Advice to the Minister for Sustainability, Environment, Water, Population and Communities from the Threatened Species Scientific Committee (the Committee) on an Amendment to the List of Threatened Ecological Communities under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act)

1. Name of the ecological community Sandstone Shrubland Complex This advice follows the assessment of information provided by a public nomination to list the ―Arnhem Plateau Sandstone Heath‖ as a threatened ecological community under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act).

Previous studies have referred to the ecological community as: heathland (Keith et al., 2002); sandstone scrub (Story 1976; Bowman et al., 1990; Dunlop and Webb, 1991); sandstone heath (Russell-Smith et al., 2002; Price et al., 2003); open heath/shrubland interspersed with hummock grasses (Russell-Smith et al., 1998); quartzite and sandstone edaphic complex (Specht, 1958) and Buldiva quartzite edaphic complex (Specht, 1958). These vegetation complexes share a distinctive sclerophyll shrub component and other characteristics (notably geographic location, vegetation type, substrate, elevation and rainfall). The ecological community occurs as a fine-grained mosaic of vegetation types that intergrade with other distinct vegetation such as rainforests and open woodlands (savanna).

The ecological community has been re-named ‗Arnhem Plateau Sandstone Shrubland Complex‘. The name reflects the general structure, substratum and distribution for the ecological community. The ecological community primarily occurs on Country (the traditional lands) of the Adjurmarllal, Barwinanga-Djelk, , Mimal and Manwurrk-Warddeken Indigenous ranger groups, within the Djelk and Warddeken Indigenous Protected Areas, and Kakadu and Nitmiluk National Parks.

2. Public Consultation The nomination and a draft description were made available for public exhibition and comment for a minimum 30 business days. A workshop was also held in June 2006 with experts and Indigenous people on the ecological community and the report on outcomes was circulated to relevant experts in 2006 and 2010. On Country visits with Indigenous people and experts were also undertaken in 2010. The Committee has had regard to all public and expert comment that was relevant to the consideration of the ecological community.

3. Summary of conservation assessment by the Committee The Committee provides the following assessment of the appropriateness of the ecological community's inclusion in the EPBC Act list of threatened ecological communities.

The Committee judges that the ecological community has been demonstrated to have met sufficient elements of:  Criterion 2 to make it eligible for listing as endangered  Criterion 3 to make it eligible for listing as endangered;  Criterion 4 to make it eligible for listing as endangered; and  Criterion 5 to make it eligible for listing as endangered. The highest category for which the ecological community is eligible to be listed is endangered.

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4. Description The Arnhem Plateau Sandstone Shrubland Complex ecological community, hereafter referred to as the Arnhem Shrubland Complex, occurs in the , predominantly on the Arnhem Plateau massif and outliers1 or isolates such as Ubirr Rock, Nawurlandja (Little Nourlangie Rock) and Burrunggui (Nourlangie Rock - Mt Brockman). The Arnhem Shrubland Complex is particularly associated with substrates of quartzose sandstone and occurs on rock pavements ‗wardde wardde‘2, through to shallow tenosols (skeletal to shallow sandsheets), typically with major rocky components. The Arnhem Shrubland Complex also occurs on laterised Cretaceous mudstone and greywacke3 sediments on the Marawal Plateau (Russell-Smith et al., 2002; NT Herbarium, 2011).

The ecological community occupies a complex position in the landscape. For example, due to the dissected nature of the Arnhem Plateau, the Arnhem Shrubland Complex often abuts deep gorges and isolated gullies containing monsoon rainforest communities. The Arnhem Shrubland Complex may also intergrade with other ecological communities, such as eucalypt open forest, closed forest (Story, 1976) and open woodlands (savanna) in sites with greater soil depth and greater moisture- holding capacity (Russell-Smith et al., 2002). Increases in phosphorus within soil can also lead to the Arnhem Shrubland Complex transitioning to open forest and open woodland (Specht, 1979).

The Arnhem Shrubland Complex represents heathlands and other shrublands that are dominated by an understorey of diverse, evergreen (Gill and Groves, 1981) sclerophyllous shrubs and herbaceous taxa, such as the following genera: Acacia, Asteromyrtus, Boronia, , Cajanus, Eriachne, Goodenia, Grevillea, Hibbertia, Hibiscus, Jacksonia, Micraira, Pityrodia, Phyllanthus, Stylidium and Tephrosia. The Arnhem Shrubland Complex contains a naturally large proportion of obligate seeder4 taxa along with some resprouter5 species (Russell-Smith et al., 2009c).

It is recognised that Indigenous people of the Arnhem Plateau have particular names for plant and animal species. However, the common names used in this document have been obtained from available flora and fauna reference sources.

Physical environment The physical environment and geology of the Arnhem Plateau is particularly important to the occurrence of this Complex. The Arnhem Plateau where the ecological community occurs comprises resistant, flat bedded Middle Proterozoic sandstones, criss-crossed by tensional joints. These have been deeply weathered and eroded to form a maze of narrow valleys, gorges and elevated flat areas such as pavements (Needham, 1988). The northern and western rims of the plateau are bounded by sheer escarpments. In restricted situations, deep sand plains have developed on the plateau summits. In the south-east, the topography is characterised by gently undulating plains and rises derived from Cretaceous sediments (Lynch and Wilson, 1998; Edwards and Russell-Smith, 2009). The plateau tilts gradually east to an extensive sandplain (Woinarski et al., 2006). Soils derived from sandstone and quartzitic rocks are inherently low in plant nutrients. Nutrients are further reduced by leaching (Specht, 1979; Edwards and Russell-Smith, 2009).

1 Sandstone outliers were separated from the main Arnhem Land Plateau 500 to 140 million years ago when ancient seas eroded older sandstone into sea cliffs (current escarpment). They were former islands in the ancient seas that once covered much of the Kakadu region. 2 Bininj Kunwok language. 3 Greywacke is texturally and mineralogically immature sandstones that contain more than 15% clay minerals. 4 Obligate seeders are plant species that only recover after disturbances e.g. germination from seed after fire. 5 Resprouters are plant species that can survive after disturbance (especially fire) by producing new shoots and regrowth.

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The Arnhem Shrubland Complex is found predominantly on the main Arnhem Plateau massif which varies in elevation from approximately 200 to 400 m above sea level (asl) and on outliers (Russell- Smith et al., 2009c) occurring from 100 m asl (Nott, 2003; Blake, 2004). The sandstone of the Arnhem Plateau is highly resistant to weathering, and consequently there has been little development of soil structure (Lynch and Wilson, 1998). Within the Buldiva and Bedford landsystems of the Arnhem Plateau, leptic rudosols6 are a dominant soil type and support open woodlands and sandstone scrubland ecological communities. Slightly deeper more structured red kandosols7 and orthic tensosols8 are also present.

The Arnhem Shrubland Complex occurs along the closely spaced joints and crevices of rock pavements and also on low-nutrient acid soils usually derived from the quartz-rich substrates such as skeletal and shallow sandsheets with major rocky components such as boulders and pinnacles. These sandy deposits, when present, are typified by deficiencies in phosphorus and nitrogen, with high levels of immobilised iron and aluminium (Specht, 1979; Groves, 1981). Localised patches also occur on laterised Cretaceous mudstone sediments such as on the margins of the Marrawal Plateau spanning the common boundary between Kakadu and Nitmiluk National Parks (Duff et al., 1991).

Due to the geomorphology of the plateau (Figure 1), the Arnhem Shrubland Complex is highly exposed to wind and solar radiation. Recurring fires are a feature of the Arnhem Plateau region, although their frequency, intensity, season of occurrence and spatial characteristics vary widely (Gill and Groves, 1981; Keith et al., 2002).

Figure 1. Diagrammatic explanation of terms used to describe terrain on the Arnhem Plateau (Noske, 1992)

Climate The Arnhem Shrubland Complex is located within the tropical monsoonal belt of northern , which is generally subject to ‗wet‘ (November to March/April) and ‗dry‘ (May to November) seasons. Indigenous people of the region recognise additional seasonal differences throughout the year. These differences include: ‗knock-em-down‘ storms which occur during the period between the wet and dry seasons (April) with strong NW-ESE winds; ‗early-cool‘ dry season (July to September) with cool nights; ‗late-hot‘ dry season (September to November) with low humidity and

6 Leptic rudosols occur within 50mm of the ground surface. They are underlain by hard rock or partially weathered rock. 7 Red kandosols are structureless, well-drained and permeable soils. 8 Tenosols are weakly developed soils with poor water retention qualities and low fertility.

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SE-NE winds; and ‗the build up‘ (October to November), which is characterised by high temperatures, very high humidity, N-NW winds and thunderstorms.

The Arnhem Plateau receives the majority of its rainfall during the wet season (November to March) (Kerle, 1996). Annual rainfall decreases from up to 1,600 mm per year in the north to 900 mm per year in the south. Temperatures are consistently high throughout the year. At Jabiru, mean daily temperatures range from 16°C to 31°C in winter and 25°C to 37°C in summer. At , the mean daily temperatures range from 15°C to 30°C in winter and 24°C to 33°C in summer (BOM, 2010). During the early dry season, cooler overnight temperatures occur. Due to the complex topography, the Arnhem Plateau supports many different microclimates (Woinarski et al., 2006; Brock, 2007).

Vegetation The structure, geographic distribution, abundance and composition of the Arnhem Shrubland Complex flora are determined by the interactions between geology, fire regimes and climate. Bowman et al. (1990) noted that vegetation patterns within the Arnhem Shrubland Complex are primarily influenced by local variations in topography, rockiness, degree of fire protection and moisture supply. In situations where rock platforms dominate, the vegetation cover can be very sparse. The Arnhem Shrubland Complex has significant biodiversity due to the plateau‘s isolation (Russell-Smith et al., 2009c), supporting a high number of endemic and fire sensitive shrub species. The dominant heath and shrub taxa of the Arnhem Shrubland Complex is characterised by scleromorphy (Gill and Groves, 1981) in the form of hard, stiff foliage (e.g. Grevillea spp.), phyllodes9 (e.g. Acacia spp.), cladodes10 (e.g. Hibbertia, Jacksonia spp.) and highly reduced foliage (e.g. Calytrix exstipulata) (Brock, 2007).

Flora species in northern Australia, such as those which occur on the Arnhem Plateau, exhibit a wide range of strategies for survival and reproduction that allow them to persist through a range of different fire regimes (Keith et al., 2002). Many of the taxa within the Arnhem Shrubland Complex consist of obligate seeder and resprouter flora species. The proportion of obligate seeder species within the Arnhem Shrubland Complex is a key functional characteristic of the ecological community. Although not documented across the entire range of this community, localised studies have shown that at least 50% of constituent plant species are obligate seeders (Russell-Smith et al., 2002). For obligate seeder species, especially those lacking soil-stored dormant seed banks, the period from germination to reproductive maturity is a critical period ensuring ongoing survival of local populations because it governs the capacity to replenish seed stocks (Russell-Smith, 2006).

The Arnhem Shrubland Complex is floristically diverse and contains taxa that also occur in other Arnhem Plateau vegetation communities, such as open woodlands (savanna). However, many constituent plant species are endemic, with numerous taxa having a very restricted distribution (e.g. Boronia viridiflora and Sauropus filicinus) or being relictual species (e.g. Drummondita calida). At least 186 flora species are endemic to the ecological community (see Appendix A). The high rate of endemism on the Arnhem Plateau is likely to have arisen partly because the plateau is highly dissected by deep gorges, and these serve to impede gene flow between isolated populations of species with limited dispersal ability. Plant species richness is also high because the Arnhem Shrubland Complex topography and geomorphology provides a diverse array of microclimates

9 Phyllodes are modified petioles (leaf stems). In some , the petioles become flattened and widened, and the true leaves may become reduced or vanish altogether. The phyllode functions as the leaf. Phyllodes are common in the genus Acacia. 10 Cladodes are modified stems or shoots that effectively replace leaves as the main photosynthetic organs of a plant. They are often flattened, but may be needle-like.

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(Specht, 1958; Ingwersen, 1995; Crisp et al., 2001; Bowman et al., 1990; Woinarski et al., 2006). The characteristic plant taxa present in the Arnhem Shrubland Complex are given in Appendix B.

A substantial floristic continuity between the sandstone ecological communities on the Arnhem Plateau has been recognised, with many species being common to adjacent vegetation communties (Bowman et al., 1990; Brock, 2007). Intergrading open-forest and open woodland (savanna) ecological communities tend to occupy sites with greater soil depth and with greater moisture- holding capacity (Specht, 1958; Story, 1976; Bowman et al., 1990; Wilson et al., 1990; Russell- Smith et al., 1998). Increases in soil phosphorus, often associated with the edaphic factors outlined above, can lead to the Arnhem Shrubland Complex intergrading to open canopy eucalypt forest/woodland (savanna) (Specht, 1979).

Canopy layer – emergent trees The ecological community is typically treeless although various tree species may be scattered above the diverse shrub stratum (Keith et al., 2002). The tree canopy is not the dominant vegetation layer for this ecological community. The species composition of the sparse tree canopy, many of which are endemic to the Arnhem Shrubland Complex, can be variable and may include genera such as Acacia, Banksia, Callitris, Corymbia, Eucalyptus, Ficus and Pandanus (Yibarbuk et al., 2001). Near rainforest zones, emergent trees such as and/or Xanthostemon, may also be present (Brock, 2007).

The tree canopy typically ranges in height from two to eight metres (Russell-Smith et al., 2002; Russell-Smith, 2006; Cowie, pers. comm., 2010). Typically the canopy cover is less than 5%. This is consistent with the cover value under the Northern Territory vegetation classification system, whereby the lower strata of this ecological community are considered the dominant or most characteristic vegetation layer (Lewis et al., 2008).

Mid layer – medium to tall shrubs and low trees Most of the plant diversity of the Arnhem Shrubland Complex occurs in the mid layer of medium to tall shrubs. These taxa can survive on very low nutrient, shallow soils and are typically composed of species from many different families such as Fabaceae, Goodeniaceae, Loganiaceae, , Phyllanthaceae, Proteaceae, Rutaceae and Verbenaceae. Typical woody genera present in the Arnhem Shrubland Complex include: Acacia, Boronia, Calytrix, Gardenia, Grevillea, Hibbertia, Hibiscus, Jacksonia, Lithomyrtus, Pityrodia and Tephrosia.

Obligate seeder shrubs comprise a large proportion of the woody mid layer taxa across the Arnhem Plateau, particularly in this ecological community. For example, of the 152 Arnhem Plateau woodland and heath species sampled by Russell-Smith et al. (1998), 71 (or 47%) were obligate seeders. Characteristic obligate seeders present in the Arnhem Shrubland Complex are from the families Dilleniaceae (e.g. Hibbertia spp.), Fabaceae (e.g. Acacia and Tephrosia spp.), Malvaceae (e.g. Hibiscus spp.), Myrtaceae (e.g. Petraeomyrtus punicea and Lithomyrtus spp.), Proteaceae (e.g. Grevillea spp.) and Rutaceae (e.g. Boronia spp.) (Bowman et al., 1990). Obligate seeders usually have a relatively short life span because of their inability to regenerate vegetatively after complete crown destruction (Nicolle, 2006).

The Arnhem Shrubland Complex ecological community also contains taxa such as the predominantly drought resistant, evergreen sandstone legumes. They include shrubs that are leafless (e.g. members of the genera Bossiaea, Jacksonia and Leptosema) or have reduced, narrow leaves (e.g. members of the genera Daviesia and Templetonia) (Brock, 2007).

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Ground Layer – grasses, other herbs and low shrubs The composition of the ground layer of the Arnhem Shrubland Complex varies significantly depending on past and present fire regimes, water availability and seasonal conditions. The ground layer consists of a diverse range of low shrubs, herbs and graminoids11, such as the genera Eriachne, Goodenia, Spermacoce, Stylidium and Utricularia. Annuals typically comprise the most common ground layer component during the wet season (Blake, 2004).

Perennial native grasses such as hummock (―spinifex‖) grasses (e.g. Triodia spp.) and mat-forming grasses (Micraira spp.) (Russell-Smith, 2002) may be interspersed amongst the ground layer vegetation or become dominant in patches. The Arnhem Plateau supports an unusually diverse set of hummock grasses (Triodia spp.), which are a common understorey over much of the sandstone plateau (Dunlop and Webb, 1991). Spinifex taxa are well adapted to fire with many of these species being able to regenerate either as seedlings arising from a soil seed bank or from resprouts at the bases of burned hummocks. In bare sandstone pavement habitats, where the micro-relief is only sufficient to trap water for short periods but too shallow to accumulate soil, Micraira spp. may be dominant plant (Brock, 2007). Micraira is a ―resurrection‖grass with leaves that desiccate and lose their chlorophyll while remaining attached to the plant, but are capable of becoming fully functional again within 24 hours of soaking rain.

The ground layer can be sparse, depending on the presence of bare rock. For instance, in the Jim Jim Falls area, where the Arnhem Shrubland Complex occurs, forbs and grasses are sparse (<20% ground cover) and ferns and vines are uncommon (Bowman, Wilson and Fensham, 1990). This site has more than 50% rock cover.

Fauna The Arnhem Plateau bioregion, where the ecological community predominantly occurs, is of international significance for relictual and threatened fauna (Woinarski et al., 2009). The bioregion also has a high level of endemism, including at least three bird species (e.g. Amytornis woodwardi — white-throated grass-wren), 12 reptiles (e.g. Morelia oenpelliensis — Oenpelli python) and five mammals (e.g. Macropus bernardus — black wallaroo). Some faunal components of the Arnhem Shrubland Complex have not been substantially documented and no studies have examined the fauna across the entire range of the ecological community. However, many localised studies, such as those conducted at Kapalga within (Woinarski et al., 2001, 2004; Andersen et al., 2005; Fitzsimons, 2010) and more broadly (Dunlop and Begg, 1981; Griffiths et al., 1996; Franklin, 1999), demonstrate the diversity of fauna across the Arnhem Plateau bioregion. This includes the Arnhem Shrubland Complex and other vegetation types that intergrade with it.

