1.3 m declaration as ‘rare flora’, but are in urgent need of further survey. Mid shrub—a perennial woody plant between 1 and 2 m in height Priority Two (P2) – Poorly Known—Taxa which are known from one or a few (generally < 5) Low shrub—a perennial woody plant less than populations, at least some of which are not 1 m in height believed to be under immediate threat (i.e. not Subshrub—a seasonally dependent, weakly currently endangered). Such taxa are under facultative perennial, generally less than consideration for declaration as ‘rare flora’, 0.5 m (50 cm) in height, usually persisting for but are in urgent need of further survey. less than two years Priority Three (P3) – Poorly Known—Taxa Perennial grass—a grass species usually which are known from several populations, at persisting for at least two years least some of which are not under immediate Annual—a short-lived plant usually persisting threat (i.e. not currently endangered). Such for less than one year taxa are under consideration for declaration as ‘rare flora’, but are in need of further Other plant forms—plants such as creepers, survey. mistletoes and sedges. Priority Four (P4) – Rare—Taxa which are Dominant species are those which were considered to have been adequately surveyed recorded as dominant in a stratum at a quarter and which, whilst being rare (in Australia), are or more of the inventory sites. Common species not currently threatened by any identifiable are subordinate species recorded at a quarter or factors. These taxa require monitoring every more sampling sites. Where less than eight 5–10 years. inventory sites were sampled for a vegetation unit, dominant and common species were Assessment of ecological considered those present at two or more sites. Other species refers to uncommon species that disturbances were infrequently recorded at less than a quarter Habitat types are described in terms of common of sampling sites. or distinctive characteristics and internal variation; this reduces natural variation into a Taxonomic conventions manageable number of ecological types within which there is strong similarity. This facilitated The plant taxonomy adopted in this survey is the assessment of range condition. The validity based on advice from the Western Australian of assessments has been achieved by Herbarium. comparing the prominence of groups of plant Species conservation status has been assigned species and soil surface condition at reference according to the declared rare and priority flora inventory (ungrazed or lightly grazed) sites with list for Western Australia (Atkins 2005). normally grazed sites. Declared Rare Flora (R) – Extant—Taxa which Influences on internal variation, such as have been adequately searched for, and for disturbances, are discussed in ecological terms which populations in the wild are deemed to rather than in terms of pastoral impacts on be rare, in danger of extinction, or otherwise pastoral productivity, though it is common for in need of special protection, and have been most changes in productivity to be related to gazetted as such. ecological changes. Priority One (P1) – Poorly Known—Taxa Ecological disturbances are considered in which are known from one or a few (generally recognition of their widespread influence on the < 5) populations which are under threat, due plants common to each habitat type. Ecological to small population size, being on lands under disturbance is discussed in terms of how distur- immediate threat (e.g. road verges, urban bances, natural or influenced by man, have areas, farmland, active mineral leases) or the affected natural resources which may have plants are under threat (e.g. from disease, implications for future land management and grazing by feral animals). It may include taxa nature conservation. Additionally, the patterns with threatened populations on protected discussed may assist present land managers to

140 better understand and work with the ecological grazing pressure. Such plants are often processes operating throughout their leases. referred to as ‘desirables’. Factors considered responsible for substantially Intermediate—Moderately palatable plants influencing the ecology of Nullarbor habitats which, under grazing, initially increase in include fire, rabbit plagues and grazing impacts, cover and density as they utilise niches particularly in association with extended dry vacated by decreasers. Intermediate plants periods. In many instances more than one may dominate the stand. They decline under disturbance factor was involved. Where a extreme grazing pressure, and may be combination of factors had contributed to common in areas regenerating from severe disturbance it was difficult to determine any one degradation. factor as the major cause or to distinguish Increaser—Generally unpalatable plants which disturbance from natural variation. This was increase in number and cover as decreaser particularly relevant in areas where there was species decline under excessive grazing little prior knowledge of the ecology of the pressure. They are commonly found in habitat types and their associated communities. disturbed areas (e.g. burnt patches, water The ecological changes some habitat types sources). In a grazing context such plants are have undergone have been so dramatic the often referred to as ‘undesirables’. original species composition of the perennial No indicator value—The abundance of these vegetation has been significantly replaced by an species is not primarily related to grazing annual component. The combination of history. They usually only decrease after ‘drought’, fire and rabbit plagues has eliminated natural disturbances such as fire or hail large areas of chenopod shrubland throughout damage. These species are usually not the survey area. These areas are now palatable or only slightly palatable or are out of considered to be in a state of irreversible reach of browsing animals. They have been transition (Beard 1975; Davey 1978; Mitchell, termed ‘stability desirables’ in recognition of McCarthy & Hacker 1979; Westoby, Walker & the role they play in maintaining soil stability Noy-Meir 1989). As such, these areas were and ecosystem function. assessed on their present form rather than considering them as a habitat type of a former Key increaser (KI) and key decreaser (KD) state in poor condition. species were identified for most habitat types. The designations of these attributes is based on Plant species indicator values for the grazed field observations of reference sites, severely situation are defined as: degraded areas and at fence effects. This Decreaser—Highly palatable plants whose information is provided to assist in future cover and density decline under excessive assessment and monitoring of grazing impacts.

Scattered myall trees (Acacia papyrocarpa) Considered to be in an irreversible transition of myall surrounded by pearl bluebush (Maireana sedifolia) woodland, this landscape is unlikely to return to its shrubland. This vegetation community represents a former state as there are no living myall of any age stable state. remaining.

141 In a broadscale survey such as this, it is difficult covered in the Geomorphology and Land to establish rigorous scientific linkages between System chapters. Summaries of visual traverse disturbances such as grazing and ecological assessments of range condition are presented variation (except where very obvious, such as a in the Resource Condition chapter. recently burnt area). It is therefore important to appreciate that many of the interpretations are Description of habitat types within based on the experience of survey team their broader habitat type groups members and their ability to recognise and explain the cause of disturbance. Fifty-three habitat types split into 10 habitat type groups are described in some detail (Table 18). This chapter in context This chapter focuses on habitat types and plant community descriptions and ecology. At a broader scale landscape characteristics are

Table 18 Habitat type groups and their component habitat types; structural definitions according to Muir’s (1977) classification method are provided in the rightmost column

A. Myall shrubland and woodland on calcareous plains 1. MSCW Myall, sugarwood mixed chenopod woodland Low Woodland A 2. MFBW Myall, false bluebush shrubland or woodland Low Woodland A 3. MXCS Myall mixed chenopod shrubland or woodland Open Low Woodland A / Open Low Scrub B 4. MSAS Myall saltbush shrubland or woodland Low Woodland A 5. MPBS Myall, pearl bluebush shrubland Open Low Woodland A / Low Scrub B 6. MHXS Myall mixed halophyte shrubland Open Low Woodland A / Low Scrub B 7. MXSS Myall mixed shrub shrubland Open Low Woodland A / Low Scrub B 8. MBIG Myall bindii grassland Open Low Woodland A 9. MSOG Myall, speargrass open grassland Open Low Woodland A B. Eucalypt shrubland and woodland on calcareous plains 10. ESCW Eucalypt, sugarwood mixed chenopod woodland Woodland 11. EXCW Eucalypt mixed chenopod woodland Woodland 12. ESAW Eucalypt saltbush shrubland or woodland Woodland 13. EXSW Eucalypt mixed scrub woodland Woodland 14. EXHS Eucalypt mixed halophytic shrubland Open Woodland / Dwarf Scrub C 15. ESOG Eucalypt, speargrass open grassland Open Woodland / Tall Grass C. Casuarina shrubland and woodland on calcrete plains 16. CXCS Casuarina mixed chenopod shrubland or woodland Low Woodland A 17. CXSS Casuarina mixed scrub shrubland Open Low Woodland A / Scrub 18. CAOS Casuarina, acacia open shrubland Open Low Woodland A / Scrub D. Shrubland and woodland on calcrete plains overlain by shallow sand 19. MHGW Mallee hummock grass (spinifex) woodland Tall Mallee / Dense Hummock Grass 20. MUXW Mulga mixed shrub woodland Low Forest A 21. ACMS Acacia mixed shrubland Scrub E. Shrubland associated with granitic outcrop 22. DEXS Dodonaea, eremophila mixed shrubland Scrub 23. GROS Granite outcrop shrubland Low Scrub A / Open Low Scrub A

142 Table 18 (continued)

F. Shrubland on calcareous plains 24. SWCS Sugarwood mixed chenopod shrubland Scrub / Low Scrub B 25. PBLS Pearl bluebush low shrubland Low Scrub B 26. PBAC Pearl bluebush, acacia shrubland Low Scrub B 27. PXCS Plain mixed chenopod shrubland Low Scrub B / Dwarf Scrub C 28. NXCS Nitraria mixed chenopod shrubland Low Scrub B 29. BSSL Bladder saltbush shrubland Dwarf Scrub C 30. LAWS Lawrencia squamata shrubland Dwarf Scrub C G. Open shrubland and grassland on calcareous plains 31. XAOS Mixed acacia open shrubland Scrub / Low Scrub A 32. XSBG Mixed shrub bindii grassland Open Scrub / Very Open Herbs 33. OBIG Open bindii grassland Open Herbs / Very Open Herbs 34. SWOG Speargrass and wallaby grass open grassland Tall Grass / Very Tall Grass 35. ANNH Annual herbland Open Herbs / Very Open Herbs H. Drainage foci shrubland 36. DOGR Donga grove Scrub / Dense Low Grass 37. DDSS Drainage depression saltbush shrubland Open Scrub / Dwarf Scrub C 38. DDXS Drainage depression mixed shrub shrubland Very Open Tree Mallee / Open Scrub 39. DRAS Drainage tract acacia shrubland Open Scrub / Open Low Scrub A 40. GGSL Gilgai grassy shrubland Dense Low Grass 41. LISW Lignum swamp Low Scrub B 42. PXLS Plain mixed low shrubland Low Scrub A / B I. Shrubland and woodland on lake margins and saline depressions 43. KOPI Kopi dune woodland Open Low Woodland / Dwarf Scrub C 44. SBLS Sandy bank lake shrubland Thicket 45. PXHS Plain mixed halophytic shrubland Low Scrub B / Dwarf Scrub C 46. SAMP Samphire shrubland Dwarf Scrub D J. Coastal zone heath and woodland 47. EMCW Eucalypt, melaleuca mixed chenopod shrubland or Open Tree Mallee woodland 48. EMEW Eucalypt, melaleuca woodland Open Tree Mallee 49. LOMW Low mallee woodland Open Tree Mallee 50. EHEW Eucalypt heath woodland Open Tree Mallee 51. ECHW Eucalypt coastal heath woodland Open Tree Mallee 52. BCHS Banksia coastal heath and scrubland Shrub Mallee 53. COAS Coastal shrubland Heath B / Open Dwarf Scrub D

143 A. MYALL SHRUBLAND AND dominates the tall shrub stratum and is WOODLAND ON CALCAREOUS commonly denser than Acacia papyrocarpa. The mid shrub layer is commonly dominated by PLAINS scattered Cratystylis conocephala (false This group of habitat types is common through- bluebush) (15–20 per cent PFC). out the survey area on calcareous plains. The 14 perennial species and one annual species overstorey is dominated by Acacia papyrocarpa were recorded at the inventory site. (myall) and the understorey by low shrubs of the Chenopodiaceae and Asteraceae families. The following species (by strata) are dominant Throughout the survey area the understorey has and/or common: commonly been reduced or removed, through Trees: Dominant—Acacia papyrocarpa the combined effects of fire, grazing by rabbits Common—Myoporum and to a lesser extent domestic stock, replaced platycarpum. by stands of perennial grasses, subshrubs and Tall shrubs: Dominant—Myoporum herbs. The presence of myall is strongly platycarpum. influenced by its growing medium and rainfall. In Mid shrubs: Dominant—Cratystylis the south myall corresponds with the location of conocephala the Hampton Tableland gradually disappearing Other—Atriplex nummularia. as the landscape transitions into the Nullarbor Low shrubs: Dominant—Not present as a land zone from which it is absent, this may also recognisable stratum relate to the gradational decrease of rainfall Others—Atriplex vesicaria (KD), from the coast. In the north and west myall Chenopodium curvispicatum, corresponds with the calcrete and Lycium australe, Maireana Recrystallised Limestone plains of the Nyanga sedifolia, Olearia calcarea, land zone. With the reduction in rabbit numbers, Solanum nummularium. due to the rabbit calicivirus, recruitment of Subshrubs: Dominant—Not present as a juvenile myall throughout myall woodland is recognisable stratum common. Most frequently observed in the north Others—Eriochiton sclerolaenoides, Maireana of the survey area this phenomenon also trichoptera (KD), Sclerolaena corresponds with areas destocked of sheep. In diacantha (KD). the south in the Hampton Tableland juvenile myall is less common and though rabbit Perennial grasses: Dominant—Not present as a recognisable stratum numbers are reduced, sheep grazing on Others—Austrostipa juvenile trees is affecting myall recruitment. platychaeta. 1. Myall, sugarwood mixed chenopod Annual species recorded include Salsola tragus. woodland (MSCW) Ecological disturbance Sampling Palatable low shrubs and subshrubs such as Atriplex vesicaria (bladder saltbush), Maireana 1 inventory site, 91 traverse points trichoptera (pink-seeded bluebush) and General information Sclerolaena diacantha (grey bindii) may be removed through overgrazing. Where this MSCW is found on calcrete plains overlain by habitat type occurs on low rises crossed by calcareous loam and on low calcrete rises. vehicle tracks these areas are prone to water Gentle slopes to 4 per cent with an abundant erosion. Prolific Myoporum platycarpum surface covering (50–90 per cent) of calcrete regrowth may be a response to a reduction in fragments. Soils are calcareous loamy earths. rabbit numbers due to the rabbit calicivirus. At This vegetation association is common in the the time of survey Myoporum platycarpum west of the survey area. dominated the tall shrub stratum. In future years Physiognomy and composition of vegetation it may become dominant in the tree strata, though natural competition or fire may also MSCW occurs as a scattered (10–15 per cent reduce its abundance. PFC) low woodland of Acacia papyrocarpa (myall). Myoporum platycarpum (sugarwood)

144 Gradational associations Santalum acuminatum, S. lanceolatum. MSCW commonly grades into Myall mixed chenopod shrubland or woodland (MXCW) as Tall shrubs: Dominant—Geijera linearifolia Others—Eremophila alternifolia, Myoporum platycarpum becomes less dense Melaleuca lanceolata. through the tall shrub stratum. Where both myall and sugarwood are replaced in Mid shrubs: Dominant—Cratystylis dominance by species of eucalyptus MSCW conocephala, Geijera linearifolia Common—Atriplex nummularia grades into Eucalypt mixed chenopod woodland Others—Nitraria billardierei, (EXCW) Senna artemisioides subsp. Land systems artemisioides. Low shrubs: Dominant—Atriplex vesicaria MSCW is a major habitat on Nyanga land (KD), Cratystylis conocephala system. Common—Enchylaena tomentosa (KD), Eremophila 2. Myall, false bluebush shrubland or deserti, Maireana erioclada, woodland (MFBW) Olearia calcarea, Westringia rigida Sampling Others—Eremophila glabra, E. latrobei (KD), E. parvifolia, 6 inventory sites, 45 traverse points Gunniopsis calcarea, Lycium General information australe, Maireana radiata, M. sedifolia, Olearia MFBW is most common in the south-east of the ramosissima, Rhagodia survey area near the Hampton Scarp, either on crassifolia, Solanum the calcarenite Roe Plains or on the Bunda lasiophyllum, S. nummularium, Plateau on residual aeolian sand deposits. Zygophyllum aurantiacum. Coarse (2–6 cm) calcareous fragments, Subshrubs: Dominant—Sclerolaena commonly calcrete nodules, are sparsely diacantha (KD), distributed across 2–10 per cent of the surface. S. patenticuspis (KI) Soils are calcareous loamy earths. Common—Maireana trichoptera (KD) Physiognomy and composition of vegetation Others—Maireana tomentosa (KD), Ptilotus symonii, MFBW occurs as a scattered to moderately Sclerolaena obliquicuspis, closed (10–25 per cent PFC) low woodland or Senecio spanomerus, Solanum shrubland. The tree stratum is dominated by ellipticum, Zygophyllum Acacia papyrocarpa (myall) and the low to mid apiculatum. shrub stratum by Cratystylis conocephala (false Perennial grasses: Dominant—Not present as a bluebush). Very scattered to scattered recognisable stratum (2.5–15 per cent PFC) Geijera linearifolia Others—Austrodanthonia (oilbush) occur in the medium to tall shrub caespitosa, Austrostipa stratum. drummondii, A. platychaeta (KD), A. scabra, Enneapogon 50 perennial species were recorded at the six caerulescens, E. cylindricus, inventory sites, with an average of 17 per site, Eragrostis dielsii. six more than the survey average. Four annual Annual species recorded include Carrichtera annua species were recorded, with an average of one (KI), Salsola tragus, Sonchus oleraceus and per site. Zygophyllum glaucum. The following species (by strata) are dominant Ecological disturbance and/or common: Trees: Dominant—Acacia papyrocarpa The palatable herbs and subshrubs Maireana Common—Myoporum tomentosa (felty bluebush), M. trichoptera (pink- platycarpum seeded bluebush) and Sclerolaena diacantha Others—Eremophila longifolia, (grey bindii) when abundant in combination with Eucalyptus gracilis (mallee), Atriplex vesicaria (bladder saltbush), E. oleosa subsp. oleosa Enchylaena tomentosa (ruby saltbush), and (mallee), E. yalatensis, Eremophila latrobei (warty-leaf eremophila) may

145 indicate good range condition. Such subshrubs 60 perennial species were recorded at the 22 may also indicate seasonal conditions and the inventory sites, with an average of 14 species level of use of the current season’s production. per site, three above the survey average. 12 Cratystylis conocephala is only occasionally annual species were recorded, with an average eaten by stock and has no known indicator of three species per site. value (Mitchell & Wilcox 1994). Cratystylis The following species (by strata) are dominant conocephala and Atriplex vesicaria are fire and/or common: intolerant and may be removed from areas frequently or intensely burnt. Trees: Dominant—Acacia papyrocarpa Common—Myoporum Gradational associations platycarpum Others—Acacia aneura, MFBW commonly grades into Myall mixed Alectryon oleifolius, Casuarina chenopod shrubland or woodland (MXCW) as pauper, Eremophila longifolia, chenopods become increasingly prominent in Eucalyptus yalatensis, the understorey or Plain mixed chenopod Pittosporum angustifolium, shrubland (PXCS) where myall disappears from Santalum acuminatum, the overstorey. S. spicatum. Tall shrubs: Dominant—Not present as a Land systems recognisable stratum MFBW is a common habitat type on Moodini Common—Myoporum and Mundrabilla land systems, and is a minor platycarpum habitat type on Nyanga and Roe land systems. Other—Geijera linearifolia. Mid shrubs: Dominant—Atriplex 3. Myall mixed chenopod shrubland nummularia, Cratystylis or woodland (MXCS) conocephala Common—Senna artemisioides Sampling subsp. x coriacea Others—Acacia ancistrophylla 22 inventory sites, 625 traverse points var. ancistrophylla, A. nyssophylla, Eremophila General information decipiens, E. latrobei, MXCS is predominantly found on calcrete plains E. scoparia, Nitraria billardierei, in the west and north of the survey area. MXCS Senna artemisioides subsp. x commonly has a mantle of small to large artemisioides. pebbles and nodules (6–60 mm), at some Low shrubs: Dominant—Atriplex vesicaria locations covering up to 90 per cent of the (KD), Maireana sedifolia surface. Soils are calcareous shallow loams Common—Chenopodium and loamy earths. This vegetation association is curvispicatum (KD), Enchylaena tomentosa (KD), Lycium also located in the south on the limestone australe, Maireana erioclada, hummocks (low rises) of the Thampanna land M. turbinata, Ptilotus obovatus, system and on the Roe Plains in the Mundrabilla Sida calyxhymenia land system. Others—Gunniopsis calcarea, Maireana georgei (KD), Physiognomy and composition of vegetation M. pentatropis, M. radiata, MXCS occurs as a very scattered (10–20 per Rhagodia crassifolia, Solanum cent PFC) shrubland or low woodland. The tree nummularium, Zygophyllum stratum is dominated by Acacia papyrocarpa aurantiacum. (myall) and the lower shrub stratum by Atriplex Subshrubs: Dominant—Not recognisable as vesicaria (bladder saltbush) and Maireana a dominant stratum sedifolia (pearl bluebush). The mid shrub Common—Atriplex acutibractea stratum commonly comprises very scattered (KI), Eriochiton sclerolaenoides (2.5–10 per cent PFC) Atriplex nummularia (old (KD), Maireana trichoptera (KD), Sclerolaena diacantha (KD) man saltbush); occasionally co-dominated with Others—Maireana tomentosa Cratystylis conocephala (false bluebush). (KD), Minuria cunninghamii, Sclerolaena densiflora (KI), S. obliquicuspis (KI),

146 S. patenticuspis (KI), Senecio development of dense clumps of palatable spanomerus, Sida shrubs under trees and seedlings or suckers spodochroma, Solanum from the palatable trees. ellipticum. Perennial grasses: Dominant—Not recognisable as Gradational associations a dominant stratum MXCS commonly grades into Plain mixed Common—Austrodanthonia chenopod shrubland (PXCS) or Nitraria mixed caespitosa, Austrostipa scabra chenopod shrubland (NXCS) as the myall tree Others—Austrostipa platychaeta (KD), Enneapogon stratum disappears. As the presence of avenaceus, E. caerulescens, Myoporum platycarpum becomes denser E. cylindricus, Enteropogon through the tall shrub stratum MXCS commonly acicularis, Eragrostis setifolia, grades into Myall, sugarwood mixed chenopod Eriachne sp., Panicum effusum. woodland (MSCW) or Sugarwood mixed Other plant forms: Occasional—Amyema chenopod shrubland or woodland (SWCS) quandang var. quandang where it replaces myall in the tree stratum. In (mistletoe). the north-west MXCS grades into Casuarina Annual species recorded include Angianthus mixed chenopod shrubland or woodland conocephalus, Carrichtera annua (KI), Dysphania (CXCS) or Mulga mixed shrub woodland melanocarpa forma leucocarpa, Erodium cicutarium, (MUXW) as casuarina or mulga begins to Euphorbia drummondii, Nicotiana occidentalis, dominate the tree stratum. Rhodanthe floribunda (KI), Salsola tragus (KI), Sonchus oleraceus, Vittadinia humerata, As the low to mid shrub stratum becomes Zygophyllum eremaeum and Z. iodocarpum (KI). dominated by one species MXCS grades into Myall, false bluebush shrubland or woodland Ecological disturbance (MFBW) or Myall, pearl bluebush shrubland The palatable low shrubs Atriplex vesicaria (MPBW). As the diversity of chenopod species (bladder saltbush), Chenopodium decreases in the understorey becoming curvispicatum, Enchylaena tomentosa (ruby replaced by non-chenopod species MXCS saltbush) and Maireana georgei (golden grades into Myall mixed shrubland or woodland bluebush) and subshrubs Eriochiton (MXSS). As the salinity of the soil increases and sclerolaenoides (woolly bindii), Maireana samphires become more frequent MXCS tomentosa (felty bluebush), M. trichoptera (pink- grades into Myall mixed halophyte shrubland seeded bluebush) and S. diacantha (grey bindii) (MHXS). may be reduced through heavy grazing In the north-west MXCS grades into Acacia pressure. In areas of poor condition palatable mixed shrubland (ACMS) where aeolian sand subshrubs are replaced by Atriplex acutibractea patches thinly cover the calcrete plain of the (toothed saltbush), Sclerolaena densiflora (hairy Nyanga land system. bindii), S. obliquicuspis (limestone bindii), S. patenticuspis (spear-fruit copperburr) and Land systems annuals such as Carrichtera annua (Ward’s MXCS is a dominant habitat type on Mundrabilla weed), Rhodanthe floribunda, Salsola tragus and Nyanga land systems, a major habitat type (roly poly) and Zygophyllum iodocarpum. on Thampanna and Virginia land systems and a Within myall mixed chenopod woodland tree- minor habitat type on Koonjarra and Pondana based clumps exist as groves around trees land systems. such as Alectryon oleifolius (mingah bush, bullock bush), Eremophila longifolia (berrigan), 4. Myall saltbush shrubland or Myoporum platycarpum (sugarwood), woodland (MSAS) Santalum acuminatum (quandong) and S. spicatum (sandalwood) as well as myall. Sampling Browsing pressure is commonly indicated by 5 inventory sites, 176 traverse points the condition of these groves and the clump understorey. Browse lines indicate moderate General information grazing but broken limbs and absent canopies MSAS occurs in the south-east of the survey indicate heavy grazing at an unsustainable level. area on low rises (limestone hummocks) with Improving range condition is indicated by the very gently inclined slopes of up to 2 per cent

147 and on stony plains. The mantle can have a Perennial grasses: Dominant—Not present as a sparse to moderate covering (2–50 per cent) of recognisable stratum limestone fragments with some limestone Common—Austrostipa scabra outcrop (< 10 per cent). Soils are shallow Others—Austrodanthonia calcareous loams and loamy earths. This caespitosa, Enneapogon cylindricus. vegetation association is also found in the north, though here it is restricted to the Nyanga land Annual species recorded include Erodium aureum, system where MSAS occurs on calcrete plains Euphorbia drummondii, Lepidium sp., Nicotiana goodspeedii, Rhodanthe floribunda, Salsola tragus, overlain by calcareous loams of varying depth. Vittadinia sp. and Zygophyllum iodocarpum. Physiognomy and composition of vegetation Ecological disturbance MSAS occurs as a scattered (10–20 per cent The density of Atriplex vesicaria (bladder PFC) low woodland or shrubland. Acacia saltbush) populations is generally a reliable papyrocarpa (myall) dominates the tree stratum indicator of range condition. Areas of MSAS with and Atriplex vesicaria (bladder saltbush) the low sparse stands of bladder saltbush should be shrub stratum. Juvenile Myoporum platycarpum considered as in poor condition. Atriplex (sugarwood), to a height of 3 m, commonly vesicaria responds to moisture stress by dominate the tall shrub stratum, and Atriplex shedding its leaves, but vegetatively responds nummularia (old man saltbush) the mid shrub quickly to rainfall. During this recovery phase it stratum. needs protection from grazing to regain vigour 23 perennial species were recorded at the five and set seed. Acacia papyrocarpa (myall) is inventory sites, with an average of 10 species long-lived with mature trees providing a slightly per site, one less than the survey average. Eight palatable source of browse. Studies have annual species were recorded with an average shown juvenile myall do not survive grazing of four species per site. (Mitchell & Wilcox 1994). However, many juvenile myall were found within this habitat type The following species (by strata) are dominant in the north of the survey area in zones of stock and/or common: disturbance near water points, formerly used by Trees: Dominant—Acacia papyrocarpa sheep but now stocked with cattle. In these Other—Alectryon oleifolius. areas it is possible the destocking of sheep and Tall shrubs: Dominant—Myoporum reduction in rabbit numbers, due to rabbit platycarpum calicivirus, has allowed Acacia papyrocarpa to Common—Nil. regenerate prolifically. Mid shrubs: Dominant—Atriplex nummularia Other—Eremophila scoparia. Gradational associations Low shrubs: Dominant—Atriplex vesicaria In the south-east MSAS is commonly found on (KD) limestone hummocks (low rises) grading Common—Chenopodium downslope into loamy or saline depressions curvispicatum, Enchylaena supporting Bladder saltbush shrubland (BSSL) tomentosa, Maireana sedifolia or Plain mixed halophyte shrubland (PXHS). As Others—Lycium australe, eucalypts start to dominate the overstorey Maireana erioclada, MSAS grades into Eucalypt saltbush shrubland M. pentatropis, Solanum or woodland (ESAW). In the north in the Nyanga nummularium, Zygophyllum aurantiacum. land system MSAS commonly grades into Bladder saltbush shrubland (BSSL). Subshrubs: Dominant—Not present as a recognisable stratum Land systems Common—Atriplex acutibractea, Eriochiton MSAS is a major habitat type on Chowilla, sclerolaenoides, Sclerolaena Nyanga and Thampanna land systems. diacantha Others—Maireana trichoptera, Sclerolaena obliquicuspis, Sida spodochroma.