Vertebrates Distribution of vertebrates within heathlands and shrublands such as the Arnhem Shrubland Complex ecological community is often patchy in consequence of fire history and the availability of food reserves e.g. seeds, fruits, nectar. Abundance of animals is frequently low, and food chains are reduced and simplified in consequence of the low nutrient status soils and low primary productivity in these vegetation formations (Specht, 1979).

Hummock grasses within the ecological community provide key habitat, shelter and food resources for many terrestrial species, such as the white-throated grass-wren. Many fauna species in the Arnhem Plateau bioregion, such as the Dasyurus hallucatus (northern quoll), have widespread ranges and also occupy other vegetation types that adjoin or intergrade with the ecological community. Long term studies in Kapalga have indicated that mammal populations have reduced

11 Graminoid is a grass-like herb that includes grasses, sedges, rushes and similar groups.

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over the last 10 to 15 years. Some animal species are now in decline as a consequence of threatening processes such as inappropriate fire regimes (Woinarski et al., 2001, 2004; Fitzsimons et al., 2010).

Among the fauna species that occur in the ecological community at the Ubirr and Nourlangie outliers are Petrophassa rufipennis (chestnut-quilled rock pigeon) and the black wallaroo. Other rare animals which occur within the ecological community include Petropseudes dahli (rock ringtail possum), Pseudothecadactylus lindneri (giant cave gecko) and Oenpelli python.

Invertebrates To date, there has been no comprehensive assessment of the richness and endemicity of the invertebrate fauna of the western Arnhem Plateau (Woinarski et al., 2009). However, studies have been conducted on some invertebrate fauna. These include two of the best known groups, ants and grasshoppers and also freshwater aquatic species such as cryptic isopod crustaceans. The ant fauna of the sandstone country associated with the western Arnhem Land escarpment is highly distinctive with perhaps 30% of species not occurring in the lowland savanna to the west. Freshwater isopod species associated with the sandstone plateau, escarpment and outliers also exhibit extremely narrow range endemism in comparison to other freshwater invertebrates away from these sandstone formations (Wilson et al., 2010).

The Kakadu region supports a highly diverse and significant grasshopper fauna, with at least 11 species endemic to the sandstone country of the Arnhem escarpment and plateau (Andersen et al., 2000). The distinctive Arnhem Plateau species, Leichhardt‘s grasshopper (Petasida ephippigera) is restricted to the plateau of western Arnhem Land and a few other sandstone outliers including the Victoria River district (Lowe, 1995). This species has special significance for the local Jawoyn people, who relate it to the ‗lightning man‘ (Namarrgon) responsible for the wet season storms. (Russell-Smith et al., 2009c). Leichhardt‘s grasshopper has a very narrow food-plant choice, with tight association with the sandstone shrubland Pityrodia species.

5. Key Diagnostic Characteristics and Condition Thresholds Much of the Arnhem Shrubland Complex ecological community has been impacted by changed fire regimes since World War II. In some cases, localised loss of obligate seeder taxa may be irreversible, or the potential for re-establishment is impractical due to the dissected nature of the landscape and difficulty in accessing remote patches.

National listing focuses legal protection on remaining patches of the ecological community that are most functional, relatively natural and in relatively good condition. Condition thresholds assist in identifying a patch of the threatened ecological community and when the EPBC Act is likely to apply to the ecological community. They provide guidance for when a patch of a threatened ecological community retains sufficient conservation values to be considered as a Matter of National Environmental Significance, as defined under the EPBC Act. This means that the referral, assessment and compliance provisions of the EPBC Act are focussed on the most valuable elements of Australia‘s natural environment, while heavily degraded patches, which do not trigger the ―significance test‖ of the EPBC Act will be largely excluded.

Although significantly degraded or modified patches are not protected as the ecological community listed under the EPBC Act, it is recognised that patches that do not meet the condition thresholds may still retain important natural values. Therefore, these patches should not be excluded from recovery and other management actions (also see p.9 ‗Surrounding environmental and landscape context‘).

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Condition thresholds are determined in consultation with experts on the particular ecological community. They include a range of criteria such as: richness and diversity of native plants and animals present, vegetation structure and cover attributes, intensity of weed invasion, patch size and proximity to native vegetation remnants.

The listed ecological community is limited to patches that meet the following key diagnostic characteristics and condition thresholds.

Key diagnostic characteristics The key diagnostic characteristics for the Arnhem Shrubland Complex ecological community are as follows:  Distribution mostly occurs within the Arnhem Plateau bioregion (IBRA v6.1). The community may extend marginally to neighbouring bioregions including , Central Arnhem, , , Gulf Fall and Uplands, and Pine Creek where outlying and isolated sandstone outcrops occur away from the main plateau.  The ecological community is mainly restricted to the Buldiva and Bedford land systems. It occurs along the closely spaced joints and crevices of rock pavements and also on low-nutrient acid soils usually derived from the quartz-rich substrates such as skeletal and shallow sandsheets with major rocky components e.g. boulders and pinnacles. Localised patches also occur on laterised Cretaceous mudstone and greywacke sediments such as on the Marrawal Plateau.  It typically occurs on substrates that range from rock pavements, shallow tenosols (skeletal to shallow sandsheets) which generally contain major rocky components. Bare rock is heavily prevalent (50% or greater of total area at typical sites, sometimes more than 70%).  It typically occurs at elevations of 200 to 400 metres above sea level on the main Arnhem Plateau massif but may occur lower (down to 100 metres) on outlying rock outcrops.  The tree canopy, when present, is typically absent to sparse and shows the following features: o Species composition is variable, typically comprising members of the genera Acacia, Blepharocarya, Corymbia, Callitris, Eucalyptus, Ficus, Gardenia, Terminalia, Owenia, Xanthostemon and/or Persoonia; and o The trees are generally widely spaced emergents with a canopy cover typically less than 5% (Lewis et al., 2008).  The mid layer shows these features: o Obligate seeder taxa comprise at least 10% of the shrub species present, but more usually comprise >50% of the shrub species present; o Obligate seeder species present include the genera: Acacia, Boronia, Calytrix, Corchorus, Cryptandra, Dicarpidium, Grevillea, Hibbertia, Hibiscus, Jacksonia, Leptosema, Lithomyrtus, Petraeomyrtus punicea, Pityrodia, Tephrosia, Thryptomene and/or Triumfetta; and o Shrub species are predominantly sclerophyllous.  The ground layer contains a variety of herbaceous and grass species, depending on seasonal conditions and site characteristics. o During the dry season the ground layer is generally dominated by perennial grass such as hummock grasses (Symplectriodia spp., Triodia spp.) and mat-forming grasses (Micraira spp.); o During the wet season, the most common ground layer vegetation typically comprises annual herbs.

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Condition Thresholds The listed ecological community is limited to patches that meet the key diagnostic characteristics and the following condition thresholds.

Patch size:  The minimum patch12 size is 5 ha. This may include areas of native vegetation that may be naturally open or contain regrowth. AND Vegetation:  Four or more obligate seeder shrub species are present in the mid (or shrub) layer of the patch. Typically this includes species from the genera Acacia (Fabaceae), Boronia (Rutaceae), Calytrix (Myrtaceae), Corchorus (Malvaceae), Cryptandra (Rhamnaceae), Dicarpidium (Malvaceae), Grevillea (Proteaceae), Hibbertia (Dilleniaceae), Hibiscus (Malvaceae), Jacksonia (Fabaceae), Leptosema (Fabaceae), Lithomyrtus (Myrtaceae), Petraeomyrtus (Myrtaceae), Pityrodia (Lamiaceae), Tephrosia (Fabaceae), Thryptomene (Myrtaceae) and Triumfetta (Malvaceae) (See Appendix A and B). However, other obligate seeder species may be present and are included if the patch meets the description of the ecological community. AND Exotic species:  5% or less of the total vegetation cover13 in the ground and mid layers comprises perennial exotic species.

Additional considerations Surrounding environmental and landscape context The condition thresholds outlined above are the minimum level at which patches are to be considered under the EPBC Act for actions that may require referral to the Australian Government. These thresholds do not represent the ideal state of the ecological community. Patches that are larger, more species rich and less disturbed are likely to provide greater biodiversity value. Additionally, patches that are spatially linked, whether ecologically or by proximity, are particularly important as wildlife habitat and to the viability of those patches of the ecological community into the future.

Therefore, in the context of actions that may have ‗significant impacts‘ and require approval under the EPBC Act, it is important to consider the environment surrounding patches that meet the condition thresholds. Some patches that meet the condition thresholds occur in isolation and require protection. Other patches that are interconnected to similar native vegetation associations that may not, in their current state, meet the condition thresholds have additional conservation value. In these instances, the following indicators should be considered when assessing the impacts of actions or proposed actions under the EPBC Act, or when considering recovery, management and funding priorities for a particular patch:  Evidence of recruitment of key native species or the presence of a range of age cohorts;

12 A patch is defined as a discrete and continuous area that comprises the ecological community as identified in the ‗Description‘, above. It does not comprise substantial elements of other ecological communities such as woodlands and forests with a clearly developed canopy or grass/forbland where sclerophyllous shrub components are minor. However, a patch may include small-scale disturbances, such as narrow gullies or rock crevices, tracks or breaks (including exposed rock, leaf litter) or small-scale variations in vegetation that do not significantly alter its overall functionality, such as allowing the easy movement of wildlife or dispersal of plant propagules. 13 Total vegetation cover includes all vascular plants but not mosses, lichens, plant litter or bare ground.

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 Good faunal habitat as indicated by patches containing natural rock outcrops, understorey shrubby flora, hummock grasses, termite mounds, diversity of landscape, contribution to movement corridors;  Species richness, as shown by the variety and proportion of native flora and the diversity of fauna species present;  Presence of listed threatened species;  Areas of minimal weeds and feral animals, or where these can be managed easily; and /or,  Patches that occur in areas where the ecological community has been heavily degraded, or that are at the natural edge of its range, or show species assemblages that represent a unique variant of the ecological community.

6 National Context Distribution The Arnhem Shrubland Complex ecological community is limited to the of the Northern Territory. It occurs predominantly on the Arnhem Plateau, with localised occurrences on the Marrawal Plateau spanning the common boundary between Kakadu and Nitmiluk National Park (Duff et al., 1991). The area of occupation includes outliers or isolates outside the core Arnhem Plateau area (Blake, 2004).

The core distribution of the ecological community lies within the Arnhem Plateau bioregion (subregions ARP1 and APR2) (Interim Biogeographic Regionalisation for Australia — IBRA V6.1). The ecological community may also extend into these neighbouring bioregions where there are outlying plateau and rock outcrops:  Arnhem Coast (ARC);  Central Arnhem (CA);  Darwin Coastal (DAC);  Daly Basin (DAB);  Gulf Fall and Uplands (GFU); and  Pine Creek (PCK)

The ecological community is known to wholly occur in the Northern Territory Natural Resource Management region.

The western portion of the Arnhem Plateau is included within Kakadu National Park and is managed jointly by its Aboriginal traditional owners and the Director of National Parks. Kakadu National Park has UNESCO World Heritage listing for outstanding cultural and natural universal values and is also listed as a Wetland of International Significance under the Ramsar Convention. These two listings are separate Matters of National Environmental Significance under the EPBC Act.

The south western portion of the ecological community is included within Nitmiluk National Park, which is jointly managed by the Jawoyn Aboriginal people and the Parks and Wildlife Commission of the Northern Territory. Relationships to State or Territory vegetation classifications Previous vegetation studies in the Northern Territory have used various classification schemes. These were recognised to have inconsistent vegetation datasets. The National Vegetation Information System (NVIS) has recently been adopted as the Northern Territory‘s vegetation classification framework. Large areas of the Arnhem Plateau are currently mapped at a broad scale

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(1:100 000) and the ecological community is not currently described at finer spatial scales. However, localised surveys have been conducted in the region where the ecological community occurs. They describe vegetation units that do not equate directly with the ecological community, but they may correspond with all or part of the ecological community and contain similar sclerophyllous components or intergrade with the ecological community (Table 1). Table 1: Relevant vegetation units that may align with the Arnhem Plateau Sandstone Shrubland Complex, at least in part. Source Vegetation unit Description Specht (1958) Quartzite and sand stone edaphic Arnhem Land regional description complex Specht (1958) Buldiva quartzite edaphic complex Arnhem Land regional description Story (1976) Sandstone scrub Arnhem Land regional description Bowman, Wilson and Fensham Sandstone scrub Arnhem Land regional description (1990) Wilson, Brocklehurst, Clark and Eucalyptus dichromophloia, E. Northern Australia regional description Dickinson (1990) miniata low open-woodland with Plectrachne pungens open-hummock grassland understorey Dunlop and Webb (1991) Sandstone scrub and heath Northern Australia regional description Specht (1994) Heathland Arnhem Land regional description Specht et al. (1994) Heathlands and related shrublands – Northern Australia regional description Tropical region. Type H7a Duff, Orr, Belbin and Andersen Heath Arnhem Land regional description (1991) Russell-Smith (1995) Sandstone heath (included as Arnhem Land regional description community within Eucalyptus dichromophloia, E. miniata low open-woodland following Wilson et al., 1990) Russell-Smith, Ryan, Klessa, Open heath/shrubland interspersed Arnhem Land regional description Waight and Harwood (1998) with hummock grasses Lynch and Wilson (1999) Tall sparse shrubland to mid high Arnhem Land regional description open woodland Keith, McCaw and Whelan Heathland Northern Australia regional description (2002) Russell-Smith, Ryan and Cheal Sandstone heath Arnhem Land regional description (2002) Price, Russell-Smith and Sandstone heath in the Arnhem Land Arnhem Land regional description Edwards (2003) Plateau Bowman, Walsh and Prior Sandstone savanna Arnhem Land regional description (2004)

Relationships to State or Territory listed threatened communities Under the Northern Territory Parks and Wildlife Conservation Act 2000, there is currently no provision for the listing of threatened ecological communities. Therefore the ecological community is not listed as threatened in the Northern Territory.

The Northern Territory Government has identified Sandsheet Heath as highly restricted and an ecosystem at risk within the Darwin region (Northern Territory Government, 2010a). It has a mix of species, typically with a diverse understorey of herbs and sedges and an overstorey of small trees or shrubs such as Banksia dentata (tropical banksia), Grevillea pteridifolia (silky grevillea), Melaleuca nervosa and Verticordia cunninghamii (tree featherflower). Sandsheet Heath covers approximately 56 km² and is frequently associated with monsoon rainforests, riparian vegetation, seasonally saturated and other wetlands. It occurs on acidic infertile soils overlaying an impermeable deposit of

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clay or laterite, and is flooded during the wet season. However, Sandsheet Heath is distinguished by the lack of rock, seasonal waterlogging and markedly different plant species, composition and structure. In particular, it does not seem to be associated with sandstone plateau or outlying platforms. Sandsheet Heath falls outside the description and known distribution of the Arnhem Shrubland Complex ecological community and is not considered to be part of the national ecological community. Adjacent vegetation communities The Arnhem Plateau hosts a complex of vegetation communities including Callitris, Corymbia or Eucalyptus dominated forests and woodlands, shrublands, rainforest patches in gullies and hummock grasslands (Story, 1976; Specht, 1979: Bowman et al., 1990). Given its wide distribution and the dissected geomorpholgy of the Arnhem Plateau, the ecological community adjoins or intergrades with several other vegetation types (Specht, 1979; Dunlop and Webb, 1991; Yibarbuk et al., 2001; Blake, 2004). Some of these other vegetation communities share the presence of a well developed sclerophyllous shrub component that is a feature of the ecological community. However, the national ecological community is distinct from these other vegetation types.

A number of ecological communities have been recognised in the Jim Jim Falls area of the Arnhem Plateau (Story, 1976), some of which intergrade with the Arnhem Shrubland Complex ecological community (Bowman et al., 1990). Many of these vegetation formations have a significant shrub layer present as an understorey. The ecological community often occurs in association with savanna open woodlands and forest that have a wide distribution on the Arnhem Plateau. Savanna open woodlands have a ground cover of grasses, typically from the genera Eriachne, Sorghum and Triodia, and an understorey of shrubs, including locally endemic taxa from the genera Acacia, Boronia, Calytrix, Gardenia, Goodenia, Grevillea, Hibiscus, Jacksonia, Lithomyrthus and Spermacoce, many of which also occur in the Arnhem Shrubland Complex. Most importantly, the woodlands have a tree canopy often dominated by various species of Corymbia and Eucalyptus. Where deeper sands occur, the ecological community intergrades with the open woodlands with dominants including Corymbia arnhemensis, C. bleeseri, C. kombolgiensis, C. latifolia, (Darwin woolybutt) and E. tetrodonta (Darwin stringybark) (Wilson et al., 1996; Woinarski et al., 2006). The fire-sensitive conifer and obligate seeder, Callitris intratropica (cypress pine), occurs widely, either singularly or in copses, on sandy soils (Yibarbuk et al., 2001). Closed canopy Allosyncarpia ternata forest, which can be co-dominated with cypress pine in patches, may also intergrade with the ecological community (Bowman et al., 1990).

Monsoon vine-forests (semi-deciduous forest) occur on a broad range of rock and soil types and vary structurally from tall evergreen forests over 30 metres in height to deciduous thickets two to three metres in height on dry, harsh sites. Within the Arnhem Plateau region, sandstone vine-forests are known to be associated with seasonally dry substrates (Brock, 2007). Due to the highly dissected nature of the Arnhem Plateau, the ecological community may also intergrade with monsoon vine- forests in areas proximate to deep gullies (Russell-Smith et al., 1998).

It is the presence of a distinct and well developed tree canopy (as distinct from widely spaced and scattered emergents) that distinguishes these various woodland and forest types from the ecological community.

7. Relevant Biology and Ecology Many types of ecological processes sustain biodiversity. These include climate processes, hydrological processes, formation of biophysical habitats, interactions between species, movement of organisms and natural disturbance regimes (Bennett et al., 2009). Movements by organisms are

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also critical to interspecific interactions such as mutualisms (pollination, seed dispersal), predation, parasitism and competition, which influence the composition of communities (Bennett et al., 2009).