148 5. Myall, pearl bluebush shrubland Low shrubs: Dominant—Maireana sedifolia (MPBS) Common—Atriplex vesicaria (KD), Chenopodium Sampling curvispicatum (KD), Lycium australe, Solanum lasiophyllum, 6 inventory sites, 155 traverse points S. nummularium Others—Enchylaena tomentosa General information (KD), Eremophila pustulata, MPBS is commonly found on stony limestone Lawrencia squamata, Ptilotus plains with 10–50 per cent of the surface obovatus, Zygophyllum covered by coarse limestone fragments of aurantiacum. mixed size. MPBS occurs predominantly in two Subshrubs: Dominant—Not present as a areas: in the southern portion of the Chowilla recognisable stratum and Shakehole land systems merging into the Common—Maireana trichoptera, north of the Thampanna land system; and on Sclerolaena diacantha, S. obliquicuspis the Recrystallised Limestone plains of the Others—Eriochiton Kanandah land system and the adjacent sclerolaenoides, Erodium Seemore land system which border the aureum. Nullarbor Plain in the north-west. The vegetation Perennial grasses: Dominant—Not present as a association is also found in the west and north recognisable stratum of the survey area on calcrete plains overlain by Common—Austrostipa scabra, calcareous loams within the Nyanga land zone Enneapogon cylindricus or on adjacent systems on elongated low lime- Others—Austrodanthonia stone ridges. Soils are shallow calcareous caespitosa, Enneapogon loams and loamy earths. caerulescens. Physiognomy and composition of vegetation Other plant forms: Occasional—Amyema quandang var. quandang MPBS consists of a scattered to moderately (mistletoe), Lysiana sp. closed (10–30 per cent PFC) low to mid shrub- (mistletoe). land of Maireana sedifolia (pearl bluebush). The Annual species recorded include Asphodelus overstorey is dominated by isolated to very fistulosus, Brachyscome sp., Calandrinia sp., Calotis scattered (2.5–10 per cent PFC) Acacia hispidula, Carrichtera annua (KI), Euphorbia papyrocarpa (myall). drummondii, Lepidium sp., Podolepis canescens, Ptilotus exaltatus, Rhodanthe floribunda, Salsola 34 perennial species were recorded at the six tragus, Sonchus sp. and Vittadinia humerata. inventory sites, with an average of 13 species per sites, two more than the survey average. 13 Ecological disturbance annual species were recorded with an average Maireana sedifolia leaves contain up to 10 per of 6 per site. cent salt (Mitchell & Wilcox 1994) and may be The following species (by strata) are dominant eaten by stock particularly if fresh water is and/or common: available. Pastoralists report stock eating only the tips of the plants, particularly when new Trees: Dominant—Acacia papyrocarpa growth occurs. Pearl bluebush is not a sensitive Others—Acacia aneura, Alectryon oleifolius, Myoporum indicator of range condition on the Nullarbor. platycarpum, Pittosporum Myall, pearl bluebush shrubland in good condi- angustifolium, Santalum tion will support dense clumps of palatable acuminatum. shrubs, such as Chenopodium curvispicatum Mid shrubs: Dominant—Not present as a and Enchylaena tomentosa (ruby saltbush). recognisable stratum Grazing pressure can be estimated by the Common—Atriplex nummularia, structure of bush clumps under trees, the Senna artemisioides subsp. x presence of the browse lines and the condition coriacea (KI) Others—Acacia burkittii, of the tree canopy. A. oswaldii, Eremophila Whilst pearl bluebush can regenerate from low scoparia, Pimelea to moderate intensity burns Acacia papyrocarpa microcephala. (myall) and Atriplex vesicaria (bladder saltbush)

149 are fire sensitive (Mitchell, McCarthy & Hacker 6. Myall mixed halophyte shrubland 1979). However all three species will be (MHXS) removed by frequent fires. Large areas where they have been lost through the combined Sampling effects of frequent fires and/or grazing by 3 inventory sites, 38 traverse points rabbits and domestic stock are considered to be in poor condition. These areas now support General information the vegetation association Myall bindii MHXS is predominantly found on the stony grassland (MBIG). limestone plains in the south of the survey area. Gradational associations It commonly has a sparse to common (2–20 per cent) mantle of medium-sized In the south of the survey area the limestone (6–20 mm) limestone fragments. Soils are plains undulate with MPBS on low rises saline calcareous loamy earths. It occasionally (limestone hummocks) and low ridges grading occurs on the calcrete plain of the Nyanga land into Pearl bluebush low shrubland (PBLS) on system on Koonjarra and Virginia pastoral marginal slopes or into Bladder saltbush leases. shrubland (BSSL) in the loamy or clay depressions. As soil salinity increases and Physiognomy and composition of vegetation samphires become common MPBS grades into MHXS consists of a scattered low shrubland Myall mixed halophyte shrubland (MHXS). In the (10–20 per cent PFC) of Atriplex vesicaria north as other chenopod species become (bladder saltbush) and Maireana sedifolia (pearl increasingly common within the understorey bluebush). The tree stratum is composed of MPBS grades into Myall mixed chenopod very scattered (2.5–5 per cent PFC) Acacia shrubland or woodland (MXCS). papyrocarpa (myall). Myoporum platycarpum Land systems (sugarwood) occasionally dominates these habitats as a tall shrub. The characteristic MPBS is the dominant habitat type on feature is the presence of Tecticornia sp. Kanandah land system and a major type on (samphire) in the lower stratum. Chowilla, Nyanga, Seemore, Thampanna and Vanesk land systems and a minor habitat type 20 perennial species were recorded at the three on Colville, Arubiddy, Jubilee, Kybo and inventory sites, with an average of 10 per site, Shakehole land systems. one less than the survey average. Three annual species were recorded.

Scattered myall trees (Acacia papyrocarpa) Myall trees (Acacia papyrocarpa) surrounded by surrounded by pearl bluebush (Maireana sedifolia) bindii grassland (MBIG). This is considered to be in shrubland. This vegetation community is considered an irreversible transition from a Myall pearl bluebush to represent a stable state. shrubland (MPBS).

150 The following species (by strata) are dominant (MXCS) or Myall pearl bluebush shrubland and or common: (MPBS). Where stony limestone plains grade Trees: Dominant—Acacia papyrocarpa into saline plains or depressions the taller Common—Nil. stratum disappears and MHXS grades into Plain mixed halophyte shrubland (PXHS). Tall shrubs: Dominant—Occasionally Myoporum platycarpum Land systems Common—Nil. Mid shrubs: Dominant—Atriplex nummularia MXHS is a minor habitat type on Nyanga, Other—Nitraria billardierei. Vanesk and Virginia land systems. Low shrubs: Dominant—Atriplex vesicaria (KD), Maireana sedifolia, 7. Myall mixed shrub shrubland Tecticornia sp. (MXSS) Common—Enchylaena tomentosa, Solanum Sampling nummularium 1 inventory site, 45 traverse points Others—Gunniopsis calcarea, Maireana pentatropis, General information M. turbinata, Olearia muelleri. MXSS is predominantly found on stony Subshrubs: Dominant—Not present as a limestone plains commonly with a moderate recognisable stratum Others—Eriochiton covering (20–50 per cent) of limestone frag- sclerolaenoides, Maireana ments. MXSS is also located in the north-west trichoptera, Sclerolaena of the survey area. brevifolia, S. diacantha (KD), S. obliquicuspis (KI). Physiognomy and composition of vegetation Perennial grasses: Dominant—Not present as a MXSS consists of a moderately closed recognisable stratum (20–25 per cent PFC) mid shrubland of variable Common—Austrostipa scabra composition. Atriplex nummularia (old man Other—Austrostipa platychaeta saltbush), Eremophila scoparia (broom bush) (KD). and Senna artemisioides subsp. x coriacea Annual species recorded include Euphorbia (desert cassia) are commonly present within drummondii, Nicotiana occidentalis and Salsola the mid shrub layer. The tree stratum is tragus. dominated by very scattered (5–10 per cent PFC) Acacia papyrocarpa (myall). Ecological disturbance 20 perennial species and two annual species Species of Tecticornia (samphire) are only were recorded at the one inventory site. valuable as forage where fresh water is avail- able, as they may contain up to 24 per cent salt. The following species (by strata) are dominant As fresh water is often uncommon samphire and/or common: has no indicator value for Nullarbor rangeland Trees: Dominant—Acacia papyrocarpa condition. Atriplex vesicaria (bladder saltbush) Common—Myoporum is a more reliable indicator. Where Atriplex platycarpum. vesicaria populations show a declining abun- Tall shrubs: Dominant—Not present as a dance rangeland condition is considered to be recognisable stratum deteriorating. The higher salt content of feed in Others—Acacia oswaldii, the lower stratum may place increased A. tetragonophylla, Senna pressure on Acacia papyrocarpa. The develop- cardiosperma (KI). ment of prominent browse lines and trampling Mid shrubs: Dominant—Variable; commonly of bush clumps also indicates increased Eremophila scoparia (KI) grazing pressure. Common—Atriplex nummularia, Senna artemisioides subsp. x Gradational associations coriacea (KI) Others—Acacia ancistrophylla As soil salinity decreases and samphires var. ancistrophylla, Eremophila become less frequent, MHXS grades into Myall sp. mixed chenopod shrubland or woodland

151 Low shrubs: Dominant—Not present as a Gradational association recognisable stratum Common—Chenopodium As the diversity of chenopod species increases curvispicatum (KD), Enchylaena in the understorey MXSS grades into Myall tomentosa (KD), Maireana mixed chenopod shrubland or woodland sedifolia (MXCS). Other—Ptilotus obovatus. Land systems Subshrubs: Dominant—Not present as a recognisable stratum MXSS is a major habitat type on Kanandah land Common—Atriplex system and a minor habitat type on Kinclaven acutibractea, Eriochiton and Nyanga land systems. sclerolaenoides, Maireana trichoptera 8. Myall bindii grassland (MBIG) Others—Sclerolaena diacantha, Sida spodochroma. Sampling Perennial grasses: Dominant—Not present as a 2 inventory sites, 44 traverse points recognisable stratum Common—Enneapogon General information caerulescens. Annual species recorded include Lepidium sp. and MBIG predominantly occurs on stony Salsola tragus. Recrystallised Limestone in the north-west or calcrete plains in the north of the survey area. Ecological disturbance Soils are calcareous shallow loams and loamy This habitat type was not sampled sufficiently earths, with coarse limestone or calcrete frag- for detailed analysis of patterns of disturbance. ments covering 20–50 per cent of the surface. However, patterns of disturbance for Myall MBIG is considered to be a degraded vegetation mixed chenopod shrubland or woodland association. The original understorey is likely to (MXCS) are considered relevant to MXSS. It is have been reduced by frequent fires and over- likely this vegetation association previously grazing, primarily by rabbits. It is unlikely the comprised an understorey with a diversity of lower shrub layer will support shrubs in any palatable species now greatly reduced through great density, since the dominance of grasses grazing pressure. This has resulted in unpalat- renders the area susceptible to fire. Stands of able genera such as eremophila and senna juvenile myall were observed between and becoming dominant. Sennas are long-lived and recorded at several traverse points. This could difficult to control by grazing or destocking be because of fewer rabbit numbers due to the paddocks alone. Eremophila scoparia may be calicivirus. grazed when young but once mature it is Physiognomy and composition of vegetation generally unpalatable. These plants increase in areas of disturbance particularly when competi- MBIG occurs as a very scattered (2.5–10 per tion from palatable lower shrubs has been cent PFC) low woodland of Acacia papyrocarpa reduced. (myall). Myoporum platycarpum (sugarwood) can be common to absent; groves of Alectryon As with Myall mixed chenopod shrubland or oleifolius (mingah or bullock bush) and woodland (MXCS) and Myall pearl bluebush Eremophila longifolia (berrigan) occur shrubland (MPBS), grazing impact may best be infrequently. The low shrub stratum is judged by the abundance and diversity of commonly dominated by Maireana trichoptera palatable low shrubs under the myall overstorey. (felty bluebush), Sclerolaena obliquicuspis Palatable shrubs found in MXSS include (limestone bindii) and the annuals Carrichtera decreasers such as Chenopodium annua (Ward’s weed) and Salsola tragus (roly curvispicatum and Enchylaena tomentosa (ruby poly). The mid and tall shrub strata are often saltbush) as well as species that respond as poorly developed. much to recent seasonal conditions as to grazing history: Maireana trichoptera (pink- 25 perennial species were recorded at the two seeded bluebush), Ptilotus obovatus (cotton inventory sites, with an average of 16 per site, bush), Sclerolaena diacantha (grey bindii) and five more than the survey average. Six annual Sida spodochroma (prostrate sida). species were recorded.

152 The following species (by stratum) are Common annual species include Carrichtera annua, dominant and or common: Erodium aureum (KI), Euphorbia drummondii, Salsola tragus, Salvia verbenaca (KI) and Zygophyllum Trees: Dominant—Acacia papyrocarpa iodocarpum (KI). Common—Alectryon oleifolius, Eremophila longifolia Ecological disturbance Others—Acacia aneura (Colville land system), Myoporum It is likely an abundance of rabbits and/or heavy platycarpum. grazing pressure from stock during post-fire Tall shrubs: Dominant—Not present as a recovery periods has contributed to the removal recognisable stratum of the original understorey of this vegetation Common—Acacia oswaldii. association. In the Carlisle, Colville and Kyarra Mid shrubs: Dominant—Not present as a land systems active rabbit warrens are still recognisable stratum common. MBIG is commonly found on marginal Common—Atriplex nummularia, slopes to drainage areas, such as dongas, and Eremophila scoparia (KI), receives considerable use resulting in regular Senna artemisioides subsp. x padding and disturbed soil crust. Dry seasonal artemisioides (KI), conditions exacerbate the deterioration as the S. artemisioides subsp. x non-perennial vegetation dies off exposing the coriacea (KI) soil surface to wind erosion. These factors have Other—Cratystylis conocephala. reduced the potential for this habitat type to Low shrubs: Dominant—Not present as a support perennial shrubs in any abundance recognisable stratum other than weakly perennial herbs and grasses. Common—Maireana sedifolia, Enchylaena tomentosa (KD), The sparseness of perennial vegetation Ptilotus obovatus increases demand on palatable species Other—Chenopodium present. The infrequent groves of Alectryon curvispicatum (KD). oleifolius (mingah/bullock bush) and Eremophila Subshrubs: Dominant—Not present as a longifolia (berrigan) provide a sought after pro- recognisable stratum tein source. Excessive total grazing pressure Common—Atriplex acutibractea will kill individuals as plant vigour is eventually (KI), Dissocarpus paradoxus reduced to below the point of recovery. The loss (KI), Maireana trichoptera, of such perennials further reduces the land- Sclerolaena diacantha (KD), scape’s ability to support herbivores during dry S. obliquicuspis (KI), periods. S. patenticuspis (KI), Sida spodochroma, Solanum ellipticum. Perennial grasses: Dominant—Not present as a recognisable stratum Common—Austrostipa scabra, Enneapogon caerulescens.

Bindii grassland surrounds a berrigan grove (Eremophila longifolia) that has been heavily browsed by cattle and camels. Without a reduction in total grazing pressure plant vigour will continue to decline. Groves in this state indicate excessive grazing pressure and deteriorating range condition.

153 Gradational association Physiognomy and composition of vegetation MBIG commonly grades into Open bindii MSOG occurs as dense grassland of grassland (OBIG) as the Recrystallised Austrostipa scabra (speargrass) in good Limestone or calcrete of the Nyanga land zone seasonal conditions. In poor seasons only the supporting the myall component gives way to basal portion of grass butts remains. The tree the underlying Nullarbor Limestone. stratum consists of isolated (0–2.5 per cent PFC) Acacia papyrocarpa (myall). All other Land systems strata are poorly developed or absent. MBIG is a major habitat type on Carlisle, 17 perennial species were recorded at the two Colville, Kanandah and Kyarra land systems inventory sites, with an average of 12 per site, and a minor habitat type on Jubilee and one greater than the survey average. Seven Kinclaven land systems. annual species were recorded. 9. Myall, speargrass open grassland The following species (by strata) are dominant (MSOG) and/or common: Trees: Dominant—Acacia papyrocarpa Sampling Other—Myoporum platycarpum. 2 inventory sites, 7 traverse points Mid shrubs: Dominant—Not present as a recognisable stratum General information Common—Cratystylis conocephala, Nitraria MSOG predominantly occurs on stony billardierei. Recrystallised Limestone and calcrete plains in the north of the survey area. MSOG can also Low shrubs: Dominant—Not present as a recognisable stratum infrequently occur wherever populations of myall Common—Atriplex vesicaria are present. It commonly has a mantle of (KD), Enchylaena tomentosa, coarse (2–6 cm) limestone fragments covering Maireana erioclada, M. sedifolia 20–50 per cent of the surface. Soils are Other—Lawrencia squamata. calcareous loamy earths. This vegetation Subshrubs: Dominant—Not present as a association is considered degraded, with the recognisable stratum original understorey removed by frequent fires Common—Atriplex and heavy grazing, particularly by rabbits. acutibractea, Eriochiton

This vegetation community of scattered myall trees Sparse myall trees (Acacia papyrocarpa) surrounded (Acacia papyrocarpa) surrounded by pearl bluebush by grassland. Note at the front right the absence of a (Maireana sedifolia) shrubland is considered to burnt stump in the centre of the dead tree; future represent a stable state. Disturbance mechanisms fires will remove any remaining dead wood promoting can irreversibly alter this state into Myall speargrass the appearance of a grassland. The increase in grass open grassland (MSOG). continues to make the area more susceptible to fire.

154 sclerolaenoides, Maireana B. EUCALYPT SHRUBLAND AND tomentosa, M. trichoptera, Sclerolaena diacantha (KD), WOODLAND ON CALCAREOUS S. obliquicuspis. PLAINS Perennial grasses: Dominant—Austrostipa scabra This group consists of habitat types with a Common—Austrodanthonia variable overstorey of eucalypt species found on caespitosa. calcareous plains. In the west and south-west Annual species recorded include Brachyscome of the survey area the eucalypts predominantly ciliaris, Carrichtera annua (KI), Euphorbia occur on calcrete plains, whilst in the south- drummondii, Nicotiana sp., Salsola tragus, Senecio east they are commonly found on limestone spanomerus and Zygophyllum ovatum. hummocks (low rises) within the limestone Ecological disturbance plains and the Roe Plains. The tree stratum typically contains various species of mallee- Austrostipa scabra (speargrass) is highly form eucalypts. Single-stemmed tree forms are responsive to good seasonal conditions. It is also common, particularly in the Gumbelt land readily eaten when young and green but is not system. palatable once it has dried off. In dry seasons areas supporting such vegetation communities 10. Eucalypt, sugarwood mixed are susceptible to wind erosion. The lack of a mid or low shrub layer to offer protection further chenopod woodland (ESCW) reduces an already declining soil crust. Less Sampling than 50 per cent soil crusting was recorded at inventory sites supporting MSOG. 3 inventory sites, 50 traverse points The abundance of speargrass makes this General information habitat type especially prone to fire. The isolated ESCW is predominantly located on calcrete occurrence of myall also alludes to its sensitivity plains overlain by calcareous loam in the west to fire. Trees killed by earlier fires, rabbit ring- of the survey area. Medium to coarse barking or old age are erased from the (6–60 mm) limestone fragments and calcrete landscape by fires which burn all evidence that nodules cover up to 30 per cent of the surface. these areas once supported woodland. Stages Soils are calcareous shallow loams and loamy of this process can be seen throughout the earths. woodlands bordering the Nullarbor Plain. (Photos in the Resource Management chapter Physiognomy and composition of vegetation show examples of this process.) ESCW occurs as a scattered to moderately Gradational associations closed (10–25 per cent PFC) woodland. The tree stratum is composed of mallee-form MSOG is commonly found on low rises of Eucalyptus gracilis (yorrell), E. oleosa (giant Recrystallised Limestone grading down onto mallee) and Myoporum platycarpum Nullarbor Limestone into Speargrass and (sugarwood). Myoporum platycarpum also wallaby grass open grassland (SWOG). This dominates the tall shrub stratum. Cratystylis gradational association shows the effects of an conocephala (false bluebush) is common increased fire frequency in preventing the throughout the mid to low shrub stratum. regrowth of shrubs. As the grasses come to dominate they further increase the susceptibility 25 perennial species were recorded at the three of the area to future fire. inventory sites, with an average of 15 species per site, four greater than the survey average. Land systems Three annual species were recorded. MSOG is a minor habitat type on Chowilla, The following species (by strata) were recorded Kanandah, Kitchener, Kyarra, Shakehole, as dominant and/or common: Thampanna and Virginia land systems. Trees: Dominant—Eucalyptus gracilis (mallee) Common—Eucalyptus oleosa, Myoporum platycarpum Other—Acacia papyrocarpa.

155 Tall shrubs: Dominant—Myoporum 11. Eucalypt mixed chenopod platycarpum woodland (EXCW) Others—Acacia oswaldii, Eremophila dempsteri, Geijera Sampling linearifolia. 5 inventory sites, 305 traverse points Mid shrubs: Dominant—Cratystylis conocephala General information Common—Atriplex nummularia, Eremophila scoparia (KI) EXCW occurs in the west of the survey area on Other—Nitraria billardierei. calcrete plains overlain by calcareous loam of Low shrubs: Dominant—Atriplex vesicaria varying depth. Fine to medium calcareous (KD), Cratystylis conocephala fragments and nodules (2–20 mm) are Common—Enchylaena common. Soils are calcareous loamy earths. It tomentosa (KD), Maireana also occasionally occurs on calcrete plains erioclada, M. radiata, M. overlain by aeolian sand. sedifolia, Olearia calcarea, Rhagodia crassifolia Physiognomy and composition of vegetation Others—Lycium australe, EXCW occurs as a scattered to moderately Maireana turbinata, Ptilotus closed (15–25 per cent PFC) woodland. When symonii, Solanum nummularium. located on calcrete plains overlain with loam the tree stratum is dominated by Eucalyptus Subshrubs: Dominant—Not present as a gracilis (yorrell) and E. oleosa subsp. oleosa recognisable stratum (giant mallee). When the surface has a shallow Common—Sclerolaena diacantha (KD). aeolian sand cover Eucalyptus salubris (gimlet) is common. The low and mid shrub stratum is Perennial grasses: Dominant—Not present as a dominated by Atriplex vesicaria (bladder recognisable stratum Common—Austrostipa saltbush) and Cratystylis conocephala (false platychaeta (KD). bluebush). Annual species recorded include Carrichtera annua 42 perennial species were recorded at the five (KI), Salsola tragus and Zygophyllum glaucum. inventory sites, with an average of 17 species per site, six greater than the survey average. Ecological disturbance Five annual species were recorded, with an This is a minor site type and was not sampled average of two species per site. for grazing impacts. It is likely that under heavy The following species (by strata) are dominant grazing palatable species will be reduced, and/or common: particularly Atriplex vesicaria (bladder saltbush), Enchylaena tomentosa (ruby saltbush) and Trees: Dominant—Eucalyptus gracilis, Austrostipa platychaeta. ESCW appears to be E. oleosa subsp. oleosa (mallee) largely unaffected by grazing due to the low Common—Alectryon oleifolius, palatability of many of the shrubs. However, Casuarina pauper, Eucalyptus rabbits may have a significant impact on seed- melanoxylon, E. salubris, ling recruitment and therefore floristic diversity Myoporum platycarpum influencing the present day species composi- Other—Acacia papyrocarpa. tion. This habitat type typically does not support Tall shrubs: Dominant—Not present as a grasses in great abundance. recognisable stratum Gradational associations Common—Geijera linearifolia Others—Acacia densiflora (KI), ESCW commonly grades into Eucalypt mixed A. hemiteles (KI), Eremophila chenopod shrubland or woodland (EXCS) or dempsteri, Senna cardiosperma Sugarwood chenopod shrubland or woodland (KI), Exocarpos aphyllus. (SWCS). Mid shrubs: Dominant—Cratystylis conocephala Land systems Common—Atriplex nummularia, ESCW is a major habitat type on Caiguna and Eremophila decipiens (KI), Gumbelt land systems. E. scoparia (KI), Pimelea microcephala, Scaevola

156 spinescens, Senna is surrounded by grass-dominated habitat artemisioides subsp. x coriacea types. This can be observed along the northern (KI) boundary of the Caiguna land system where it Other—Eremophila glabra. borders the Nightshade land system. Low shrubs: Dominant—Atriplex vesicaria (KD), Maireana sedifolia Eucalyptus fraseri subsp. melanobasis is a Common—Eremophila Priority 2 species on the declared rare and pustulata, Frankenia sp., priority flora list, and was recorded in this habitat Maireana erioclada, Olearia type. calcarea, Ptilotus obovatus, Rhagodia crassifolia, Solanum Gradational associations nummularium, Zygophyllum EXCW grades into Eucalypt, sugarwood mixed aurantiacum chenopod woodland (ESCW) or Sugarwood Others—Enchylaena mixed chenopod shrubland (SWCS) as tomentosa, Maireana radiata, Olearia muelleri, Westringia Myoporum platycarpum increases in the tall rigida. shrub and/or tree stratum. Where Myoporum platycarpum and Acacia papyrocarpa replace Subshrubs: Dominant—Not recognisable as eucalypts as the dominant species EXCW a dominant stratum Common—Eriochiton grades into Myall, sugarwood mixed chenopod sclerolaenoides, Maireana woodland (MSCW). trichoptera, Sclerolaena EXCW grades into Eucalypt mixed halophytic diacantha (KD) shrubland (EXHS) where the topsoil becomes Others—Sclerolaena more saline. In the west of the survey area obliquicuspis, Zygophyllum apiculatum. EXCW commonly grades into Eucalypt mixed scrub woodland (EXSW) forming a woodland Perennial grasses: Dominant—Not recognisable as mosaic of variable understorey alternating in a dominant stratum Other—Austrostipa platychaeta dominance between chenopod and mixed (KD). shrubs. Where the soil becomes sandier EXCW grades into Mallee hummock grass Annual species recorded include Nicotiana sp., (spinifex) woodland (MHGW). Ptilotus exaltatus, Salsola tragus, Zygophyllum compressum and Z. eremaeum. In the Mardabilla land zone where granite outcrop occurs through the calcareous plains Ecological disturbance EXCW merges into Dodonaea, eremophila The composition of the understorey is the most mixed shrubland (DEXS) or abuts Granite reliable indicator of grazing impacts. Austrostipa outcrop shrubland (GROS). platychaeta is sensitive to grazing pressure and As the woodland becomes more scattered and may indicate good resource condition when open, EXCW commonly grades into Plain plentiful. In good condition a mix and density of mixed chenopod shrubland (PXCS). palatable low shrub species would be expected in the open and under trees and tall shrubs. An Land systems indication of grazing pressure is a reduction in EXCW is the dominant habitat type on Gumbelt floristic diversity, firstly in the open areas and land system and a major habitat type on then later in the more protected areas under Caiguna and Thampanna land systems. trees and tall shrubs [See tree-based clump condition monitoring photographic guide in the 12. Eucalypt saltbush shrubland or Resource Management chapter.] In poor woodland (ESAW) condition increaser species belonging to the genera Eremophila, Senna and Acacia become Sampling abundant. 4 inventory sites, 71 traverse points EXCW appears to be less susceptible to fire than similar eucalypt shrubland or woodland General information where Austrostipa scabra (speargrass) is ESAW predominantly occurs on low rises common through the lower strata. EXCW tends (limestone hummocks) which are gently to be more at threat from fire where it borders or inclined with up to 6 per cent slope and stony

157 limestone plains in the south-east of the survey Subshrubs: Dominant—Not recognisable as area. ESAW has a mantle composed of fine to a dominant stratum coarse (2–60 mm) limestone fragments Common—Maireana tomentosa covering up to 50 per cent of the surface, with (KD) limestone outcrop occurring in up to 50 per cent Others—Atriplex acutibractea (KI), Sclerolaena diacantha of habitats. Soils are calcareous loamy earths. (KD), S. obliquicuspis, This vegetation unit commonly borders the Zygophyllum apiculatum. Hampton Scarp. Perennial grasses: Dominant—Not recognisable as Physiognomy and composition of vegetation a dominant stratum Common—Austrostipa scabra ESAW occurs as a scattered to moderately Others—Austrostipa acrociliata, closed (10–30 per cent PFC) woodland. The A. elegantissima (KD), tree stratum is dominated by variable A. platychaeta (KD). eucalyptus species, though commonly contains Other plant forms: Occasional—Dianella revoluta Eucalyptus gracilis (yorrell) and/or Eucalyptus (lily), Marsdenia australis yalatensis (yalata mallee). Atriplex nummularia (creeper). (old man saltbush) is commonly present within Annual species recorded include Carrichtera annua the mid shrub stratum and the lower shrub (KI), Euphorbia drummondii and Nicotiana stratum is dominated by Atriplex vesicaria goodspeedii. (bladder saltbush). Ecological disturbance 35 perennial species were recorded at the four inventory sites, with an average of 13 species The close gradational association to chenopod per site, two greater than the survey average. shrubland in lower-lying areas results in lime- Three annual species were recorded. stone hummocks that support ESAW receiving increased utilisation from herbivores. The trees The following species (by strata) are dominant on these limestone rises provide shelter for both and/or common: animals and other plants. ‘Tree-based clumps’ Trees: Dominant—variable; Eucalyptus develop under trees and have an important role diversifolia, E. gracilis, in arid environments in sustaining other plant E. oleosa subsp. ampliata, species by improving conditions, such as E. yalatensis retaining soil moisture and providing protection Others—Eucalyptus urna, from desiccation by wind and sun. In good Myoporum platycarpum. condition a mix and density of palatable shrub Tall shrubs: Dominant—Not present as a and perennial grass species, such as Atriplex recognisable stratum vesicaria, Austrostipa elegantissima (feather Common—Acacia oswaldii Others—Eremophila dempsteri speargrass), A. platychaeta, Chenopodium (KI), Psydrax suaveolens (KD). curvispicatum, Enchylaena tomentosa (ruby saltbush), Maireana tomentosa (felty bluebush), Mid shrubs: Dominant—Atriplex nummularia Ptilotus obovatus (cotton bush), Psydrax Others—Cratystylis conocephala, Scaevola suaveolens and Scaevola spinescens (currant spinescens, Senna bush), would be expected to radiate out from artemisioides subsp. x coriacea under the canopies into the spaces between (KI). tree clumps. An indication of decreasing Low shrubs: Dominant—Atriplex vesicaria rangeland condition would be a reduction in (KD) floristic diversity, first in the open areas and then Common—Enchylaena later in the more protected areas under the tomentosa (KD), Maireana trees [See tree-based clump condition pentatropis, M. sedifolia, monitoring photographic guide in the Resource Olearia muelleri Management chapter.] Others—Chenopodium curvispicatum (KD), Eremophila Gradational associations oblonga, Lawrencia squamata, Maireana erioclada, Ptilotus ESAW grades downslope into Plain mixed obovatus, Zygophyllum chenopod shrubland (PXCS) or Bladder aurantiacum. saltbush shrubland (BSSL) where colluvial-filled depressions lie adjacent to low rises (limestone

158 hummocks) within limestone plains. Where species were recorded, with an average of one myall begins to dominate the overstorey ESAW species per site. grades into Myall saltbush shrubland or The following species were dominant and/or woodland (MSAS). common: Land systems Trees: Dominant—Eucalyptus gracilis, E. oleosa, E. yalatensis ESAW is a dominant habitat type on (mallee) Thampanna land system and a minor type on Common—Eucalyptus Moodini land system. diversifolia (mallee) Others—Acacia aneura, 13. Eucalypt mixed scrub woodland A. papyrocarpa, Alectryon (EXSW) oleifolius, Casuarina pauper, Eucalyptus conglobata (mallee), Sampling E. discreta (mallee), E. fraseri subsp. fraseri, E. oleosa subsp. 27 inventory sites, 232 traverse points oleosa (mallee), E. melanoxylon, E. salubris, General information E. urna, Myoporum platycarpum, EXSW is predominantly found on calcrete Pittosporum angustifolium, plains in the western perimeter of the survey Santalum acuminatum, area. Up to 90 per cent of the surface mantle of S. lanceolatum. the plain is covered by medium to large Tall shrubs: Dominant—Melaleuca (6–60 mm) calcrete nodules; occasionally a lanceolata layer of sand is present. Soils are commonly Common—Eremophila calcareous loams or, occasionally, red loams dempsteri, E. scoparia (KI), and sandy earths where the surface is overlain Geijera linearifolia Others—Acacia hemiteles (KI), by sand. This vegetation association is also A. oswaldii, A. tetragonophylla, present in the south-east of the survey area on Dodonaea lobulata (KI), limestone hummocks (low rises) with gentle Eremophila alternifolia, slopes of up to 3 per cent, on residual E. longifolia, Exocarpos depositional surfaces, formerly aeolian aphyllus, Melaleuca quadrifaria, calcarenite, behind the Hampton scarp face and Senna cardiosperma (KI), along the scarp. Templetonia retusa, T. sulcata. Mid shrubs: Dominant—Atriplex nummularia Physiognomy and composition of vegetation Common—Cratystylis EXSW occurs as a scattered to moderately conocephala, Dodonaea closed (10–25 per cent PFC) woodland or stenozyga, E. scoparia (KI), scrubland. The tree stratum is dominated by Scaevola spinescens, Senna artemisioides subsp. x coriacea eucalypts, commonly Eucalyptus gracilis (KI) (yorrell) and E. oleosa subsp. oleosa (giant Others—Acacia anceps, mallee). Other species are also common but A. ancistrophylla var. their distribution may be restricted such as ancistrophylla, Alyxia buxifolia, Eucalyptus yalatensis (yalata mallee) in the Nitraria billardierei, Acacia south on the Hampton Tableland and nyssophylla, Eremophila E. diversifolia (soap mallee) on the scarp of the decipiens (KI), E. deserti (KI), Hampton Range. The composition of shrubs is E. glabra (KI), E. ionantha, variable though the tall shrub stratum is Leptomeria pachyclada, commonly dominated by Melaleuca lanceolata, Pomaderris myrtilloides, Pultenaea heterochila, Senna the mid shrub stratum by Atriplex nummularia artemisioides subsp. x (old man saltbush) and the low shrub stratum artemisioides (KI), Sida by Westringia rigida. calyxhymenia (KD). 104 perennial species were recorded at the 27 Low shrubs: Dominant—Westringia rigida inventory sites, including two priority species, Common—Atriplex vesicaria with an average of 17 species per site, six (KD), Enchylaena tomentosa greater than the survey average. 11 annual (KD), Eremophila weldii,

159 Maireana erioclada, The increase in abundance of unpalatable M. sedifolia, Olearia calcarea, species such as Acacia hemiteles (tan wattle), Ptilotus obovatus (KD), Dodonaea lobulata (bead hopbush), Eremophila Rhagodia crassifolia scoparia (broom bush), Senna artemisioides Others—Acacia erinacea, subsp. x artemisioides (silver cassia) and Chenopodium curvispicatum Senna artemisioides subsp. x coriacea (desert (KD), Dodonaea caespitosa, Eremophila oblonga, cassia) may be in response to rabbit grazing E. parvifolia (KD), Gunniopsis during post-fire recovery phases. calcarea, Halgania The susceptibility of EXSW to fire is largely andromedifolia, Lawrencia dependent on the development of the grass squamata, Lycium australe, strata within the habitat type. Maireana pentatropis, M. radiata, M. turbinata, Thysanotus baueri a Priority 1 species, on the Microcybe multiflora, Olearia declared rare and priority flora list, and muelleri, Pomaderris Eucalyptus fraseri subsp. melanobasis a myrtilloides, Ptilotus obovatus, Priority 2 species were recorded among this P. symonii, Rhagodia ulicina, eucalypt woodland habitat type. Thysanotus Solanum lasiophyllum, S. nummularium, Tecticornia baueri means the area has a high conservation sp., Zygophyllum aurantiacum value. (KD). Gradational associations Subshrubs: Dominant—Not recognisable as a dominant stratum EXSW occurring in the south-west of the survey Common—Goodenia affinis, borders poorly developed karst depression land Maireana trichoptera, Wurmbea units often supporting Plain mixed chenopod tenella, Zygophyllum apiculatum shrubland (PXCS). In areas where the topsoil Others—Atriplex acutibractea becomes more saline EXSW grades into (KI), Sclerolaena diacantha Eucalypt mixed halophytic shrubland (EXHS) or (KD), S. obliquicuspis (KI), sandier Mallee hummock grass woodland S. patenticuspis (KI), Sida (MHGW). In the west of the survey area EXSW spodochroma. commonly grades into Eucalypt mixed Perennial grasses: Dominant—Not present as a chenopod woodland (EXCW) forming a recognisable stratum woodland mosaic of variable understorey Common—Austrostipa scabra alternating in dominance between chenopod Others—Austrodanthonia caespitosa, Austrostipa and mixed shrubs. Where Casuarina pauper elegantissima (KD), begins to replace eucalypts as the dominant A. platychaeta (KD), Eragrostis tree EXSW may grade into Casuarina mixed leptocarpa, Triodia scariosa. scrub shrubland (CXSS). Other plant forms: Occasional—Comesperma In specific coastal areas Banksia coastal heath volubile (creeper), Dianella and scrubland (BCHS) occurs between EXSW revoluta (lily). and the Baxter Cliffs. On the Roe Plains as the Annual species recorded include Carrichtera annua density of Melaleuca species increases EXSW (KI), Euphorbia drummondii, Podolepis canescens, grades into Eucalypt, melaleuca woodland Salsola tragus (KI), Swainsona formosa, Vittadinia (EMEW). nullarborensis, Zygophyllum compressum, Z. eremaeum, Z. glaucum, Z. iodocarpum (KI) and In the Mardabilla land zone where granite out- Z. ovatum. crop protrudes EXSW merges into Dodonaea, eremophila mixed shrubland (DEXS) or abuts Ecological disturbance Granite outcrop shrubland (GROS). EXSW is largely unaffected by grazing. The Land systems most reliable indication of grazing impact is the diversity and density of palatable low and EXSW is a dominant habitat type on Zanthus subshrubs which are often most numerous land system and a major habitat type on under trees and sparse in the open. Rabbits are Caiguna, Gumbelt, Moodini and Thampanna likely to have had an impact on seedling land systems. regeneration of many of the palatable species.

160 14. Eucalypt mixed halophyte Ecological disturbance shrubland (EXHS) This is a minor habitat type and was not sampled for grazing impacts. Tecticornia Sampling species can be of indicator value when stock 1 inventory site, 17 traverse points water is fresh. If fresh water is available the presence of samphire can indicate good to fair General information condition. Palatable, less-saline shrubs such as EXHS predominantly occurs in depressions in Atriplex vesicaria, Maireana trichoptera (pink- calcrete plains in the south of the survey area. seeded bluebush) and Sclerolaena diacantha Soils are commonly calcareous loamy earths (grey bindii) are likely to be reduced under heavy with saline subsoils. grazing. In such saline locations rabbits may eat juvenile eucalypts and other plants in preference Physiognomy and composition of vegetation to halophytes. EXHS occurs as a very scattered to moderately Gradational associations closed (5–25 per cent PFC) low shrubland of Tecticornia species (samphire) and Atriplex EXHS grades into Eucalypt mixed scrub vesicaria (bladder saltbush). Very scattered woodland (EXSW) or Eucalypt mixed chenopod (2.5–5 per cent PFC) eucalypts form the tree woodland (EXCW) as the topsoil becomes less stratum. saline with increasing soil depth. Where the subsoil remains saline and eucalypts are 19 perennial species, including two species of absent EXHS grades into Plain mixed halophyte Tecticornia, and two annual species were shrubland (PXHS). recorded at the one inventory site and 17 traverse points. Land systems The following species (by strata) are dominant EXHS is a minor habitat type on Caiguna, and/or common: Gumbelt and Thampanna land systems. Trees: Dominant—Eucalyptus gracilis Others—Eucalyptus oleosa, 15. Eucalypt, speargrass open E. oleosa subsp. oleosa grassland (ESOG) (mallee), Myoporum platycarpum. Sampling Tall shrubs: Dominant—Not present as a 2 inventory sites, 15 traverse points recognisable stratum Others—Eremophila dempsteri, General information Myoporum platycarpum. ESOG is located in the central south of the Mid shrubs: Dominant—Atriplex nummularia survey area. It is considered to be an Other—Cratystylis conocephala. irreversible state of a former habitat possibly Low shrubs: Dominant—Atriplex vesicaria once similar to Eucalypt mixed chenopod (KD), Tecticornia doleiformis, woodland (EXCW) or Eucalypt saltbush Tecticornia sp. shrubland or woodland (ESAW). The lower Others—Gunniopsis calcarea, shrub stratum has likely been removed by rabbit Maireana erioclada, M. sedifolia, Olearia calcarea. grazing in conjunction with frequent fires. ESOG occurs on gently inclined low rises (limestone Subshrubs: Dominant—Not present as a hummocks) with up to 2 per cent slope and can recognisable stratum extend down onto the edges of adjacent Others—Maireana trichoptera (KD), Sclerolaena diacantha limestone and calcrete plains. Soils are (KD), S. obliquicuspis. calcareous shallow loams. Small (6–20 mm) fragments of limestone commonly cover up to Perennial grasses: Dominant—Not present as a recognisable stratum 90 per cent of the surface and limestone Others—Austrostipa outcrop occurs through up to 10 per cent of platychaeta (KD), A. scabra. these habitats. Annual species recorded include Brachyscome sp. and Salsola tragus.

161 Physiognomy and vegetation composition Others—Maireana sedifolia, Westringia rigida. ESOG occurs as dense grassland of Austrostipa scabra (speargrass) under very Subshrubs: Dominant—Not present as a recognisable stratum scattered (2.5–10 per cent PFC) mallee-form Common—Maireana trichoptera Eucalyptus yalatensis (yalata mallee) and Other—Sclerolaena diacantha occasionally E. gracilis (yorrell). (KD). 21 perennial species were recorded at the two Perennial grasses: Dominant—Austrostipa scabra inventory sites, with an average of 13 species Others—Austrodanthonia per site, two greater than the survey average. caespitosa, Austrostipa Four annual species were recorded. platychaeta (KD). The following species (by strata) are dominant Annual species recorded include Carrichtera annua and/or common: (KI), Podolepis canescens, Salsola tragus and Zygophyllum glaucum. Trees: Dominant—Eucalyptus yalatensis (mallee) Ecological disturbance Others—Eucalyptus gracilis ESOG is an altered vegetation association in an (mallee), Myoporum platycarpum, Pittosporum irreversible state of transition. Large mallee angustifolium. roots are capable of upheaving limestone boulders as they grow. Many of these eucalypts Tall shrubs: Dominant—Not present as a recognisable stratum and the associated understorey have been killed Common—Geijera linearifolia by increased fires. Holes containing burnt Others—Acacia oswaldii, stumps and charcoal surrounded by upheaved Dodonaea stenozyga, limestone boulders are the only evidence for Eremophila alternifolia (KI), this vegetation association once supporting E. dempsteri. more eucalypts. The increased fire frequency is Mid shrubs: Dominant—Not present as a a result of activities associated with European recognisable stratum settlement. Plant recovery is further hindered by Common—Eremophila scoparia the grazing of juvenile shrubs and tree shoots (KI) that germinate or resprout following fire. The Others—Chenopodium dominance of Austrostipa scabra further curvispicatum (KD), Cratystylis increases the susceptibility of the area to fire. conocephala. Speargrass is readily eaten when young and Low shrubs: Dominant—Not present as a green, but has reduced palatability when dry. recognisable stratum Dry conditions following good seasons make Common—Enchylaena this a combustible fuel source. tomentosa (KD), Maireana erioclada

Remnant yalata mallee (Eucalyptus yalatensis) Intact mallee woodland considered to be the former surrounded by grassland. Burnt stumps and charcoal condition of ESOG prior to an increased fire regime. fragments are common through the area indicating it Mallee-form yorrell (Eucalyptus gracilis) and yalata once supported woodland. mallee (Eucalyptus yalatensis) dominate.

162 Gradational associations pauper (black oak) and the shrub stratum by Maireana sedifolia (pearl bluebush). A very ESOG often occurs on low limestone rises, scattered (2.5–10 per cent PFC) mid shrub crests and gently undulating ridges grading layer of Atriplex nummularia (old man saltbush) down into Speargrass and wallaby grass open and Cratystylis conocephala (false bluebush) is grassland (SWOG) surrounding the rise or commonly present. ridge. On the land systems where ESOG occurs it is more common along the northern 39 perennial species were recorded at the eight perimeter of the Hampton Tableland where it inventory sites, with an average of 15 species merges into the vegetation associations of the per site, four more than the survey average. 11 Nullarbor Plain often dominated by a grass annual species were recorded, with an average component, maintaining increased fire of three species per site. susceptibility. The following perennial species (by stratum) are Land systems dominant and/or common: Trees: Dominant—Casuarina pauper ESOG is a minor habitat type on Caiguna, Common—Acacia papyrocarpa, Nightshade and Thampanna land systems. Alectryon oleifolius Others—Myoporum platycarpum, Pittosporum C. CASUARINA SHRUBLAND AND angustifolium, Santalum WOODLAND ON CALCRETE acuminatum. PLAINS Tall shrubs: Dominant—Not present as a recognisable stratum This group occurs on calcrete plains in the Others—Acacia burkittii (KI), north-west of the survey area. The vegetation in A. oswaldii, A. tetragonophylla, this group is dominated by an overstorey of Geijera linearifolia. Casuarina pauper (black oak). Casuarina Mid shrubs: Dominant—Atriplex nummularia, woodlands commonly occur on low rises or on Cratystylis conocephala low fault scarps within the calcrete plain of the Common—Eremophila scoparia Nyanga land zone, as well as on the plain itself. (KI), Senna artemisioides Isolated casuarina shrubland or woodland also subsp. x coriacea (KI) occur on residual calcrete low rises overlying Other—Eremophila glabra (KI). Nullarbor Limestone out on the Nullarbor Plain. Low shrubs: Dominant—Maireana sedifolia Common—Atriplex vesicaria 16. Casuarina mixed chenopod (KD), Chenopodium shrubland or woodland (CXCS) curvispicatum (KD), Enchylaena tomentosa (KD), Maireana Sampling erioclada, Ptilotus obovatus Others—Lycium australe, 8 inventory sites, 111 traverse points Maireana radiata, Olearia calcarea, Rhagodia crassifolia General information (KD), Solanum lasiophyllum, CXCS is commonly found on calcrete plains S. nummularium. and low rises with a common to abundant Subshrubs: Dominant—Not present as a (20–90 per cent) mantle of fine to large calcrete recognisable stratum fragments and nodules (0.6–20 cm) and Common—Atriplex acutibractea occasional outcrop (< 10 per cent). Soils are (KI), Maireana trichoptera, calcareous shallow loams and loamy earths. Sclerolaena diacantha (KD) Very gentle slopes rarely exeed 2 per cent. Others—Eriochiton sclerolaenoides, Sclerolaena CXCS may also occur where shallow deposits obliquicuspis. of sand overlie calcrete plains. Perennial grasses: Dominant—Not present as a Physiognomy and composition recognisable stratum Common—Austrostipa scabra CXCS occurs as a very scattered to moderately Others—Austrodanthonia closed (2.5–30 per cent PFC) low woodland. caespitosa, Austrostipa The tree stratum is dominated by Casuarina elegantissima (KD),

163 A. platychaeta (KD), Kanandah, Naretha, Nightshade, Pondana and Enneapogon caerulescens, Vanesk land systems. E. cylindricus. Other plant forms: Occasional—Marsdenia 17. Casuarina mixed scrub shrubland australis (creeper). (CXSS) Annual species recorded include Brachyscome ciliaris, Calocephalus knappii, Carrichtera annua (KI), Sampling Euphorbia drummondii, Mesembryanthemum 2 inventory sites, 17 traverse points crystallinum, Ptilotus exaltatus, Salsola tragus, Vittadinia humerata, Zygophyllum eremaeum, General information Z. iodocarpum (KI) and Z. ovatum. CXSS occurs in the north-west of the survey Ecological disturbance area. It is most common on calcrete plains with Palatable perennial species such as Atriplex a sparse (2–20 per cent) mantle composed of vesicaria (bladder saltbush), Austrostipa calcrete fragments and nodules. It is also found elegantissima (feather speargrass), on calcrete plains overlain by sand. Soils are A. platychaeta, Chenopodium curvispicatum, calcareous loamy earths and shallow loams or Enchylaena tomentosa (ruby saltbush), red shallow loams where the surface is overlain Enneapogon caerulescens (limestone grass) with sand. Ptilotus obovatus (cotton bush) and Rhagodia Physiognomy and composition of vegetation crassifolia may be removed through excessive grazing of the understorey. Browsing pressure CXSS occurs as a scattered (10–20 per cent is commonly indicated by the condition of PFC) tall shrubland of acacias, eremophilas Alectryon oleifolius (mingah bush, bullock bush) and sennas. The tree stratum comprises very and, to a lesser degree, Pittosporum scattered (2.5–5 per cent PFC) Casuarina angustifolium (native willow) and Santalum pauper (black oak). The mid and low shrub acuminatum (quandong). Browse lines indicate stratum is commonly composed of very scat- moderate grazing but broken limbs and tered Atriplex nummularia (old man saltbush) smashed canopies indicate heavy grazing and and Maireana sedifolia (pearl bluebush). total grazing pressure at an unsustainable level. 29 perennial species were recorded at the two [See tree-based clump condition monitoring inventory sites, with an average of 20 species photographic guide in the Resource per site, nine greater than the survey average. Management chapter.] Improving range Two annual species were recorded. condition is indicated by the development of clumps of palatable shrubs under trees and The following species (by strata) are dominant dense foliage on Alectryon oleifolius. Rabbit and/or common: warrens were often common. The presence of Trees: Dominant—Casuarina pauper warrens and/or past fires was often associated Common—Myoporum with poor condition ratings for CXCS. platycarpum Others—Acacia aneura, Gradational associations A. papyrocarpa, Alectryon oleifolius, Pittosporum CXCS commonly grades into Myall mixed angustifolium. chenopod shrubland or woodland (MXCW), as Tall shrubs: Dominant—Not present as a Acacia papyrocarpa becomes increasingly recognisable stratum dominant in the overstorey. Where CXCS is Others—Acacia burkittii (KI), located on calcrete rises and faultline low ridges A. tetragonophylla. it commonly grades downslope into Plain mixed Mid shrubs: Dominant—Atriplex nummularia chenopod shrubland (PXCS). In the north-west Common—Eremophila latrobei CXCS grades into Mulga mixed shrub woodland subsp. latrobei, Scaevola (MUXW) as mulga begins to dominate the tree spinescens, Senna stratum. artemisioides subsp. x coriacea (KI) Land systems Others—Eremophila glabra (KI), CXCS is a major habitat type on Nyanga land E. scoparia (KI), Senna system and a minor habitat type on Gumbelt, artemisioides subsp. x artemisioides (KI).

164 Low shrubs: Dominant—Maireana sedifolia 18. Casuarina, acacia open shrubland Common—Atriplex vesicaria (CAOS) (KD), Chenopodium curvispicatum (KD), Ptilotus Sampling obovatus (KD) Others—Sida calyxhymenia 2 inventory sites, 8 traverse points (KD), Solanum nummularium, Westringia rigida. General information Subshrubs: Dominant—Not present as a CAOS is restricted to the mid-west of the recognisable stratum. survey area, primarily the 1:250 000 Naretha Others—Maireana trichoptera map sheet. It occurs on residual calcrete low (KD), Sclerolaena obliquicuspis. rises with gentle slopes to 3 per cent. Large Perennial grasses: Dominant—Not present as a stones (6–20 cm) cover 50–90 per cent of the recognisable stratum surface. Soils are calcareous shallow loams Common—Austrostipa scabra, and loamy earths. Enneapogon cylindricus Others—Austrodanthonia Physiognomy and composition of vegetation caespitosa, Enneapogon caerulescens. CAOS occurs as a scattered tall shrubland of Acacia burkittii (jam) and Alectryon oleifolius Other plant forms: Occasional—Marsdenia australis (creeper). (mingah bush, bullock bush) trees (up to 15 per cent PFC) with an overstorey of very scattered Annual species recorded include Eriachne pulchella Casuarina pauper (black oak) to 10 per cent subsp. pulchella and Salsola tragus. PFC. Ecological disturbance 19 perennial species were recorded at the two A diverse mix of the following palatable inventory sites, with an average of 11 species perennials would be indicative of an area in per site, the same as the survey average. Two good resource condition: Atriplex vesicaria annual species were recorded. (bladder saltbush), Chenopodium The following species (by strata) are dominant curvispicatum, Maireana trichoptera (pink- and or common: seeded bluebush), Ptilotus obovatus (cotton Trees: Dominant—Casuarina pauper bush), Scaevola spinescens (currant bush) and Common—Alectryon oleifolius Sida calyxhymenia (tall sida). Acacia burkittii Others—Acacia aneura, (jam), Senna artemisioides subsp. x A. papyrocarpa. artemisioides (silver cassia) and Senna Tall shrubs: Dominant—Acacia burkittii (KI) artemisioides subsp. x coriacea (desert cassia) Other—Acacia oswaldii. may increase under heavy grazing or frequent burning. Mid shrubs: Dominant—Not present as a recognisable stratum Gradational associations Other—Eremophila scoparia (KI). CXSS grades into Mixed acacia open shrubland Low shrubs: Dominant—Not present as a (XAOS) and Mixed shrub bindii grassland recognisable stratum (XSBG) where the underlying Nullarbor Others—Chenopodium Limestone geology is indurated by calcrete. curvispicatum, Enchylaena Where soils become increasingly sandier and tomentosa, Maireana erioclada, eucalypts begin to dominate the tree strata Ptilotus obovatus (KD). CXSS may grade into Eucalypt mixed scrub Subshrubs: Dominant—Not present as a woodland (EXSW). recognisable stratum Common—Eriochiton Land systems sclerolaenoides, Sclerolaena CXSS is a minor habitat type on Gumbelt, diacantha (KD) Naretha and Nyanga land systems. Others—Atriplex acutibractea (KI), Maireana trichoptera (KD), Sclerolaena obliquicuspis (KI), S. patenticuspis (KI).

165 Perennial grasses: Dominant—Not present as a D. SHRUBLAND AND WOODLAND recognisable stratum Common—Enneapogon ON CALCRETE PLAINS cylindricus OVERLAIN BY SHALLOW SAND Other—Enneapogon caerulescens. This group of habitat types commonly occurs on calcrete plains overlain by shallow sheets of Annual species recorded include Lepidium sp. and Salsola tragus. aeolian sand. They typically support closed woodland or tall shrubland dominated by Ecological disturbance acacias or mallee-form eucalypts. This group of habitat types is found in the north-west of the The limited structure and composition of the survey area. mid and low shrub strata are an indication of the level of animal usage these habitats receive. This is further demonstrated by the presence of 19. Mallee hummock grass (spinifex) rabbit warrens, recent cattle activity and rem- woodland (MHGW) nant root stumps in deteriorating plant mounds. Samples Commonly the soil surface is poor owing to the high level of animal disturbance, with less than 7 inventory sites, 47 traverse points 40 per cent surface crusting. The combination General information of the landform and associated vegetation mean these low calcrete rises appeal to herbivores. MHGW occurs on calcrete plains overlain by The soil development associated with the shallow aeolian sand or calcareous aeolian calcrete, compared to the surrounding skeletal sandplain. Calcrete nodules are often present at soils associated with the Nullarbor Limestone, a depth of greater than 30 cm. Fine to coarse supports trees and provides suitable locations calcrete nodules (2–60 mm) may cover up to for rabbit warrens. Rabbit piospheres radiating 2 per cent of the surface. Soils are calcareous out from warrens are common. Trees provide loamy earths and red shallow sand and loams. shelter and browse for large herbivores and MHGW is located in the north-west and west of many areas have the appearance of livestock the survey area. ‘camps’, particularly when favourable browse such as Alectryon oleifolius is present. The Physiognomy and composition of vegetation condition of Alectryon oleifolius groves indicates MHGW consists of a scattered to closed the grazing pressure in an area. [See tree- (15–50 per cent PFC) low woodland of mallee- based clump condition monitoring photographic form eucalypts over an understorey of dense guide in the Resource Management chapter.] Triodia scariosa (spinifex). The most common The breakdown of Alectryon oleifolius groves is eucalypt to dominate MHGW is Eucalyptus an indication of poor range condition and oleosa subsp. oleosa (giant mallee). overgrazing. The development of clumps of 27 perennial species were recorded at the palatable shrubs under trees and dense foliage seven inventory sites, with an average of nine on Alectryon oleifolius indicates range condition species per site, two less than the survey is improving. average. No annual species were recorded. Gradational associations The following species (by strata) were dominant CAOS grades into Mixed acacia open and/or common: shrubland (XAOS) as residual calcrete low rises Trees: Dominant—Eucalyptus oleosa give way to the underlying Nullarbor Limestone. subsp. oleosa Common—Allocasuarina Land systems helmsii, Eucalyptus concinna, CAOS is a minor habitat type of the Nyanga and E. gracilis, E. oleosa, Santalum acuminatum Kitchener land systems. Other—Eucalyptus melanoxylon. Tall shrubs: Dominant—Not present as a recognisable stratum Common—Exocarpos aphyllus, Melaleuca eleuterostachya

166 Others—Acacia densiflora, earths. This site type is more closely related to A. hemiteles, A. ligulata, mulga vegetation communities more common A. rigens, Eremophila caperata, to the northern Coolgardie and south-western E. dempsteri. Great Victoria Desert Biogeographic Regions Mid shrubs: Dominant—Not present as a than those of the Nullarbor Biogeographic recognisable stratum Region. The presence of MUXW represents the Common—Scaevola spinescens beginning of a transition between the three Others—Eremophila decipiens, botanical regions. Melaleuca uncinata, Rulingia craurophylla, Senna Physiognomy and composition of vegetation artemisioides subsp. x coriacea. MUXW comprises a closed (30–50 per cent Low shrubs: Dominant—Not present as a recognisable stratum PFC) low woodland of Acacia aneura (mulga) Common—Westringia rigida with an understorey of mixed shrubs. The lower Others—Acacia camptoclada, shrub stratum is commonly dominated by A. xerophila, Grevillea acuaria, scattered (15–20 per cent PFC) Ptilotus Olearia calcarea. obovatus (cotton bush). Subshrubs: Dominant—Not present as a 18 perennial species were recorded at the one recognisable stratum inventory site and seven traverse points. No Other—Scaevola collaris. annual species were recorded. Perennial grasses: Dominant—Triodia scariosa Common—Nil. The following species were dominant and/or common: Ecological disturbance Trees: Dominant—Acacia aneura MHGW is largely unaffected by grazing. Spinifex Others—Acacia papyrocarpa, hummock grass and most shrubs associated Casuarina pauper. with this habitat are not favoured by stock. The Tall shrubs: Dominant—Not present as a grazing value is generally seasonally dependent, recognisable stratum with heavy rains promoting new plant growth, Others—Acacia tetragonophylla, particularly after fire. Alectryon oleifolius, Dodonaea lobulata (KI), Eremophila Gradational associations alternifolia (KI). Mid shrubs: Dominant—Not present as a MHGW occurs as a component of a broader recognisable stratum eucalypt woodland mosaic, grading into Others—Atriplex nummularia, Eucalypt mixed chenopod woodland (EXCW), Senna artemisioides subsp. x Eucalypt mixed scrub woodland (EXSW) and coriacea (KI). Sugarwood mixed chenopod shrubland or Low shrubs: Dominant—Ptilotus obovatus woodland (SWCS) on calcrete plains. Near Lake (KD) Boonderoo MHGW grades downslope into Others—Enchylaena tomentosa Sandy bank lake shrubland (SBLS). (KD), Maireana pentatropis, M. sedifolia, M. thesioides (KD), Land systems Solanum lasiophyllum, MHGW is the dominant habitat type on the S. nummularium. Zanthus land system. Subshrubs: Dominant—Not present as a recognisable stratum 20. Mulga mixed shrub woodland Other—Solanum ellipticum. (MUXW) Perennial grasses: Dominant—Not present as a recognisable stratum Sampling Other—Enneapogon caerulescens. 1 inventory site, 7 traverse points Ecological disturbance General information This site type was not adequately sampled to This minor vegetation association is found on discuss grazing impacts. However, patterns for calcrete plains overlain by sand in the north- similar mulga-dominated woodlands from west of the survey area. Soils are red loamy previous rangeland surveys in the Coolgardie,

167 Great Victoria Desert and Murchison The following species (by strata) are dominant Biogeographic Regions (Curry et al. 1994; and/or common: Pringle, Van Vreeswyk & Gilligan 1994; Payne Trees: Dominant—Not present as a et al. 1998) provide some indication of the likely recognisable stratum grazing impacts. In good condition, palatable Others—Acacia aneura, shrubs such as Ptilotus obovatus, Enchylaena A. papyrocarpa, Casuarina tomentosa (ruby saltbush) and Maireana pauper. thesioides (lax bluebush) would be expected to Tall shrubs: Dominant—Variable; Acacia be common. Conversely, a history of heavy oswaldii, A. tetragonophylla (KI) grazing would be indicated by an abundance of Common—Nil. Dodonaea lobulata (bead hopbush) and Senna Mid shrubs: Dominant—Atriplex nummularia artemisioides subsp. x coriacea (desert cassia) Common—Eremophila latrobei and a noticeable absence of palatable species. (KD), E. sp. Others—Senna artemisioides Gradational associations subsp. artemisioides (KI), Sida MUXW grades into Casuarina mixed chenopod calyxhymenia (KD). shrubland or woodland (CXCS) and Myall mixed Low shrubs: Dominant—Not present as a chenopod shrubland or woodland (MXCS) as recognisable stratum Acacia aneura disappears from the tree strata, Others—Atriplex vesicaria (KD), replaced by either Casuarina pauper or Acacia Chenopodium curvispicatum (KD), Maireana sedifolia, papyrocarpa respectively. Ptilotus obovatus. Land systems Subshrubs: Dominant—Not present as a recognisable stratum MUXW is a minor habitat type on Gumbelt and Common—Atriplex acutibractea Nyanga land systems. (KI), Eriochiton sclerolaenoides. Perennial grasses: Dominant—Occasionally 21. Acacia mixed shrubland (ACMS) Enneapogon cylindricus Sampling Common—Nil. Annual species recorded include Euphorbia 1 inventory site, 9 traverse points drummondii and Salsola tragus. General information Ecological disturbance ACMS is a minor habitat type in the Western ACMS was not sampled sufficiently for detailed Nullarbor but has previously been described in analysis of grazing impacts. Continuous heavy the Carnarvon Basin (Payne, Curry & Spencer grazing is likely to result in a reduction in 1987). In the Western Nullarbor ACMS occurs palatable species such as Atriplex vesicaria on calcrete plains overlain by sand and/or (bladder saltbush), Enchylaena tomentosa calcareous loams in the north-west of the (ruby saltbush), Chenopodium curvispicatum, survey area. Soils are calcareous shallow Eremophila latrobei (warty-leaf eremophila) and loams or red sandy earths where the surface is Sida calyxhymenia (tall sida). With declining overlain by aeolian sand. condition an increase in unpalatable species Physiognomy and composition of vegetation such as Acacia tetragonophylla (curara) and Senna artemisioides subsp. artemisioides ACMS commonly occurs as a scattered to (silver cassia) may occur. closed (10–50 per cent PFC) tall scrubland of sclerophyllous shrubs, commonly dominated by Gradational associations species of Acacia, Eremophila and Senna. ACMS grades into Myall mixed chenopod When present Enneapogon cylindricus is the shrubland or woodland (MXCS) as the overlying dominant perennial grass. sand disappears. 16 perennial species and two annual species Land systems were recorded at the one inventory site and nine traverse points. ACMS is a minor habitat type on Nyanga land system.