Vegetation dynamics The Arnhem Shrubland Complex ecological community is characterised by its sclerophyllous shrub layer and grass understorey taxa. The flora of the ecological community is an essential resource for many fauna species. Shrub and grass taxa provide direct (blossom, seed) and indirect (attracts insects which are eaten by birds, reptiles and bats) food resources; shelter, nesting and roosting sites among leaves, branches and hummocks. The movement of some vertebrate fauna is affected by the distance between remnants, and consequently the dispersal of some flora taxa is affected by the mobility of their animal dispersers. For example, flora taxa dispersed by small mammals, such as the Zyzomys argurus (common rock-rat) are more likely to be limited by distances between patches than flora taxa dispersed by birds. The behaviour of different bird species also affects seed dispersal.

The Arnhem Plateau environment consists largely of rock with minimal soil development and varies between seasonally hot, and very dry, to seasonal hot, and very wet. The complex topographic makeup of the Arnhem plateau and outliers contain large areas of bare stone pavements, where the micro-relief is sufficient to trap water for short periods but too shallow to accumulate soil. Where soils are present, they are often thin veneers of sand no more than 150 cm thick (Petty et al., 2007).

Due to the dissected nature of the Arnhem Plateau geomorphology, understorey flora taxa within the ecological community, such as the threatened EPBC listed species Boronia quadrilata, and B. viridiflora, may have very restricted distributions. Other rare flora species have a broader distribution. For example, the NT listed species Lithomyrtus linariifolia, is known from 14 locations. The species is found in the ecological community, eucalypt woodlands on sandstone, in sandy or skeletal soils, and often along the margins of Allosyncarpia ternata forest and almost always growing amongst Triodia microstachya. Lithomyrtus linariifolia is fire sensitive, found only in longer-unburnt and fire protected pockets amongst sandstone boulders and outcrops. Monitoring suggests that the species is an obligate seeder as no individuals have been observed to resprout (Cowie, pers. comm., 2010).

The ground layer varies with rainfall and substrate, with the most common components for the ecological community being grass species: hummock grasses in the genus Symplectrodia and Triodia are found on low-nutrient soils. These grass species typically grow as an expanding dome or dense hummock, with the green leaves on the outer surface. The inside of the hummock consists of densely matted stems (stolons) and dead leaves. When the leaves are young they are flat and relatively soft, but as they age the edges roll under, the leaves become very stiff and pointed. Generally the hummocks are less than a metre tall. As the plants age, the centre of the hummock may collapse, forming ‗rings‘ with a central dead ‗core‘ surrounded by live shoots. Fires in hummock grasslands tend to be patchy, leaving fire scars of different ages that add to the subtle patterning of the landscape.

Hummock grass species are mixed among the sandstone shrublands of this ecological community and are also the dominant component of the understorey in some adjacent woodlands. Hummock grasses may dominate boulder fields and pavements providing habitat for a variety of terrestrial mammal, bird and reptile species. The white-throated grass-wren in particular, rely on unburnt Triodia spp. (Spinifex) hummock grasses in Arnhem Plateau sandstone habitat (Russell-Smith et al., 2009c).

The Arnhem Plateau also contains a diversity of Micraira spp., which are amongst the best examples of plants adapted to the harsh conditions on the Arnhem Plateau. These resurrection grasses are well represented in the ecological community. Resurrection grasses mostly occur on rock pavements with Arnhem Plateau Sandstone Shrubland Complex Page 13

little or no soil. They are typically highly localised species which have adapted to the extreme seasonal nature of such sites. They have a moss-like appearance and spirally arranged leaves which desiccate and lose their chlorophyll, yet remain attached to the plant. Resurrection grasses show a rapid response to moisture by rehydrating their foliage and becoming functional again within 24 hours of soaking rain.

Annual Sarga spp. (formally Sorghum / An-ngulubu14) grows to over two metres and may become a dominant understorey plant towards the end of the wet season in adjoining vegetation formations such as open woodlands (savanna) and open forests. Annual Sarga sp. is the dominant fuel in most high-grass savanna open woodland environments. They often provide fuel to support intense fires on an annual basis and can impact on areas of the ecological community. Fuel loads in northern Australia are known to increase within two to three years following a fire (Gill et al., 1990; Cook et al., 1995). However, there is evidence that the biomass of annual Sarga declines with time since last burnt (Andrew and Mott, 1983; Russell-Smith et al., 1998; Vigilante and Bowman, 2004).

Role of fire Fires are significant disturbance events in the majority of Australian ecosystems and play an important role in creating and maintaining biodiversity patterns and processes in the Northern Territory landscape (Williams et al., 2002; Gole, 2006). Fire severity generally increases with the progression of the dry season given increasingly severe fire weather (stronger winds, higher temperatures, lower humidity), and lower fuel moisture conditions (Gill et al., 1996; Russell-Smith and Edwards, 2006). Despite the presence of storms and lightning strikes that cause some wildfires, most fires in the Arnhem region are anthropogenic in origin.

Heathland flora species, such as those which occur in the ecological community, are renowned for their flammability. Features contributing to the fire-prone nature of this ecological community and the intense fires it supports include the presence of well-aerated fine fuel, the tendency for dead foliage to persist on some plant species (e.g. Micraira spp.) and the direct exposure of fuel particles to wind and solar radiation in the absence of tree canopies. Flammable terpenes15 and waxes present in the foliage of some shrubs may also promote combustion of live fuel components. These factors result in heathlands remaining fire-prone throughout much of the year (Bradstock et al., 2002).

Ecological communities with biomass dominated by shrubs, such as this ecological community, have diverse flora, with many plant species highly flammable and reliant on fire for regeneration (Gill and Groves, 1981; Specht, 1981; Bradstock et al., 1996). Keith et al. (2002) noted that heathlands are a highly flammable vegetation type, can support high intensity fires in relatively moderate conditions and are often able to burn within a few days after rainfall. The bulk of the fuel available to fires in shrub-dominated communities is living vegetation. In other vegetation types, such as forests and grasslands, fires mainly burn in dead fuels such as leaf litter and cured grass, with living fuel burning only when mixed with dead fuels or during crown fires which only occur under extreme conditions (Plucinski, 2006).

Several studies have demonstrated that fire regimes affect plant species abundance on the Arnhem Plateau (Bowman et al., 1988; Fensham, 1990; Russell-Smith et al., 1998; Williams et al., 1999) and particularly for the ecological community. Different species respond to variations in fire regimes and there is an array of biological responses to contemporary fire regimes (Gill et al., 1999; Whelan et al., 2006; Yates et al., 2008; TSSC, 2010).

14 Bininj Kunwok language – Garde et al., (2009). 15 Terpenes are volatile, high carbon compounds that evaporate relatively easily.

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Flora species, such as those which occur on the Arnhem Plateau, exhibit a wide range of strategies for survival and reproduction that allow them to persist through a range of different fire regimes (Keith et al., 2002). The biological process of fire plays a crucial role in determining the structure and composition of the ecological community.

Heathlands and shrublands like this ecological community are largely devoid of species that have recruitment strategies unrelated to fire (Gill and Groves, 1981; Keith et al., 2002). Fire is also important in maintaining the diversity of mammals and birds within the ecological community, by creating a variety of habitats within the vegetation that suit different species (Fox, 1983). Depending on the timing, frequency and intensity of any given fire, many flora species within the ecological community are able to utilise resprouter or obligate seeder fire-response strategies. The recruitment of obligate seeders within the ecological community is almost entirely restricted to the immediate post-fire period, when seeds are released from dormancy or storage and dispersed. Of the 152 Arnhem Plateau woodland and heath species sampled by Russell-Smith et al. (1998), first seeding for 46 species occurred within three years of germination, while 16 species required up to five years.

Prior to European colonisation in the Northern Territory from about 1880, the Indigenous people managed fire, lighting most in the early part of the dry season (Russell-Smith et al., 1997b). Indigenous people of the Arnhem region have traditionally used fire for a variety of reasons: ease of travel; communication; ‗cleaning‘ country; hunting; and to maintain food sources. In the Kakadu region, for example, burning started very late in the wet season (March) as soon as the country began to dry out, and continued for nine to ten months until the monsoon arrived. Activity would peak in June to July, but diminish in August to September.

Mid to late dry season burns also traditionally occurred under controlled situations. These ‗fire- drives‘ were for food, cultural, social and spiritual reasons. Factors such as seasonality, wind direction and species targeting were considered. Patchwork burns earlier in the season were conducted, so as to control the intensity of the fire and contain the area to be burnt (Russell-Smith et al., 2009c). Since 1880 (1940 on the Arnhem Plateau) Indigenous fire management in the Northern Territory has altered. The impacts of altered fire regimes are discussed under Description of threats, below.

It is very difficult to exclude fire from the landscape given the high frequency of lightning ignitions. However, it is apparent that Indigenous people of the region could pre-empt widespread, intense fires caused by lightning, by frequently burning small areas before the start of the thunder activity that characterises the end of the dry season (Braithwaite and Estbergs, 1985; Haynes, 1985; Bowman and Panton, 1993).

In flat ground without rock protection, dry season fires can burn large tracts of land without any unburned patches. If fires kill all mature plants in an area and there is no viable seed, then these plants will occur there in the future only if they can recolonise via seed dispersal from individuals beyond the burned area. Whether this occurs will depend on the size of the burned area and the dispersal ability of the species. Seeds of many sandstone vegetation species, such as those which occur in the Arnhem Shrubland Complex, are thought to be mainly dispersed by gravity, although there are limited data on the dispersal ability of many Arnhem Plateau plant species. Keith (1996) reported that an intense late season fire in the Kakadu National Park affected more than 1000 km², and it was likely that many sandstone species would recolonise very slowly in the absence of internal patchiness found among rocky sites. Fauna populations with low dispersal or long generation times may also be very slow to re-establish in these circumstances (Price et al., 2003).

Rocks and sandstone platforms can provide protection for plants from fire, and especially in more intense fires. In studies conducted in patches where rocks were absent every plant was burned. In Arnhem Plateau Sandstone Shrubland Complex Page 15

rocky sites, even the most intense fires are not likely to burn the entire surface and so kill all the plants. Populations of fire-sensitive plants may decline, but they are likely to persist in rocky areas (Price et al., 2003; Russell-Smith, 2006). Some plants that reproduce only from seed and are easily killed by fire require a fire-free period of five years to reach reproductive stage and begin to replenish their seed bank (Russell-Smith, 1998).

Obligate seeder and resprouter plants and fire For fire sensitive species, the production of seed following fire may be more critical to species persistence because successive fires within the period required for seed production will eliminate the species from the site. The minimal period for seed production to occur following seedling establishment has been called the ‗primary juvenile period‘ by Gill (1975). For example, the fire sensitive, obligate seeder cypress pine which occurs in the intergrading vegetation formation requires a fire free period of at least ten years to mature sufficiently to set seed (Wilson et al., 1996; Russell-Smith, 2006; Woinarski et al., 2006).

Populations of plants that rely on seeds for recovery from disturbance by fire (obligate seeders) are sensitive to low and high frequency fire regimes (Bradshaw et al., 1995; Russell-Smith et al., 2002) and those with canopy seed banks that are unable to recruit seedlings in the absence of fire may decline to local extinction (Gill and Bradstock, 1995). The life span of obligate seeder species can be relatively short in natural environments because of their inability to regenerate vegetatively following complete crown destruction after fire (Nicolle, 2006). Obligate seeders comprise a large proportion of the ecological community‘s woody understorey taxa, whereas resprouters are considered predominant in adjoining woodland and forest vegetation formations (Russell-Smith et al., 1998; Yates and Russell-Smith, 2003; Russell-Smith et al., 2010).

The retention of seed on the plant until released by fire (or other environmental triggers) is known as serotiny. Many plant species of Australian heathlands are serotinous. This is the case for many species of the families Casuarinaceae, Myrtaceae and Proteaceae, although it has been noted that this is rarer in floristically depauperate formations in the north of Australia (Keith et al., 2002). Plants which retain seed until the advent of fire can exploit the open seed bed.

Germination is one of the principal causes of depletion of the soil seed bank for the ecological community. Many species of heathland plants have hard seeds, especially species of the Fabaceae family. For hard seeds, the appropriate conditions for germination may not occur until the plant community is burned, yet the individual plants producing the seed may be declining in vigour or have died (Bradshaw et al., 1995). Seed predation is also an issue which is discussed in ‗Faunal dynamics and roles‘.

In some resprouter species, burial of regenerative organs provides a high level of protection from fire because the soil, when present, is a good insulator and only absorbs a small quantity of the total heat released by the fire. Most of the heat of heathland fires is directed upwards through convection and radiation.

Young seedlings are often vulnerable to fire because the apex of the plant and the reserve buds are exposed to fire. After fire, stump sprouting from buried stem buds is very common amongst some shrubs. The ability of the shrub or tree to sprout from basal buds, rhizomes or roots seems to decline with age of the shoot system. Therefore, although burning can lead to enhanced vigour for some components of the ecological community, it can lead to death in others.

Faunal dynamics and roles Due to the complex geomorphology and presence of various substrate types and depths on the Arnhem Plateau, the ecological community supports a variety of vegetation formations which

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provide a range of habitats for fauna species. A number of characteristic habitat features of value to vertebrate and invertebrate fauna occur within the specific ecological community including grass hummocks; shrubby understorey; termite mounds; and areas of pinnacles, rock shelves, caves and flat sandstone exfoliations.

Vertebrates Despite the relatively high floristic diversity within the ecological community, food productivity for bird species is low due to the reduced nutrient status of the substrate. The total energy available for animals is limited compared with other habitats such as grasslands and open woodlands. Nectar may therefore be an important energy source in the ecological community as it is readily available, though subject to seasonal variation (Kikkawa et al., 1979).

Despite the low nutrient soils present on the Arnhem Plateau, the various vegetation formations provide habitat for many threatened vertebrates such as Erythrotriorchis radiatus (red goshawk), Erythrura gouldiae (Gouldian finch) and Geophaps smithii (partridge pigeon). Other bird species which show a particular fidelity for the sandstone habitat of the Arnhem Plateau, such as the Arnhem Shrubland Complex ecological community, include the white-throated grass-wren and Petrophassa rufipennis (chestnut-quilled rock-pigeon) (Appendix C). The abundance and diversity of bird species and the frequency with which fires interrupt this succession may contribute to longer-term habitat changes that have consequences for vertebrate populations (Kikkawa et al., 1979).

The white-throated grass-wren is restricted to the Arnhem Plateau, where it occurs predominantly in the ecological community. This small ground-dwelling bird, whose diet comprises invertebrates, seeds and other vegetable matter (Noske, 1992), often occurs in small family groups, in territory sizes of approximately 10 ha. Breeding occurs from December to June, nesting in clumps of hummock (Triodia spp.) and mat-forming grasses (Micraira spp.). There is limited information available on population trends, but the little available data suggest that it is declining, due most probably to broad-scale change in habitat quality associated with altered fire regimes (Russell-Smith et al., 2002).

The white-throated grass-wren may be adversely affected by the burning of their habitat in three main ways, as their diet includes living plants and insects taken from living vegetation: fire reduces the availability of living plants, so the species may temporarily be more dependent on insects (and perhaps seeds); a fire before or during the breeding season could reduce the availability of nest sites (having a devastating effect on reproduction and recruitment) (Rowley and Brooker, 1987; Noske, 1992); and the species may be killed by intense fires owing to their poor flying ability, although boulders, steep gullies and labyrinthine cliffs could act as refuges during fires (Noske, 1992).

Many birds are known to be attracted to fire and smoke. During bushfires in northern Australia, including on the Arnhem Plateau, raptors have been observed following fire to take advantage of the small animals that are flushed out by the blaze. Falco berigora (brown falcon – karrkkanj)16 in particular has been observed to swoop down and pick up a fire brand and fly off to drop into unburnt patches (Kikkawa et al., 1979; Russell-Smith et al., 2009c).

As is the case with the flora component, many of the vertebrate fauna species present in the bioregion are unlikely to be restricted to the ecological community. However, some mammal species are sandstone specialists and include Macropus bernardus (black wallaroo), Petrogale concinna (Nabarlek rock-wallaby), Petropseudes dahli (rock ringtail possum), Pseudantechinus bilarni (sandstone antechinus) and the EPBC listed Zyzomys maini (Arnhem rock-rat).

16 Bininj Kunwok language – Garde et al., (2009).

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Arnhem rock-rats are mostly associated with fire-sensitive monsoon rainforest vegetation formations with rocky components (Begg, 1981; Russell-Smith et al., 1993) but may also extend into adjoining habitats, including sandstone heathlands and hummock grasslands such as the (Begg, 1981; Woinarski et al., 1992). The intricate mix of these environments, as a consequence of the complex topography of the Arnhem Plateau, may be an important factor in defining habitat suitability and persistence of Arnhem Rock-rats (Woinarski et al., 1992). A range of locally available environments may help maintain access to resources across the year (Begg, 1981; Freeland et al., 1988). The Arnhem rock-rat is not known to be prone to extreme population fluctuations. However, the species does show rapid response to fire, declining severely soon after a fire and remaining at low abundance for at least a further 12 months (the recovery time is unknown beyond this period) (Begg et al., 1981).

The Arnhem rock-rat feeds on flora species that occur in the ecological community, e.g. Pavetta brownii. Begg and Dunlop (1980) postulated that seeds are collected and because some are extremely hard and take considerable time to open, they are carried back to rock crevices. Here they can be consumed while more protected from potential predators than in the open. Predators include Dasyurus hallucatus (northern quoll) and several species of snakes and birds, particularly the Oenpelli python, Ninox connivens (winking owl), Ninox novaeseelandiae (boobook owl), Ninox rufa (rufous owl) and Tyto alba (barn owl) (Begg and Dunlop, 1980).

The northern quoll is a generalist predator occurring in a wide range of habitats including the Arnhem Shrubland Complex. It consumes a wide range of prey including invertebrates such as grasshoppers and spiders, and vertebrates such as the northern brown bandicoot, rats, insectivorous bats, quails, bird eggs and snakes. They also eat fruit, nectar, and are known to feed on carrion. Typically northern quolls have an annual life cycle with litters of young being born in the mid dry season. The most suitable habitat for the northern quoll appears to be rocky areas containing crevices and caves, such as those occurring within the ecological community, which can be used for dens during the day. (Northern Territory Government, 2007).