168 E. SHRUBLAND ASSOCIATED WITH Tall shrubs: Dominant—Dodonaea lobulata (KI) GRANITIC OUTCROP Common—Eremophila This group of habitat types predominantly alternifolia occurs within the Mardabilla land zone, where Others—Acacia burkittii (KI), A. tetragonophylla, Geijera granite outcrop protrudes through limestone and linearifolia. calcrete plains. These habitat types are dominated by sclerophyllous vegetation Mid shrubs: Dominant—Not present as a recognisable stratum including Senna, Eremophila and Ptilotus, Others—Atriplex nummularia, occurring as scattered to moderately closed, tall Eremophila decipiens, and mid shrubland. Sparse trees and grasses E. latrobei (KD), Senna are also present. Soils tend to be shallow. artemisioides subsp. x artemisioides (KI). 22. Dodonaea, eremophila mixed Low shrubs: Dominant—Ptilotus obovatus shrubland (DEXS) (KD) Common—Solanum Sampling nummularium 2 inventory sites, 11 traverse points. Others—Chenopodium curvispicatum, Enchylaena General information tomentosa, Maireana pentatropis, Olearia axillaris. DEXS is commonly found associated with the Subshrubs: Dominant—Not present as a slopes of granite domes and outcrop within the recognisable stratum Mardabilla land zone. Increased water catch- Others—Sclerolaena ment at the margin of the granite outcrop patenticuspis, Sida promotes dense shrubland. Medium to large spodochroma, Solanum (6–60 cm) stones of granite mixed with calcrete ellipticum. fragments cover up to 90 per cent of the Perennial grasses: Dominant—Not present as a surface. Granite outcrop occurs through 10 per recognisable stratum cent of these habitats. Soils are red shallow Others—Austrodanthonia sands and calcareous shallow loams. DEXS caespitosa, Enneapogon also occur in the central west of the survey area caerulescens, E. cylindricus. where sand and calcrete nodules overlie Annual species recorded include Brachyscome sp. calcrete plains of the Nyanga land zone. and Salsola tragus. Physiognomy and composition of vegetation Ecological disturbance DEXS occurs as a moderately closed This habitat type was not sufficiently sampled (20–25 per cent PFC) tall shrubland of variable to investigate disturbance impacts as the composition, mostly dominated by Eremophila proportion it occupies in the survey area is alternifolia or Dodonaea lobulata (bead small. DEXS appeared to be largely unaffected hopbush). by domestic grazing. 24 perennial species were recorded at the two Gradational associations inventory sites, with an average of 13 species per site, two greater than the survey average. In the south-west of the survey area DEXS Two annual species were recorded. abuts Granite outcrop shrubland (GROS) or grades into the Eucalypt mixed chenopod The following species (by strata) were dominant woodland (EXCW) or Eucalypt mixed scrub and/or common: woodland (EXSW) surrounding the granite Trees: Dominant—Not present as a outcrop. In the central west of the survey area recognisable stratum DEXS commonly grades into Mixed acacia Common—Pittosporum open shrubland (XAOS). angustifolium Others—Acacia aneura, Land system Eucalyptus gracilis (mallee). DEXS is a major habitat type on Balladonia land system and a minor type on Nyanga land system.

169 23. Granite outcrop shrubland (GROS) Sclerolaena patenticuspis, Sida spodochroma, Solanum Sampling nummularium Others—Eriochiton 4 inventory sites, 9 traverse points sclerolaenoides, Sclerolaena General information cuneata, S. diacantha, S. obliquicuspis. GROS is found in association with granite Perennial grasses: Dominant—Not present as a outcrop and low granite rises in the south-west recognisable stratum of the survey area within the Mardabilla land Common—Austrodanthonia zone. Soils are red shallow loams. Coarse caespitosa, Austrostipa scabra. granitic and calcareous fragments (2–20 cm) Other plant forms: Occasional—Carpobrotus sp. cover up to 10 per cent of the surface with (succulent perennial herb), granite outcrop occurring through up to 50 per Cheilanthes lasiophylla (fern). cent of the area. The granite outcrop may rise to Annual species recorded include Brachyscome sp., 5 m. Calandrinia sp., Carrichtera annua (KI), Eriachne Physiognomy and composition of vegetation aristidea, Goodenia sp., Mesembryanthemum crystallinum, M. nodiflorum, Salsola tragus, Senecio GROS comprises a very scattered to scattered quadridentatus and Vittadinia nullarborensis. mid to tall shrubland (5–20 per cent PFC) of variable composition. The lower shrub stratum Ecological disturbance is commonly dominated by Ptilotus obovatus Different soil chemistries associated with (cotton bush). granitic and calcareous rock types are the likely 32 perennial species were recorded at the four reason for the natural variation in the species inventory sites, with an average of 13 species composition of this habitat. An abundance of per site, two greater than the survey average. palatable species such as Austrodanthonia 10 annual species were recorded, with an caespitosa (wallaby grass), Chenopodium average of four species per site. curvispicatum, Enchylaena tomentosa (ruby saltbush), Maireana georgei (golden bluebush), The following species (by strata) were dominant Ptilotus obovatus and Sida calyxhymenia (tall and/or common: sida) indicates that GROS is in good condition. Tall shrubs: Dominant—Variable; Dodonaea Rainwater accumulation in depressions within lobulata (KI) granite outcrop offers an ephemeral water Common—Acacia ligulata (KI), source. These areas will receive concentrated Eremophila alternifolia, grazing pressure from native and introduced Myoporum platycarpum. animals whilst ephemeral pools remain. In such Mid shrubs: Dominant—Variable; Acacia instances palatable flora is likely to be greatly ligulata (KI), Atriplex reduced and the immediate area may become nummularia dominated by unpalatable species such as Common—Sida calyxhymenia Acacia ligulata, Dodonaea lobulata (bead (KD) hopbush) and Eremophila deserti. Others—Eremophila deserti (KI), Pimelea microcephala Gradational associations Low shrubs: Dominant—Variable; Ptilotus GROS commonly abuts Dodonaea, eremophila obovatus (KD) Common—Atriplex vesicaria, mixed shrubland (DEXS) or is bordered by Enchylaena tomentosa (KD), Eucalypt mixed chenopod woodland (EXCW) or Rhagodia ulicina Eucalypt mixed scrub woodland (EXSW) with Others—Atriplex stipitata, the resumption of the overlying calcareous Chenopodium curvispicatum plains. (KD), Maireana erioclada, M. georgei (KD), M. sedifolia, Land systems Olearia calcarea, Tecticornia GROS is a major habitat type on Balladonia sp. land system. Subshrubs: Dominant—Not present as a recognisable stratum Common—Boerhavia repleta,

170 F. SHRUBLAND ON CALCAREOUS Physiognomy and composition of vegetation PLAINS SWCS comprises a scattered (10–20 per cent PFC) tall shrubland. The tree and/or tall shrub This group of habitats consists of ‘succulent stratum is dominated by Myoporum steppe’ according to Beard (1975). It is platycarpum (sugarwood) and the shrub characterised by a dominant low shrub stratum stratum by Maireana sedifolia (pearl bluebush). frequently containing species from the genera Atriplex and Maireana of the Chenopodiaceae 35 perennial species were recorded at the four family. These shrubs are well adapted to arid inventory sites, with an average of 13 species environments. This habitat is common through- per site, two greater than the survey average. out the Nullarbor. Four annual species were recorded, with an average of two species per site. This habitat group occurs from the Nullarbor through to the Pilbara and is considered to have The following species (by strata) are dominant some of the highest pastoral value in the arid and or common: southern shrublands. Hacker (1979) researched Trees: Dominant—Myoporum the ecology and impact of grazing on chenopod platycarpum shrubland present on depositional landscapes. Common—Nil. The research was conducted on Glenorn Tall shrubs: Dominant—Myoporum Station in the north-eastern Goldfields. Hacker platycarpum concluded excessive grazing pressure reduced Common—Geijera linearifolia shrub cover which in turn led to the extension of Other—Exocarpos aphyllus. naturally present small scalds. Once scalds Mid shrubs: Dominant—Not present as a had extended beyond a certain threshold a recognisable stratum reduction in grazing pressure was not enough Common—Atriplex nummularia, to reverse the process. Scalded surfaces are Cratystylis conocephala less productive and become unsuitable as Others—Acacia nyssophylla, germination sites for most plants. These Eremophila decipiens (KI), findings are reinforced throughout the Nullarbor E. deserti (KI), E. glabra (KI), survey area and are particularly evident from Nitraria billardierei, Scaevola spinescens. satellite imagery highlighting the piosphere effect around water points, especially within the Low shrubs: Dominant—Maireana sedifolia Nullarbor land zone. The coalescing effect of Common—Atriplex vesicaria (KD), Gunniopsis calcarea, scalds in heavily utilised areas emphasises the Lycium australe, Maireana importance of monitoring vegetation, and erioclada, Rhagodia ulicina appropriately responding to deteriorating Others—Chenopodium condition, in order to prevent this process, curvispicatum (KD), Enchylaena which leads to reduced landscape function and tomentosa (KD), Frankenia sp., resilience. Maireana turbinata, Olearia calcarea, Ptilotus symonii, 24. Sugarwood mixed chenopod Solanum nummularium, shrubland (SWCS) Zygophyllum aurantiacum. Subshrubs: Dominant—Not present as a Sampling recognisable stratum Common—Maireana trichoptera, 4 inventory sites, 106 traverse points Sclerolaena diacantha (KD), General information Sida spodochroma Others—Atriplex acutibractea SWCS is predominantly found on stony (KI), Eriochiton sclerolaenoides, limestone or calcrete plains overlain by Sclerolaena patenticuspis (KI). calcareous loams in the west of the survey Perennial grasses: Dominant—Not present as a area. Soils are calcareous shallow loams or recognisable stratum clay loams. Common—Austrodanthonia caespitosa, Austrostipa scabra Others—Austrostipa platychaeta (KD), Panicum effusum.

171 Annual species recorded include Brachyscome sp., Physiognomy and composition of vegetation Euphorbia drummondii, Nicotiana goodspeedii and Salsola tragus. PBLS comprises a very scattered to scattered (10–15 per cent PFC) low shrubland of Ecological disturbance Maireana sedifolia (pearl bluebush), occasion- Dense stands of juvenile Myoporum ally moderately closed (< 25 per cent PFC). A platycarpum frequently occur in the south of the sparse mid shrub stratum of mixed shrubs is survey area. It is thought this is in response to sometimes present. reduced grazing pressure from rabbits due to 47 perennial species were recorded at the 24 the rabbit calicivirus. Myoporum platycarpum inventory sites, with an average of 10 species was also observed recolonising some recently per site, one less than the survey average. 23 burnt areas. annual species were recorded, with an average Gradational associations of five species per site. The following species by strata were dominant SWCS often occurs as a transitional habitat and/or common: type, as shallow calcareous loams marginally deepen, between Myall mixed chenopod Trees: Dominant—Not present as a shrubland or woodland (MXCS), Eucalypt mixed recognisable stratum chenopod woodland (EXCW) or Eucalypt, Common—Myoporum sugarwood mixed chenopod woodland (ESCW) platycarpum (in the south) Others—Acacia papyrocarpa, and Plain mixed chenopod shrubland (PXCS), Eremophila longifolia, occurring in clay depressions or corridors Pittosporum angustifolium. between low-lying ridges. Where the soil Tall shrubs: Dominant—Not present as a surface becomes sandier SWCS grades into recognisable stratum Mallee hummock grass (spinifex) woodland Common—Acacia oswaldii. (MHGW). Mid shrubs: Dominant—Not present as a Land systems recognisable stratum Common—Senna artemisioides SWCS is a major habitat type on Nanambinia subsp. artemisioides (KI) land system and a minor habitat type on Others—Atriplex nummularia, Woorlba land system. Cratystylis conocephala, Eremophila maculata, Senna 25. Pearl bluebush low shrubland artemisioides subsp. x coriacea (PBLS) (KI), S. artemisioides subsp. petiolaris, Sida calyxhymenia. Sampling Low shrubs: Dominant—Maireana sedifolia 24 inventory sites, 1202 traverse points Common—Atriplex vesicaria (KD), Chenopodium General information curvispicatum (KD), Lawrencia squamata, Lycium australe, PBLS is the most common vegetation associa- Ptilotus obovatus tion in the Nullarbor land zone as well as one of Others—Atriplex cryptocarpa, the most common communities throughout the Enchylaena tomentosa, entire survey area. It is found on the stony Gunniopsis calcarea, Maireana slopes and crests of the undulating limestone erioclada, M. radiata, plains of the Nullarbor Plain. PBLS occurs on M. turbinata, Solanum gently undulating stony slopes up to 3 per cent, nummularium, Tecticornia sp., but often less than 2 per cent, with up to 90 per Zygophyllum aurantiacum. cent of the surface covered by medium to Subshrubs: Dominant—Not present as a coarse limestone fragments (6–60 mm). Soils recognisable stratum are shallow calcareous loams with limestone Common—Atriplex acutibractea (KI), Eriochiton sclerolaenoides outcrop generally occurring through less than (KD), Sclerolaena diacantha 10 per cent of the habitat type. On the calcrete (KD), S. obliquicuspis (KI), plains of the Nyanga Plain PBLS is less S. patenticuspis (KI), Sida common. The mantle is variably stony. spodochroma, Solanum ellipticum, Wurmbea tenella

172 Others—Desmocladus vegetation association has good diversity, myriocladus, Maireana including palatable perennials such as Atriplex trichoptera, Minuria vesicaria (bladder saltbush) and Chenopodium cunninghamii curvispicatum, numerous subshrubs (i.e. Perennial grasses: Dominant—Austrostipa scabra Eriochiton sclerolaenoides, Sclerolaena Common—Austrodanthonia diacantha) and palatable grasses such as caespitosa, Austrostipa Austrodanthonia caespitosa (wallaby grass) platychaeta (KD) and Austrostipa platychaeta. In fair condition Others—Austrostipa nitida, these species will be reduced and replaced by Enneapogon caerulescens, E. cylindricus, Eragrostis less palatable, seasonally dependent facultative setifolia. perennials Atriplex acutibractea (toothed saltbush), Sclerolaena obliquicuspis (limestone Other plant forms: Occasional—Glycine rubiginosa bindii) and S. patenticuspis (spear-fruit (creeper), Marsdenia australis (creeper). copperburr); and in poor condition by unpalat- able annuals such as Carrichtera annua Annual species recorded include Angianthus (Ward’s weed), Salsola tragus (roly poly) and conocephalus, Brachyscome ciliaris, Calandrinia sp., Zygophyllum iodocarpum, with Austrostipa Carrichtera annua (KI), Dysphania melanocarpa forma leucocarpa, Erodium cicutarium, E. cygnorum, scabra (speargrass) dominating the areas Euphorbia drummondii, E. tannensis subsp. between the bluebush mounds. Soils in healthy eremophila, Goodenia pinnatifida, Isoetopsis PBLS communities have well developed graminifolia, Lepidium sp., Mesembryanthemum cryptogamic crusts of algae, lichens and crystallinum, Podolepis canescens, Rhodanthe liverworts, which improve nutrient cycling, soil chlorocephala, R. floribunda, Salsola tragus (KI), moisture retention, and provide protection Senecio pinnatifolius, Sonchus oleraceus, Tetragonia against raindrop impact, sheet flow and wind eremaea, Vittadinia humerata, Zygophyllum erosion. The loss of cryptogamic crust is an iodocarpum (KI) and Z. ovatum. indicator of deteriorated soil condition. Ecological disturbance Following a fire of moderate to low intensity Maireana sedifolia leaves contain up to 10 per Maireana sedifolia can regenerate if not cent salt (Mitchell & Wilcox 1994) and may be severely grazed during its recovery (Mitchell, eaten by stock if fresh water is available. McCarthy & Hacker 1979), though it can be Pastoralists have observed stock eating only eliminated by frequent or intense fires. The the tips of the plants particularly when there are ability to regenerate from fire and cope with arid new shoots. Maireana sedifolia is not a conditions has allowed it to become a dominant sensitive indicator of range condition in the climax species throughout the Nullarbor Nullarbor. When in good condition this landscape.

Pearl bluebush (Maireana sedifolia) regrowth after a low intensity fire caused by lightning.

173 On the Nullarbor Plain Maireana sedifolia is General information immensely important in providing habitat and PBAC predominantly occurs on stony limestone shelter to animals, including steppe and grass- plains with up to 20 per cent of the surface land birds, to other plants and soil protection covered by medium-sized limestone fragments from wind erosion. Its function in reducing wind (6–20 mm). Soils are commonly calcareous speed at ground level is significant, reducing the shallow loams. PBAC occurs in the central wind’s desiccating effect on inter-mound sub- west of the survey area. shrubs. Whilst not diminishing its ecological importance there is concern the continuous Physiognomy and composition of vegetation grazing pressure by all herbivores, particularly PBAC occurs as a very scattered to scattered through dry seasons, is reducing the diversity of (5–15 per cent PFC) mid to low shrubland. PBLS to homogenous communities dominated Species of Acacia dominate the mid shrub by Maireana sedifolia and Austrostipa scabra. In stratum. The lower shrub stratum is commonly some locations within the landscape PBLS also co-dominated by Maireana sedifolia (pearl represents a degraded state of a Plain mixed bluebush) and Ptilotus obovatus (cotton bush). chenopod shrubland (PXCS). The loss of many fire-sensitive and/or palatable species leaves a 23 perennial species were recorded at the two PBLS community with extensive interpatch inventory sites, with an average of 15 species areas with only the Maireana sedifolia bush per site, four greater than the survey average. mounds remaining. Six annual species were recorded. Gradational associations The following species (by strata) are dominant and/or common: PBLS commonly occur on crests and marginal Trees: Dominant—Not present as a slopes adjacent to depressions dominated by recognisable stratum Plain mixed chenopod shrubland (PXCS), Plain Other—Pittosporum mixed halophyte shrubland (PXHS), Bladder angustifolium. saltbush shrubland (BSSL), Speargrass and Tall shrubs: Dominant—Acacia burkittii (KI), wallaby grass open grassland (SWOG), Annual A. tetragonophylla (KI) herbland (ANNH), areas prone to water inunda- Other—Dodonaea lobulata (KI). tion, i.e. Lignum swamp (LISW), Drainage Mid shrubs: Dominant—Not present as a depression saltbush shrubland (DDSS), donga recognisable stratum groves (DOGR) and Gilgai grassy shrubland Others—Scaevola spinescens, (GGSL). On the Naretha land system as acacia Senna artemisioides subsp. x tall shrubs become more common PBLS artemisioides (KI), Sida grades into Pearl bluebush, Acacia shrubland calyxhymenia (KD). (PBAC), elsewhere degraded PBLS is replaced Low shrubs: Dominant—Maireana sedifolia, by Mixed acacia open shrubland (XAOS). Ptilotus obovatus (KD) Others—Chenopodium Land systems curvispicatum (KD), Enchylaena tomentosa (KD), Solanum PBLS is the dominant habitat on Balgair, Lowry, orbiculatum. Moonera and Morris land systems. PBLS is a Subshrubs: Dominant—Not present as a major habitat type on Arubiddy, Chowilla, Gafa, recognisable stratum Kinclaven, Kybo, Pondana, Reid, Seemore, Common—Atriplex acutibractea Shakehole, Skink, Thampanna, and Vanesk land (KI), Eriochiton sclerolaenoides systems and a minor habitat type on Bullseye, (KD), Sida spodochroma, Jubilee, Nurina, Oasis and Woorlba land Solanum ellipticum systems. Others—Maireana trichoptera (KD), Sclerolaena diacantha 26. Pearl bluebush, acacia shrubland (KD), S. obliquicuspis (KI). (PBAC) Perennial grasses: Dominant—Not present as a recognisable stratum Sampling Common—Austrodanthonia caespitosa, Austrostipa scabra, 2 inventory sites, 38 traverse points Enneapogon cylindricus Other—Enneapogon caerulescens.

174 Annual species recorded include Aristida contorta, 27. Plain mixed chenopod shrubland Carrichtera annua (KI), Erodium aureum, Euphorbia (PXCS) drummondii, Oxalis sp. and Salsola tragus. Sampling Ecological disturbance 16 inventory sites, 705 traverse points Acacia tetragonophylla (curara) is well adapted to arid conditions and may be browsed but General information generally only during extended dry periods when other species are suffering from water stress PXCS is common throughout the survey area. (Mitchell & Wilcox 1994). Palatable perennial On the limestone plains of the Bunda Plateau it herbs and grasses, such as Eriochiton can occur on either stony surfaces with fine to sclerolaenoides (woolly bindii), Maireana coarse calcareous fragments (2–60 mm) trichoptera (pink-seeded bluebush), covering up to 20 per cent of the surface, on Austrodanthonia caespitosa (wallaby grass) marginal slopes to drainage floors with and Enneapogon caerulescens (limestone calcareous loams of varying depth or in the grass) are likely to be preferentially sought when lower-lying depressions. In the west PXCS also seasonal conditions are favourable. occurs on the calcrete plains of the Nyanga Plain which are overlain by calcareous loam of The vegetation structure and composition of variable depth. Soils are calcareous loamy PBAC is unique. Grazing may have altered the earths. In the south on the Roe Plains PXCS floristic composition resulting in an increase of also occurs on the calcareous loamy earths the more dominant, unpalatable species Acacia overlying the Roe Calcarenite. burkittii (jam), Acacia tetragonophylla and Dodonaea lobulata (bead hopbush). However, Physiognomy and composition of vegetation the vegetation association may also be PXCS exists as a scattered (10–20 per cent influenced by ancient river courses nearby and PFC) mid to low shrubland, co-dominated by proximity to the adjacent calcrete plain. These Maireana sedifolia (pearl bluebush) and Atriplex components of the physical geography may vesicaria (bladder saltbush). have influenced soil characteristics. These factors in combination or individually form a 41 perennial species were recorded at the 16 floristic interzone of mixed species composition inventory sites, with an average of 11 species between the calcrete plain of the Nyanga land per site, the survey average. 12 annual species zone and the Nullarbor Plain of the Nullarbor were recorded, with an average of three land zone. species per site. Gradational associations The following species (by strata) were dominant and/or common: PBAC commonly grades into Pearl bluebush Trees: Dominant—Not present as a low shrubland (PBLS) as acacia species recognisable stratum become less common. In areas altered by fires Others—Myoporum and overgrazing PBAC is commonly replaced platycarpum, Pittosporum by Open bindii grassland (OBIG) and/or Mixed angustifolium. acacia open shrubland (XAOS). Tall shrubs: Dominant—Not present as a Land systems recognisable stratum Others—Acacia oswaldii, PBAC is a major habitat type on Naretha land Exocarpos aphyllus. system and a minor habitat type on Moonera Mid shrubs: Dominant—Not present as a land system. recognisable stratum Common—Atriplex nummularia, Geijera linearifolia Others—Cratystylis conocephala, Eremophila decipiens, E. scoparia, Nitraria billardierei, Pimelea microcephala. Low shrubs: Dominant—Atriplex vesicaria (KD), Maireana sedifolia

175 Common—Enchylaena platychaeta and Enneapogon cylindricus. tomentosa (KD), Lawrencia Increaser species include Lawrencia squamata squamata (KI), Lycium australe, (grey fan leaf), Sclerolaena densiflora (hairy Maireana erioclada bindii), S. obliquicuspis (limestone bindii), Others—Chenopodium S. patenticuspis (spear-fruit copperburr) and the curvispicatum (KD), Gunniopsis annuals Carrichtera annua (Ward’s weed), calcarea, Maireana radiata, M. turbinata, Olearia calcarea, Rhodanthe floribunda, Salsola tragus (roly poly) O. ramosissima, Rhagodia and Zygophyllum iodocarpum. Pringle, Van ulicina. Vreeswyk and Gilligan (1994) also found the Subshrubs: Dominant—Not present as a extent of cryptogamic crusting was less in recognisable stratum grazed areas, leaving such areas susceptible to Common—Eriochiton soil erosion. sclerolaenoides, Maireana Fire can alter the species composition of these trichoptera, Sclerolaena habitats considerably. At graded fencelines and obliquicuspis (KI), S. patenticuspis (KI), Sida tracks acting as firebreaks, the ability of spodochroma Maireana sedifolia to recover from moderate to Others—Erodium aureum, low intensity fires is visible, unlike fire-sensitive Minuria cunninghamii, Atriplex vesicaria that is unable to recover, Sclerolaena densiflora (KI), particularly in the presence of high rabbit S. diacantha (KD), Tecticornia numbers or continuous grazing. Across some sp. locations with the same geophysical character- Perennial grasses: Dominant—Not present as a istics PXCS has been reduced to a homog- recognisable stratum enous stand of Maireana sedifolia (similar to a Common—Austrodanthonia Pearl bluebush low shrubland PBLS), whilst caespitosa (KD), A. setacea, nearby in fire excluded areas PXCS remains Austrostipa platychaeta (KD), diverse. A. scabra Others—Austrodanthonia Gradational associations setacea, Enneapogon cylindricus (KD). PXCS commonly grades into Myall mixed chenopod shrubland or woodland (MXCS), Other plant forms: Occasional—Marsdenia australis (creeper). Myall, false bluebush shrubland or woodland (MFBW), Eucalypt mixed chenopod woodland Annual species recorded include Arabidella trisecta, (EXCW), Sugarwood mixed chenopod Brachyscome ciliaris, Carrichtera annua (KI), shrubland or woodland (MXCS) or Casuarina Dysphania melanocarpa forma leucocarpa, Euphorbia mixed chenopod shrubland or woodland drummondii, Mesembryanthemum crystallinum, (CXCS) as tree species begin to dominate the Nicotiana occidentalis, Rhodanthe floribunda (KI), upper strata. In the south-west of the survey Salsola tragus (KI), Tetragonia eremaea, Vittadinia area PXCS is commonly found in the depres- sp. and Zygophyllum iodocarpum (KI). sions and lower-lying ‘corridors’ between the Ecological disturbance undulating patterns of joint controlled limestone ridges supporting Pearl bluebush low shrubland Curry et al. (1994) suggested excessive grazing (PBLS), Eucalypt saltbush shrubland or pressure reduced projected foliar cover (PFC), woodland (ESAW) or Eucalypt mixed scrub leaving PXCS habitats susceptible to woodland (EXSW). PXCS can also occur on accelerated soil erosion and/or increases in marginal slopes to drainage floors as a vegeta- unpalatable shrubs. Pringle, Van Vreeswyk and tion transition between PBLS-dominated low Gilligan (1994) found the prominence of key ridges and lower-lying Bladder saltbush decreaser species was the most sensitive shrubland (BSSL) or Samphire shrubland indicator of range condition and to a lesser (SAMP). On the Roe Plains PXCS grades into extent increaser species rather than PFC. Key Nitraria mixed chenopod shrubland (NXCS) as decreaser shrub species include Atriplex Nitraria billardierei begins to dominate the mid vesicaria, Chenopodium curvispicatum and shrub layer. Enchylaena tomentosa (ruby saltbush) and palatable grasses include Austrodanthonia caespitosa (wallaby grass), Austrostipa

176 Land systems Subshrubs: Dominant—Not present as a recognisable stratum PXCS is a dominant habitat type on Koonjarra Common—Eriochiton and Woorlba land systems and a major habitat sclerolaenoides, Sclerolaena type on Chowilla, Gafa, Moonera, Morris, patenticuspis (KI), Tetragonia Nanambinia, Nyanga, Reid, Shakehole, implexicoma Thampanna and Vanesk land systems. Others—Maireana trichoptera, Sclerolaena diacantha (KD). 28. Nitraria with mixed chenopod Perennial grasses: Dominant—Not present as a shrubland (NXCS) recognisable stratum Common—Austrodanthonia Sampling caespitosa, Austrostipa drummondii, A. scabra 3 inventory sites, 17 traverse points Other—Austrostipa platychaeta (KD). General information Annual species recorded include Brachyscome NXCS is named after the dominance of Nitraria lineariloba, Carrichtera annua (KI), Erodium billardierei (nitre bush). Soils are calcareous cicutarium, Nicotiana goodspeedii, N. occidentalis, loamy earths overlying the calcarenite Roe Senecio pinnatifolius, Sonchus oleraceus and Plains. It occurs in the south of the survey area Trichanthodium skirrophorum. on the north of the Roe Plains, where the soils overlying the Roe Calcarenite remain shallow Ecological disturbance and are less sandy. Nitraria billardierei is not highly desirable to stock, except for the fruit which is eaten by Physiognomy and composition of vegetation sheep, and may increase at the expense of NXCS varies considerably from a very scattered palatable low shrubs such as Atriplex vesicaria, to moderately closed (5–25 per cent PFC) Enchylaena tomentosa (ruby saltbush) and shrubland. Nitraria billardierei (nitre bush) Maireana georgei (golden bluebush) which dominates the mid shrub stratum with the lower decrease under excessive grazing pressure. In shrub stratum dominated by Atriplex vesicaria areas of heavy grazing pressure Nitraria (bladder saltbush). billardierei shelters palatable grasses such as Austrostipa platychaeta within its spreading 21 perennial species were recorded at the three clump-like form. inventory points, with an average of 12 species per site, one greater than the survey average. Nitraria billardierei can also increase in Eight annual species were recorded, with an response to track or roadside disturbances. average of five species per site. This is evident along the Eyre Highway and the old Eyre telegraph line where Nitraria billardierei The following species (by strata) are dominant has increased due to the combination of and/or common: disturbance opening the tree canopy and Trees: Dominant—Not present as a greater accumulation of water at the road or recognisable stratum track edge. Common—Acacia papyrocarpa. Tall shrubs: Dominant—Not present as a Nitraria billardierei is readily dispersed by birds recognisable stratum and as a result it commonly occurs under Other—Geijera linearifolia. potential perch sites including telegraph poles and fence posts. Mid shrubs: Dominant—Nitraria billardierei (KI) Gradational associations Common—Atriplex nummularia. Low shrubs: Dominant—Atriplex vesicaria NXCS commonly grades into Plain mixed (KD) chenopod shrubland (PXCS) or Myall mixed Common—Enchylaena chenopod shrubland or woodland (MXCS) as tomentosa (KD), Gunniopsis Nitraria billardierei becomes less common. calcarea, Lawrencia squamata (KI), Maireana erioclada Others—Maireana georgei (KD), M. sedifolia, Zygophyllum aurantiacum (KD).