Many vertebrate fauna species, including reptiles (Appendix D), have adapted to fire within their habitat. For example, Griffiths (2005) noted that the Chlamydosaurus kingii (frillneck lizard) had a strong preference for remaining in burnt habitat and increased the volume of food in their stomach immediately after fires, especially after late fires. However, late fires were responsible for 30% direct mortality on the species. Late fires occurring at a frequency of greater than two years in the same population greatly increase the risk of local extinction. This fire frequency increased the risk of the number of animals killed by fire not being matched by the level of reproduction and immigration. While early fires, even on an annual basis, posed no real threat to the persistence of frillneck populations, habitat unburnt for periods longer than 20 years become unsuitable for the species. Although this study was conducted within Arnhem lowland ecological communities, similar threatening processes are occurring within the Arnhem Shrubland Complex particularly for emergent trees.

Invertebrates Myrmecochory (seed dispersal by ants) is a prominent dispersal mechanism in many environments, and can play a key role in local vegetation dynamics (Parr et al., 2007). In studies undertaken in eastern Australian heathlands, it was noted that sclerophyll flora has the highest proportion of plants with ant-dispersed seeds of anywhere in the world (Berg, 1975). Keith (2004) noted that many heathland genera, including Acacia, Boronia and Hibbertia, provide lipid-rich food for ants. Ants collect the seeds and store them in their nests, later detaching and eating the elaiosome17 and

17 Elaiosome is a fleshy oil-containing appendage present on seeds (SPRAT glossary)

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discarding the seed, which may remain viable until fire stimulates germination. Even though some seeds may be damaged or consumed, the burial of seeds can protect them from seed predators and intense bushfires. Burial of seeds also increases their access to soil moisture. As a result, ants have a major role in dispersing seeds to safe sites in the soil, although they only do so over short distances (Keith, 2004).

The invertebrate Petasida ephippigera (Leichhardt's grasshopper) lives only on a few species of sandstone heath shrubs within the genus Pityrodia (Family Lamiaceae) and is endemic to the sandstone escarpment, plateau country and outliers of the Top End of the Northern Territory (Lowe, 1995; Barrow, 2010). The occurrence of Leichhardt's grasshopper is linked to the distribution of the strongly aromatic shrubs Pityrodia jamesii in Kakadu National Park and Mt Borradaile, Pityrodia pungens in Nitmiluk National Park near Katherine and Pityrodia ternifolia in ; these are primary food sources for both juvenile and adult Leichhardt's grasshopper. The nymphs generally hatch after the last storms of the wet season. The nymphs have a slow growth rate during the dry season. Dispersal takes place after the first storms of the wet season. In all stages the nymphs exhibit low dispersal ability and adults do not fly readily (Lowe, 1995). Unburnt patches of habitat are likely to be critical as refuges for the species, providing protection from flames during fire and from predation after fire (Barrow, 2010). The full distribution of the species is unknown (Clarke and Spier-Ashcroft, 2003) but current information indicates it has a very restricted distribution and there have been local extinctions (Russell-Smith pers. comm., 2010).

Listed threatened species The Arnhem Plateau contains at least 11 threatened fauna species listed under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) and at least 20 threatened fauna species listed under the Territory Parks and Wildlife Conservation Act 2000 Northern Territory (NT) (Woinarski et al., 2009). Within the ecological community, habitat is known or likely to occur for at least six listed threatened fauna species under the EPBC Act and twelve NT listed threatened fauna species (Appendix E).

Within the Arnhem Shrubland Complex ecological community, at least four flora species are listed nationally as threatened species under the EPBC Act and four flora species are listed as threatened under the Territory Parks and Wildlife Conservation Act 2000 of the Northern Territory (Table 2).

Table 2: Listed plant species known to occur in the Arnhem Plateau Sandstone Shrubland Complex ecological community. Scientific Name Growth Form Conservation Status (December 2010) NT EPBC Boronia quadrilata shrub Vulnerable Vulnerable Boronia viridiflora shrub Vulnerable Vulnerable Hibiscus brennanii shrub Vulnerable Vulnerable Lithomyrtus linariifolia shrub Vulnerable Sauropus filicinus shrub Vulnerable

Connectivity and landscape context Connectivity between remnants of the ecological community and with other native vegetation remnants is an important determinant of habitat quality at the landscape scale for native flora and fauna, as well as the overall condition of the ecological community. For flora, connectivity varies with the species in question. Generally it is important as it increases pollination and spread of propagules among individuals and populations. For vertebrate groups, the diversity and abundance of fauna may depend on connectivity of a patch of the ecological community to other remnant vegetation.

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Due to the dissected geology of the Plateau, the ecological community is naturally fragmented. A survey conducted by Edwards and Russell-Smith (2009) found that patch sizes varied greatly within the ecological community, but averaged 61 ha. The Arnhem Shrubland Complex often intergrades with other ecological communities. The presence of extensive savanna woodlands (i.e. open canopy eucalypt forest/woodland), monsoon vine-forests and Allosyncarpia ternata forest adjacent to the ecological community on the Arnhem Plateau ensures connectivity amongst native vegetation types.

8. Description of Threats The threats to the Arnhem Shrubland Complex ecological community are common to many adjoining ecosystems on the Arnhem Plateau. The principle threat to the ecological community is inappropriate fire regimes. Secondary threats may include impacts from feral animals, weeds and climate change. These threats to the ecological community also have adverse impacts on species associated with the ecological community, including threatened species.

Changed fire regimes The tropical north of Australia has been characterised by Liedloff and Cook (2007) as ―perhaps the most extensive and flammable ecosystem in the world‖. Fires affect all landscapes and land tenures (Dyer et al., 2001; Williams et al., 2002; Gill et al., 2009). Fire is considered to be a key event-based driver of ecosystems across northern Australia (Gill et al., 2009). The fauna and flora of the Arnhem Plateau, and particularly the ecological community, has evolved with fire: fires themselves do not necessarily pose a great threat.

Prior to European colonisation, Indigenous people in the Arnhem region of the Northern Territory used fire as a primary landscape management tool, systematically burning parts of the landscape as soon as the fuels dried sufficiently to carry a fire (Jones, 1975; Haynes, 1985, 1991; Russell-Smith et al., 1997b, 2003; Yibarbuk et al., 2001; Garde et al., 2009). As detailed in Garde et al. (2009), substantial ethnographic evidence, including contemporary customary practice, indicates that parts of traditional estates were burnt in the early to mid-dry season (before the onset of relatively severe late dry season fire-weather conditions starting around August). This was part of the management regime to reduce fuels and burn breaks along water courses, walking tracks, and around important resources (including the protection of hunting areas planned for burning later in the year).

The traditional fire regimes used in various tropical vegetation formations (e.g. open woodland savannas and heathlands) of northern Australia, such as the Arnhem Shrubland Complex ecological community, are generally accepted to have involved a fine-scale, patchy fire regime that created and maintained a mosaic of burnt and unburnt patches across the landscape—it can be assumed that, had this not been the case, then regional fire-sensitive species (e.g. Callitris intratropica) and assemblages (e.g. sandstone heaths) would not have survived into the present day (Bowman and Panton, 1993; Bowman et al. 2001; Russell-Smith et al., 2003). Although historical evidence of past fire history for the Arnhem plateau itself is limited (Cooke, 2009), it is recognised that pre-European traditional fire regimes are still a functioning part of Indigenous knowledge systems (Yibarbuk and Cook, 2001; Yibarbuk et al., 2001; Garde et al., 2009).

With the advent of European settlement in the Top End from the late 1880s, there was a shift in the Indigenous population and associated fire management practices (Levitus, 2009; Ritchie, 2009). On the Arnhem Plateau, changes to traditional patterns of habitation and management can be traced to the early Twentieth Century associated with substantial depopulation of the plateau itself and increasing concentration in fringing settlements (Cooke, 2009; Levitus, 2009). Although documentation is lacking, it is presumed that it was during this transitional period that the fine- grained pattern of customary fire management was increasingly replaced by a boom and bust cycle of extensive, relatively intense late season fires, followed by one to two years of little fire activity as

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fuels accumulated. Cattle and buffalo both came to the Plateau in the early Twentieth Century, and reduced the abundance of grasses, thereby reducing the frequency and intensity of fires (Petty et al., 2007). However, with further grazing changes, by the early 1980s, the boom and bust cycle had been firmly established, as evident in available fire history records derived from satellite monitoring, commencing with early studies conducted in Kakadu National Park (Day, 1985; Press, 1988; Russell-Smith et al., 1997b; Gill et al., 2000; Edwards et al., 2003), and subsequently for other regional assessments (Edwards et al., 2001; Edwards and Russell-Smith, 2009; Russell-Smith et al., 2009b; Russell-Smith et al., unpublished ms).

Vegetation monitoring, such as the Kapalga experiments in Kakadu National Park, indicate that the regional contemporary fire regimes are responsible for significant and continuing declines of the floristic diversity and extent of heathlands (Russell-Smith et al., 1998, 2002). There is evidence of a continuing reduction in the abundance of individual fire-sensitive plant species in the Arnhem region (Bowman and Panton, 1993; Bowman, 1994; Price and Bowman, 1994; Bowman et al., 2001a) including those within the Arnhem Shrubland Complex ecological community. Changed fire regimes have also been implicated in widespread declines in many bird and mammal species (Franklin, 1999; Woinarski et al., 2001; Price et al., 2007).

Acknowledgement of the international cultural and biodiversity values of the Arnhem Plateau region has occurred since the Ranger Uranium Inquiry in the 1970s (Fox, 1977), including the formation of Kakadu and Nitmiluk National Parks on the western rim of the plateau, the Djelk and Warddeken Indigenous Protected Areas in the centre-north and the inclusion of Kakadu National Park as a World Heritage site. However, effective fire management over this remote, rugged and generally inaccessible region has remained problematic and challenging. Published data for approximately 4000 km2 of the Arnhem Plateau and associated scarps included in Kakadu National Park show that, whereas the average annual extent of burning was similar over the periods between 1980–1994 and 1995–2004, at 28.5% and 26.1% respectively, there was a shift to a more early dry season, management-imposed fire regime, from 7.5% to 12.9%, over respective periods (Russell-Smith et al., 1997b, 2009a).

Following extensive fires in biodiverse sandstone habitats in 2001, 2004 and 2006, Kakadu National Park has developed a fire management plan which incorporates thresholds criteria specifically for the Arnhem Plateau (Petty et al. 2007) (based on the model developed for Kruger NP, South Africa by van Wilgen et al., 1998, 2003). For Nitmiluk National Park, published data for the period 1989– 2004, show that an average of 50% of the plateau unit burnt annually over this period, with the majority of this in the late dry season (Edwards et al., 2001; Russell-Smith et al., 2009a). However, Nitmiluk National Park has developed a fire management strategy that outlines the broad objectives and strategies for fire management, research and wildfire suppression. Strategies include long-term satellite mapping of fire impact and on-ground vegetation monitoring, which has commenced within the park.

Indigenous outstations and mobile family groups have maintained traditional fire regimes to some extent. However, for the majority of the Arnhem Plateau which lies to the east of Kakadu and Nitmiluk National Parks, reinstatement of customary fire regimes only began in the late 1990s with the establishment of the Western Arnhem Land Fire Abatement (WALFA) project. WALFA was developed (at the instigation of traditional owners) as a collaborative partnership between senior traditional owners, Indigenous organisations (including Adjumarlarl, Djelk-Bawinanga, Jawoyn, Mimal and Warddeken-Manwurrk Ranger groups, and the Northern Land Council), Bushfires NT (the rural fire agency of the NT Government), and a research consortium under the auspices of the Tropical Savannas Cooperative Research Centre (TSCRC). Focusing initially on developing regional fire management capacity, from 2000 the WALFA partnership undertook research to position the

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project as a greenhouse emissions abatement project—with the objective of reducing the incidence of severe late dry season wildfires through the strategic early dry season application of prescribed fire management.

Fire regimes as a threatening process Key fire regime issues confronting Arnhem Shrubland Complex flora and fauna comprise the contemporary frequency of very extensive, relatively non-patchy and severe late dry season wildfires (Yates et al., 2008; Edwards and Russell-Smith, 2009). Obligate seeder taxa with maturation periods in excess of five years and relatively immobile vertebrate fauna with small home ranges are especially vulnerable to extensive and frequent fires (Woinarski et al., 2005; Yates et al., 2008).

Available information indicates that around 50% of western Arnhem Land heath shrub taxa are obligate seeders, with as many as 10% exhibiting primary juvenile periods (the time taken to onset of maturation) of five years and more (Russell-Smith et al., 1998; Russell-Smith et al., unpublished ms). While the majority of these obligate seeders comprise species with dormant soil-borne seedbanks (e.g. Acacia — and legumes generally, Hibbertia, Hibiscus, Lithomyrtus), and therefore may be regarded as being able to persist (sensu Pausas et al., 2004) in the face of at least some repeat short-interval fires, others like the long-lived serotinous shrub, Petraeomyrtus punicea (rock myrtle) (Russell-Smith, 2006), do not exhibit this capacity. Even allowing for some degree of fire patchiness in sandstone terrain (Price et al., 2003), the high frequency of large fires documented for western Arnhem Land is a significant threat to the ecological community, especially when it is considered that patch sizes of sandstone heath habitats are typically very small (median 3 ha; Edwards and Russell-Smith, 2009).

The effect of repeat fires at short intervals (<5 years) on localised loss of longer maturing obligate seeder taxa has been observed at monitoring plots both within Kakadu (Russell-Smith, 2006; Russell-Smith et al., unpublished ms), and Nitmiluk National Parks (J Russell-Smith, pers. comm., 2011). In addition, repeat short fire-intervals in Nitmiluk have been observed to promote fire- carrying grasses and significantly reduce recruitment of woody taxa (Russell-Smith et al., 2002). Notably, in four instances (three in Kakadu, one in Nitmiluk), localised species loss (at the plot scale) involved Acacia spp., an important component of the ecological community. In central Australia, Wright and Clarke (2009) found that, despite prolific production of dormant seed in some Acacia spp., seed predation reduced the soil seedbank to negligible levels. Similar observations of very low to non-existent soil seedbanks under some Acacia stands have been observed in extensive soil-seedbank germination studies conducted in western Arnhem Land sandstone habitats (J. Russell- Smith, unpublished data).

Vulnerable regionally endemic fauna that are part of the ecological community include Petasida ephippigera (Leichhardt‘s Grasshopper), a species with an annual lifecycle reliant on food-plants of the genus Pityrodia (Lowe, 1995; Barrow, 2008, 2010); the white-throated grasswren, a species reliant on long-unburnt habitat comprising hummocks of spinifex grasses (Triodia, Symplectrodia) (Noske, 1992; Woinarski, 1992); and various small mammals with typically very small home ranges and low dispersability (Friend and Taylor, 1985; Woinarski et al., 2001, 2005). For example, during the dry season, populations of flightless nymphs of the Leichhardt‘s Grasshopper, live on Pityrodia shrubs typically in areas <1 ha in extent (Barrow, 2008). The negative effects of even single fires on population sizes (particularly associated with food resource depletion) of vulnerable fauna species have been observed in studies of Leichhardt‘s grasshopper (including localised extinctions; Barrow, 2008), rock rats (Begg et al., 1981), partridge pigeon (Fraser et al., 2003), and in modelling the impacts of spatio-temporal fire patterning on the food resources of the black-footed tree rat (Woinarski et al., 2005).

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Current status There is growing recognition of the impact of contemporary fire regimes on fire-sensitive components of both Arnhem Plateau flora and fauna, and significant efforts outlined above, to address fire management challenges across that region. However, recent data derived from long-term monitoring plots established in Kakadu National Park in the mid-1990s illustrate that the status and condition of much of the ecological community‘s flora and fauna is in decline.

Significant relationships derived from an assessment of the impacts of fire regime parameters on Arnhem Plateau heath and woodland obligate seeder species from 48 monitoring plots, (Russell- Smith et al. unpublished ms) show that frequencies of four or more fires over the fifteen year (1995– 2009) assessment period (i.e. an annual fire frequency of 0.27, or one fire every 3.75 years) have resulted in loss of obligate seeder species that require four or more years to attain sexual maturity. That same assessment also shows that 53% of the entire mapped Arnhem Shrubland Complex has experienced four or more fires over that period, and 30% of the Arnhem Shrubland Complex has experienced five or more fires (i.e. an annual fire frequency of 0.33, or one fire every three years). Figure 2 illustrates the geographic magnitude of the impact of contemporary fire regimes on the proportion of the ecological community occurring in 10 x 10 km cells which has been affected by four or more fires over the 15 year study period.

The fauna assessment undertaken by Woinarski et al. (2010) for Kakadu monitoring plots generally, shows clearly that trapping success rates for individual small mammal species and number of individuals are directly negatively related to fire frequency. Other factors such as predation, disease, cane toads (Rhinella marinus), may also contribute to that decline (Woinarski et al., 2010).

Despite on-going fire management for the Arnhem region, monitoring suggests that fire-sensitive vegetation, including the ecological community, and relatively immobile fauna with small home- ranges, remain vulnerable to contemporary fire regimes (Woinarski et al., 2005; 2010; Yates et al., 2008).

Invasive species As noted above the Arnhem Shrubland Complex ecological community provides habitat for a diverse range of animal and plant species. Several species on the Arnhem Plateau have declined substantially following the colonization by the cane toad (mostly from 2000-2001). The most extreme of these declines has been for the northern quoll (Watson and Woinarski, 2003), which has suffered local extinctions in some areas of its large range (Woinarski et al., 2009; Warddeken Management Board, pers. comm., 2010). Declines are also suspected for some small dasyurid marsupials, for example, the northern brush-tailed phascogale (Phascogale pirata), some agamid lizards and some snake species (Watson and Woinarski, 2003).

Impacts from the feral cat (Felis catus) may be associated with reductions in terrestrial fauna species in the Arnhem region, particularly reptiles, ground dwelling mammals such as the Arnhem rock-rat and birds such as the partridge pigeon (Russell-Smith et al., 2009). Bird species that forage, nest and roost on the ground are highly susceptible to predation by feral cats.