177 Land systems Low shrubs: Dominant—Atriplex vesicaria Common—Maireana georgei NXCS is a major habitat type on Mundrabilla (KD), M. sedifolia land system and a minor habitat type on Roe Others—Atriplex cryptocarpa, land system. Enchylaena tomentosa, Frankenia densa, Gunniopsis 29. Bladder saltbush shrubland (BSSL) calcarea, Lycium australe, Maireana erioclada, Sampling M. pentatropis, M. radiata, M. turbinata, Nitraria billardierei, 31 inventory sites, 578 traverse points Rhagodia crassifolia, R. ulicina, General information Solanum nummularium, Tecticornia doleiformis, BSSL can occupy a variety of positions within Tecticornia sp., Zygophyllum the landscape. It predominantly occurs in the aurantiacum. loamy depressions of undulating limestone Subshrubs: Dominant—Not present as a plains in the south-east of the survey area. In recognisable stratum the south-west BSSL occurs in clay depres- Common—Eriochiton sions with saline subsoils. In the north BSSL sclerolaenoides (KD), occurs on deflated marginal slopes to drainage Sclerolaena diacantha (KD), floors with limestone fragments of mixed size S. obliquicuspis (KI), (1–30 cm) generally covering up to 50 per cent S. patenticuspis (KI), Sida of the surface. BSSL also dominates drainage spodochroma Others—Atriplex acutibractea floors and ancient river courses throughout the (KI), Maireana trichoptera (KD), survey area. Shrub patches are commonly Sclerolaena brevifolia, Solanum intersected with naturally occurring scalded ellipticum. interbands. Soils are calcareous loamy earths. Perennial grasses: Dominant—Austrostipa scabra When present in clay depressions and drainage Common—Austrodanthonia floors red/brown non-cracking clays dominate. caespitosa Others—Austrodanthonia Physiognomy and composition of vegetation setacea, Austrostipa nitida, BSSL comprises a scattered to moderately A. platychaeta (KD), closed (10–25 per cent PFC) low shrubland of Enneapogon caerulescens, Atriplex vesicaria (bladder saltbush). E. cylindricus, Eragrostis dielsii, Panicum decompositum. 52 perennial species were recorded at the 31 Other plant forms: Occasional—Glycine rubiginosa inventory sites, with an average of eight species (creeper). per site, three less than the survey average. 23 annual species were recorded, with an average Annual species recorded include Arabidella trisecta, Brachyscome sp., Carrichtera annua (KI), Centaurea of four species per site. melitensis, Dysphania melanocarpa forma The following species (by strata) are dominant leucocarpa, Erodium aureum, Euphorbia drummondii, and/or common: Lepidium rotundum, Lotus cruentus, Mesembryanthemum crystallinum, Nicotiana Tall shrubs: Dominant—Not present as a goodspeedii, N. occidentalis, Oxalis corniculata, recognisable stratum Podolepis canescens, Rhodanthe floribunda (KI), Others—Acacia tetragonophylla, Salsola tragus (KI), Senecio pinnatifolius, Geijera linearifolia. S. quadridentatus, Senecio spanomerus, Swainsona Mid shrubs: Dominant—Not present as a microphylla, Vittadinia humerata, Zygophyllum recognisable stratum iodocarpum and Zygophyllum ovatum. Common—Atriplex nummularia Others—Cratystylis Ecological disturbance conocephala, Eremophila Atriplex vesicaria responds to moisture stress decipiens (KI), E. deserti, E. glabra (KI), E. scoparia (KI), by shedding leaves, but will recover quickly in Pimelea microcephala. response to rainfall and soil moisture conditions that stimulate germination. During this recovery phase Atriplex vesicaria needs protection from grazing pressure to allow germinant

178 establishment and for mature plants to regain 30. Lawrencia squamata shrubland vigour and set seed. Sustained heavy grazing is (LAWS) likely to reduce perennial vegetation cover as well as reducing other palatable species such Sampling as Eriochiton sclerolaenoides (woolly bindii), 3 inventory sites, 16 traverse points Maireana georgei (golden bluebush), M. trichoptera (pink-seeded bluebush) and General information Sclerolaena diacantha (grey bindii). This may LAWS is a minor vegetation association pre- lead to the expansion of naturally occurring dominantly occurring on the calcrete breakaway scalded interbands. Further threats to Atriplex slopes of the Koonjarra land system. Moderately vesicaria include its lack of tolerance to fire and inclined slopes of up to 10 per cent have out- inability to regenerate after burning. crop occurring through 50 per cent of the area, In BSSL an increase in unpalatable species with 90 per cent of the surface covered by loose such as Eremophila spp., Atriplex acutibractea calcrete fragments of mixed size. Soils are (toothed saltbush), Sclerolaena obliquicuspis commonly red/brown non-cracking clays. (limestone bindii), S. patenticuspis (spear-fruit LAWS are found in the central west of the copperburr), Carrichtera annua (Ward’s weed), survey area. LAWS are also found infrequently Rhodanthe floribunda and Salsola tragus (roly on stony limestone plains of the Kinclaven and poly) indicates declining range condition. Shakehole land system where it replaces mixed chenopod shrubland. Gradational associations BSSL commonly grades out of depressions and Physiognomy and composition of vegetation lower-lying areas into Plain mixed chenopod LAWS comprises scattered (10–15 per cent) shrubland (PXCS), Pearl bluebush low low shrubland of Lawrencia squamata (grey fan shrubland (PBLS) or Open bindii grassland leaf). (OBIG) occupying the marginal slopes and 16 perennial species were recorded at the three crests of the gentle undulating Nullarbor Plain. inventory sites, with an average of nine species Transitional associations can also occur in the per site, two less than the survey average. Four same land unit, usually lower-lying depressions, annual species were recorded. between BSSL and Speargrass and wallaby grass open grassland (SWOG) and, depending The following species (by strata) were dominant on soil salinity, Plain mixed halophyte shrubland and/or common: (PXHS). In ancient river courses BSSL Trees: Dominant—Not present as a commonly surrounds the drainage foci recognisable stratum supporting Lignum swamp (LISW). Common—Acacia papyrocarpa. Due to the common occurrence of BSSL in Mid shrubs: Dominant—Not present as a depressions and low-lying areas, other habitat recognisable stratum associations may occur on the surrounding Common—Atriplex nummularia, Nitraria billardierei higher slopes of undulating country such as Other—Cratystylis conocephala. eucalypt and/or myall shrubland or woodland. Low shrubs: Dominant—Lawrencia squamata Land systems Common—Atriplex vesicaria (KD), Maireana sedifolia BSSL is a major habitat type on Arubiddy, Others—Cratystylis Balgair, Chowilla, Gafa, Haig, Moonera, Morris, subspinescens, Frankenia sp., Reid, Shakehole, Skink, Thampanna and Maireana turbinata, Rhagodia Woorlba land systems and a minor habitat type crassifolia. on Bullseye, Jubilee, Kanandah, Moodini, Subshrubs: Dominant—Not present as a Nurina, Nyanga, Oasis, Pondana and Vanesk recognisable stratum land systems. Common—Maireana trichoptera (KD), Sclerolaena diacantha (KD).

179 Perennial grasses: Dominant—Not present as a have once supported a low shrub stratum which recognisable stratum has since been removed through the combined Common—Austrostipa scabra effects of increased fire frequency and over- Others—Austrodanthonia grazing, primarily by rabbits. The replacement caespitosa, Eragrostis dielsii. of perennial shrubs by grasses, particularly Annual species recorded include Carrichtera annua Austrostipa scabra (speargrass), has increased (KI), Euphorbia drummondii, Nicotiana occidentalis the susceptibility of these habitats to fire. These and Salsola tragus. irreversibly altered vegetation associations are Ecological disturbance unlikely to support a low shrub stratum of palatable perennial shrubs in the future. They Whilst Lawrencia squamata is occasionally now carry open grassland and sparse shrub- eaten by stock, in some areas it may be land. Low-lying areas such as claypans, clay increasing in abundance in response to a loss plains and drainage areas in some locations of more palatable flora. If Atriplex vesicaria may originally have supported these seasonally (bladder saltbush), Maireana trichoptera (pink- dependent vegetation associations, but with a seeded bluebush) and Sclerolaena diacantha more diverse suite of palatable perennials or (grey bindii) are present in large numbers and subshrubs than what is supported by these with numerous juveniles the area can be areas today. In good seasons these habitats assumed to be in good condition. The latter two support dense stands of perennial and annual species are subject to seasonal conditions and grasses and herbs. In dry periods these caution should be used when selecting them habitats are susceptible to wind erosion due to alone to determine range condition. the scarcity of plants. The breakaway slopes of this habitat are highly susceptible to water erosion. Vehicle tracks 31. Mixed acacia open shrubland have resulted in rilling and gullying. Short (XAOS) spaced bunds across the tracks would divert water flow off the tracks. This would prolong the Sampling tracks usefulness, reduce erosion and the 4 inventory sites, 66 traverse points deteriorating condition of the breakaway slopes impacted by the tracks. General information XAOS commonly occurs in the central west of Gradational associations the survey area on stony limestone plains In the Koonjarra land system LAWS is where up to 90 per cent of the surface is commonly found midslope between sparse covered by coarse (2–20 cm) limestone frag- Myall mixed chenopod shrubland or woodland ments. It occasionally occurs on calcrete plains (MXCS) and grading downslope into Plain overlain by stony calcareous loams. Soils are mixed chenopod shrubland (PXCS). Where it is red shallow loams and calcareous shallow present on limestone plains it often grades into loams. Open bindii grassland (OBIG). Physiognomy and composition of vegetation Land systems XAOS occurs as a scattered (10–15 per cent LAWS is a minor habitat type on Kinclaven, PFC) tall shrubland of acacias. The most domi- Koonjarra and Shakehole land systems. nant acacia is Acacia burkittii (jam), though A. aneura (mulga) is also common. Ptilotus obovatus (cotton bush) commonly dominates G. OPEN SHRUBLAND AND the low shrub stratum. GRASSLAND ON CALCAREOUS 34 perennial species were recorded at the four PLAINS inventory sites, with an average of 17 species This group of habitat types occurs on the lime- per site, six greater than the survey average. stone and calcrete plains of the Bunda Plateau Nine annual species were recorded, with an and is predominantly altered vegetation average of five species per site. associations now in an irreversible state of transition. These habitat types are thought to

180 The following species (by strata) are dominant Ecological disturbance and/or common: Acacia burkittii is not grazed by stock and this Trees: Dominant—Not present as a may have contributed to its dominance through recognisable stratum this habitat type. In many areas Acacia burkittii Occasional—Acacia aneura, was of uniform height and therefore possibly of A. papyrocarpa, Alectryon similar age. This may be a post-fire related oleifolius, Myoporum platycarpum, Pittosporum response. angustifolium, Santalum XAOS represents a floristic ecotone of mixed spicatum. species composition between the calcrete plain Tall shrubs: Dominant—Acacia burkittii (KI) of the Nyanga land zone and the Nullarbor Plain Common—Acacia aneura of the Nullarbor land zone. The occurrence of Others—Acacia oswaldii, red shallow loam soils through the XAOS of the A. tetragonophylla (KI), Naretha land system indicates the vegetation Dodonaea lobulata (KI), association may be influenced by the proximity Myoporum platycarpum. to the calcrete plain and ancient water courses. Mid shrubs: Dominant—Not present as a Alternatively, the soil surface may reflect sand recognisable stratum mobility caused through past or present Others—Eremophila latrobei disturbance events. subsp. glabra, E. scoparia (KI), Scaevola spinescens, Senna Ptilotus obovatus is palatable though its artemisioides subsp. x condition and presence varies with seasonal artemisioides (KI), conditions. The grasses Enneapogon S. artemisioides subsp. x caerulescens (limestone grass) and coriacea (KI), Sida Enneapogon cylindricus are highly palatable to calyxhymenia (KD). stock, but abundance depends with seasonal Low shrubs: Dominant—Ptilotus obovatus conditions. Dense stands of such species may Common—Atriplex vesicaria, indicate fair to good rangeland condition. Enchylaena tomentosa, Maireana sedifolia Gradational associations Other—Solanum nummularium. XAOS commonly grades into low shrubland Subshrubs: Dominant—Not present as a recognisable stratum such as Pearl bluebush low shrubland (PBLS) Common—Eriochiton and Pearl bluebush, acacia shrubland (PBAC). sclerolaenoides (KD), In the Naretha land system ancient river Sclerolaena diacantha (KD), courses supporting Drainage Acacia shrubland S. patenticuspis (KI), Sida (DRAS) meander through XAOS. spodochroma, Solanum Where residual calcrete rises occur over the ellipticum Others—Maireana trichoptera Nullarbor Limestone and Casuarina pauper (KD), Minuria cunninghamii, (black oak) begins to occur in the overstorey Sclerolaena obliquicuspis (KI). XAOS grades into Casuarina, acacia open Perennial grasses: Dominant—Not present as a shrubland (CAOS) or Casuarina mixed scrub recognisable stratum shrubland (CXSS). Where sand overlies Common—Austrostipa scabra, calcrete rises, XAOS grades into Dodonaea, Enneapogon caerulescens, eremophila mixed shrubland (DEXS). E. cylindricus Other—Austrodanthonia Land systems caespitosa. XAOS is a major habitat type on Kitchener and Other plant forms: Occasional—Marsdenia Naretha land system and a minor habitat type australis (creeper). on Nyanga land system. Annual species recorded include Abutilon oxycarpum subsp. prostratum, Aristida contorta, Carrichtera annua (KI), Dysphania melanocarpa forma leucocarpa, Erodium cygnorum, Euphorbia drummondii, Lepidium sp., Malvastrum americanum and Salsola tragus.

181 32. Mixed shrub bindii grassland tomentosa (KD), Maireana (XSBG) sedifolia Others—Atriplex vesicaria (KD), Sampling Lycium australe, Maireana radiata, Ptilotus obovatus (KD), 6 inventory sites, 269 traverse points Solanum nummularium. General information Subshrubs: Dominant—Sclerolaena obliquicuspis (KI) XSBG is predominantly found on stony lime- Common—Atriplex acutibractea stone plains. Up to 90 per cent of the stony (KI), Eriochiton sclerolaenoides surface is strewn with limestone fragments of (KD), Sclerolaena diacantha mixed size, and outcrop is common through up (KD), S. patenticuspis (KI), Sida to 50 per cent of these habitats. Soils are spodochroma, Solanum calcareous loamy earths and shallow loams. ellipticum Others—Maireana trichoptera XSBG is found in the north-west of the survey (KD), Sclerolaena brevifolia. area. Perennial grasses: Dominant—Austrodanthonia Physiognomy and composition of vegetation caespitosa, Austrostipa scabra Common—Enneapogon XSBG is highly variable and may occur as a caerulescens, E. cylindricus very scattered to scattered (2.5–15 per cent Other—Eragrostis setifolia. PFC) herbland, mid or tall shrubland. The mid Other plant forms: Occasional—Glycine rubiginosa and tall shrubland is commonly dominated by (creeper), Marsdenia australis sclerophyllous shrubs and the herbland by (creeper). species of Sclerolaena (bindii). Annual species recorded include Carrichtera annua 36 perennial species were recorded at the six (KI), Dysphania melanocarpa forma leucocarpa, inventory sites, with an average of 15 species Erodium aureum, E. cygnorum, Euphorbia per site, four greater than the survey average. drummondii, Lepidium sp., Malvastrum americanum, 13 annual species were recorded, with an Rhodanthe floribunda (KI), Salsola tragus (KI), Salvia average of six species per site. verbenaca (KI), Sisymbrium erysimoides, Xanthium spinosum and Zygophyllum iodocarpum. The following species (by strata) are dominant and/or common: Ecological disturbance Trees: Dominant—Not present as a XSBG is an altered vegetation association. The recognisable stratum presence of Maireana sedifolia (pearl bluebush) Common—Pittosporum stumps and remnant bush mounds indicates angustifolium these areas previously supported chenopod Other—Acacia papyrocarpa. shrubland. Many of the shrubs now dominating Tall shrubs: Dominant—Variable; these areas are unpalatable, including increaser occasionally Eremophila species such as Acacia burkittii (jam), longifolia, A. tetragonophylla A. tetragonophylla (curara) and Senna (KI) artemisioides subsp. x coriacea (desert Common—Acacia burkittii (KI), cassia). These shrubs are generally resilient, A. oswaldii. capable of surviving dry conditions and known Mid shrubs: Dominant—Variable; to respond in abundance after a fire. occasionally Senna artemisioides subsp. x coriacea The lower stratum of XSBG is regularly (KI) dominated by unpalatable subshrubs and Common—Atriplex nummularia annuals such as Atriplex acutibractea (toothed Others—Eremophila latrobei saltbush), Sclerolaena obliquicuspis (limestone subsp. glabra, Pimelea bindii), S. patenticuspis (spear-fruit copperburr), microcephala, Sida Carrichtera annua (Ward’s weed), Rhodanthe calyxhymenia (KD). floribunda, Salsola tragus (roly poly) and Salvia Low shrubs: Dominant—Occasionally verbenaca (wild sage). During dry periods these Lawrencia squamata (KI) seasonally dependent plants disappear and the Common—Chenopodium area becomes prone to wind erosion. This curvispicatum, Enchylaena further reduces the capacity to support

182 vegetative growth. The extensively stony surface The following species (by strata) are dominant of this habitat is evidence of active erosive and/or common. processes. Trees: Dominant—Not present as a recognisable stratum Gradational associations Occasional—Acacia XSBG is a common component in areas with a papyrocarpa, Casuarina pauper, record of long-term continuous grazing and a Eremophila longifolia, history of fire. This degraded habitat type Pittosporum angustifolium. commonly grades into Open bindii grassland Mid shrubs: Dominant—Not present as a (OBIG). recognisable stratum Occasional—Atriplex In the northern Nullarbor Plain XSBG commonly nummularia, Scaevola surrounds dongas supporting berrigan and spinescens. curara groves (DBGR and DCGR) as well as Low shrubs: Dominant—Not present as a small areas of Gilgai grassy shrubland (GGSL). recognisable stratum Where Nullarbor Limestone is overlain by thick Others—Atriplex cryptocarpa, calcrete and Casuarina pauper (black oak) A. vesicaria, Enchylaena begins to appear in the overstorey XSBG grades tomentosa, Lycium australe, Maireana sedifolia, Ptilotus into Casuarina mixed scrub shrubland (CXSS). obovatus. Land systems Subshrubs: Dominant—Sclerolaena patenticuspis (KI), Eriochiton XSBG is the dominant habitat on Kinclaven land sclerolaenoides (KD) system, a major type on Kanandah and Common—Atriplex acutibractea Kitchener land systems and a minor habitat type (KI), Sclerolaena diacantha on Naretha land system. (KD), S. obliquicuspis (KI), Sida spodochroma 33. Open bindii grassland (OBIG) Others—Maireana trichoptera (KD), Sclerolaena brevifolia, Sampling Solanum ellipticum. 11 inventory sites, 492 traverse points Perennial grasses: Dominant—Austrostipa scabra Common—Austrodanthonia General information caespitosa (KD), Enneapogon cylindricus (KD). OBIG predominantly occurs on stony limestone and calcrete plains across the north of the Other plant forms: Occasional—Glycine rubiginosa survey area. Coarse gravel and stones (creeper). (2–20 cm) of limestone may cover up to 90 per Annual species recorded include Carrichtera annua cent of the surface. OBIG also commonly (KI), Erodiophyllum elderi, Euphorbia drummondii, occurs on the marginal slopes to drainage floors Lepidium sp., Mesembryanthemum crystallinum, of clay plains and claypans in the north. Soils Nicotiana occidentalis, Rhodanthe floribunda (KI), Salsola tragus (KI), Vittadinia sp. and Zygophyllum are commonly calcareous shallow loams, and iodocarpum (KI). where present on clay plains, red/brown non- cracking clays. Ecological disturbance Physiognomy and composition of vegetation Total grazing pressure has influenced the floris- tic composition of this habitat type in different OBIG occurs as a very scattered to moderately locations. In good condition, palatable perennial closed (2.5–25 per cent PFC) grassland with herbs such as Eriochiton sclerolaenoides mixed Sclerolaena species, most commonly (woolly bindii), Maireana trichoptera (pink- Sclerolaena patenticuspis (spear-fruit seeded bluebush) and Sclerolaena diacantha copperburr). (grey bindii) and perennial grasses such as 25 perennial species were recorded at the 11 Austrodanthonia caespitosa (wallaby grass) inventory sites, with an average of six species and Enneapogon cylindricus are abundant. In per site, five less than the survey average. 10 poor condition, unpalatable species dominate. annual species were recorded, with an average These include Atriplex acutibractea (toothed of five species per site. saltbush), Carrichtera annua (Ward’s weed),

183 Salsola tragus (roly poly), Sclerolaena SWOG occurs across the survey area on obliquicuspis (limestone bindii), limestone plains with up to 50 per cent of the S. patenticuspis, Rhodanthe floribunda and surface overlain by coarse (2–20 cm) limestone Zygophyllum iodocarpum. In dry seasons these fragments. It also occurs in both closed and areas are prone to erosion and scalding as open depressions on calcareous loamy plains, there is very little protection offered by the clay plains and claypans. Soils are calcareous seasonally dependent plants. shallow loams and loamy earths, and red/brown non-cracking clays in claypans. Gradational associations Physiognomy and composition of vegetation OBIG commonly grades into Myall bindii grassland (MBIG) as myall begins to appear. In SWOG consists of open grassland of the northern Nullarbor land zone OBIG Austrostipa scabra (speargrass) and commonly surround the various forms of donga Austrodanthonia caespitosa (wallaby grass). and small patches of Gilgai grassy shrubland 52 perennial species were recorded at the 29 (GGSL). Southwards in the Nullarbor land zone, inventory sites, with an average of six species as dongas give way to claypans and clay plains, per site, five less than the survey average. 27 OBIG surrounds vegetation associations annual species were recorded, with an average commonly occupying such depressions such of four species per site. as Bladder saltbush shrubland (BSSL), Annual herbland (ANNH) or Speargrass and wallaby The following species (by strata) were dominant grass open grassland (SWOG). As the density and/ or common: of shrubs begins to increase in the mid and tall Trees: Dominant—Not present as a shrub strata OBIG grades into Mixed shrub recognisable stratum bindii grassland (XSBG) or Pearl bluebush, Occasional—Acacia acacia shrubland (PBAC). papyrocarpa, Eremophila longifolia, Eucalyptus gracilis, Land systems E. yalatensis, Myoporum platycarpum. OBIG is the dominant habitat on Oasis and Rabbit land systems, a major habitat type on Tall shrubs: Dominant—Not present as a Bullseye, Carlisle, Gafa, Jubilee, Kinclaven, recognisable stratum Occasional—Acacia burkittii, Kitchener, Kyarra, Kybo and Nurina land A. hemiteles, A. oswaldii, systems and a minor type on Haig, Moonera, Geijera linearifolia. Pondana, Reid, Shakehole and Skink land Mid shrubs: Dominant—Not present as a systems. recognisable stratum Common—Atriplex nummularia 34. Speargrass and wallaby grass open Others—Acacia nyssophylla, grassland (SWOG) Cratystylis conocephala, Nitraria billardierei, Pimelea Sampling microcephala, Scaevola 29 inventory sites, 635 traverse points spinescens, Senna artemisioides subsp. x General information coriacea. SWOG is considered a fire-induced vegetation Low shrubs: Dominant—Not present as a recognisable stratum association. Patches are likely to have always Common—Atriplex vesicaria, existed in a mosaic state and transition pattern Maireana sedifolia between saltbush and bluebush low shrubland. Others—Chenopodium The vegetation has become irreversibly altered curvispicatum, Enchylaena as a result of increased fire frequency and tomentosa, Frankenia densa, through grazing by rabbits in plague proportions. Lycium australe, Maireana SWOG now dominates extensive areas, having erioclada, M. pentatropis, replaced other habitat types by increasing the M. radiata, Ptilotus obovatus, fire susceptibility of much of the Nullarbor. Rhagodia crassifolia, Solanum nummularium, S. orbiculatum, Tecticornia sp., Zygophyllum aurantiacum.

184 Subshrubs: Dominant—Not present as a Gradational association recognisable stratum Common—Atriplex acutibractea SWOG is often extensive and grades into Open (KI), Eriochiton sclerolaenoides, bindii grassland (OBIG), Pearl bluebush low Sclerolaena diacantha, shrubland (PBLS) and Bladder saltbush S. obliquicuspis, shrubland (BSSL). Where soil salinity increases S. patenticuspis, Sida SWOG may grade into Plain mixed halophytic spodochroma shrubland (PXHS) or Samphire shrubland Others—Maireana tomentosa, (SAMP). As eucalypt mallee or myall begin to M. trichoptera, Sclerolaena occur on ridges and rises SWOG grades into brevifolia, S. densiflora, Solanum Eucalypt, speargrass open grassland (ESOG) ellipticum, Swainsona affinis, Teucrium racemosum, Wurmbea or Myall, speargrass open grassland (MSOG). tenella. Land systems Perennial grasses: Dominant—Austrostipa scabra Common—Austrodanthonia SWOG is the dominant habitat type on caespitosa (KD) Nightshade land system, a major type on Others—Austrostipa drummondii, Bullseye, Carlisle, Chowilla, Gafa, Kybo, Oasis, Enneapogon cylindricus (KD), Nurina, Shakehole and Skink land systems and Eragrostis dielsii, E. setifolia. a minor habitat type on Culver, Jubilee, Other plant forms: Occasional—Marsdenia australis Kitchener, Kyarra, Moonera, Morris, (creeper). Nanambinia, Nyanga, Rabbit, Reid, Thampanna and Woorlba land systems. Annual species recorded include Angianthus conocephalus, Arabidella trisecta, Asteridea athrixioides, Brachyscome sp., Carrichtera annua (KI), 35. Annual herbland (ANNH) Dysphania melanocarpa forma leucocarpa, Erodium aureum, Euphorbia drummondii, Goodenia pinnatifida, Sampling Isoetopsis graminifolia, Lepidium sp., 7 inventory sites, 28 traverse points Mesembryanthemum crystallinum, Nicotiana goodspeedii (KI), N. occidentalis (KI), N. occidentalis General information subsp. obliqua, Oxalis corniculata, Podolepis canescens, Rhodanthe floribunda (KI), Salsola tragus ANNH is located in areas receiving local (KI), Senecio pinnatifolius, Sonchus oleraceus, drainage such as the claypans and clay plains. Tetragonia eremaea, Trichanthodium skirrophorum, Occurring throughout the Nullarbor Plain, such Vittadinia nullarborensis, Xanthium spinosum, drainage areas are more common in the north, Zygophyllum iodocarpum (KI) and Zygophyllum becoming less frequent in the south. Soils are ovatum. red/brown non-cracking clays. Ecological disturbance Physiognomy and composition of vegetation In good seasons SWOG is highly productive and ANNH occurs as a very scattered to scattered during the active growth phase is readily grazed. (2.5–15 per cent PFC) herbland of perennial Austrostipa scabra has maximum nutritional and annual herbs and grasses. value when it has new green shoots, becoming 28 perennial species were recorded at the less appealing as it becomes dry and harsh. seven inventory sites, with an average of six Austrodanthonia caespitosa is highly palatable species per site, five less than the survey and is preferentially sought by herbivores. If total average. 20 annual species were recorded, with grazing pressure is not effectively managed an average of seven species per site. wallaby grass can be eliminated with SWOG becoming dominated by only speargrass and The following species (by stratum) are unpalatable species such as Atriplex dominant and/or common: acutibractea (toothed saltbush), Carrichtera Trees: Dominant—Not present as a annua (Ward’s weed), Nicotiana spp., Salsola recognisable stratum tragus (roly poly), Sclerolaena densiflora (hairy Occasional—Eremophila bindii), S. obliquicuspis (limestone bindii), longifolia, Pittosporum S. patenticuspis (spear-fruit copperburr), angustifolium. Rhodanthe floribunda and Zygophyllum spp. Tall shrubs: Dominant—Not present as a reducing the long-term carrying capacity of the recognisable stratum grassland.