Feral buffalo (Bubalus bubalis) have a negative impact within the Arnhem region which is primarily related to their movements and feeding. The most obvious signs of buffalo damage are disturbance of soils and vegetation owing to overgrazing and wallowing in mud. The species is also a vector for invasive weeds. The National Brucellosis and Tuberculosis Eradication Campaign in the 1970s significantly reduced buffalo numbers in the low-lands of coastal west Arnhem Land. Targeted culling is conducted in some areas of the Arnhem Plateau, for example, the Djelk Indigenous Protected Area and Kakadu National Park (Djelk Rangers, 2010; Kakadu Board of Management, 2007). Buffalo tend to have the greatest impact on wetlands, springs and water quality. The species Arnhem Plateau Sandstone Shrubland Complex Page 23

does not appear to have a direct major impact on the stone country of the ecological community, although an increase in numbers may increase the incidence of weed impact.

Introduced ant species have the potential to eliminate many native animal species and seriously disrupt ecological processes. Invasive ant species have not adversely impacted the ecological community to date. However eradication programs have been implemented in or near the Arnhem region for the African big headed ant (Pheidole megacephala), tropical fire ant or ginger ant (Solenopsis geminata) and yellow crazy ant (Anoplolepis gracilipes). African big headed ants and yellow crazy ants can form huge colonies, totally displacing native animals. These species are capable of displacing native invertebrate species such as green ants (Oecophylla smaragdina), altering food availability for native species within the ecological community. They can also cause outbreaks of sap-sucking insects, which in turn are able to kill vegetation (CSIRO, 2010). African big headed ants were controlled in Kakadu National Park in 2001. However, there is the potential for the introduction of other invasive ant species.

In general, weeds have considerable impacts on native flora due to their ability to outcompete native species for resources in the face of largely absent natural controls (Muyt, 2001; Coutts-Smith and Downey, 2006). Invasion by weeds follows large recruitment events and leads to competition for space and resources and, in so doing, displaces native species and contributes to a reduction in native plant abundance and diversity. This is particularly the case for high impact, invasive weeds that are difficult to manage. In certain cases, the presence of weeds can transform the vegetation structure of an ecological community e.g. where native understorey and groundcover is replaced by high densities of tall invasive grasses.

Due to the highly dissected, isolated and largely inaccessible nature of the Arnhem Plateau, the ecological community is not currently known to be subject to heavy invasion by weeds. However, the Northern Territory Government has identified alien invasive grass species that have the potential to threaten native vegetation in the region (Table 3). These vigorous weeds were introduced into northern Australia to increase the productivity of pastures for cattle. Although many of the weeds present within adjoining bioregions are common weeds of pastures that are under management programs that extend into disturbed native vegetation remnants, the potential spread of the invasive species remains a real threat to the ecological community. For example, gamba grass (Andropogon gayanus) is in the management zone near the western boundary of Kakadu National Park and the southern boundary of Nitmiluk National Park (NT Government, 2010b). Currently most of these ecosystem transforming weed species, such as gamba grass, mission grass (Pennisetum polystachion and hairy fountain grass (P. pedicellatum), which occur in Kakadu (Cowie and Werner, 1993) and some parts of the Arnhem Plateau, are relatively localised and under active management (Edwards et al., 2003; Warddeken Land Management, 2010; Woinarski et al., 2010).

Table 3: Weed species that may occur in the Arnhem Plateau Sandstone Shrubland Complex. Scientific Name Common Name Andropogon gayanus gamba grass Crotalaria goreensis rattlepod Hibiscus sabdariffa rosella Hyptis suaveolens hyptis, horehound Passiflora foetida wild passionfruit Pennisetum polystachion mission grass Pennisetum pedicellatum hairy fountain grass Sida cordifolia flannel weed Stylosanthes humilis Townsville stylo

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Introduced grasses, such as gamba grass and mission grass, can alter fire regimes to the extent that the structure and composition of vegetation is strongly affected (D‘Antonio and Vitousek, 1992; Gill et al., 2009). Gamba grass and mission grass pose the greatest potential threats to the ecological community due to high fuel loads (Rossiter et al., 2003). Invasive grasses, such as gamba and mission grasses, can cause changes in fire regimes through a positive feed-back cycle known as the ‗grass-fire cycle‘. The grass-fire cycle occurs when these tall alien grasses invade an area and lead to an increase of fire frequency and, in some cases, intensity. This causes a decline in tree and shrub cover, facilitating further grass invasion, which in turn increases the likelihood of more frequent fire in a self-perpetuating cycle (NT Government, 2006, 2010b). For example, high intensity fires in open woodlands (savanna) can substantially reduce woody species recruitment (Setterfield, 2002) and cause considerable tree stem mortality and reduce tree recruitment. Fire-promoting grasses also have the potential to alter the nutrient cycle and carbon cycling processes over large areas of Australia‘s savanna ecosystems (Rossiter et al., 2003).

The incidence of weeds on the Arnhem Plateau is generally low in comparison to adjacent lowlands and pastoral lands (Franklin et al., 2008). Road corridors, current and former development sites such as mines and other disturbed sites, feral animals and macropods, are the most likely introduction and dispersal vectors (Woinarski et al., 2009; Cook, pers. comm., 2010). Mineral exploration may also provide a potential dispersal vector. The current incidence of weeds on the Arnhem Plateau is currently localised, so that eradication and further spread may be possible given appropriate resources (Woinarski et al., 2009; Cooke, pers. comm., 2010; Warddeken Land Management, pers. comm., 2010).

Fire-fuel loads are on average four times greater in savannas heavily invaded by gamba grass. The grass species grows up to 4.75 metres over the wet season whereas native tall grasses are typically between 1 and 3 metres. Mission grass, being a perennial, dries off later than native annual grasses and has a greater fuel load. This alters natural fire patterns and results in extremely hot fires late in the dry season (Douglas et al., 2004). Once established, mission grass has a competitive advantage over annual grasses, which can impact on native biodiversity (NT Government, 2006). Gamba grass also cures later and remains erect for longer into the dry season, forming a taller denser fuel load than the native grasses (Rossiter et al., 2003).

Gamba grass invasion is likely to result in substantial changes to the savanna fire regime. Even in the early dry season, the large fuel loads resulting from gamba grass invasion can support fires on average eight times more intense than those fuelled by native grasses. Fire frequency may also increase because gamba grass has the potential to support fire more than once a year due to its high tolerance to fire and ability to resprout soon after fire (Bowden 1963). Gamba grass can produce sufficient biomass to support a second fire in the same season (Rossiter et al., 2003).

High intensity fires in open woodlands (savanna) can substantially reduce woody species recruitment (Setterfield, 2002) and cause considerable tree stem mortality and reduce tree recruitment. As with other fire-promoting grasses, the ecosystem ‗transformer‘ (gamba grass) has the potential to alter ecological community structure, and the nutrient cycle and carbon cycling processes over large areas of Australia‘s savanna ecosystems (Rossiter et al., 2003).

Level of protection in reserves A straight north-south tenure line dissects the Arnhem Plateau. Much of the Arnhem Shrubland Complex ecological community occurs on land managed and owned by Indigenous people or in conservation reservations. Approximately 22.5% (136 063 ha) of the Arnhem Shrubland Complex ecological community is located within Kakadu National Park and 3.5% (21 047 ha) within Nitmiluk National Park. A major portion of the north-western edge of the Arnhem Plateau is conserved in

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Kakadu National Park which is also a listed World Heritage area under the EPBC Act. Much of the eastern portion of Arnhem Plateau is incorporated within the Djelk and Warddeken Indigenous Protected Areas (Table 4).

The extent of the ecological community under conservation tenure is significant but the key threats and their impacts remain.

Table 4: Estimates of the Arnhem Plateau Sandstone Shrubland Complex ecological community that exist in protected areas in the Northern Territory. Name of reserve Estimated area % of current extent reserved (ha) Kakadu National Park 136 063* 22.5 Nitmiluk National Park 21 047* 3.5 Djelk and Warddeken Indigenous Protected 224 000–324 635* 37–53.8 Areas * Areas include intergrades of heath/woodland and heath/rainforest.

Climate Change Climate change is now understood to pose a serious long-term threat to terrestrial, coastal and aquatic ecosystems and to have the potential to change the ecology of these environments. Not only does climate change directly threaten species that cannot adapt, it could also exacerbate existing threats, including loss of habitat, altered hydrological regimes, altered fire regimes and invasive species which, themselves, are not adequately managed at present. The potential large scale impacts of climate change could influence the species composition of this ecological community through their responses to disturbance and the very nature of those disturbances.

Current trends suggest there are likely to be impacts due to changes for northern Australia by 2030, as a consequence of greenhouse gas-induced global warming. These trends suggest there will be a decrease in relative humidity and an increase in evapotranspiration. The southern trade winds, which predominate during the dry season also have a bearing on fire regimes. Ignition of fires due to lightning strike may increase, while there is likely to be an increase in the frequency of severe cyclones.

Kakadu National Park is a biodiversity hotspot containing many narrow ranged endemic native species. It has been identified to be at high risk from climate change via a number of mutually amplifying processes. Elevated carbon dioxide levels in the atmosphere may favour the growth of some woody species, whilst other species have already declined due to high fire frequencies. Extended dry periods and more frequent and intense rainfall events are likely as shifts occur in the timing and intensity of monsoonal rainfall. This is likely to enhance future fire risk and influence the structure and species compostion of ecological communities within the Park. Climate change will also cause shifts in the ability of invasive species to compete with native species, especially if native species are also under stress from changing habitat quality and altered fire regimes.

Key Threatening Processes The following EPBC Act listed Key Threatening Process are considered relevant to the ‗Arnhem Plateau Sandstone Shrubland Complex‘ ecological community:  Invasion of northern Australia by gamba grass and other introduced grasses  Predation by feral cats  The biological effects, including lethal toxic ingestion, caused by cane toads (Bufo rhinella marinus)

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 Loss of terrestrial climatic habitat caused by anthropogenic emissions of greenhouse gases  Fire regimes that cause biodiversity decline

9. How judged by the Committee in relation to the EPBC Act criteria. Criterion 1 - Decline in geographic distribution There are gaps in knowledge about the pre-European and current extent of the Arnhem Shrubland Complex ecological community, due to limited mapping and vegetation modelling for the ecological community across its range. The most recent and comprehensive estimates of current extent for the ecological community are from Blake (2004) and Edwards et al. (2009). The ecological community is estimated to cover at least 603 000 ha. It should be noted that this estimate does not take the condition criteria prescribed above into account so it is likely that the extent which remains in good condition is less than this estimate.

However, there are no available estimates for the pre-European extent of the ecological community. Consequently, the decline in extent of the ecological community cannot be reliably estimated.

There are insufficient data available to determine the decline in extent for the ecological community. Therefore, the Committee considers the ecological community is not eligible for listing in any category under this criterion.

Criterion 2 - Small geographic distribution coupled with demonstrable threat This criterion recognises that an ecological community subject to ongoing threats faces an inherently higher risk of extinction if its geographic distribution is small or highly fragmented. Three indicative measures apply to this criterion: the total extent of occurrence of the ecological community, its area of occupancy, and the size distribution of known patches. The latter is indicative of the degree of fragmentation. If any of the three measures is demonstrated to apply to the ecological community it is considered to have a small geographic distribution, either naturally or that has become so through modification.

As detailed in Section 8 Description of threats, above, the Arnhem Shrubland Complex ecological community is subject to ongoing and demonstrable threats, notably from the impacts of altered fire regimes and the invasion of weeds and feral animals into the ecological community.

The Arnhem Shrubland Complex covers a large proportion of the Arnhem Plateau bioregion and outlying rock outcrops. Its extent of occurrence is, consequently, large at more than 1.8 million hectares (Blake, 2004). The total area of occupancy of the Arnhem Shrubland Complex is also large and estimated to be at least 603 000 ha (Blake, 2004), not including isolated outlying outcrops. Even if this estimate is interpreted as an overestimate due to caveats or inaccuracies associated with vegetation mapping, the remaining extent is likely to exceed the thresholds for considering its geographic distribution as limited (i.e. > 1 million ha for extent of occurrence and >100 000 ha for area of occupancy. Therefore, the geographic distribution of the ecological community is such that it cannot be considered to be limited based on these measures.

Table 5: Patch size attributes in the West Arnhem Land Fire Abatement (WALFA) Project Area (Edwards and Russell-Smith, 2009). Vegetation type Mean patch (ha) Median patch (ha) Max patch (ha) Sandstone Heath 61 3 69 055 Sandstone woodland 44 2 93 274

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Although fine scale vegetation mapping is not available across the ecological community‘s entire range, summary patch size statistics are available for the West Arnhem Land Fire Project Area (WALFA) (Table 5). Individual patch sizes for the ecological community range up to 69 055 ha and it is estimated the mean patch size to be 61 ha. However, of the 8754 patches within the ecological community, the median patch size is only 3 ha (Edwards and Russell-Smith, 2009). This implies that more than half of the patches are < 10 ha in size. Fragmentation may be natural due to the dissected nature of the topography and geology of sandstone habitats on the Arnhem Plateau; but, a degree of fragmentation may also be due to the impacts of altered fire regimes. For example, within the 1990—2005 WALFA study period, 63.9% of the ecological community was burnt by fires ranging over 1 km² (100 ha) or more (Edwards and Russell-Smith, 2009). Patch size data suggests that the ecological community is very restricted with at least 50% of patches being < 0.1 km² (10 ha) in size. Many key obligate seeder taxa within the ecological community have restricted propagule dispersal distances in the order of tens of metres from parent canopies. Given the threats operating, particularly fire regimes, and the difficulty for natural recruitment to occur in such a complex landscape, further fragmentation of the ecological community is likely to continue due to localised loss and degradation of patches.

Summary The Committee considers that the ecological community has a very restricted geographic distribution, based on the fragmentation of remnants into small patch sizes, coupled with demonstrable ongoing threats that could cause it to be lost in the near future. Therefore, the ecological community is eligible for listing under Criterion 2 as endangered.

Criterion 3 - Loss or decline of functionally important species The biology, ecology and threats relating to the Arnhem Shrubland Complex ecological community are detailed in Sections 7 and 8, above. The ecological community is a variable and dynamic ecological community and one consequence of this is that plant species composition varies throughout its range and there is no single species that can be regarded as key to the definition or functional importance of the ecological community. However, one consistent diagnostic feature of the ecological community is the presence of a suite of obligate seeder taxa within the shrub layer. In some patches of the ecological community, 50% or more of the shrub taxa comprises obligate seeder species (Russell-Smith et al., 2002), though this proportion may be lower, down to 10%, but not less.

The responses of obligate seeder species to altered fire regimes are detailed in Section 8, above. Fire intervals longer than the primary juvenile period (time from germination to first seed production), but shorter than the plant‘s life span are advantageous to obligate seeders because they allow time for sufficient seed production (Gill and Groves, 1981). Approximately 90% of the obligate seeder taxa for the ecological community have primary juvenile periods of up to three years and the remainder have primary juvenile periods of five years or longer. Consequently a change in fire regimes that results in fire frequencies of less than three to five years are highly likely to be deleterious for the long-term persistence of the key obligate seeder group. The impacts of altered fire regimes on obligate seeder recruitment, operates on top of other environmental limitations to recruitment, such as the naturally stochastic nature of recruitment events (due to variations in e.g. seasonal conditions or site characteristics) and seed predation.

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Table 6: Kakadu study site – presence of obligate seeder Petraeomyrtus punicea (rock myrtle) (Russell-Smith, 2002) Sample No. live mature plants No. live Year (>5 cm basal diameter) seedlings/juveniles 1998 39 0 Fire late 1998 - before 1999 sample 1999 19 100 2002 19 30 2003 19 30 2004 19 30 Fire late 2004 - before 2005 sample 2005 15 5

Petraeomyrtus punicea (rock myrtle) is a key endemic species for this ecological community and is one of the longer-generation obligate seeder shrubs (Russell-Smith et al., 1998). A study of the ecology of rock myrtle illustrates the nature of the impacts of altered fire regimes to obligate seeder taxa. While maturation in a small number of individuals of rock myrtle may occur in the fourth wet season following a recruitment event, more substantial production of seed capsules occurs at least one to two years later (Russell-Smith, 2006). Seed fall is limited to the near vicinity of adult plants, with some secondary transport downslope. Both juveniles and adult plants are killed if totally scorched (Russell-Smith, 2006).

Table 6 highlights the impact of two fires six years apart on adult and juvenile rock myrtle at a site in Kakadu National Park. Over this period, the number of adult individuals declined by more than 60% and, despite an initial increase in recruitment of juveniles after the first fire, the population of juvenile plants plummeted, especially after the second fire. Similar trends are also apparent at other study sites. For instance, of 145 individuals of rock myrtle at another Kakadu study site, only 14% of juveniles survived within one year after a late season fire and no new recruitment was observed (Russell-Smith, 2006).

The observed trends in the decline of rock myrtle are likely to apply for the obligate seeder shrub group as a whole, even though a majority of species have an even shorter primary juvenile period of less than three years and, therefore, have the potential to recruit from seed within the immediate future (i.e. within the next one to two years).

The Description of threats (Section 8), details evidence that substantial areas of the Arnhem Shrubland Complex ecological community are subject to repeat burning at frequent intervals. For instance, during the period 1995 to 2005, 53% of the WALFA area experienced a fire every 3.7 years, while 30% of patches experienced a fire every three years (Russell-Smith, unpublished). Edwards and Russell-Smith (2009) indicated that, between 1990 to 2005, 62.2% of the ecological community within the WALFA area experienced a repeat fire within two years. Edwards et al. (2001) found that 40% of the ecological community in Nitmiluk National Park was burnt on at least three occasions over the nine years from 1989–1997.

The extent and intervals of the current fire regimes have the potential to adversely affect the recruitment of the obligate seeder group across a substantial part of the national ecological community. Recruitment is impacted because short fire intervals of less than five years can deplete the existing seed bank of obligate seeder species and also does not allow sufficient time for juveniles to reach maturity where they can bear enough fruit to build-up a future seedbank. Trends in surveyed populations of P. punicea demonstrates that late maturing, long-lived obligate seeder species can

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decline quickly and are likely to become lost from the ecological community. The extent of decline of P. punicea is over 50%, which suggests a severe decline in the abundance of obligate seeder taxa.

Since the impacts of altered fire regimes act directly upon seeding and recruitment, the restoration of key obligate seeders, such as the endemic rock myrtle, is prevented or delayed, pending any possibility that seedlings might migrate to a site from adjacent unburnt areas. However, within patches that continue to be regularly burnt at intervals of three years or less, regeneration is highly unlikely in the immediate future (10 years or three generations) and is also unlikely to occur within the near future (20 years or five generations).

The Committee therefore considers that, for the Arnhem Shrubland Complex ecological community:  the obligate seeder group of native plants has a major functional and characteristic role;  it can be inferred that obligate seeders are undergoing a severe decline in abundance, of 50% or more, across large parts of the ecological community‘s range; and  restoration of the community is not likely to be possible in the near future. Therefore, the ecological community is eligible for listing as endangered under this criterion.

Criterion 4 - Reduction in community integrity The main threats and disturbances that contribute to a reduction in the integrity of the Arnhem Shrubland Complex are: altered fire regime - notably increased fire frequencies; and invasion by weeds and feral animals. The nature of these threats are detailed in Section 8 Description of Threats, above.

Reduction in integrity through loss of vegetative components Obligate seeders are a key functional group within the ecological community. Up to 50% of the ecological community‘s flora taxa are obligate seeders and many of these have maturation periods of three to five years. A high proportion of obligate seeder species within the ecological community do not form persistent longer-term soil seed banks and seed fall is often restricted to within a few metres of the parent plant. Consequently, if these species are removed from a patch of the ecological community through a threatening process, they are difficult to re-establish naturally and the loss may be effectively irreversible.

Table 7: Proportion (%) of Arnhem Plateau Sandstone Shrubland Complex ecological community with a fire return period of three years or less. Study site Years Area (%) Kakadu National Park (Russell-Smith et al., 1998) 1980–1994 40 Nitmiluk National Park (Edwards et al., 2001) 1989–1997 40 WALFA (Edwards and Russell-Smith, 2009) 1990–2005 66 WALFA (Russell-Smith, unpublished) 1995–2009 30

Large areas of the ecological community are impacted by recurring fires at short intervals that are often less than the three to five year maturation periods for obligate seeder species. Depending on the study area involved, between 30 to 66% of vegetation patches were subject to altered fire intervals marked by increased frequency (Table 7). Based on compiled fire regime data, Edwards and Russell-Smith (2009) estimated that up to 83% of the ecological community was affected by fires with minimum return intervals of one to three years. For large fires (≥ 100 km²), 66% of the ecological community was burnt at least once within one to three years of having been burnt previously. The extent of the ecological community affected by short fire intervals, therefore, greatly exceeds the critical threshold values for its continued survival (Table 8).

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Table 8: Fire regime vulnerability components and threshold parameters for Arnhem Plateau Sandstone Heath vegetation (Edwards and Russell-Smith, 2009) Fire regime vulnerability Critical threshold Juvenile periods for obligate seeder shrubs: ≥10% of sandstone heath patches - most 3 years, affected by one or more recurring - some 5 years, fires within 3 years - few (e.g. some Acacia spp., Petraeomyrtus punicea) c.10 years. (Russell-Smith et al., 1998; 2002; Russell-Smith, 2006; Russell-Smith pers. comm., 2011) Limited dispersal capacity for many obligate seeder taxa ≥10% of sandstone heath patches (Russell-Smith, 2006) affected by one or more large (≥100 km²) recurring fires within 3 years

The reduction in community integrity is demonstrated by surveys that measure the loss of key obligate seeder species, such as rock myrtle, from the ecological community. Russell-Smith (unpublished) observed that mature specimens of this key endemic species declined by approximately 61% within an eight year study period (Table 6). The decline in the survival of mature individuals and recruitment of juvenile plants suggests that restoration of the ecological community‘s integrity is unlikely in the near to immediate future, even if the proportion of the ecological community impacted by inappropriate fire frequency decreases. The existing impacts of fire to the recruitment of the obligate seeder species within the ecological community means that a substantial proportion of these taxa will continue to decline or effect slow recovery over the immediate to near future.

It should be noted that the impacts of altered fire regime are not necessarily limited to the shrub layer but may also impact upon the structure and integrity of the emergent tree and ground layers. These may also be adversely affected through death of mature plants from fire and a lack of regeneration. The establishment of tree seedlings requires a confluence of conditions, such as rainfall events, adequate seed supply and availability of good recruitment sites in order to succeed. Disturbed remnants may not have all the requirements to effect natural recruitment, for instance a lack of good quality sites for seedlings to establish, competition for space with invasive weeds, poor fruiting by the surrounding native plants, and impacts through increased seed predation or herbivory.

Reduction in integrity through loss of faunal components The action of various threats and subsequent changes to the vegetative components of the ecological community also impact upon the faunal components of this ecological community. The effects of fire on vertebrates within the ecological community, varies with the frequency and intensity of the fire, its patchiness, the type of vegetation burnt and the time of the year when the fire occurs. Some reptile, and mammal species, need a fine-scaled mosaic to provide food and shelter throughout the year. Emergent trees can provide habitat for fauna species. Fire can lead to a loss of key habitat elements for fauna species. For instance, a decline in the abundance and cover of emergent trees may impact on reptile species, such as frilledneck lizards, which utilise emergent trees. Changes in the understorey composition could impact upon granivorous bird species, such as the white-throated grass-wren (Woinarski, 1992), Gouldian finch and Geohaps smithi smithi (partridge pigeon) and small mammals such as the Arnhem rock rat. Intense regular fires promote Sorghum at the expense of other native grasses such as Alloteropsis semialata. The EPBC listed endangered Gouldian finch is reliant on Alloteropsis as a food source in the early wet season.

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Some faunal components of the ecological community are experiencing localised extinctions. The endemic invertebrate species, Leichhardt‘s grasshopper, which is reliant on Pityrodia species, has experienced localised extinctions within the last ten years as a result of inappropriate fire regimes. This species is known to be very restricted in distribution and has not been observed to recolonise sites from which it previously disappeared in the near to immediate future.

The impacts of altered fire regimes and weed invasions on the faunal components of the ecological community appear to be less well studied than are the impacts to vegetation. Although detailed data on faunal declines are absent or scant, declines may be inferred given the nature of the impacts to vegetation, noted above. Changes in species composition and the outright loss of certain plant taxa or functional groups from the ecological community are likely to have flow-on effects to native fauna.

Reduction in integrity through weed invasion The nature of the weed threat and their potential impacts on the ecological community are discussed above, under Description of Threats. Weed invasion is an actual threat to the degradation of this ecological community. Given the broad extent of the ecological community, the range of weed species that could invade the ecological community is potentially large.

Gamba grass and mission grasses are recognised as Key Threatening Processes under the EPBC Act. These weeds are known to occur within the ecological community (Warddeken Land Management, 2010) and in adjacent vegetation communities. These introduced pasture species are recognised to have a high impact and be highly invasive, with a strong potential to spread and adversely alter fire regimes. Their high biomass and rapid growth allows them to out-compete native grasses and produce significantly increased fuel loads which promote intense, late, dry season fires. For example, gamba grass has fuel loads up to seven times higher than native grasses (Rossiter et al., 2003). This produces fires that are eight times more intense than those produced by native grasses (Rossiter-Rachor et al., 2008). Research by Rossiter-Rachor et al. (2008) found that the mean rate of spread of fires in gamba grass plots was five times that of native grass plots. These factors modify ecosystem processes and have a detrimental effect on native flora and fauna, ultimately resulting in a system dominated by exotic grass monocultures.

The issue of high environmental impact and invasiveness also extends to other weed species that have demonstrated an ability to spread into native vegetation and adversely affect native species, either through direct competition or by altering fire regimes. For instance, rattlepod (Crotalaria goreensis) can rapidly spread along road edges and disturbed land, such as when fire promotes seed germination (particularly wet season fires) (Petty et al., 2007). The development of a dense ground layer of exotic grasses contributes to altered fire regimes, with additional consequent impacts on the native biodiversity of grassy ecosystems. It also alters the fuel loads which has adverse impacts on fire regimes, where hotter and more frequent fires may result.

To date, weed infestations within the Djelk and Warddeken Indigenous Protected Areas have mainly been centred in areas of high activity. For example, during 2008–2009, the most prevalent weed species to be recorded and treated in the Djelk IPA was mission grass, which accounted for 34% of all control events at outstations (Djelk, 2010). Although these IPAs have generally received minimal vehicle traffic to date, increased vehicle numbers associated with safari and tourist industries, outstation development and mineral exploration has the potential to further spread weeds. The presence of any high impact weeds within the ecological community and other intergrading ecological communities poses an actual threat with the potential for significant further degradation if the weed is not appropriately managed. Weed management within the ecological community is not widespread due to the remoteness and rugged terrain of the landscape. Indigenous rangers have

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conducted weed management activities within IPAs since 2007 and Kakadu and Nitmiluk National Parks have implemented Weed Management programs. However, the effective long-term management of weeds is often resource intensive and requires considerable commitment and effort. Given that many of the weeds now present in the ecological community are highly invasive, plus the threat from the establishment and spread of new weed species, and the difficulties of implementing management in this landscape, weeds will continue to contribute to the reduction in integrity of the ecological community into the future.

Summary The Committee considers that the reduction in integrity experienced by the ecological community as indicated by the loss of vegetative components, faunal components and the impacts of invasive species, with consequent degradation of habitat values, is severe. This is due to a severe degradation of the community and disruption of its processes, evident across much of the ecological community from altered fire regimes. This is likely to continue into the near future. There is also the potential for further degradation from key threatening weed species, which are known to occur in and near to the ecological community. The nature of the changes in integrity within the ecological community are such that the regeneration of many patches is unlikely to occur within the near to immediate future, even with positive human intervention. Therefore, the ecological community is eligible for listing as endangered under this criterion.

Criterion 5 - Rate of continuing detrimental change In previous assessments of ecological communities in the intensive land use zones of southern Australia, the Committee has used available data on the decline in extent by area or number of extant patches over a known period to address this criterion. For instance, estimates of how many hectares and how many patches were known to be cleared over the past decade were used for the assessment of the Shale Woodlands and Shale-Gravel Transition Forest (TSSC 2009).

The ecological community lies outside of intensive land use zones and outright clearing is not a major issue. Despite this, the ecological community is subject to threats, notably altered fire regimes, which can affect a substantial part of the ecological community and alter its composition and structure. The nature of these impacts is described in Section 8 Description of Threats, above.

Data on fire frequencies and the proportion of heath communities impacted have been compiled for the WALFA region for the period 1995–2009 (Russell-Smith, unpublished). The WALFA region was divided into 254 10x10 km cells and the proportion of heath communities impacted by altered fire regime determined for each cell. In 75% of cells, more than 40% of the heath community was affected by altered fire regimes, and in more than half the cells, the proportion of heath communities impacted was greater than 60% (Table 9). In this study, the fire regime involved four or more fires over a 15 year period, a mean fire interval of 3.75 years or shorter (also see figure 2).

Such a fire frequency would certainly have impacted adversely on obligate seeder species with maturation periods greater than four years e.g. rock myrtle, a key obligate seeder species endemic to the ecological community. Russell-Smith (2006) showed that rock myrtle has undergone a high rate of decline, with only 38% of a population surviving a low intensity fire within five years of return fire. No individuals survived a high intensity fire. Of 145 plants sampled at a study site in Kakadu National Park, only 14% of juveniles survived one year after a late season fire, with no observed new recruitment observed. It is likely altered fire regimes could also have disrupted the seeding process for obligate-seeder species in the ecological community that have shorter maturation periods, especially where more than four fires occurred in an area.

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Table 9. The proportion of heath communities affected by four or more fires in 15 years within the WALFA region. Impacts were determined for individual 10x10 km cells across the region. % of heath communities affected No. of 10x10 km cells % of 10x10 km cells > 0 to 40 63 24.8 41 to 60 50 19.7 61 to 80 71 28.0 81 to 100 70 27.5 Total 254 100.0

A similar degree of impact due to altered fire regimes is apparent for other parts of the ecological community‘s range. For instance, Edwards et al. (2001) found that 40% of ecological community in Nitmiluk National Park was burnt on at least three occasions over the nine year period, 1989–1997.

The available data on fire frequency indicates that substantial areas of the ecological community are affected by altered fire regimes. Estimates of the proportion of the ecological community that has been adversely impacted in recent decades are in the order of 40% to 75% and there are indications that such fire regimes are likely to continue into the immediate future. The Committee considers that the rate of continuing detrimental change to the ecological community is severe, as indicated by: (a) a severe rate of continuing decline in a population of a native species that is believed to play a major role in the community (in this case, the species is indicative of obligate seeder taxa which play a key role within the ecological community); and (b) an intensification, across most of its geographic distribution, in degradation, or disruption of important community processes (in this case the impacts due to altered fire regime, and particularly increased fire frequency). Therefore, the ecological community is eligible for listing as endangered under this criterion.

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Figure 2: Proportion of heath communities affected by four of more fires in 15 years (Russell-Smith et al., unpublished)

West Arnhem Land

Kakadu National Park

Criterion 6 - Quantitative analysis showing probability of extinction There are no quantitative data available to assess this ecological community under this criterion. Therefore, it is not eligible for listing under this criterion.

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10. Conclusion Conservation status This advice follows the assessment of information to include the Arnhem Plateau Sandstone Heath ecological community in the list of threatened ecological communities referred to in Section 181 of the EPBC Act. The Arnhem Plateau Sandstone Shrubland Complex ecological community meets:  Criterion 2 as endangered because the very restricted geographic distribution, based on the fragmentation of remnants into small patch sizes, makes it likely that the action of a threatening process could cause it to be lost in the near future;  Criterion 3 as endangered because the loss or decline of functionally important species is severe;  Criterion 4 as endangered because the reduction in integrity by degradation of the community is severe; and  Criterion 5 as endangered because the rate of continuing detrimental change is severe and is projected to continue in the near future. The highest category for which the ecological community is eligible to be listed is endangered. Recovery Plan The Committee considers that there should be a recovery plan for this ecological community. The Committee recognises the ecological community to be endangered and that threats to the community are ongoing and complex in nature. Considerable work is needed to ensure continued protection for this ecological community. It is expected that any existing management plans or conservation initiatives would be taken into account for future plans.

11. Recommendation The Committee recommends that: (i) The list referred to in section 181 of the EPBC Act be amended by including in the list in the endangered category: Arnhem Plateau Sandstone Shrubland Complex; (ii) The Committee recommends that the Minister decide to have a recovery plan for this ecological community. (iii) The Committee recommends that the Minister provide the following reason for his decision: The actions required to conserve and promote recovery of the ecological community include short and longer term activities that need to be evaluated and prioritised through the preparation of a recovery plan. A recovery plan would promote a coordinated approach to recover the ecological community and provide guidance to land managers. (iv) In making this recommendation, the Committee draws to the Minister‘s attention the key role Indigenous engagement has played for this assessment.

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12. Publications used to assess the nomination Allen GE and Willson A (1995). Learning more about fire in the Top End: processing and interpreting spatial and temporal fire history data derived from NOAA AVHRR satellite images. NARGIS, 95, 2nd North Australian Remote sensing and Geographic information systems forum, pp. 21–26. Supervising scientist, Commonwealth of Australia, Canberra. Altman J (2003). People on country, healthy landscapes and sustainable Indigenous futures: The Arnhem Land case. In: ‗The Drawing Board: An Australian Review of Public Affairs‘. Available on the intenet at: http://www.australianreview.net/journal/v4/n2/altman.pdf Andersen AN, Cook GD, Corbett LK, Douglas MM, Eager RW, Russell-Smith J, Setterfield SA, Williams RJ and Woinarski JCZ (2005). Fire frequency and biodiversity conservation in Australian tropical savannas: implications from the Kapalga fire experiment. Austral Ecology 30/2: 155–167. Andersen AN, Lowe LM and Rentz DCF (2000). The grasshopper (Orthoptera: Acridoidea, Eumastacoidea and Tettigonioidea) fauna of Kakadu National Park in the Australian seasonal tropics: biogeography, habitat associations and functional groups. Australian Journal of Zoology 48, 431–442. Andrew MH and Mott JJ (1983). Annuals with transient seedbanks: The population biology of indigenous Sorghum species of tropical north-west Australia. Australian Journal of Ecology 8: 265–76. Auld TD (1987). Population dynamics of the shrub Acacia suaveolens (Sm.) Willd.: Survivorship throughout the life cycle, a synthesis. Australian Journal of Ecology 12/2: 139–151. Auld TD and O‘Connell MA (1991). Predicting patterns of post-fire germination in 35 eastern Australian Fabaceae. Australian Journal of Ecology 16: 53–70. Australian Natural Resource Atlas (2009). Viewed: 10 June 2010 Available on the internet at: http://www.anra.gov.au/topics/vegetation/assessment/nt/ibra-arnhem-plateau.html#birds Barrow PH (2008). The role of fire in the ecology of Leichhardt‘s grasshopper (Petasida ephippigera) and its food plants, Pityrodia spp. Unpublished PhD thesis. (Charles Darwin University: Darwin) Barrow P (2010). Impact of fire regimes on Leichhardt‘s grasshoppers. In ‗Kakadu National Park Landscape Symposia. Series 2007–2009. Symposium 3: Fire management, 23–24 April 2008, Aurora Kakadu (South Alligator), Kakadu National Park‘. Internal Report 566, Supervising Scientist. Darwin. Unpublished paper. Begg, RJ (1981). The small mammals of Little Nourlangie Rock, N.T. IV. Ecology of Zyzomys woodwardi, the large rock-rat, and Zyzomys argurus, the common rock-rat (Rodentia : Muridae). Australian Wildlife Research 8: 307–320. Begg RJ and Dunlop CR (1980). Security eating and diet in the large rock-rat Zyzomys woodwardi (Rodentia: Muridae). Australian Wildlife 7: 63–70. Begg RJ, Martin, KC and Price NF (1981). The small mammals of Little Nourlangie Rock, N.T. V. The effects of fire. Australian Wildlife Research 8: 515–527. Bennett AF, Haslem A, Cheal DC, Clarke MF, Jones RN, Koehn JD, Lake PS, Lumsden LF, Lunt ID, Mackey BG, MacNally R, Menkhorst PW, New TR, Newell GR, O'Hara T, Quinn GP, Radford JQ, Robinson D, Watson JEM and Yen AL (2009). Ecological processes: A key