185 Occasional—Acacia obliquicuspis (limestone bindii), S. patenticuspis tetragonophylla. (spear-fruit copperburr), Rhodanthe floribunda Low shrubs: Dominant—Not present as a and Zygophyllum iodocarpum and the crypto- recognisable stratum gamic crust is breaking down or absent. In dry Occasional—Atriplex periods these areas are highly susceptible to cryptocarpa, A. vesicaria, wind erosion as the annuals and subshrubs die Chenopodium curvispicatum, leaving the ground surface exposed. Enchylaena tomentosa, Maireana turbinata, Olearia Gradational associations calcarea, Westringia rigida. ANNH is commonly found in low-lying areas Subshrubs: Dominant—Sclerolaena such as claypans grading onto marginal slopes patenticuspis (KI) Common—Atriplex acutibractea of the surrounding stony plains which support (KI), Sclerolaena obliquicuspis low shrubland such as Pearl bluebush low (KI), Sida spodochroma shrubland (PBLS) or their degraded equivalents Others—Cullen cinereum, such as Open bindii grassland (OBIG). Eriochiton sclerolaenoides (KD), Maireana trichoptera (KD), Land systems Sclerolaena brevifolia, ANNH is a major habitat type on Kybo land S. diacantha (KD), Solanum system and a minor habitat on Culver, ellipticum, Swainsona affinis, Kinclaven, Oasis, Pondana, Reid and Vanesk S. formosa. land systems. Perennial grasses: Dominant—Austrostipa scabra Common—Austrodanthonia caespitosa (KD) H. DRAINAGE FOCI SHRUBLAND Others—Austrostipa drummondii, Enneapogon This group of habitat types usually occurs as cylindricus (KD), Eragrostis small localised drainage foci being the lowest dielsii. parts in the immediate area, commonly vast Other plant forms: Occasional—Glycine rubiginosa undulating plains. These drainage sumps are (creeper). highly fertile and often support unique vegetation associations such as Donga groves (DOGR), Annual species recorded include Angianthus conocephalus, Asteridea athrixioides, Calotis Lignum swamp (LISW) and Gilgai grassy multicaulis, Carrichtera annua (KI), Cephalipterum shrubland (GGSL). Most of these habitats are drummondii, Dysphania melanocarpa forma uncommon and make up a very small propor- leucocarpa, Erodiophyllum elderi, Erodium aureum, tion of the survey area, with the exception of Euphorbia drummondii, Goodenia pinnatifida, Lotus Donga groves which are a common habitat cruentus, Malvastrum americanum, through the north of the Nullarbor Plain. Mesembryanthemum crystallinum, Nicotiana occidentalis, Podolepis canescens, Rhodanthe 36. Donga groves (DOGR) floribunda (KI), Salsola tragus (KI), Sisymbrium erysimoides, Sonchus oleraceus and Zygophyllum Sampling iodocarpum (KI). 18 inventory sites, 45 traverse points Ecological disturbance General information When this vegetation association is in good condition palatable perennial herbs such as Dongas are predominantly found in the north of Eriochiton sclerolaenoides (woolly bindii), the survey area. They are rounded, shallow, Maireana trichoptera (pink-seeded bluebush) closed depressions, generally 1.5–3 m below and Sclerolaena diacantha (grey bindii) and the surrounding stony plain. Donga arrange- perennial grasses such as Austrodanthonia ment can occur randomly or parallel with caespitosa (wallaby grass) and Enneapogon neighbouring ridge and corridor relief. They cylindricus are abundant with good cryptogamic commonly have flat clay floors up to several crusting. In overgrazed areas palatable species hundred metres across with gently sloped are replaced by Atriplex acutibractea (toothed margins. The whole depression may be up to saltbush), Carrichtera annua (Ward’s weed), 2 km in diameter, however generally they are Salsola tragus (roly poly), Sclerolaena significantly smaller. The clay floors often

186 contain gilgai or crabhole structure with irregular • Donga grevillea grove (DGGR) consists of surfaces. Limestone floaters (boulders and Grevillea nematophylla groves with a low slabs) of mixed size have been bought to the shrub understorey surrounded by dense surface by alternating wetting and drying cycles grass patches. DGGR is predominantly associated with gilgai soils. Boulders and slabs found in the north-east of the survey area. can protrude through up to 10 per cent of donga • Donga pittosporum grove (DPGR) consists surfaces. Their formation is believed to have of scattered stands of Pittosporum occurred by water run-off ponding in depres- angustifolium (native willow) surrounded by sions in the limestone plain and solution further dense grass patches. DPGR is commonly dissolving the limestone. Dongas are con- found in dongas in the north-east of the sidered solution dolines rather than collapsed survey area. caves (Jennings 1963; Lowry 1970). Soils are variable: commonly they consist of deep red/ In many instances, dongas contain trees or tall brown non-cracking clays or cracking clays, shrub species from all varieties of donga grove less commonly of silty-clay loam often with fine habitats. The differences occur in the density aeolian sand deposits. within the tall, mid and low shrub strata. The donga floors commonly support a sparse Physiognomy and composition of vegetation tree cover or clumps of small groves over a Donga berrigan grove (DBGR) consists of variety of perennial shrubs, annual herbs and scattered to very scattered (2.5–15 per cent grasses. Dongas are some of the most PFC) stands of Eremophila longifolia (berrigan) pastorally productive land units in the survey occupying a central location within the donga. area. In the pastoral areas water point location Very scattered (5–10 per cent PFC) Lycium is commonly associated with dongas, to the australe (water bush) or scattered to moder- detriment of the associated vegetation. Donga ately closed (10–25 per cent PFC) Atriplex groves serve an important role in ‘arid proofing’ cryptocarpa commonly surround these berrigan the northern Nullarbor as a source of browse to groves. Austrostipa scabra (speargrass) be protected for dry periods. The close spacing commonly dominates the perennial grasses. of water points in dongas and the preferential grazing of the associated vegetation is leading Donga curara grove (DCGR) is predominantly to their deterioration within pastoral boundaries. vegetated with perennial grasses and annuals Mature trees and shrubs are browsed out of in the centre of the donga. The perimeter of reach with no recruitment stages of seedlings these dongas support very scattered to or saplings in the lower layers. When these scattered (2.5–15 per cent PFC) stands of mature trees eventually die, or are killed, there Acacia tetragonophylla (curara). are no younger trees to replace them. The Donga grevillea grove (DGGR) consists of a benefits donga groves offer to the local scattered to moderately closed (10–25 per cent ecosystem, as well as their significant regional PFC) tall shrubland of Grevillea nematophylla ecological value, will be lost. groves with a low shrub understorey dominated Donga habitat types were split into four sub- by Chenopodium curvispicatum surrounded by groups according to the dominant genus in the dense grass patches of variable composition. tree or tall shrub strata; Donga pittosporum grove (DPGR) consists of • Donga berrigan grove (DBGR) consists of very scattered to scattered (2.5–15 per cent small groves of Eremophila longifolia PFC) stands of Pittosporum angustifolium (berrigan) interspersed with perennial shrubs (native willow) with a scattered to moderately of the low to mid strata and a diverse variety closed (10–25 per cent PFC) understorey of of annuals. DBGR occurs predominantly Chenopodium curvispicatum. The grove is within dongas in the north-west of the survey commonly densely surrounded by grasses of area. variable composition. Very scattered to scattered (2.5–15 per cent PFC) stands of • Donga curara grove (DCGR) consists of Acacia tetragonophylla (curara) commonly stands of Acacia tetragonophylla (curara) occur on the perimeter. that form a sparse perimeter around the centre of a donga. DCGR is commonly found 56 perennial species were recorded at the 18 in the north-west and central-north of the inventory sites, with an average of 10 species survey area.

187 per site, one less than the survey average. Sclerolaena brevifolia, Solanum 27 annual species were recorded with an ellipticum, S. nigrum, Teucrium average of six species per site. racemosum. Perennial grasses: Dominant—Variable; Austrostipa The following species (by strata) are dominant scabra, Eragrostis dielsii, E. and/or common: setifolia Trees: Dominant—DBGR: Eremophila Common—Austrodanthonia longifolia caespitosa, Enneapogon Dominant—DGGR: Grevillea cylindricus nematophylla Others—Austrostipa platychaeta Occasional—Acacia salicina (KD), Enneapogon caerulescens. (north-east only) Other plant forms: Occasional—Amyema quandang Dominant—DPGR: Pittosporum var. quandang (mistletoe), angustifolium Glycine rubiginosa (creeper), Common—Eremophila Marsdenia australis (creeper). longifolia, Pittosporum Annual species recorded include Angianthus angustifolium conocephalus, Calotis hispidula, C. multicaulis, Others—Acacia aneura, Carrichtera annua (KI), Carthamus lanatus, Citrullus Alectryon oleifolius, Santalum lanatus, Dysphania cristata, Emex australis, Erodium spicatum. cygnorum, Euphorbia drummondii (KI), E. tannensis Tall shrubs: Dominant—DCGR: Acacia subsp. eremophila, Goodenia pinnatifida, Lepidium tetragonophylla fasciculatum, Lotus cruentus, Malva preissiana, Common—Acacia Mesembryanthemum crystallinum (KI), M. nodiflorum, tetragonophylla (KI) Nicotiana occidentalis (KI), Phlegmatospermum Others—Acacia burkittii (KI), cochlearinum, Rhodanthe floribunda, Salsola tragus A. oswaldii, Exocarpos aphyllus. (KI), Salvia verbenaca (KI), Sisymbrium erysimoides, Swainsona affinis, Vittadinia sp., Xanthium spinosum Mid shrubs: Dominant—Lycium australe and Zygophyllum iodocarpum (KI). Common—Pimelea microcephala, Scaevola Ecological disturbance spinescens Others—Atriplex nummularia, The inward drainage of the surrounding land- Eremophila decipiens (KI), scape results in soil accumulation and improved E. latrobei, E. maculata, Senna soil moisture storage. This provides favourable artemisioides subsp. x conditions for plant growth. Donga groves offer artemisioides (KI), shelter, a valuable source of browse and support S. artemisioides subsp. x annual plant growth for longer than other areas, coriacea (KI), Sida typically stony limestone plains. Animals calyxhymenia (KD). preferentially visit and graze them. The extra soil Low shrubs: Dominant—Chenopodium moisture-holding capacity of dongas means curvispicatum (KD), Enchylaena dongas in good condition can support a diverse tomentosa (KD) variety of perennial trees, shrubs and annual Common—Atriplex cryptocarpa, Lycium australe herbs. Others—Atriplex vesicaria, In the pastoral areas there has been a tendency Maireana radiata, M. sedifolia, for water points to be located in dongas leading M. turbinata, Ptilotus obovatus, to the degradation of the vegetation through Solanum nummularium, continuous grazing and the destruction of bush Zygophyllum aurantiacum. clumps, as herbivores attracted to the water Subshrubs: Dominant—Sclerolaena seek browse and shelter. Eremophila longifolia, patenticuspis (KI) Grevillea nematophylla and Pittosporum Common—Atriplex acutibractea angustifolium are palatable to stock with foliage (KI), Cullen cinereum, Eriochiton sclerolaenoides, that persists during dry periods. They provide an Erodium aureum, Sclerolaena important source of browse during dry condi- diacantha, S. obliquicuspis, tions. In dongas with water points continuous Sida spodochroma grazing can eventually lead to the trees’ death Others—Maireana trichoptera, and reduces the population to only older trees as Malvastrum americanum, seedlings and juveniles are eaten.

188 The dominant genera that differentiate donga [See tree-based clump condition monitoring habitat types and form the structural nuclei photographic guide in the Resource around which donga groves develop are Management chapter.] referred to as ‘tree-based clumps’. Bush The structure and diversity of the tree-based clumps are partly developed by frugivorous clumps indicates the condition of donga groves. birds dispersing the seeds of berry-fruited Those in good condition often have an plants such as Chenopodium curvispicatum, abundance of the palatable grasses Eragrostis Enchylaena tomentosa (ruby saltbush) and dielsii (mallee lovegrass) and E. setifolia Rhagodia species. These clumps offer (neverfail) surrounding groves over dense important habitat refuges in these exposed and clumps of berry-fruited plants. Dongas near arid landscapes not only to animals but also to water points are regularly degraded. Degraded other plants, prolonging the life of annuals and donga groves lack tree-based clumps, have no subshrubs, that otherwise do not endure the bird dispersed palatable berry plants and have climatic extremes of the Nullarbor as prominent browse lines as a result of successfully out in the open. The destruction of herbivorous grazing. The abundance of Acacia nuclei trees and the deterioration of understorey tetragonophylla-dominated dongas without the clumps reduces the ecological value of donga development of an understorey through northern groves leading to a reduction in the overall pastoral leases indicates the deteriorating carrying capacity of the landscape as it loses condition of donga habitats as a consequence ability to support herbivores during dry periods. of grazing.

Browsing pressure sequence of dongas dominated by Grevillea nematophylla. As browsing pressure increases the structure and diversity of the groves deteriorates. If grazing pressure does not ease the forage reserve offered by the donga, which herbivores rely on during dry periods, will be lost.

189 In poor condition, donga groves can be reduced • DCGR is a major habitat type on Kinclaven to sparse stands of aged trees surrounded by land systems and a minor habitat type on undesirable short-lived species such as Atriplex Balgair, Bullseye, Gafa, Kanandah, acutibractea (toothed saltbush), Carrichtera Kitchener, Kybo, Naretha, Nyanga and Oasis annua (Ward’s weed), Euphorbia drummondii land systems. (balsam), Mesembryanthemum crystallinum, • DGGR a major habitat type on Bullseye and Nicotiana occidentalis, Salsola tragus (roly Oasis land systems and is a minor habitat poly), Salvia verbenaca (wild sage), type on Carlisle, Jubilee, Kinclaven, Nyanga, Sclerolaena patenticuspis (spear-fruit Reid and Seemore land systems. copperburr), Rhodanthe floribunda and Zygophyllum iodocarpum. Considerable soil • DPGR is a major habitat type on Oasis land loss occurs during dry periods as the donga system and a minor habitat type on Carlisle, gradually becomes more open and exposed. Bullseye, Gafa, Jubilee, Kyarra, Reid and The increase in unpalatable species is also Skink land systems. compounded by the susceptibility of this vegetation association to invasion by exotic 37. Drainage depression saltbush species such as the declared weeds shrubland (DDSS) Carthamus lanatus (saffron thistle), Emex australis (doublegee) and Xanthium spinosum Sampling (Bathurst burr). 1 inventory site, 7 traverse points Gradational associations General information All forms of donga groves grade upslope from DDSS occurs in claypans and clay plains in the the donga floor into stony plains supporting west of the survey area. DDSS can also occur vegetation associations such as Mixed shrub in narrow drainage tracts associated with bindii grassland (XSBG), Open bindii grassland ancient river courses. Soils are red/brown non- (OBIG) and/or Pearl bluebush low shrubland cracking clays. (PBLS). DBGR and DCGR can also grade upslope from the donga into Mixed shrub bindii Physiognomy and composition of vegetation grassland (XSBG). DDSS comprises a moderately closed Land systems (20–25 per cent PFC) low shrubland of Atriplex species. Acacia burkittii (jam) and Eremophila • DBGR is a minor habitat type on Balgair, longifolia (berrigan) occur as closed stands or Kanandah, Kitchener, Kybo, Nurina and as isolated individuals. Nyanga land systems. 11 perennial species and four annual species were present at the one inventory site. The following species are dominant and/or common: Trees: Dominant—Not present as a recognisable stratum Occasional—Eremophila longifolia, Pittosporum angustifolium. Tall shrubs: Dominant—Not present as a recognisable stratum Common—Acacia burkittii (KI) Other—Acacia oswaldii. Low shrubs: Dominant—Variable; Atriplex cryptocarpa (KI) Common—Chenopodium Curara (Acacia tetragonophylla) dominated donga in curvispicatum (KD), Enchylaena poor condition. Trampling and grazing have reduced tomentosa (KD), Maireana the soil to a loose, powdery surface that is readily sedifolia deflated by wind. Other—Solanum nummularium.

190 Subshrubs: Dominant—Not present as a of large (20–60 cm) limestone fragments. Soils recognisable stratum are light calcareous loams overlain by dark Common—Atriplex acutibractea ‘organic’ loams. (KI), Sclerolaena patenticuspis (KI) Physiognomy and composition of vegetation Other—Swainsona affinis. DDXS occurs as a scattered (15–20 per cent Annual species recorded include Erodiophyllum PFC) tall shrubland of Acacia cyclops (coastal elderi, Mesembryanthemum crystallinum, Nicotiana wattle) with very scattered (2.5–5 per cent PFC) occidentalis (KI) and Sisymbrium erysimoides. Eucalyptus yalatensis (yalata mallee) forming Ecological disturbance the tree stratum. Acacia cyclops and Eucalyptus yalatensis form bush clumps Due to a lack of sampling not much is known of providing shelter and support for a variety of the disturbance mechanisms for DDSS. The perennial shrubs. low-lying landscape position makes it prone to receiving concentrated flow with potential for 21 perennial species, including one priority greater soil moisture retention. This makes it species, and two annual species were recorded prone to preferential grazing. Past grazing at the one inventory site. pressure is likely to have favoured the The following species (by stratum) were emergence of more grazing tolerant, less dominant and/or common: palatable species such as Atriplex acutibractea Trees: Dominant—Eucalyptus (toothed saltbush), A. cryptocarpa and yalatensis (mallee) Sclerolaena patenticuspis (spear-fruit Common—Santalum copperburr). acuminatum. Tree-based clumps commonly develop around Tall shrubs: Dominant—Acacia cyclops Acacia burkittii (jam), A. oswaldii, Eremophila Common—Templetonia retusa, longifolia (berrigan) and Pittosporum Exocarpos sparteus. angustifolium (native willow) with bird-dispersed Mid shrubs: Dominant—Not present as a berry-fruited plants common in the understorey. recognisable stratum Such palatable shrubs as Chenopodium Common—Acacia anceps, curvispicatum and Enchylaena tomentosa (ruby Scaevola spinescens, saltbush) may decrease under continuous Low shrubs: Dominant—Not present as a grazing pressure. recognisable stratum Common—Acacia erinacea, Gradational associations Enchylaena tomentosa, DDSS grades upslope into stony plains Rhagodia crassifolia Others—Acrotriche patula, supporting Pearl bluebush low shrubland Eremophila decipiens subsp. (PBLS). decipiens. Land systems Subshrubs: Dominant—Not present as a recognisable stratum DDSS is a minor habitat type on Naretha and Common—Heliotropium Pondana land systems. asperrimum, Sclerolaena patenticuspis 38. Drainage depression mixed shrub Other—Opercularia loganioides. shrubland (DDXS) Perennial grasses: Dominant—Not present as a recognisable stratum Sampling Common—Austrodanthonia 1 inventory site caespitosa. Other plant forms: Common—Billardiera fusiformis General information (creeper), Cassytha melantha DDXS occurs in drainage foci at the base of (creeper), Lepidosperma sp. (perennial sedge), Tetraria limestone hummocks (low rises) on the capillaris (perennial sedge), Toolinna and Abrakurrie Limestone towards the coast in the south of the survey area. The Annual species recorded include Euphorbia surface has a sparse (2 per cent) stony mantle drummondii and Podolepis canescens.

191 Ecological disturbance Rawlinna Station and occurs in both narrow and wide drainage tracts. Some of these shallow This habitat occurs outside of pastoral lease drainage lines may represent ancient river boundaries. Insufficient sampling precludes courses draining from the north-west. Some detailed quantitative description of disturbance drainage tracts feature fine well-worked quartz mechanisms. These areas receive localised grains in the soil profile. Soils are calcareous water shed from the stony surfaces of the loamy earths. limestone hummocks. In comparison to the surrounding land units these drainage foci have Physiognomy and composition of vegetation accumulated deeper soils, infrequently being areas with higher soil moisture content support- DRAS occurs as a very scattered (2.5–5 per ing subshrubs, Austrodanthonia caespitosa cent PFC) shrubland of acacias and Ptilotus (wallaby grass) and annuals. This makes DDXS obovatus (cotton bush). ecologically important as a preferentially sought 13 perennial species and four annual species after food source for the native herbivores living were recorded at the one inventory site. among the closed low woodland (LOMW) and The following species (by strata) were dominant scrub that dominate the area back from the and/or common: Baxter Cliffs. Trees: Dominant—Not present as a Much of the species diversity in this habitat type recognisable stratum is found within the bush clumps under Acacia Common—Acacia aneura, cyclops, Eucalyptus yalatensis and tall shrubs. Myoporum platycarpum Deterioration in bush clump health is likely to Other—Santalum spicatum. have a significant impact on the floristic diversity Tall shrubs: Dominant—Acacia burkittii (KI), of the associated plant community. A. tetragonophylla Thysanotus baueri, a Priority 1 species on the Common—Nil. declared rare and priority flora list, was Low shrubs: Dominant—Ptilotus obovatus recorded in this habitat. As such these habitat (KD) types are considered areas of high conservation Common—Enchylaena tomentosa (KD), Sida value. calyxhymenia (KD). Gradational associations Subshrubs: Dominant—Not present as a recognisable stratum DDXS is surrounded by irregular limestone Common—Sclerolaena hummocks supporting Low mallee woodland patenticuspis (KI), Sida (LOMW). spodochroma. Land systems Perennial grasses: Dominant—Not present as a recognisable stratum DDXS is a minor habitat on Toolinna land Common—Austrostipa scabra, system. Enneapogon caerulescens, E. cylindricus. 39. Drainage tract acacia shrubland Annual species recorded include Carrichtera annua (DRAS) (KI), Nicotiana occidentalis, Salsola tragus (KI) and Sisymbrium erysimoides. Sampling Ecological disturbance 1 inventory site, 5 traverse points Insufficient information was obtained for a General information detailed report on disturbance. From similar DRAS was previously described in the north- occurrences of DRAS from other surveys, eastern Goldfields survey (Pringle, Van overgrazing will cause decline in rangeland Vreeswyk & Gilligan 1994) as Drainage mulga condition, resulting in the reduction of palatable shrubland (DRMS). It was re-described in the perennial shrubs and grasses such as Sandstone–Yalgoo–Paynes Find survey (Payne Enchylaena tomentosa (ruby saltbush), Sida et al. 1998) as DRAS to recognise the promin- calyxhymenia (tall sida), Ptilotus obovatus ence of acacias other than Acacia aneura (cotton bush) and Enneapogon species may (mulga). On the Nullarbor, DRAS is restricted to result. Santalum spicatum (sandalwood) is a

192 common source of browse; the presence of The following species are dominant and/or juveniles indicates improving range condition. common: Unpalatable species such as Carrichtera annua Trees: Dominant—Nil (Ward’s weed), Sclerolaena patenticuspis Common—Occasionally; (spear-fruit copperburr) and Salsola tragus (roly Eremophila longifolia, poly) may increase under continuous grazing Pittosporum angustifolium pressure. Other—Acacia papyrocarpa. Tall shrubs: Dominant—Not present as a Gradational associations recognisable stratum DRAS grades out of the drainage line into the Common—Acacia oswaldii, surrounding Mixed acacia open shrubland A. tetragonophylla (KI). (XAOS). Mid shrubs: Dominant—Not present as a recognisable stratum Land systems Common—Atriplex nummularia, DRAS is a minor habitat type on Naretha land Eremophila maculata, Nitraria billardierei system. Others—Pimelea microcephala, Scaevola spinescens, Senna 40. Gilgai grassy shrubland (GGSL) artemisioides subsp. x artemisioides (KI), Sampling S. artemisioides subsp. x 11 inventory sites, 24 traverse points coriacea (KI). Low shrubs: Dominant—Lycium australe General information Common—Atriplex vesicaria, Gilgai formations result from the wetting and Chenopodium curvispicatum, drying of clays with high montmorillonite Enchylaena tomentosa, Maireana radiata, M. sedifolia content. Areas with gilgai soils are commonly Others—Atriplex cryptocarpa, found in the north of the survey area. Gilgai Zygophyllum aurantiacum structures often occur in dongas or at the base Subshrubs: Dominant—Not present as a of depressions on the limestone plain. In the recognisable stratum west of the survey area gilgai structures also Common—Atriplex acutibractea occur on the drainage floors of the large (KI), Cullen cinereum, depressions within the calcrete Nyanga Plain. Eriochiton sclerolaenoides, Soil heaving associated with wetting and drying Sclerolaena diacantha, cycles of gilgai soils bring limestone rocks to S. obliquicuspis, the surface. Limestone debris ranging from S. patenticuspis, Sida coarse fragments to boulders (6–200 cm in spodochroma, Solanum diameter) can cover up to 20 per cent of the ellipticum surface. Soils are cracking clays. Others—Erodium aureum, Maireana trichoptera, Sida Physiognomy and composition of vegetation intricata, Swainsona affinis. GGSL commonly occurs as low shrubs of very Perennial grasses: Dominant—Variable; Austrostipa scabra, Eragrostis scattered (5–10 per cent PFC) Lycium australe dielsii (KD), E. setifolia (KD). (water bush) among dense patches of perennial Common—Austrodanthonia grass of variable composition. Occasionally, caespitosa (KD) isolated Eremophila longifolia (berrigan) or Others—Enneapogon Pittosporum angustifolium (native willow) trees caerulescens, E. cylindricus, are present. Panicum decompositum. 41 perennial species were recorded at the 11 Other plant forms: Occasional—Glycine rubiginosa inventory sites, with an average of 13 species (creeper), Marsdenia australis (creeper). per site, two greater than the survey average. 25 annual species were recorded, with an Annual species recorded include Angianthus average of nine species per site. conocephala, Brachyscome sp., Calotis multicaulis, Carrichtera annua (KI), Centaurium erythraea, Chenopodium murale, Citrullus lanatus, Dysphania

193 melanocarpa forma leucocarpa, Erodium cygnorum, LISW occurs occasionally and is found Euphorbia drummondii, Goodenia pinnatifida, randomly through the survey area dependent on Lepidium sp., Lotus cruentus, Malva preissiana, local topography in areas subject to inundation. Mesembryanthemum crystallinum (KI), M. nodiflorum, Nicotiana goodspeedii, N. occidentalis (KI), Oxalis Physiognomy and composition of vegetation corniculata, Podolepis canescens, Rhodanthe floribunda (KI), Salsola tragus (KI), Sisymbrium LISW is dominated by a very scattered to erysimoides, Vittadinia sp. and Zygophyllum scattered (5–20 per cent PFC) shrubland of iodocarpum (KI). Muehlenbeckia florulenta. Species that can cope with temporary inundation such as Ecological disturbance Marsilea hirsuta (Nardoo) and Rhagodia ulicina Due to the landscape position of GGSL as are common. Muehlenbeckia florulenta grows in drainage foci and the potential to retain soil closed communities with few other plants. moisture for longer periods than the surrounding 22 perennial species were recorded at the four stony plains, this vegetation association inventory sites, with an average of seven supports an abundance of short-lived species. species per site, four less than the survey GGSL is preferentially grazed due to the average. 15 annual species were recorded, with abundance of palatable grasses it supports, an average of six species per site. particularly Eragrostis species. Under continu- ous heavy grazing the palatable grasses The following species (by strata) were dominant Austrodanthonia caespitosa (wallaby grass), and/or common: Eragrostis dielsii (mallee lovegrass) and Mid shrubs: Dominant—Muehlenbeckia E. setifolia (neverfail) decline and are replaced florulenta by less palatable grasses and annuals. GGSL is Other—Nitraria billardierei. also susceptible to invasion by exotic species. Low shrubs: Dominant—Not present as a recognisable stratum Gradational associations Common—Rhagodia ulicina GGSL grades into Open bindii grassland Others—Atriplex vesicaria, Enchylaena tomentosa, Lycium (OBIG), Mixed shrub bindii grassland (XSBG) australe, Maireana sedifolia, and Pearl bluebush low shrubland (PBLS) on the Rhagodia crassifolia. surrounding stony limestone plains. Subshrubs: Dominant—Not present as a Land systems recognisable stratum Common—Atriplex acutibractea GGSL is a major habitat type on Nurina land Others—Cullen cinereum, system and a minor habitat type on Balgair, Maireana trichoptera, Jubilee, Kanandah, Kinclaven, Koonjarra, Sclerolaena obliquicuspis, Nyanga and Seemore land systems. S. patenticuspis, Solanum ellipticum, S. nigrum, 41. Lignum swamp (LISW) Swainsona affinis. Perennial grasses: Dominant—Eragrostis setifolia Sampling (KD) 4 inventory sites Common—Eragrostis dielsii (KD) General information Others—Enneapogon caerulescens, Enteropogon LISW was previously described as a minor ramosus (KD), Eragrostis habitat type in the Sandstone–Yalgoo–Paynes australasica. Find survey area (Payne et al. 1998). LISW Other plant forms: Common—Marsilea hirsuta occurs within areas where water inundation (fern). occurs periodically such as in claypans, low- lying areas of karst depressions (‘corridors’ and Annual species recorded include Carrichtera annua dongas) and in ancient river courses. These (KI), Centaurea melitensis, Chenopodium murale, areas sometimes have gilgai structure with Citrullus lanatus, Eriachne sp., Goodenia pinnatifida, Isolepis congrua, Medicago sp., Menkea sp., Muehlenbeckia florulenta (lignum) distributed Mesembryanthemum crystallinum (KI), Nicotiana according to the micro-relief, preferring the occidentalis (KI), Rhodanthe floribunda, Senecio sp., raised areas. Soils are calcareous loamy earths Sonchus oleraceus and Zygophyllum iodocarpum (KI). and cracking clays where gilgai are present.