Arnhem Plateau Sandstone Shrubland Complex Page 37

element in strategies for nature conservation. Ecological Management and Restoration, 10: 192–199. Blake G (2004). An Object-Orientated Approach to Mapping the Distribution of Sandstone Heath Vegetation on the Arnhem Plateau. Unpublished honours thesis. Charles Darwin University. Darwin. Bowman DMJS (1991). Environmental determinants of Allosyncarpia ternata forests that are endemic to western Arnhem Land, northern Australia. Australian Journal of Botany 39: 575– 589. Bowman DMJS (1992). Monsoon forests in north-western Australia. II. Forest-savanna transitions. Australian Journal of Botany 40: 89–102. Bowman DMJS (1994). Preliminary observations on the mortality of Allosyncarpia ternate stems on the Arnhem Land plateau, northern Australia. Australian Forestry 57: 62–64. Bowman DMJS (1998). Tansley Review No. 101: The impact of Aboriginal landscape burning on the Australian biota. New Phytologist 140: 385–410. Bowman DMJS and Panton WJ (1993). Decline of Callitris intratropica R.T. Baker and H.G. Smith in the Northern Territory: Implications for Pre- and Post-European Colonisation Fire Regimes. Journal of Biogeography 20/4: 373–381. Bowman DMJS and Prior LD (2004). Impact of Aboriginal landscape burning on woody vegetation in Eucalyptus tetrodonta savanna in Arnhem Land, northern Australia. Journal of Biogeography 31: 807–817. Bowman DMJS, Price O, Whitehead PJ and Walsh A (2001a). The ‗wilderness effect‘ and the decline of Callitris intratropica on the Arnhem Land Plateau, northern Australia. Australian Journal of Botany 49/5: 665–672. Bowman DMJS and Vigilante T (2001b). Conflagrations: the culture, ecology and politics of landscape burning in the North Kimberly. Ngoonjook: A Journal of Australian Indigenous Issues 30:38–45. Bowman DMJS, Walsh A and Prior LD (2004). Landscape analysis of Aboriginal fire management in Central Arnhem Land, north Australia. Journal of Biogeography 31: 207–223. Bowman DMJS, Wilson BA and Dunlop CR (1988). Response of Callitris intratropica R.T. Baker and H.G. Smith to fire protection, Murgenella, northern Australia. Australian Journal of Ecology 13: 14–159. Bowman DMJS, Wilson BA and Fensham RJ (1990). Sandstone vegetation pattern in the Jim Jim Falls region, Northern Territory, Australia. Australian Journal of Ecology 15: 163–174. Bradshaw RA, Bedward M, Scott J and Keith DA (1995). Simulation of the effects of Spatial and Temporal Variation in Fire Regimes on Population Viability of a Banksia Species. Conservation Biology 10/3: 776–784. Bradstock RA, Williams JE and Gill Am (2002). Flammable Australia: the fire regimes and biodiversity of a continent. Cambridge University Press. United Kingdom. Braithwaite RW and Estbergs JA (1985). Fire patterns and woody vegetation trends in the Alligator Rivers region of Northern Australia. In ‗Ecology and Management for World‘s savannas‘ (eds JC Toghill and JJ Mott). Australian Acadamy of Science. Canberra. Brock J (2007). Native Plants of Northern Australia. Reed New Holland. Sydney.

Arnhem Plateau Sandstone Shrubland Complex Page 38

Clarke GM and Spier-Ashcroft F (2003). A review of the conservation status of selected Australian non-marine invertebrates. Cook GD, Hurst DF and Griffith DWT (1995). Atmospheric trace gas emissions from tropical Australian savanna fires. CALMScience Supplement 4: 123–128. Cooke PM (2000). Fire management on Aboriginal lands in the Top End of the Northern Territory, Australia. In ‗Fire and sustainable agricultural forestry development in eastern Indonesia and northern Australia‘. ACIAR, 91: 102–107. Cooke PM (2009). Buffalo and tin, baki and Jesus: the creation of a modern wilderness. In ‗Culture, Ecology and Economy of Savanna Fire Management in Northern Australia: Rekindling the Wurrk Tradition‘ (eds J Russell-Smith, PJ Whitehead and PM Cooke). CSIRO Publications, Melbourne. Coutts-Smith AJ and Downey PO (2006). The impact of weeds on threatened biodiversity in New South Wales. Technical Series No. 11, CRC for Australian Weed Management, Adelaide, South Australia, Australia. Cowie I (2005). Kakadu threatened flora volume 3. Department of Infrastructure, Planning and Environment, Northern Territory Government. Cowie ID and Werner PA (1993). Alien plant species invasive in Kakadu National Park, tropical Northern Australia. Biological Conservation 63/2: 127–135. Crisp MD, Laffan S, Linder HP, and Monro A (2001). Endemism in the Australian flora. Journal of Biogeography 28: 183–198. CSIRO (2010). Eradicating pest ants from the Top End. Viewed: 10 June 2010 Available on the internet at: http://www.csiro.au/science/TropicalPestAnts.html D'Antonio CM and Vitousek PM (1992). Biological invasions by exotic grasses, the grass/fire cycle, and global change. Annual Review of Ecology and Systematics 23: 63–87. Day JC (1985). Applications of satellite imagery for fire management in Kakadu National Park. In ‗Towards an Expert System for Fire Management at Kakadu National Park‘ (eds J Walker, JR Davis and AM Gill). CSIRO Division of Water and Land Resources, Canberra, Technical Memorandum 85/2: 122–137. Djelk Rangers (2010). Annual Report 2009–2010. Viewed: 10 December 2010 Available on the internet at: http://caepr.anu.edu.au/system/files/cck_project_partners/2010/04/Djelk%20Annual%20Report %202010%20web.pdf Duff GA, Orr TM, Belbin L and Andersen A (1991). Flora Survey of Kakadu Stage III. Unpublished report to the Australian National Parks and Wildlife Service. Canberra. Dunlop CR and Begg RJ (1981). The small mammals of Little Nourlangie rock, N.T. I. description of study site. Australian Wildlife Research 8: 51–56. Dunlop CR and Webb LJ (1991). Flora and vegetation. In ‗Monsoonal Australia: Landscape Ecology and Man in the Northern Lowlands‘ (eds CD Haynes, MG Ridpath and MAJ Williams). Balkema, Rotterdam. Dyer R, Jacklyn P, Partridge I, Russell-Smith J and Williams D (2001). Savanna Burning: understanding and using fire in northern Australia, Tropical Savannas CRC, Darwin.

Arnhem Plateau Sandstone Shrubland Complex Page 39

Edwards A, Hauser P, Andersen M, McCartney J, Armstrong M, Thackway R, Allan G and Russell- Smith J. (2001). A tale of two parks: contemporary fire regimes of Litchfield and Nitmiluk National Parks, monsoonal northern Australia. International Journal of Wildland Fire 10: 79– 89. Edwards A, Kennett R, Price O, Russell-Smith J, Spiers G and Woinarski J (2003). Monitoring the impacts of fire regimes on vegetation in northern Australia: an example from Kakadu National Park. International Journal of Wildland Fire 12/3–4: 427–440. Edwards AC and Russell-Smith J (2009). Ecological thresholds and the status of fire-sensitive vegetation in western Arnhem Land, northern Australia: implications for management. International Journal of Wildland Fire 18: 127–146. Fensham RJ (1990). Interactive effects of fire frequency and site factors in tropical Eucalyptus forests. Australian Journal of Ecology 16: 363–374. Fensham RJ (1997). Aboriginal fire regimes in Queensland, Australia: analysis of the explorers' record. Journal of Biogeography 24: 11–22. Fitzsimons J, Legge S, Traill B and Woinarski J (2010). Into Oblivion? The disappearing native mammals of northern Australia. The Nature Conservancy. Melbourne. Fox RW (1977). Ranger Uranium Environmental Inquiry: Second Report. Australian Government Publishing Service. Canberra. Franklin DC (1999). Evidence of disarray in gravinous bird assemblages in the savannas of northern Australia, a region of sparse human settlement. Biological Conservation 90: 53–68 Franklin DC, Petty AM, Williamson GJ, Brook BW and Bowman DMJS (2008). Monitoring contrasting land management in the savanna landscapes of northern Australia. Environmental Management 41: 501–515. Fraser F, Lawson V, Morrison S, Christopherson P, McGregor S and Rawlinson M (2003). Fire management experiment for the declining Partridge Pigeon, Kakadu National Park. Ecological Management and Restoration 4: 94–102. Freeland WJ, Winter JW and Raskin S (1988). Australian rock-mammals: a phenomenon of the seasonally dry tropics. Biotropica 20: 70–79. Friend GR and Taylor JA (1985). Habitat preferences of small mammals in tropical open-forests of northern Australia. Australian Journal of Ecology 10: 173-185. Garde M, Nadjamerrek LB, Kolkiwarra M, Kalarriya J, Djandjomerr J, Birriyabirriya B, Bilindja R, Kubarkku M and Biless P (2009). The language of fire: seasonality, resources and landscape burning on the Arnhem Land Plateau. In ‗Culture, ecology and economy of savanna fire management in northern Australia: rekindling the Wurrk tradition‘ (eds J Russell-Smith, PJ Whitehead and PM Cooke). CSIRO Publications. Melbourne. Gill AM (1975). Fire and the Australian flora: a review. Australian Forestry 38: 4–25. Gill AM (1981). Adaptive responses of Australian species to fire. In ‗Fire and the Australian Biota‘ (eds AM Gill, RH Groves and IR Noble). Australian Acadamy of Science. Canberra. Gill AM and Bradstock RA (1995). Extinction of the biota by fires. In: ‗Conserving Biodiversity: Threats and Solutions‘. Surrey Beatty and Sons. Sydney. Gill AM and Groves RH (1981). Fire regimes in heathlands and their plant-ecological effects. In ‗Ecosystems of the World 9B – Heathlands and related shrublands‘ (ed RL Specht). Elsevier, Amsterdam.

Arnhem Plateau Sandstone Shrubland Complex Page 40

Gill AM, Hoare JRL, Cheney NP (1990). Fires and their effects in the wet-dry tropics of Australia. In ‗Fire and the tropical biota‘. In ‗Ecosystem processes and global challenges‘ (ed JG Goldammer). Springer-Verlag. New York. Gill AM, Moore PHR and Williams RJ (1996). Fire weather in the wet-dry tropics of the World Heritage Kakadu National Park, Australia. Australian Journal of Ecology 21: 302–308. Gill AM, Ryan PG, Moore PHR, Gibson M (2000). Fire regimes of World Heritage Kakadu National Park, Australia. Austral Ecology 21: 302–308. Gill M, Williams RJ and Woinarski CZ (2009). Fires in Australia‘s tropical savannas: Interactions with biodiversity, global warming, and exotic biota. In ‗Tropical Fire Ecology. Climate change, land use and ecosystem dynamics‘ (ed MA Cochrane). Praxis Publishing Ltd. United Kingdom. Gill AM, Woinarski JCZ and York A (1999). Australia‘s Biodiversity – Responses to Fire: plants, birds and invertebrates. Biodiversity Technical paper No. 1. Department of Environment and Heritage. Canberra. Goldammer JG and Price C (1998). Potential impacts of climate change on fire regimes in the tropics based on MAGICC and a GISS GCM-derived lightning model. Climate Change 39: 273–296. Gole C (2006). The ecoregion: jewel of the Australian continent, Southwest Australia Ecoregion Initiative. Available on the internet at: http://wwf.org.au/publications/southwest-australia-ecoregion-jewel-booklet/ Griffiths A (2005). Fire and biodiversity. CSIRO‘s Kapalga fire experiment – Kakadu National Park. Viewed: 5 October 2010 Available on the internet at: http://www.terc.csiro.au/fws_fli.asp Griffiths AD and Christian KA (1996). The effects of fire on the frillneck lizard (Chlamydosaurus kingii) in northern Australia. Australian Journal of Ecology 21: 386–398. Groves RH (1981). Australian Vegetation. Cambridge University Press. Haynes CD (1985). The pattern and ecology of munwag: traditional Aboriginal fire regimes in north-central Arnhem Land. Proceedings of the Ecological Society of Australia 13: 203–214. Haynes CD (1991). Use and impact of fire. In ‗Monsoonal Australia: Landscape Ecology and Man in the Northern Lowlands‘ (eds CD Haynes, MG Ridpath and MAJ Williams). Balkema. Rotterdam. Horner P (1992). Skinks of the Northern Territory. Northern Territory Museum of Arts and Sciences. Darwin. Ingwersen F (1995). Kakadu-Alligator Rivers Region, Northern Territory, Australia—CPD Site Au4. In ‗Centres of Plant Diversity: A Guide and Strategy for their Conservation, Vol. 2. Asia, Australasia and the Pacific‘ (eds SD Davis, VH Heywood, AC Hamilton, WWF and IUCN). Cambridge. United Kingdom. Jones R (1975). The Neolithic, Palaeolithic and the hunting gardeners: man and land in the antipodes. In ‗Quaternary Studies‘ (eds RP Suggate and MM Cresswell). The Royal Society of New Zealand. Wellington. Kakadu Board of Management (2007). Kakadu National Park Management Plan 2007-2014. Director of National Parks. Australian Government. Darwin.

Arnhem Plateau Sandstone Shrubland Complex Page 41

Keith D (1996). Fire-driven extinction of plant populations: a synthesis of theory and review of evidence from Australian vegetation. Proceedings of the Linnean Society of N.S.W. 116: 37– 78. Keith D (2004). Ocean Shores to Desert Dunes – The native vegetation of New South Wales and the ACT. NSW Department of Environment and Conservation. Hurstville. Keith DA, McCaw WL and Whelan RJ (2002). Fire regimes in Australian heathlands and their effects on plants and animals. In ‗Flammable Australia – The Fire regimes and biodiversity of a Continent‘ (eds RA Bradstock, JE Williams and MA Gill). Cambridge University Press. United Kingdom. Kerle JA (1996). Bioregions of the Northern Territory. Draft report Conservation Commission of Northern Territory. Palmerston, Northern Territory. Kikkawa J, Ingram GJ and Dwyer PD (1979). The Vertebrate fauna of Australian Heathlands-An evolutionary Perspective. In Specht RL (1979). ‗Ecosystems of the World 9A – heathlands and related Shrublands‘. Elsevier. Amsterdam. Levitus R (2009). Change and catastrophe: adaptation, re-adaptation and fire in the Alligator Rivers region. In ‗Culture, Ecology and Economy of Savanna Fire Management in Northern Australia: Rekindling the Wurrk Tradition‘ (eds J Russell-Smith, PJ Whitehead and PM Cooke). CSIRO Publications. Melbourne. Lewis D, Brocklehurst PB, Thackway R and Hill JV (2008). Adopting national vegetation guidelines and the National Vegetation Information System (NVIS) framework in the Northern Territory. Cunninghamia 10/4: 557–567. Liddle DT and Gibbons A (2006). National Recovery Plan for Boronia quadrilata and Boronia viridiflora in the Northern Territory of Australia. Northern Territory Department of Natural Resources, Environment and the Arts Darwin. Liedloff AC and Cook GD (2007). Modelling the effects of rainfall variability and fire on tree populations in an Australian tropical savanna with the FLAMES simulation model. Ecological Modelling 201: 269–282. Lowe L (1995). Preliminary Investigations of the Biology and Management of Leichhardt's Grasshopper, Petasida ephippigera White. Journal of Orthoptera Research 4: 219–221. Lynch BT and Wilson P (1999). Land Systems of Arnhem Land. Department of Lands, Planning and Environment. Northern Territory. Mooney S, Radford K and Hancock G (2001). Clues to the ‗burning question‘: Pre-European fire in the Sydney coastal region from sedimentary charcoal and palynology. Ecological Management and Restoration 2/3: 203–212. Mooney SD, Webb M and Attenbrow V (2007). A Comparison of Charcoal and Archaeological Information to Address the Influences on Holocene Fire Activity in the . Australian Geographer 38/2: 177–194. Muyt A (2001). Bush invaders of South-East Australia: A guide to the identification and control of environmental weeds found in South-East Australia. RG and FJ Richardson, Melbourne. Nicolle (2006). A classification and census of regenerative strategies in the eucalypts (Angophora, Corymbia and Eucalyptus – Myrtaceae), with special reference to the obligate seeders. Australian Journal of Botany 54: 391–407.