194 Ecological disturbance parvifolia (KD), Lycium australe, Maireana sedifolia, Olearia Muehlenbeckia florulenta is rarely eaten and calcarea, O. muelleri, has very low forage value. The palatable Tecticornia sp. grasses Eragrostis dielsii (mallee lovegrass) Subshrubs: Dominant—Not present as a and E. setifolia (neverfail) may decline under recognisable stratum continuous grazing pressure. Common—Sclerolaena diacantha (KD), Sida Gradational association spodochroma LISW has defined boundaries dependent on Others—Hypoxis glabella var. local topography being confined to areas subject glabella, Minuria cunninghamii, to periodic inundation. It is commonly Senecio quadridentatus, surrounded by Pearl bluebush low shrubland Solanum nigrum, Wahlenbergia communis, Wurmbea tenella. (PBLS) or Bladder saltbush shrubland (BSSL). Perennial grasses: Dominant—Austrodanthonia Land systems caespitosa (KD), Austrostipa scabra LISW is a minor habitat type on Bullseye, Gafa, Common—Austrostipa Kinclaven, Koonjarra and Nyanga land systems. elegantissima (KD), A. platychaeta (KD). 42. Plain mixed low shrubland (PXLS) Other plant forms: Occasional—Cassytha Sampling melantha (creeper). Annual species recorded include Anagallis arvensis, 2 inventory sites, 3 traverse points Carduus nutans, Erodium cicutarium, Nicotiana General information goodspeedii, Sonchus oleraceus and Xanthium spinosum. PXLS occurs in clay depressions to the south of the survey area. Soils are calcareous loamy Ecological disturbance earths and red/brown non-cracking clays. This vegetation association was insufficiently Physiognomy and composition of vegetation sampled to obtain detailed quantitative informa- tion regarding disturbance characteristics. PXLS comprises scattered (10–15 per cent Overgrazing of PXLS is likely to result in a PFC) mid shrubland dominated by Eremophila decline in palatable shrubs such as Enchylaena species. tomentosa (ruby saltbush) and Sclerolaena 30 perennial species were recorded at the two diacantha (grey bindii), and the perennial inventory sites, with an average of 17 species grasses Austrodanthonia caespitosa (wallaby per site, six greater than the survey average. Six grass), Austrostipa elegantissima (feather annual species were recorded with an average speargrass) and A. platychaeta. of three species per site. Gradational associations The following species (by strata) were dominant PXLS changes abruptly into the surrounding and/or common: Low mallee woodland (LOMW) and Eucalypt Tall shrubs: Dominant—Not present as a mixed scrub woodland (EXSW) at the boundary recognisable stratum of the karst depression and the resumption of Common—Acacia cyclops, the stony calcrete plain. Geijera linearifolia Other—Exocarpos aphyllus. Land system Mid shrubs: Dominant—Eremophila PXLS is a minor habitat type on Caiguna and decipiens (KI), E. deserti Common—Atriplex nummularia, Culver land systems. Nitraria billardierei Others—Leptomeria pachyclada, Solanum symonii. Low shrubs: Dominant—Occasionally; Lawrencia squamata (KI) Common—Enchylaena tomentosa (KD), Eremophila

195 I. SHRUBLAND AND WOODLAND Three annual species were recorded at one ON LAKE MARGINS AND SALINE site. DEPRESSIONS The following species (by strata) were dominant and/or common: This group of habitat types is generally confined Trees: Dominant—Casuarina pauper to the margins of lake beds or occurs in saline Common—Myoporum low-lying closed or open depressions within platycarpum, Eucalyptus undulating plains. Occurring on saline and concinna, E. conglobata. gypsiferous soils, these habitat types Tall shrubs: Dominant—Not present as a characteristically support halophytic plants, recognisable stratum such as species of Tecticornia (samphire) and Common—Senna artemisioides Frankenia (frankenia). They make up a small subsp. x coriacea proportion of the survey area. Others—Acacia ligulata, Geijera linearifolia. 43. Kopi dune woodland (KOPI) Mid shrubs: Dominant—Not present as a recognisable stratum Sampling Common—Atriplex nummularia, 2 inventory sites, 8 traverse points Cratystylis conocephala, Eremophila scoparia General information Others—Acacia nyssophylla, Dodonaea lobulata. KOPI has previously been described in the Low shrubs: Dominant—Chenopodium north-eastern Goldfields (Pringle, Van Vreeswyk curvispicatum (KD), Tecticornia & Gilligan 1994) and the Sandstone–Yalgoo– doleiformis, Tecticornia sp. Paynes Find (Payne et al. 1998) survey areas. Common—Atriplex vesicaria KOPI occurs on the kopi dunes surrounding (KD), Disphyma crassifolium, Lake Boonderoo, fringing Ponton Creek and salt Enchylaena tomentosa (KD), lakes in the very south-west of the survey area. Frankenia densa, Lycium Kopi dunes form by prevailing winds deflating australe, Maireana erioclada, lake beds and building up powdery dunes of Olearia ramosissima, Rhagodia gypsum around the lake margins. The dunes crassifolia (KD), Zygophyllum aurantiacum. have gently inclined slopes of up to 3 per cent and coarse (2–6 cm) limestone fragments are Subshrubs: Dominant—Not present as a common on the surface. Soils are calcareous recognisable stratum Common—Maireana trichoptera, loamy earths. Sclerolaena diacantha (KD), Physiognomy and composition of vegetation S. obliquicuspis, S. patenticuspis. KOPI occurs as a scattered (10–20 per cent Perennial grasses: Dominant—Not present as a PFC) low shrubland of Tecticornia species recognisable stratum (samphire) and Chenopodium curvispicatum. Common—Austrodanthonia The overstorey consists of very scattered caespitosa, Austrostipa scabra. (2.5–5 per cent PFC) Casuarina pauper (black Other plant forms: Occasional—Dianella revoluta oak). In the south-west of the survey area (lily). Eucalyptus species are also present on kopi dunes alongside Casuarina pauper. Around Annual species recorded include Carrichtera annua, Eriachne sp. and Zygophyllum glaucum. Lake Boonderoo many trees are dead as a result of inundation when the water level Ecological disturbance increased following Cyclone Bobby in 1995. Inundation due to the associated effects of Areas supporting this vegetation around Lake Cyclone Bobby in 1995 dramatically altered the Boonderoo are now in a state of ecological composition and structure of Lake Boonderoo transition as water level subsides. KOPI. Much of the casuarina woodland 31 perennial species were recorded at the two surrounding the lake has died and is now in a inventory sites, with an average of 16 species state of transition as water levels subside. The per site, five greater than the survey average. high soil salinity is influencing the vegetation colonisation sequence.

196 After infrequent periods of inundation Lake sandy banks appears to influence the proportion Boonderoo is known to contain fresh water, of non-halophytic shrubs to halophytic shrubs however during the survey period the water was occurring adjacent to SBLS on the Boonderoo highly saline due to the concentration of salts lake bed. These red, deep sandy soils provide through evaporation. Grazing impact will be the associated vegetation with increased water determined by the quality of nearby drinking availability through enhanced infiltration, deeper water. If the quality of drinking water is fresh storage and reduced evaporation rates. then continuous grazing may result and a decline in the palatable shrubs Atriplex vesicaria Physiognomy and composition of vegetation (bladder saltbush), Chenopodium SBLS consists of a non-halophytic component curvispicatum, Enchylaena tomentosa (ruby which generally is more prominent on the upper saltbush), Maireana trichoptera (pink-seeded banks. Chenopods become more abundant on bluebush), Rhagodia crassifolia and the lower banks and bank margins, possibly due Sclerolaena diacantha (grey bindii) could be to the development of duplex soils and expected. However the absence of these increasing soil salinity associated with the species from an area may be natural rather proximity to Lake Boonderoo. This variability is than as a result of grazing. observed in the range of composition and form of this vegetation type. Gradational association SBLS occurs as a closed (30–50 per cent PFC) Sloping down to the margin of Lake Boonderoo, tall shrubland, commonly dominated by species KOPI grades into Samphire shrubland (SAMP) of acacia, such as Acacia ligulata (umbrella and/or Plain mixed halophyte shrubland (PXHS) bush). The tree component is variable, the dominated by Atriplex and Tecticornia species. species composition often reflecting a transition Land systems from adjacent habitats. Low shrubs are prominent and perennial grasses such as KOPI is a minor habitat type on Boonderoo, Triodia scariosa (spinifex) vary from common to Lefroy and Ponton land systems. absent. 44. Sandy bank lake shrubland (SBLS) 21 perennial species were recorded at the two inventory sites. Sampling The following species (by strata) are dominant 2 inventory sites and/or common: General information Trees: Dominant—Not present as a recognisable stratum SBLS has been previously described in the Common—Casuarina pauper, north-eastern Goldfields (Pringle, Van Vreeswyk Eucalyptus concinna, E. sp. and Gilligan 1994) and the Sandstone–Yalgoo– Fraser Range Paynes Find (Payne et al. 1998) survey areas. It Others—Myoporum platycarpum, Psydrax attenuata. occurs on sandy banks adjacent to bare lake beds. The formation of the sandy banks is due Tall shrubs: Dominant—Acacia ligulata to a combination of transported sandy sediment Common—Eremophila via prevailing winds, infrequent lake inundation dempsteri. and by high energy sheet flow from landforms Mid shrubs: Dominant—Not present as a adjacent to and above the sandy slopes. Soils recognisable stratum are generally deep red sands. Common—Eremophila latrobei subsp. glabra The banks support two different floristic Others—Grevillea sp., Rhagodia components: non-halophytic species such as preissii subsp. preissii (KD), Acacia spp., Casuarina pauper (black oak), Senna sp. Eucalyptus spp. and Triodia scariosa (spinifex); Low shrubs: Dominant—Not present as a and chenopod species such as Atriplex recognisable stratum vesicaria (bladder saltbush), Chenopodium Common—Atriplex vesicaria curvispicatum, Enchylaena tomentosa (ruby (KD), Chenopodium saltbush), Maireana sedifolia (pearl bluebush) curvispicatum (KD), Enchylaena and Rhagodia spp. The morphology of the tomentosa (KD), Maireana sedifolia, Ptilotus obovatus,

197 Rhagodia ulicina (KD), Solanum Find (Payne et al. 1998) and Pilbara (Van nummularium. Vreeswyk et al. 2004) survey areas. It was also Subshrubs: Dominant—Not present as a described in the Murchison survey area (Curry recognisable stratum et al. 1994) as Mixed halophyte shrubland Common—Maireana trichoptera. (MXHS). PXHS commonly occurs in saline Perennial grasses: Dominant—Not present as a depressions on marginal slopes or within drain- recognisable stratum age floors and in clay depressions between Common—Triodia scariosa. gently undulating plains. It also occurs on lake Other plant forms: Occasional—Marsdenia beds and margins. Soils are calcareous loamy australis (creeper). earths or red/brown non-cracking clays. Where present at lake bed margins soils may be saline Only one annual (Eriachne sp.) was observed at the time of sampling, however it should be noted that the wet soils or red deep sands. It is found through- area was in a dry period. out the survey area. Ecological disturbance Physiognomy and composition of vegetation Insufficient information was obtained for a PXHS exists as a scattered to moderately qualitative assessment of disturbance closed (10–25 per cent PFC) low shrubland of mechanisms. The most noticeable indicators of Atriplex vesicaria (bladder saltbush), Maireana grazing impact in SBLS would be in the sedifolia (pearl bluebush) and Tecticornia palatable low shrub component where pastures species (samphire). become more saline. Under heavy grazing the 68 perennial species were recorded at the 27 palatable shrubs Atriplex vesicaria (bladder inventory sites, with an average of 11 species saltbush), Chenopodium curvispicatum, per site, the survey average. 22 annual species Enchylaena tomentosa (ruby saltbush), were recorded, with an average of three Maireana trichoptera (pink-seeded bluebush) species per site. and Rhagodia spp. may decline. However, the absence of these species may not be as a The following species (by strata) were dominant result of grazing and may reflect natural and/or common: variability in species composition. Trees: Dominant—Not present as a recognisable stratum Gradational associations Others—Acacia papyrocarpa, Eucalyptus gracilis, Melaleuca SBLS grades upslope on to calcrete plains quadrifaria, Myoporum overlain by sand supporting Mallee hummock platycarpum, Pittosporum grass (spinifex) woodland (MHGW). The lower angustifolium, Santalum slopes of sandy banks are usually clearly acuminatum, Tamarix aphylla. defined as the adjacent halophytic plant Tall shrubs: Dominant—Not present as a communities, Plain mixed halophyte shrubland recognisable stratum (PXHS), associated with Lake Boonderoo Others—Exocarpos aphyllus, replace the non-halophytic species. Geijera linearifolia. Land systems Mid shrubs: Dominant—Occasionally: Atriplex nummularia SBLS is a minor habitat type on Boonderoo and Common—Cratystylis Ponton land systems. conocephala, Nitraria billardierei Others—Eremophila decipiens 45. Plain mixed halophyte shrubland (KI), E. deserti, E. scoparia (KI), Scaevola spinescens, Senna (PXHS) artemisioides subsp. x Sampling artemisioides (KI), S. artemisioides subsp. x 27 inventory sites, 316 traverse points coriacea (KI). General information Low shrubs: Dominant—Atriplex vesicaria (KD), Maireana sedifolia, PXHS has previously been described in the Tecticornia doleiformis, north-eastern Goldfields (Pringle, Van Vreeswyk Tecticornia sp. & Gilligan 1994), Sandstone–Yalgoo–Paynes Common—Atriplex cryptocarpa,

198 A. stipitata, Enchylaena Ecological disturbance tomentosa (KD), Frankenia densa, Gunniopsis calcarea, The low-lying landscape position can improve Lawrencia squamata, Lycium growing conditions for plants by providing areas australe, Maireana erioclada, with longer higher soil moisture retention. This M. georgei (KD), can lead to an abundance in subshrubs and M. oppositifolia, M. turbinata, annuals, which in turn can lead to preferential Nitraria billardierei grazing by herbivores. If good quality water is Others—Chenopodium available grazing pressure can lead to reduc- curvispicatum (KD), Cratystylis tions in palatable plants. Where PXHS has subspinescens (KD), Disphyma previously been described (Curry et al. 1994; crassifolium, Gunniopsis quadrifida, Olearia calcarea, Pringle, Van Vreeswyk & Gilligan 1994; Payne et O. muelleri, Rhagodia al. 1998; Van Vreeswyk et al. 2004) it was found crassifolia, R. ulicina, Solanum that the most sensitive indicator of grazing nummularium, Westringia impact was the prominence of key decreaser rigida. species and, to a lesser extent, increaser Subshrubs: Dominant—Not present as a species. Under heavy grazing pressure recognisable stratum palatable shrubs that tend to decrease include Common—Cullen cinereum, Atriplex vesicaria, Chenopodium curvispicatum, Eriochiton sclerolaenoides (KD), Enchylaena tomentosa (ruby saltbush), Maireana tomentosa (KD), Eriochiton sclerolaenoides (woolly bindii), M. trichoptera (KD), Sclerolaena Maireana tomentosa (felty bluebush), diacantha (KD), M. trichoptera (pink-seeded bluebush) and S. obliquicuspis (KI), Sclerolaena diacantha (grey bindii). With the S. patenticuspis (KI) loss of palatable species Tecticornia spp. Others—Atriplex acutibractea (KI), Lawrencia spicata, Minuria (samphire) can become dominant. Other cunninghamii, Sclerolaena increaser plants include species of Senna and densiflora (KI), Senecio Eremophila. If unpalatable subshrubs such as spanomerus, Sida Atriplex acutibractea (toothed saltbush), spodochroma, Wurmbea Sclerolaena densiflora (hairy bindii), tenella, Zygophyllum billardierei. S. obliquicuspis (limestone bindii) and Perennial grasses: Dominant—Not present as a S. patenticuspis (spear-fruit copperburr) occur recognisable stratum in abundance repeatedly each year then an area Common—Austrodanthonia is also considered to be in poor condition. caespitosa, Austrostipa scabra Others—Austrodanthonia The saline nature of the subsoil makes it setacea, Austrostipa susceptible to scald development. As scalds drummondii, A. platychaeta begin to coalesce the capacity of the area to (KD), Enneapogon support plant growth is reduced. Loss of peren- caerulescens, Enteropogon nial species and scald development can result ramosus. in accelerated soil loss through wind erosion. Other plant forms: Occasional—Carpobrotus The declared weeds Tamarix aphylla (athel virescens (succulent perennial pine) and Xanthium spinosum (Bathurst burr) herb), Dianella revoluta (lily). were recorded at this habitat type. Annual species recorded include Angianthus conocephalus, Atriplex codonocarpa, Brachyscome Gradational associations ciliaris, Calandrinia sp., Calotis sp., Carrichtera As the subsoil becomes less saline PXHS annua (KI), Eriachne sp., Erodium sp., Euphorbia drummondii, Lepidium sp., Nicotiana occidentalis commonly grades into Bladder saltbush (KI), Oxalis corniculata, Podolepis canescens, shrubland (BSSL) and Speargrass and wallaby Rhodanthe chlorocephala, Salsola tragus (KI), grass open grassland (SWOG). Where kopi or Senecio pinnatifolius, Sonchus oleraceus, sandy dunes surround Lake Boonderoo and the Trichanthodium skirrophorum, Vittadinia humerata, salt lakes of the Lefroy land system or fringe Xanthium spinosum, Zygophyllum iodocarpum (KI) Ponton Creek, PXHS is bordered by Kopi dune and Z. ovatum. woodland (KOPI) or Sandy bank lake shrubland (SBLS). As eucalypt or myall species start to appear but soils remain saline PXHS grades

199 into Eucalypt mixed halophyte shrubland Maireana erioclada, (EXHS) or Myall mixed halophyte shrubland M. oppositifolia (MHXS). PXHS depressions are commonly Others—Frankenia densa, surrounded by Pearl bluebush low shrubland Gunniopsis calcarea, Kippistia (PBLS) or less commonly in the south-east by suaedifolia. Myall saltbush shrubland or woodland (MSAS). Subshrubs: Dominant—Not present as a recognisable stratum Land systems Common—Sclerolaena diacantha (KD) PXHS is a major habitat type on Boonderoo, Other—Lawrencia spicata. Damper, Vanesk and Virginia land systems and a minor habitat on Arubiddy, Caiguna, Chowilla, Perennial grasses: Dominant—Not present as a recognisable stratum Nanambinia, Nightshade, Ponton, Reid, Others—Austrostipa scabra. Shakehole, Thampanna and Woorlba land systems. Other plant forms: Occasional—Carpobrotus modestus (succulent perennial herb), C. virescens (succulent 46. Samphire shrubland (SAMP) perennial herb). Sampling Annual species recorded include Brachyscome ciliaris, Lepidium sp., Senecio pinnatifolius, Sonchus 5 inventory sites, 29 traverse points oleraceus and Trichanthodium skirrophorum. General information Ecological disturbance SAMP was previously described in the Due to the high salt content of most plants, Carnarvon Basin (Payne, Curry & Spencer predominantly samphires, the habitat type is 1987), north-eastern Goldfields (Pringle, Van resilient to grazing. Pringle, Van Vreeswyk and Vreeswyk & Gilligan 1994), Murchison River Gilligan (1994) noted stock preferred other less catchment (Curry et al. 1994) and Sandstone– saline pastures where available, unless nearby Yalgoo–Paynes Find (Payne et al. 1998) water supplies are fresh and there is little else surveys. SAMP is associated with highly saline, to eat. Some of the more palatable species gypsiferous soils fringing the lake beds in the such as Atriplex vesicaria (bladder saltbush) south-west of the survey area. It is also found and Sclerolaena diacantha (grey bindii), com- on the Roe Plains on the Damper land system prising a minor component of this vegetation and in saline depressions between gentle association, may be removed through grazing, undulations in the south on the Bunda Plateau. though this is not a reliable indicator of condition Soils are calcareous shallow loams and loamy as such species can be absent from ungrazed earths, and red/brown non-cracking clays. areas. Physiognomy and composition of vegetation Gradational associations SAMP comprises a low shrubland of very SAMP populations associated with lake scattered to scattered (5–20 per cent PFC) systems in the south-west of the survey area Tecticornia species (samphire). are commonly surrounded by Kopi dune 15 perennial species were recorded at the five woodland (KOPI) or Sandy bank lake shrubland inventory sites, with an average of five species (SBLS). Elsewhere SAMP commonly grades per site, six less than the survey average. Five upslope to Speargrass and wallaby grass open annual species were recorded, with an average grassland (SWOG) or Plain mixed chenopod of two species per site. shrubland (PXCS). The following species (by strata) are dominant Land systems and/or common: SAMP is the dominant habitat type on Damper Mid shrubs: Dominant—Not present as a land system and a minor habitat type on recognisable stratum Boonderoo, Lefroy and Ponton land systems. Other—Nitraria billardierei. Low shrubs: Dominant—Tecticornia disarticulata, T. doleiformis Common—Atriplex vesicaria (KD), Lawrencia squamata,

200 J. COASTAL ZONE SCRUBLAND The following species (by stratum) were AND WOODLAND dominant and/or common: Trees: Dominant—Variable; Eucalyptus The habitat types in this group predominantly brachycalyx (mallee), E. gracilis occur on aeolian sand sheets and dunes, in (mallee), E. oleosa subsp. various stages of stabilisation, along the coast- ampliata (mallee) line of the Great Australian Bight in the south of Common—Eucalyptus the survey area. These coastal habitats tend to conglobata (mallee), E. oleosa grade inland coastward from eucalyptus– subsp. oleosa (mallee), melaleuca woodland into eucalypt mallee wood- E. yalatensis (mallee), Myoporum platycarpum land and finally develop into scrubland and Others—Acacia papyrocarpa, coastal heath at the coast. This gradational Eucalyptus discreta (mallee), pattern corresponds with increasing depth of E. diversifolia (mallee), sand associated with dune development and Pittosporum angustifolium, structural modifications and adaptations related Santalum spicatum. to coastal influences. Tall shrubs: Dominant—Melaleuca lanceolata 47. Eucalypt, melaleuca mixed Common—Melaleuca chenopod shrubland or woodland quadrifaria, Exocarpos aphyllus, (EMCW) Geijera linearifolia Others—Eremophila alternifolia, Sampling Templetonia retusa. 9 inventory sites, 8 traverse points Mid shrubs: Dominant—Cratystylis conocephala General information Common—Atriplex nummularia, Eremophila glabra, Nitraria EMCW commonly occurs on the steep stony billardierei slope (up to 30 per cent) of the Hampton Scarp. Others—Dodonaea stenozyga, Limestone colluvial debris (2–60 cm) covers up Eremophila deserti, E. glabra. to 90 per cent of the scree slope; up to 50 per Low shrubs: Dominant—Atriplex vesicaria cent of the area can have scarp outcrop (KD), Maireana erioclada protruding through it. EMCW also occurs on the Common—Enchylaena Roe Plains where a scattered mantle of mixed- tomentosa, Lycium australe, sized calcareous gravel (0.2–6 cm) can cover Olearia calcarea, Rhagodia up to 10 per cent of the surface. Soils are crassifolia, Zygophyllum calcareous loamy earths and shallow loams. aurantiacum Others—Eremophila weldii, Physiognomy and composition of vegetation Frankenia sessilis, Maireana georgei (KD), M. radiata, EMCW consists of a scattered (10–20 per cent M. sedifolia, Olearia PFC) low woodland or shrubland. The tree ramosissima, Ptilotus stratum is composed of mallee-form eucalypts obovatus, P. symonii, of variable species but Eucalyptus brachycalyx Tecticornia sp., Westringia (gilja), E. gracilis (yorrell) and E. oleosa subsp. rigida. ampliata dominate. The tall shrub stratum is Subshrubs: Dominant—Not present as a dominated by Melaleuca lanceolata (Rottnest recognisable stratum tea-tree), the mid shrub stratum by Cratystylis Common—Maireana tomentosa conocephala (false bluebush) and the low shrub (KD), Sclerolaena diacantha stratum by Atriplex vesicaria (bladder saltbush) (KD), S. obliquicuspis, S. patenticuspis, Tetragonia and/or Maireana erioclada. implexicoma 58 perennial species were recorded at the nine Others—Eriochiton inventory sites, with an average of 16 perennial sclerolaenoides (KD), Maireana species per site, five greater than the survey trichoptera (KD), Sclerolaena average. 11 annual species were recorded, with densiflora, Zygophyllum apiculatum. an average of three species per site.

201 Perennial grasses: Dominant—Not present as a General information recognisable stratum Common—Austrostipa EMEW predominantly occurs on the calcarenite platychaeta (KD), A. scabra Roe Plains. Soils are calcareous loamy earths Others—Austrodanthonia and calcareous shallow sands. A variable caespitosa (KD), Austrostipa mantle of fine calcareous fragments (2–6 mm) drummondii, A. elegantissima commonly covers less than 10 per cent of the (KD). surface, but can cover up to 90 per cent. Other plant forms: Occasional—Carpobrotus EMEW is also present in interdune swales of modestus (succulent perennial stabilised sand dunes. In the south-east of the herb), Dianella revoluta (lily). survey area EMEW also occurs on residual old Annual species recorded include Asteridea dunes now altered to sandy clay and calcrete athrixioides, Aristida sp., Brachyscome ciliaris, on the southern edge of the Hampton Tableland B. lineariloba, Carrichtera annua, Erodium sp., behind the Hampton Scarp. Euphorbia drummondii, Rostraria pumila, Sonchus oleraceus, Zygophyllum glaucum and Z. ovatum. Physiognomy and composition of vegetation Ecological disturbance EMEW occurs as a scattered to moderately closed (10–30 per cent PFC) low woodland or EMCW commonly occurs adjacent to areas tall scrubland. The tree stratum is dominated by that are actively grazed and are not preferen- mallee-form eucalypts of various species and tially sought after. However, heavy grazing will by melaleucas through the tall shrub stratum. result in a reduction of palatable low shrubs and grasses such as Atriplex vesicaria, Austrostipa 67 perennial species were recorded at the 20 platychaeta, A. elegantissima, Austrodanthonia inventory sites, with an average of 11 species caespitosa, Enchylaena tomentosa, Eriochiton per site, the same as the survey average. sclerolaenoides, Maireana trichoptera, Seven annual species were recorded with an M. tomentosa and Sclerolaena diacantha. average of one species per site. The following species (by strata) were dominant Gradational associations and/or common: EMCW grades into Eucalypt melaleuca Trees: Dominant—Variable; Eucalyptus woodland (EMEW) where the chenopod brachycalyx (mallee), E. gracilis component becomes sparse and the tree (mallee), E. oleosa (mallee), stratum becomes denser and closed. In other E. oleosa subsp. oleosa areas EMCW tends to have a defined boundary (mallee) such as where these woodland areas lie Common—Eucalyptus adjacent to chenopod shrubland, commonly conglobata (mallee), E. discreta (mallee), E. diversifolia Plain mixed chenopod shrubland (PXCS), or (mallee), E. oleosa subsp. where stabilised dunes support a heath ampliata (mallee), E. urna understorey such as Eucalypt heath woodland Others—Allocasuarina helmsii, (EHEW) or Eucalypt coastal heath woodland Eucalyptus yalatensis (mallee), (ECHW). Myoporum platycarpum, Santalum acuminatum. Land systems Tall shrubs: Dominant—Melaleuca EMCW is a major habitat type on Roe land lanceolata, M. quadrifaria system and a minor habitat type on Thampanna Common—Eremophila and Wurrengoodyea land systems. dempsteri, Exocarpos aphyllus, Geijera linearifolia 48. Eucalypt, melaleuca woodland Others—Acacia oswaldii, Templetonia sulcata. (EMEW) Mid shrubs: Dominant—Occasionally; Sampling Cratystylis conocephala Common—Atriplex nummularia, 20 inventory sites, 81 traverse points Eremophila deserti Others—Acacia anceps, A. merrallii, Alyxia buxifolia, Dodonaea bursariifolia,

202 D. stenozyga, Eremophila Gradational associations decipiens, Nitraria billardierei, Scaevola spinescens. EMEW commonly grades into Eucalypt, melaleuca mixed chenopod shrubland or Low shrubs: Dominant—Olearia calcarea woodland (EMCW) or Eucalypt mixed scrub Common—Atriplex vesicaria, Enchylaena tomentosa, woodland (EXSW) as the tree stratum becomes Eremophila weldii, Maireana scattered and the density of the melaleuca erioclada, Rhagodia crassifolia, component reduces as chenopods or mixed Westringia rigida, Zygophyllum shrubs begin to dominate the lower shrub aurantiacum stratum. EMEW also grades into Eucalypt Others—Acacia erinacea, heath woodland (EHEW) on stabilised dunes or Atriplex isatidea, Eremophila Coastal shrubland (COAS) as dunes become oblonga, E. parvifolia, more mobile. Low mallee woodland (LOMW) Frankenia densa, Gunniopsis replaces EMEW when outcrop starts to occur calcarea, Lawrencia squamata, as calcareous shallow sands disappear and Maireana pentatropis, Microcybe pauciflora subsp. calcareous loamy earths become shallower. pauciflora, Olearia muelleri, Land systems O. ramosissima, Pultenaea elachista, Scaevola EMEW is a major habitat type on Moopina and bursariifolia, Sclerolaena Roe land systems and a minor habitat type on brevifolia, Tecticornia sp. Caiguna, Culver, Toolinna and Wurrengoodyea Subshrubs: Dominant—Not present as a land systems. recognisable stratum Common—Sclerolaena 49. Low mallee woodland (LOMW) diacantha Others—Eriochiton Sampling sclerolaenoides, Maireana tomentosa, Sclerolaena 11 inventory sites, 80 traverse points obliquicuspis, S. patenticuspis, General information Threlkeldia diffusa. Perennial grasses: Dominant—Not present as a LOMW occurs on limestone and calcrete plains recognisable stratum in the south of the survey area. The mantle is Common—Austrostipa scabra variable, becoming stonier coastward. Medium- Other—Austrostipa platychaeta. sized (6–20 mm) angular, calcareous Other plant forms: Occasional—Carpobrotus fragments can cover up to 50 per cent of the modestus (succulent perennial surface. Indurated calcareous outcrop occurs herb), Cassytha melantha through 10–50 per cent of habitats depending (creeper), Comesperma volubile on the variability of the overlying calcareous (creeper), Dianella revoluta (lily), shallow loam. On limestone hummocks the Gahnia lanigera (perennial outcrop is greater and the surface is commonly sedge). pitted due to weathering. Annual species recorded include Asteridea athrixioides, Euphorbia drummondii, Oncosiphon Physiognomy and composition of vegetation suffruticosum, Trichanthodium skirrophorum, LOMW occurs as scattered (10–20 per cent Zygophyllum glaucum, Z. iodocarpum and Z. ovatum. PFC) low mallee woodland of variable eucalypt Ecological disturbance species over scattered to moderately closed mixed scrub, sedges and occasionally Little is known about the disturbance mechan- hummock grasses. isms in EMEW in the Nullarbor region. This habitat has limited occurrence within the 65 perennial species were recorded at the 11 pastoral leases and is generally unfavoured for inventory sites, including one priority species, grazing owing to the lack of grasses and domi- with an average of 13 species per site, two nance of unpalatable eucalypts and melaleucas. greater than the survey average. One annual Where low shrubs and subshrubs occur in any species was recorded. abundance it would be expected palatable species would decline under continuous grazing pressure.

203 The following species (by strata) are dominant Subshrubs: Dominant—Not present as a and/or common: recognisable stratum Others—Goodenia affinis, Trees: Dominant—Eucalyptus oleosa G. concinna, Lomandra sp., subsp. oleosa (mallee) Variable; Wahlenbergia communis. Eucalyptus brachycalyx (mallee), E. conglobata Perennial grasses: Dominant—Not present as a (mallee), E. cooperiana recognisable stratum (mallee), E. gracilis, Common—Triodia scariosa E. yalatensis (mallee) (hummock grass) Common—Allocasuarina Other—Austrostipa platychaeta. helmsii, Eucalyptus diversifolia Other plant forms: Dominant—Gahnia lanigera (mallee) (perennial sedge) Other—Santalum acuminatum. Common—Dianella revoluta Tall shrubs: Dominant—Allocasuarina (lily), Tetraria capillaris helmsii, Melaleuca lanceolata (perennial sedge) Common—Dodonaea Others—Cassytha melantha stenozyga, Templetonia retusa, (creeper), Lepidosperma sp. Eremophila dempsteri (perennial sedge), Schoenus Others—Acacia cyclops, subflavus subsp. hispid culms Allocasuarina scleroclada, (perennial sedge). Exocarpos aphyllus, Annual species recorded include Calandrinia sp. E. sparteus, Geijera linearifolia. Mid shrubs: Dominant—Not present as a Ecological disturbance recognisable stratum This habitat type generally occurs outside of Others—Acacia cupularis, pastoral lease boundaries and little is known A. sulcata var. platyphylla, about the grazing ecology or other disturbance Beyeria lechenaultii, Dodonaea bursariifolia, D. stenozyga, mechanisms. Grevillea sparsiflora, Kunzea Thysanotus baueri, a Priority 1 species on the pulchella, Lasiopetalum declared rare and priority flora list, was compactum, Leptomeria recorded in this habitat and as such the area is pachyclada, Melaleuca of high conservation value. pentagona var. latifolia, Pultenaea heterochila, Scaevola Gradational associations spinescens, Senna artemisioides subsp. x LOMW commonly grades into Eucalypt artemisioides, S. artemisioides melaleuca woodland (EMEW) as calcareous subsp. x coriacea. loamy earths deepen and calcareous shallow Low shrubs: Dominant—Not present as a sands cover outcrop. LOMW has a defined recognisable stratum boundary against aeolian sand dunes support- Common—Acacia erinacea, ing Banksia coastal heath and scrubland Halgania andromedifolia, Olearia (BCHS) behind cliff faces. Also occurring calcarea, O. muelleri, randomly through the LOMW are karst depres- Pomaderris myrtilloides, sions supporting Plain mixed low shrubland Prostanthera serpyllifolia subsp. (PXLS) or Drainage depression mixed shrub serpyllifolia, Pultenaea shrubland (DDXS) within the indurated stony elachista, Spyridium tricolor, Westringia rigida calcareous plains and between limestone Others—Acacia excentrica, hummocks. Acrotriche cordata, A. patula, Calytrix tetragona, Land systems Conostephium drummondii, LOMW is the dominant habitat type on Toolinna Eremophila weldii, Hibbertia and Culver land systems. nutans, Microcybe multiflora, Olearia picridifolia, Philotheca fitzgeraldii, Pimelea serpyllifolia, Scaevola bursariifolia.

204 50. Eucalypt heath woodland (EHEW) drummondii, Pomaderris myrtilloides Sampling Others—Acacia mutabilis subsp. angustifolia, Acrotriche 7 inventory sites, 15 traverse points cordata, Boronia crassifolia, General information Cryptandra sp., Enchylaena tomentosa, Hibbertia nutans, EHEW occurs on partially consolidated, aeolian Lechenaultia formosa, sand dunes stabilised by vegetation, along the Leucopogon sp., Lysinema top of the Baxter Cliffs and on the landward side ciliatum, Microcybe pauciflora of younger mobile dunes fringing the coastal subsp. pauciflora, Olearia Israelite and Roe Plains. The dunes generally muelleri, Pultenaea elachista, Spyridium tricolor, Synaphea have gently inclined slopes, though near the oligantha. Wurrengoodyea Hills they can be steep and up to 90 m. Soils are calcareous deep sands or Subshrubs: Dominant—Not present as a pale deep sands with a calcrete horizon recognisable stratum Other—Desmocladus developed at or near the surface. myriocladus. Physiognomy and composition of vegetation Perennial grasses: Dominant—Not present as a recognisable stratum EHEW comprises scattered to closed Other—Austrostipa platychaeta. (15–50 per cent PFC) low woodland of various eucalypt species in mallee-form over scattered Other plant forms: Common—Carpobrotus modestus (succulent perennial to closed low shrubland of variable heath herb), Comesperma volubile species. (creeper), Dianella revoluta (lily), 48 perennial species were recorded at the Lepidosperma sp. A2 Island Flat seven inventory sites with an average of 10 (perennial sedge), Marianthus species per site, one less than the survey bicolor (creeper) Others—Gahnia deusta average. No annual species were recorded. (perennial sedge), G. lanigera The following species (by strata) are dominant (perennial sedge), Schoenus and/or common: lanatus (perennial sedge). Trees: Dominant—Eucalyptus discreta Ecological disturbance (mallee), E. diversifolia (mallee), E. incrassata (mallee) This habitat type generally occurs outside of Common—Callitris preissii, pastoral lease boundaries and little is known Eucalyptus brachycalyx about the grazing ecology. Burnt areas show a (mallee), E. conglobata (mallee) mosaic pattern, often confined to this habitat Others—Allocasuarina helmsii, type, indicating this woodland is more suscep- Eucalyptus yalatensis (mallee). tible to fire than the vegetation associations Tall shrubs: Dominant—Not present as a adjacent to it. recognisable stratum Common—Exocarpos aphyllus, Gradational associations Melaleuca lanceolata EHEW commonly grades into Eucalypt, Others—Acacia oswaldii, melaleuca woodland (EMEW) on stabilised Exocarpos sparteus, Templetonia retusa. dunes and Eucalypt, melaleuca mixed chenopod/woodland (EMCW) where calcareous Mid shrubs: Dominant—Not present as a loamy earths and shallow loams become recognisable stratum Common—Pultenaea overlain by sandy soils. heterochila Land systems Others—Beaufortia empetrifolia, Dodonaea stenozyga, Grevillea EHEW is a major habitat type on sparsiflora, Hakea nitida. Wurrengoodyea land system. Low shrubs: Dominant—Adenanthos forrestii Common—Acacia cochlearis, Beaufortia micrantha, Bossiaea leptacantha, Conostephium

205 51. Eucalypt coastal heath woodland Pomaderris myrtilloides, (ECHW) Pultenaea elachista, Spyridium microcephalum, Synaphea Sampling oligantha. Subshrubs: Dominant—Not present as a 3 inventory sites recognisable stratum General information Others—Harperia eyreana, Lomandra sp. ECHW occurs where coastal aeolian sand Other plant forms: Others—Amyema melaleucae dunes have accumulated. This predominantly (mistletoe), Carpobrotus sp. occurs on the Roe Plains but there are also (succulent perennial herb), aeolian sand deposits at the edge of the Cassytha melantha (creeper), Hampton Range and Baxter Cliffs. These sandy Dianella revoluta (lily), deposits occur as sand sheets and coastal Lepidosperma sp. A2 Island Flat dunes in the south of the survey area near the (perennial sedge), Marianthus coast. Where dunes occur they are gently bicolour var. bicolour (creeper), sloping (up to 6 per cent). Soils vary from Mesomelaena stygia (perennial sedge), Schoenus caespititius calcareous deep sands to pale deep sands. (perennial sedge), S. lanatus Physiognomy and composition of vegetation (perennial sedge), S. subflavus subsp. hispid culms (perennial ECHW consists of a scattered to moderately sedge). closed (15–30 per cent PFC) low woodland of mallee-form eucalypts. Scattered (10–15 per Ecological disturbance cent PFC) mixed shrubs form the understorey. The disturbance mechanisms of this habitat 38 species were recorded at the three inventory have not been investigated in any significant sites, with an average of 15 species per site, detail in this region. Disturbance by vehicles four greater than the survey average. No annual and/or fire may result in wind erosion of the species were recorded. dunes. The following species were dominant and/or Gradational associations common: ECHW commonly grades into Coastal Trees: Dominant—Variable; Eucalyptus shrubland (COAS) as dune development discreta (mallee), E. gracilis, becomes unconsolidated. ECHW has a defined E. incrassata (mallee) boundary where the stabilised sand dunes Common—Callitris preissii overlie calcareous loamy earths and shallow Other—Eucalyptus cooperiana loams that support Eucalypt, melaleuca mixed (mallee). chenopod shrubland or woodland (EMCW). Tall shrubs: Dominant—Variable; Melaleuca lanceolata Land systems Common—Callitris preissii Others—Exocarpos aphyllus, ECHW is a minor habitat type of Toolinna and Rhagodia preissii, Templetonia Wurrengoodyea land systems. retusa. Mid shrubs: Dominant—Variable; Beaufortia 52. Banksia coastal heath and empetrifolia, Hakea nitida scrubland (BCHS) Others—Adenanthos cuneatus, Dodonaea amblyophylla, Sampling Pultenaea heterochila, Styphelia 3 inventory sites hainesii. Low shrubs: Dominant—Not present as a General information recognisable stratum BCHS is a unique vegetation association. It Common—Pimelea serpyllifolia Others—Acrotriche cordata, occurs on stabilised sand dune deposits on the Bossiaea leptacantha, Israelite Plain, above the Baxter Cliffs and Wylie Conostephium drummondii, Scarp. Sand dunes have developed between Grevillea pauciflora, Hibbertia the Wylie Scarp and the landward side of nutans, Lysinema ciliatum, mobile coastal dunes on the Israelite Plain.

206 These older dunes are likely to have formed Boronia crassifolia, during a sea regression, forming beaches at the Conostephium drummondii base of the cliff. Winds built sand ramps and Others—Acrotriche patula, transported large amounts of sand to the Bossiaea leptacantha, Grevillea clifftops (Jennings 1968). Later sea level nudiflora, Hibbertia nutans, Stirlingia anethifolia, Verticordia increases have removed some dune ramps but sieberi. aeolian clifftop deposits have remained above the Baxter Cliffs and Wylie Scarp. BCHS is Subshrubs: Dominant—Not present as a recognisable stratum largely restricted to these aeolian sand Others—Desmocladus deposits. myriocladus, Euphorbia sp. Along the edge of the Baxter Cliffs the BCHS Other plant forms: Occasional—Cassytha vegetation association is present in a dwarfed melantha (creeper), Dianella form due to wind exposure causing high evapo- revoluta (lily), Lepidosperma sp. transpiration and wind-borne salt spray causing A2 Island Flat (perennial leaf tip necrosis and asymmetric growth forms sedge), Schoenus caespititius (Parsons 1970). The banksia population found (perennial sedge), S. lanatus above Toolinna Cove is the most easterly (perennial sedge), Tetraria capillaris (perennial sedge). population of a Western Australian banksia species (Nelson 1974). Ecological disturbance Physiognomy and composition of vegetation The mechanisms of disturbance in BCHS have not been investigated in any significant detail. BCHS comprises closed (30–50 per cent) Dune erosion has resulted when disturbance thickets of banksia, eucalyptus and melaleuca, caused by vehicles and/or fire has damaged or except along the cliff edge where BCHS is a removed stabilising vegetation. dwarfed closed low heathland. The lower shrub stratum is variable and can be dominated by Gradational associations Beaufortia micrantha or Pomaderris forrestiana. BCHS commonly grades into scattered Low 36 perennial species were recorded at the three mallee woodland (LOMW) or Eucalypt mixed inventory sites, with an average of 10 species scrub woodland (EXSW). Coastward as the per site, one less than the survey average. No stabilised colluvial dune apron becomes less annual species were recorded. consolidated and foredunes and swales develop The following species were dominant and/or BCHS is replaced by Coastal shrubland common: (COAS). Tall shrubs: Dominant—Banksia media, Land systems Eucalyptus incrassata, Melaleuca pentagona var. BCHS is the dominant habitat type on the latifolia Baxter and Wylie land systems. Others—Allocasuarina helmsii, Banksia speciosa, 53. Coastal shrubland (COAS) Calothamnus gracilis, Eucalyptus diversifolia, Sampling Melaleuca lanceolata. 7 inventory sites, 2 traverse points Mid shrubs: Dominant—Occasionally Melaleuca quadrifaria General information Common—Pultenaea COAS occurs on recently mobile or fixed dunes heterochila Others—Adenanthos cuneatus, fringing the Israelite and Roe coastal plains. In Grevillea sparsiflora, Hakea places dunes form large masses such as the cinerea, H. nitida, Isopogon Bilbunya Dunes near Point Culver and the trilobus, Melaleuca pulchella, Delisser Sandhills near Eucla. Foredunes are Petrophile teretifolia. usually 3–10 m high with gently inclined slopes Low shrubs: Dominant—Occasionally to 8 per cent, though at the Bilbunya Dunes they Beaufortia micrantha, are more steeply inclined, with relief up to 90 m. Pomaderris forrestiana Soils are deep calcareous sands. Common—Adenanthos forrestii,

207 Physiognomy and composition of vegetation Ecological disturbance COAS commonly occurs as a mid to low shrub- This habitat is susceptible to dune erosion when land of varying composition. It ranges from coastal vegetation is damaged or removed. supporting isolated shrubs (0–2.5 per cent Common disturbance mechanisms causing PFC) to closed (30–50 per cent PFC) shrub- dune instability include vehicle impact and fire. land. Vegetation characteristic to coastal areas such as Euphorbia paralias (sea spurge), Gradational associations Ficinia nodosa (knotted club rush), Leucophyta COAS commonly grades into Samphire brownii and Scaevola crassifolia (thick-leaved shrubland (SAMP) growing in lagoonal habitats fan-flower) are common. immediately between or behind recent coastal 29 perennial species were recorded at the dunes. As unconsolidated dunes become seven inventory sites with an average of seven increasingly stabilised COAS grades into species per site, four less than the survey Banksia coastal heath and scrubland (BCHS), average. Two annual species were recorded. Eucalypt coastal heath woodland (ECHW) or Eucalypt, melaleuca woodland (EMEW). The following species were dominant and/or common to this vegetation association: Land systems Tall shrubs: Dominant—Occasionally: COAS is the dominant habitat type on the Acacia cyclops, Eucalyptus Bilbunya and Delisser land systems. conglobata (mallee), Melaleuca lanceolata References Others—Myoporum platycarpum, Olearia axillaris. Atkins, KJ 2006, Declared Rare and Priority Mid shrubs: Dominant—Acacia anceps Flora List for Western Australia, Dept of Others—Atriplex isatidea, Conservation and Land Management, Nitraria billardierei, Pultenaea Western Australia. heterochila. Beard, JS 1975, Vegetation survey of Western Low shrubs: Dominant—Occasionally: Australia, 1:1 000 000 Vegetation Series, Leucophyta brownii, Scaevola Explanatory notes to sheet 4, University of crassifolia Common—Olearia axillaris, Western Australia Press, Perth. Rhagodia crassifolia, Frankenia Curry, PJ, Payne, AL, Leighton, KA, Hennig, P & sessilis, Westringia rigida Blood, DA 1994, An inventory and condition Others—Acacia cochlearis, survey of the Murchison River catchment Atriplex cinerea, Darwinia and surrounds, Western Australia. diosmoides, Pimelea ferruginea, Tecticornia sp. Department of Agriculture, Western Australia, Technical Bulletin No. 84. Subshrubs: Dominant—Threlkeldia diffusa Others—Euphorbia paralias, Davey, A 1978, Resource Management of the Senecio spanomerus, Nullarbor Region, WA, a report by the Tetragonia implexicoma, Australian Speleological Federation for the Zygophyllum apiculatum, Western Australian Environmental Protection Z. billardierei. Authority, 1978. Perennial grasses: Dominant—Not present as a recognisable stratum Hacker, RB 1979, Studies of the ecology and Common—Spinifex hirsutus. range condition of two arid ecosystems, PhD thesis, University of New South Wales. Other plant forms: Common—Carpobrotus modestus (succulent perennial Jennings, JN 1963, ‘Some geomorphological herb), C. virescens (succulent problems of the Nullarbor Plain’, Transactions perennial herb), Ficinia nodosa of the Royal Society of South Australia, 87, (perennial sedge). 41–62. Annual species recorded include Cakile maritima and Jennings, JN 1968, ‘The Nullarbor Plain, Senecio pinnatifolius. Australia: A dryland karst region’, New Zealand Geographical Society, 45, 17–19.

208 Lowry, DC 1970, Geology of the Western Tinley, KL 1991, ‘4: Vegetation and site types’, in Australian part of the Eucla Basin, Geological Ecological Survey of Abydos – Woodstock Survey of Western Australia, Bulletin 122. Reserve, Western Australia, Records of the Western Australian Museum Supplement No. Mitchell, AA, McCarthy, RC & Hacker, RB 1979, 37, pp. 30–37. A range inventory and condition survey of part of the Western Australian Nullarbor Westoby, M, Walker, B & Noy-Meir, I 1989, Plain, 1974, Western Australian Department ‘Opportunistic management for rangelands of Agriculture, Technical Bulletin No. 47. not at equilibrium’, Journal of Range Management, 42(4), 266–274. Mitchell, AA & Wilcox, DG 1994, Arid shrubland plants of Western Australia, revised edition, University of Western Australia Press, Perth. Muir, BG 1977, Biological Survey of the Western Australian Wheatbelt Part 2: Vegetation and habit of Bendering Reserve, Records of the Western Australian Museum Supplement 3. Nelson, EC 1974, ‘Disjunct plant distributions on the south-western Nullarbor Plain, Western Australia’, Journal of the Royal Society of Western Australia, 57 (Part 4), 105–117. Parsons, RF 1970, ‘Mallee vegetation of the southern Nullarbor and Roe Plains, Australia’, Transactions of the Royal Society of South Australia, 94, 227–241. Payne, AL, Mitchell, AA & Holman, WF 1988, An inventory and condition survey of rangelands in the Ashburton River catchment, Western Australia, revised edition, Western Australian Department of Agriculture, Technical Bulletin No. 62. Payne, AL, Curry, PJ & Spencer, GF 1987, An inventory and condition survey of rangelands in the Carnarvon Basin, Western Australia, Western Australian Department of Agriculture, Technical Bulletin No. 73. Payne, AL, Van Vreeswyk, AME, Pringle, HJR, Leighton, KA & Hennig, P 1998, An inventory and condition survey of rangelands in the Sandstone-Yalgoo-Paynes Find area, Western Australia, Agriculture Western Australia, Technical Bulletin No. 90. Pringle, HJ., Van Vreeswyk, AME & Gilligan, SA 1994, An inventory and condition survey of the north-eastern Goldfields, Western Australia, Western Australian Department of Agriculture, Technical Bulletin No. 87. Society for Range Management 1991, ‘SRM recommends new range terminology’, Trailboss News, supplement to Journal of Range Management, September 1991.

209 Land systems • brief description of land management considerations such as susceptibility to soil PA Waddell erosion Within the survey area 54 land systems have • traverse condition summary been identified, 34 of which are described for the first time and the other 20 previously • locality map showing the distribution of the described in adjacent surveys. The land land system systems are derived from aerial photography • plan showing the physical features of the and descriptions are built up using field data system, and with each land unit identified collected during traversing and at inventory • list of land units, normally in order of highest sites. With improved aerial photography and the to lowest position in the landscape, with the benefit of LANDSAT imagery the land systems number of sampling points. Not all units in identified in the eastern part of the Western each land system are shown in diagrams or Australian Nullarbor Plain during the 1974 described in tables. Minor units that were survey (Mitchell, McCarthy & Hacker 1979) have encountered very occasionally whilst been reassessed and in some cases traversing the land system are listed as boundaries have been modified. Four land ‘other’ in the summary table. systems from the 1974 survey were extensively modified resulting in one system being renamed On each opposing page a summary of the and three systems incorporated into others. biophysical components for each land unit provides additional detail: Land systems are grouped into land types according to a combination of landforms, soils, • unit area, estimated from aerial photograph vegetation and drainage patterns. Table 19 interpretation and field observation, is shows the land types and their component land presented as a percentage of the total land systems. This amalgamation of the 54 land system area systems into 15 land types provides information • landform—lists each land unit with a at a more appropriate level for use when description of the landform considering a regional scale, and provides a simpler way to colour code regional scale • soils—generalised description with reference maps. to the appropriate soil groupings (refer to the Soils chapter) The location of each inventory site, with the site number and a code for the land unit on which it • vegetation—the vegetation is described in occurred, is shown on pastoral lease maps. three parts: foliar cover (refer to Table 8 of Table 20 provides a list of land units with the the Methodology chapter); formation (refer to codes used on the maps. the Vegetation chapter) and dominant species, e.g. ‘Pearl bluebush low shrubland Land systems are described in alphabetical (PBLS)’. The four-letter code for the habitat order in this chapter. A summary description of type (refer to the Habitat type ecology each system’s major features is followed by chapter) is also listed. more detailed accounts of the units that com- prise each system. The format used for the summary description is: • land system name, area and percentage of the survey area • reference to any previous description • brief descriptive statement of dominant landform(s) and vegetation • land type (refer to Table 19) • major geological formation or land surface types • geomorphology overview

210 Table 19 Land types and their land systems

Land type Description and land systems 1 1 – Calcrete plains overlain by aeolian sandy loam with eucalypt woodland and spinifex grasses Land system—Zanthus 2 2 – Calcrete plains with eucalypt woodland and mixed scrub understorey Land systems—Caiguna and Gumbelt 3 3 – Calcrete plains with myall woodland and mixed shrubland Land systems—Colville and Nyanga 4 4 – Calcrete plains with sparse myall and bindii grassland or chenopod shrubland Land systems—Carlisle, Haig, Jubilee, Kyarra and Rabbit 5 5 – Large depressions within calcrete plains with chenopod shrubland or bindii grassland Land systems—Koonjarra and Woorlba 6 6 – Low granite outcrop protruding through calcrete plains with fringing acacia–dodonaea– eremophila shrubland Land system—Balladonia 7 7 – Level to gently undulating calcareous plains with eucalypt–melaleuca–myall woodland and chenopod shrubland Land systems—Moodini, Moopina, Thampanna and Weebubbie 8 8 – Undulating calcareous plains with eucalypt woodland, mixed scrub and heathland Land systems—Culver and Toolinna 9 9 – Recrystallised (weathered) limestone plains with myall woodland and bluebush shrubland or bindii grassland Land systems—Kanandah, Lowry and Virginia 10 10 – Deflated limestone plains with myall woodland and chenopod shrubland or bindii grassland Land systems—Chowilla, Seemore, Shakehole and Vanesk 11 11 – Deflated limestone plains with open bluebush and saltbush shrublands or bindii grassland Land systems—Arubiddy, Balgair, Gafa, Kitchener, Kybo, Moonera, Morris, Nanambinia, Naretha, Nightshade, Pondana, Reid and Skink 12 12 – Deflated limestone plains with regular karst drainage depressions (dongas) surrounded by bindii grassland Land systems—Bullseye, Kinclaven, Nurina and Oasis 13 13 – Level calcarenite coastal plains with eucalypt–melaleuca–myall woodland and mixed shrubland Land systems—Mundrabilla and Roe 14 14 – Coastal plains, cliffs, dunes, lagoonal deposits and beaches; varied vegetation Land systems—Baxter, Bilbunya, Delisser, Wurrengoodyea and Wylie 15 15 – Salt lakes and fringing saline plains with halophytic shrubland Land systems—Boonderoo, Damper, Lefroy and Ponton

These are modified land types taken from the Department of Agriculture and Food, WA State Land Type list.

211 Table 20 Land units and their codes

Code Land unit BAS Sandy bank BEA Beach BRX Breakaway CLA Claypan CLD Clay depression CLP Clay plain DFL Drainage floor DON Donga (karst depression) DRF Drainage focus DRN Narrow drainage floor (< 0.5 km) DRT Drainage tract (ancient river course) DUN Dune FOL Lower footslope – concave FOR Foredune GIL Gilgaied depression KOP Kopi dune KPL Calcrete plain overlain by calcareous loam of varying depth KRL Calcrete (residual) rise overlain by calcareous loam of varying depth KSP Calcrete stony plain LAK Lake bed including playa lake LAM Lake margin LGR Low granite rise MDF Marginal slope to drainage floor PCL Calcarenite plain overlain by calcareous loam PGR Gritty-surfaced plain with shallow soil on granite PGY Gypsiferous plain PKE Calcareous loam plain overlain by shallow aeolian sand PLS Highly saline depression LHR Limestone hummock (low rise) SCF Scarp face SLP Stony limestone plain SWA Swale SWP Swamp

212 Sampling intensity Table 21 indicates the area and intensity of sampling on each system in the survey area.

Table 21 Land system areas and sampling intensity

No. of Traverse sampling intensity Area % of total Land system inventory 2 (km2) survey area No. of km per Density sites assessments rating index* Arubiddy 2 046 1.7 5 210 10 1.74 Balgair 1 937 1.6 4 195 10 1.70 Balladonia 145 0.1 5 31 5 3.63 Baxter 285 0.2 1 0 Bilbunya 47 < 0.1 1 0 Boonderoo 83 0.1 5 14 6 2.85 Bullseye 8 817 7.4 15 15 588 0.03 Caiguna 7 066 6.0 16 201 35 0.48 Carlisle 2 066 1.7 0 0 Chowilla 1 532 1.3 1 21 73 0.23 Colville 421 0.4 0 0 Culver 1 707 1.4 9 48 36 0.48 Damper 390 0.3 7 35 11 1.52 Delisser 150 0.1 6 2 75 0.23 Gafa 8 501 7.2 5 138 62 0.27 Gumbelt 5 053 4.3 12 381 13 1.28 Haig 552 0.5 7 115 5 3.53 Jubilee 934 0.8 1 8 117 0.14 Kanandah 1 641 1.4 10 223 7 2.30 Kinclaven 4 790 4.0 14 542 9 1.91 Kitchener 405 0.3 8 56 7 2.34 Koonjarra 1 067 0.9 14 186 6 2.95 Kyarra 2 099 1.8 4 62 34 0.50 Kybo 1 289 1.1 12 174 7 2.28 Lefroy 9 < 0.1 3 3 3 5.94 Lowry 65 0.1 1 16 4 4.14 Moodini 123 0.1 7 51 2 7.04 Moonera 4 234 3.6 10 319 13 1.27 Moopina 107 0.1 2 7 15 1.11 Morris 3 323 2.8 0 49 68 0.25 Mundrabilla 1 688 1.4 19 127 13 1.27 Nanambinia 570 0.5 5 114 5 3.38 Naretha 1 547 1.3 7 139 11 1.52 Nightshade 3 373 2.8 7 286 12 1.43 Nurina 2 247 1.9 9 204 11 1.54 Nyanga 12 990 11.0 38 1 045 12 1.36 Oasis 4 180 3.5 1 0 Pondana 1 649 1.4 6 188 9 1.93 Ponton 23 < 0.1 0 0 Rabbit 350 0.3 0 0 Reid 3 998 3.4 1 38 105 0.16 Roe 2 853 2.4 20 64 45 0.38 Seemore 415 0.4 2 15 28 0.61 Shakehole 4 045 3.4 11 355 11 1.48 Skink 4 000 3.4 2 85 47 0.36 Thampanna 5 284 4.5 36 723 7 2.31 Toolinna 1 879 1.6 9 55 34 0.50 Vanesk 1 107 0.9 6 64 17 0.98 Virginia 1 689 1.4 4 144 12 1.44 Weebubbie 416 0.4 2 14 30 0.57 Woorlba 554 0.5 10 163 3 4.97 Wurrengoodyea 1 946 1.6 14 23 85 0.20 Wylie 52 < 0.1 1 0 Zanthus 619 0.5 6 49 13 1.34 118 358 401 6 997 * Density index: measure of sampling intensity relative to the mean of the survey area (16.9 km2 per assessment)

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