Arnhem Plateau Sandstone Shrubland Complex Page 42

Northern Territory Government (2006). Management of Mission Grass. Agnote No: F38. Viewed: 18 June 2010 Available on the internet at: http://www.nt.gov.au/d/Content/File/p/Weed/453.pdf Northern Territory Government (2007). Lost from our landscape: threatened species. (eds Woinarski J, Pavey C, Kerrigan R, Cowie I and Ward S). Northern Territory Government Printing Office. Northern Territory Government (2010a). Sensitive Vegetation in the Northern Territory: Sandsheet Heath. Viewed: 1 July 2010 Available on the internet at: http://www.nt.gov.au/nreta/natres/natveg/brochures/pdf/220310_sensitive_sandsheet.pdf Northern Territory Government (2010b). Weed Management Plan for Andropogon gayanus (Gamba Grass). Viewed: 10 September 2010 Available on the internet at: http://www.nt.gov.au/nreta/natres/weeds/find/gamba/pdf/weed_notes_gamba_mar10.pdf Noske R (1992). The status and ecology of the White-throated Grasswren Amytornis woodwardi. Emu 92: 39–51. Nott J (2003). Kakadu-Arnhem Land Region Northern Territory. School of Tropical Environment Studies and Geography, James Cook University, Cairns. Viewed: 26 May 2010 Available on the internet at: http://crcleme.org.au/RegLandEvol/KakaduArnhem.pdf Parr CL, Andersen AN, Chastagnol C and Duffaud C (2007). Savanna fires increase rates and distances of seed dispersal by ants. Oecologia 151/1: 33–41. Pausas JG, Bradstock RA, Keith DA, Keeley JE, and the GCTE (Global Change of Terrestrial Ecosystems) Fire Network (2004). Plant functional traits in relation to fire in crown-fire ecosystems. Ecology 85: 1085–1100. Pearce KB, Holper PN, Hopkins M, Bouma WJ, Whetton PH, Hennessy KJ, Power SB. (eds). (2007). Climate change in Australia: technical report 2007. Aspendale: CSIRO Marine and Atmospheric Research. Petty AM, Alderson J, Muller R, Scheibe O, Wilson K, and Winderlich S (2007). Kakadu National Park, Arnhem Land Plateau fire management plan. Kakadu National Park and Tropical Savannas CRC. Jabiru, Northern Territory. Viewed: 5 December 2010 Available on the internet at: http://www.environment.gov.au/parks/publications/kakadu/pubs/fire-plan.pdf Plucinski MP (2006). Fuel dynamics in shrub-dominated landscapes. Bushfire conference 2006 – Brisbane 6–9 June 2006. Life in a fire-prone environment: translating science into practice. Viewed: 12 July 2010 Available on the internet at: http://www.cabdirect.org/abstracts/20103143218.html Preece N (2002). Aboriginal fires in monsoonal Australia from historical accounts. Journal of Biogeography 29: 321–336. Press AJ (1988). Comparisons of the extent of fire in different land management systems in the Top End of the Northern Territory. Proceedings of the Ecological Society of Australia 15: 167–175. Arnhem Plateau Sandstone Shrubland Complex Page 43

Price O and Bowman DMJS (1994). Fire-stick forestry: a matrix model in support of skilful fire management of Callitris intratropica by north Australian Aborigines. Journal of Biogeography 21: 573–580. Price O, Russell-Smith J and Edwards A (2003). Fine-scale patchiness of different fire intensities in sandstone heath vegetation in northern Australia. International Journal of Wildland Fire 12: 227–236. Price OF, Edwards AC and Russell-Smith J (2007). Efficacy of permanent firebreaks and aerial prescribed burning in western Arnhem Land, Northern Territory, Australia. International Journal of Wildland Fire 16: 295–305. Ritchie D (2009). Things fall apart: the end of an era of systematic indigenous fire management. In ‗Culture, Ecology and Economy of Savanna Fire Management in Northern Australia: Rekindling the Wurrk Tradition‘ (eds J Russell-Smith, PJ Whitehead and PM Cooke). CSIRO Publications. Melbourne. Rossiter NA, Setterfield SA, Douglas MM and Hutley LB (2003). Testing the grass-fire cycle: alien grass invasion in the tropical savannas of northern Australia. Diversity and Distributions 9: 169–176. Rowley I and Brooker MG (1987). The response of a small insectivorous bird to fire in heathlands. In ‗Nature Conservation: The Role of Remnants of Native Vegetation‘ (eds DA Saunders, GW Arnold, AA Burbidge and AJM Hopkins). Surrey Beatty and CSIRO. Sydney. Russell-Smith J (1995). Flora. In ‗Kakadu: Natural and Cultural Heritage and Management‘ (eds A Press, D Lee, A Webb and G Alistair). Australian Nature Conservation Agency and North Australia Research Unit, Australian National University. Darwin. Russell-Smith J (2002). Pre-contact Aboriginal, and contemporary fire regimes of the savanna landscapes of northern Australia: patterns, changes and ecological processes. In ‗Australian fire regimes: contemporary patterns (April 1998 – March 2000) and changes since European settlement‘ (eds J Russell-Smith, R Craig, AM Gill, R Smith and J Williams). Australia State of the Environment Second Technical Paper Series (Biodiversity). Department of the Environment and Heritage. Canberra. Russell-Smith J (2006). Recruitment dynamics of the long-lived obligate seeders Callitris intratropica (Cupressaceae) and Petraeomyrtus punicea (Myrtaceae). Australian Journal of Botany 54: 479–485. Russell-Smith J and Bowman DMJS (1992). Conservation of monsoon rainforest isolates in the Northern Territory, Australia. Biological Conservation 59: 51–63. Russell-Smith J and Dunlop CR (1987). The status of monsoon vine forests in the Northern Territory: a perspective. In ‗The rainforest legacy. Vol.1: The nature, distribution and status of rainforest types‘ (eds G Werren and P Kershaw). Australian Government Publishing Service. Canberra. Russell-Smith J and Edwards AC (2006). Seasonality and fire severity in savanna landscapes of monsoonal northern Australia. International Journal of Wildland Fire 15: 541–550. Russell-Smith J, Edwards AC, Price OF and Watt F (Unpublished). Monitoring the matrix: response and trajectory of biodiverse mosaics in fire-prone Australian savanna. Russell-Smith J, Edwards AC, Woinarski JCZ, McCartney J, Kerin S, Winderlich S, Murphy BP and Watt F (2009a). An assessment of the first ten years of the three parks (Kakadu, Litchfield, Nitmiluk) fire regime and biodiversity monitoring program. In ‗Culture, Ecology and Economy of Savanna Fire Management in Northern Australia: Rekindling the Wurrk

Arnhem Plateau Sandstone Shrubland Complex Page 44

Tradition‘ (eds J Russell-Smith, PJ Whitehead and PM Cooke). CSIRO Publications. Melbourne. Russell-Smith J, Lucas D, Gapindi M, Gunbunuka B, Kapirigi N, Namingun G, Lucas K, Giuliani P and Chaloupka G. (1997a). Aboriginal resource utilisation and fire management practice in Western Arnhem Land, monsoonal northern Australia: notes for prehistory, lessons for the future. Human Ecology 25: 159–194. Russell-Smith J, Murphy BP, Meyer CP, Cook GD, Maier S, Edwards AC, Schatz J, Brocklehurst P (2009b). Improving estimates of savanna burning emissions for greenhouse accounting in northern Australia: limitations, challenges, applications. International Journal of Wildland Fire 18: 1–18. Russell-Smith J, Ryan PG and DuRieu R (1997b). A LANDSAT MSS-derived fire history of Kakadu National Park, monsoonal northern Australia, 1980-1994: seasonal extent, frequency and patchiness. Journal of Applied Ecology 34: 748–766. Russell-Smith J, Ryan P, Klessa D, Waight G and Harwood R (1998). Fire regimes, fire-sensitive vegetation and fire management of the sandstone Arnhem Plateau, monsoonal northern Australia. Journal of Applied Ecology 35: 829–846. Russell-Smith J, Ryan P and Cheal DC (2002). Fire regimes and the conservation of sandstone heath in monsoonal northern Australia: frequency, interval, patchiness. Biological Conservation 104: 91–106. Russell-Smith, J, Whitehead PJ, Cook GD and Hoare JL (2003). Response of Eucalyptus-dominated savanna to frequent fires: lessons from Munmarlary, 1973-1996. Ecological Monographs 73: 349-375. Russell-Smith J, Yates CP, Edwards A, Allan GE, Cook GD, Cooke P, Craig R, Heath B, Smith R (2003). Contemporary fire regimes of northern Australia: change since Aboriginal occupancy, challenges for sustainable management. International Journal of Wildland Fire, 12: 283–297. Russell-Smith J, Whitehead PJ and Cooke P (2009c). Culture, Ecology and Economy of Fire Management in Northern Australian Savannas. Rekindling the Wurrk Tradition. CSIRO Publications. Melbourne. Russell-Smith J, Watt F, Edwards AC and Price OF (Draft 2010). Management of fire-sensitive sandstone vegetation in northern Australia: implications from long-term monitoring in Kakadu National Park. Sadlier RA (1990). The terrestrial and semiaquatic reptiles (Lacertilia, Serpentes) of the Magela Creek region, Northern Territory. Technical Memorandum 32. Australian Government Publishing Service. Setterfield SA (2002). Seedling establishment in an Australian tropical savanna: effects of seed supply, soil disturbance and fire. Journal of Applied Ecology 39: 949-959. Sharp BR and Bowman DMJS (2004). Patterns of long-term woody vegetation change in a sandstone-plateau savanna woodland, Northern Territory, Australia. Journal of Tropical Ecology 20: 259–270. Specht RL (1958). The climate, geology, soils and plant ecology of the northern portion of Arnhem Land. In ‗Records of the American-Australian Scientific Expedition to Arnhem Land, vol. 3, Botany and Plant Ecology‘ (eds RL Specht and CP Mountford). Melbourne University Press. Melbourne.

Arnhem Plateau Sandstone Shrubland Complex Page 45

Specht RL (1979). Heathlands and related shrublands of the world. In ‗Ecosystems of the World. Vol. 9A. Heathlands and Related Shrublands. Descriptive Studies‘ (ed RL Specht). Elsevier. Amsterdam. Specht RL (1981). Foliage projective covers of overstorey and understorey strata of mature vegetation in Australia. Australian Journal of Ecology 8/4: 433–439. Specht RL (1994). Heathlands. In ‗Australian Vegetation, 2nd Edition‘ (ed RH Groves). Cambridge University Press. Cambridge. SPRAT Glossary Viewed: 23 January 2010 Available on the internet at: http://www.environment.gov.au/cgi-bin/sprat/public/spratglossary.pl Steffen W, Burbidge AA, Hughes L, Kitching R, Lindenmayer D, Musgrave W, Stafford Smith M and Werner P (2009). Australia‘s biodiversity and climate change: a strategic assessment of the vulnerability of Australia‘s biodiversity to climate change. A report to the Natural Resource Management Council commissioned by the Commonwealth Department of Climate change. CSIRO Publishing. Story R (1976). Vegetation of the Alligator Rivers area. In ‗Land Systems of the Alligator Rivers Area, Northern Territory‘ (ed R Story). CSIRO, Melbourne, Land Research Series No. 38: pp.89–110. Taylor J and Dunlop CR (1985). Plant communities of the wet-dry tropics of Australia: The Alligator Rivers region, Northern Territory. Proceedings of the Ecological Society of Australia, Vol. 13: 83–127. TSSC (2009). Listing advice — Cumberland Plain Shale Woodlands and Shale-Gravel Transition Forest. Department of Environment, Water, Heritage and the Arts. Canberra. TSSC (2010). Draft nomination to list ‗Fire regimes that cause biodiversity decline‘ as a key threatening process. Department of Sustainability, Environment, Water, Population and Communities. Canberra. van Wilgen BW, Biggs HC and Potgieter ALF (1998). Fire management and research in the Kruger National Park, with suggestions on the detection of thresholds of potential concern. Koedoe 41: 69–87. van Wilgen BW, Trollope WSW, Biggs HC, Potgieter ALF, Brockett BH (2003). Fire as a driver of ecosystem variability. In ‗The Kruger Experience: ecology and management of savanna heterogeneity‘ (eds JT du Toit, KH Rogers and HC Biggs). Island Press. Washington. Vigilante T (2001). Analysis of explorers‘ records of Aboriginal landscape burning in the Kimberly region of Western Australia. Australian Geographical Studies 39: 135–155. Vigilante T and Bowman DMJS (2004). Effects of fire history on the structure and floristic composition of woody vegetation around Kalumburu, North Kimberley, Australia: a landscape-scale natural experiment. Australian Journal of Botany 52: 381–404. Warddeken Land Management (2010). Annual Report 2009–2010. Viewed: 13 January 2011 Available on the internet at: http://caepr.anu.edu.au/system/files/cck_misc_documents/2011/01/Warddeken%20AR%20200 9-2010%20web.pdf Watson M and Woinarski JCZ (2003). Vertebrate monitoring and resampling in Kakadu National Park, 2002. Parks and Wildlife Commission of the Northern Territory, Darwin.

Arnhem Plateau Sandstone Shrubland Complex Page 46

Whelan RJ, Kanowski P, Gill M and Andersen A, (2006). Living in a Land of Fire, in Integrative Commentary, Australia State of the Environment 2006, Department of the Environment and Water Resources, Australian Government, Canberra. Viewed: 19 November 2010 Available on the internet at: http://ro.uow.edu.au/scipapers/47 Whitehead PJ, Bowman DMJS, Preece N, Fraser F and Cooke P (2003). Customary use of fire in indigenous peoples in northern Australia: its contemporary role in savanna management. International Journal of Wildland Fire 12: 415–425. Whitehead PJ, Purdon P, Cooke PM, Russell-Smith J and Sutton S (2009). The West Arnhem Land Fire Abatement Project: the institutional environment and its implications. In ‗Culture, Ecology and Economy of Savanna Fire Management in Northern Australia: Rekindling the Wurrk Tradition‘ (eds J Russell-Smith, PJ Whitehead and PM Cooke). CSIRO Publications. Melbourne. Whitehead PJ, Purdon P, Russell-Smith J, Cooke PM and Sutton S (2008). The management of climate change through prescribed savanna burning: emerging contributions of indigenous people in north Australia. Public Administration and Development, 28: 374–385. Whitehead PJ, Woinarski JCZ, Franklin D and Price O (2002). Landscape ecology, wildlife management and conservation in northern Australia: Linking policy, practice and capability in regional planning. In ‗Landscape Ecology and Resource Management: Linking Theory with Practice‘ (eds J Bisonette and I Storch). Island Press. New York. Williams PR, Congdom RA, Grice AC and Clarke PJ (2003). Effects of fire regime on plant abundance in a tropical eucalypt savanna of north-eastern Australia. Austral Ecology 28: 327– 338. Williams RJ, Cook GD, Gill AM and Moore PHR (1999). Fire regime, fire intensity and tree survival in a tropical savannas in northern Australia. Australian Journal of Ecology 24/1: 50– 59. Williams RJ, Gill AM and Moore PHR (1998). Seasonal changes in fire behaviour in a tropical savanna in northern Australia. International Journal of Wildland Fire 8: 227–239. Williams RJ, Gill AM and Moore PHR (2003). Fire behaviour. In ―Fire in Tropical Savannas: The Kapalga Experiment‘ (eds AN Andersen, GD Cook and RJ Williams). Springer-Verlag. New York, USA. Williams RJ, Griffiths AD and Allan GE (2002). Fire regimes and biodiversity in the savannas of northern Australia. In ‗Flammable Australia: the fire regimes and biodiversity of a continent‘ (eds RA Bradstock, JE Williams and AM Gill). Cambridge University Press. United Kingdom. Wilson S and SwanG (2008). A complete guide to reptiles of Australia. New Holland. Australia. Wilson BA, Brocklehurst PS, Clark MJ and Dickinson KJM (1990). Vegetation Survey of the Northern Territory. Conservation Commission of the Northern Territory, Darwin, Technical Report No.49. Wilson BA, Russell-Smith J and Williams R (1996). Terrestrial vegetation. In ‗Landscape and Vegetation Ecology of the Kakadu region, Northern Australia‘ (eds CM Finlayson and I von Oertzen). Kluwer Academic Publications. Netherlands. Wilson DF, Humphrey CL, Colgan DJ, Gray K and Johnson RN (2010). Monsoon-influenced speciation patterns in a species flock of Eophreatoicus Nicholls (Isopoda; Crustacea). Molecular Phylogenetics and Evolution 51: 349364.

Arnhem Plateau Sandstone Shrubland Complex Page 47

Woinarski JCZ (1992). The conservation status of the White-throated Grasswren Amytornis woodwardi, an example of problems in status designation. Northern Territory Naturalist 13: 1– 5. Woinarski JCZ, Armstrong M, Brennan K, Fisher A, Griffith F, Hill B, Milne DJ, Palmer C, Ward S, Watson M, Winderlich S and Young S (2010). Monitoring indicates rapid and severe decline of native small mammals in Kakadu National Park, Northern Australia. Wildlife Research 37: 116–126. Woinarski JCZ, Braithwaite RW, Menkhorst KA, Griffin S, Fisher A and Preece N (1992). Gradient analysis of the distribution of mammals in Stage III of Kakadu National Park, with a review of the distribution patterns of mammals across north-western Australia. Wildlife Research 19: 233–262. Woinarski JCZ and Gambold N (1992). Gradient Analysis of a Tropical Herpetofauna: Distribution Patterns of Terrestrial Reptiles anmd Amphibians in Stage III of Kakadu National Park, Australia. Wildlife Research 19: 105–127. Woinarski JCZ, Hempel C, Cowie I, Brennan K, Kerrigan R, Leach G and Russell-Smith J (2006). Distributional pattern of plant species endemic to the Northern Territory, Australia. Australian Journal of Botany 54: 627–640. Woinarski JCZ, Milne DJ and Wanganeen G (2001). Changes in mammal populations in relatively intact landscapes of Kakadu National Park, Northern Territory, Australia. Austral Ecology 26: 360–370. Woinarski JC, Risler J and Kean L (2004). Response of vegetation and vertebrate fauna to 23 years of fire exclusion in a tropical Eucalyptus open forest, Northern Territory, Australia. Austral Ecology 29/2: 156–176. Woinarski JCZ, Russell-Smith J, Andersen AN and Brennan K (2009). Fire management and biodiversity of the western Arnhem Land plateau. In: ‗Culture, ecology and economy of fire management in northern Australia: Rekindling the Wurkk Tradition‘ (eds J Russell-Smith, PJ Whitehead and P Cooke). CSIRO Publications. Melbourne. Woinarski JCZ, Williams RJ, Price O and Rankmore B (2005). Landscapes without boundaries: wildlife and their environments in northern Australia. Wildlife Research 32: 377–388. Yates CP, Edwards AC and Russell-Smith J (2008). Big fires and their ecological impacts in Australian savannas: size and frequency matters. International Journal of Wildland Fire 17: 768–781. Yates C and Russell-Smith J (2003). Fire regimes and vegetation sensitivity analysis: an example from Bradshaw Station, monsoonal northern Australia. International Journal of Wildland Fire 12: 349–358. Yibarbuk D and Cooke P (2001). Bininj mak balanda kunwale manwurrk-ken. Ngoonjook 20: 33– 37. Yibarbuk D, Whitehead PJ, Russell-Smith J, Jackson D, Godjuwa C, Fisher A, Cooke P, Choquenot D and Bowman DMJS (2001). Fire ecology and Aboriginal land management in central Arnhem Land, northern Australia: a tradition of ecosystem management. Journal of Biogeography 28: 325–343.

Arnhem Plateau Sandstone Shrubland Complex Page 48