Values at a glance

  • 20,000 square kilometres of land and sea country
  • Intact and biodiversity rich
  • Stone and gorge country - 70% of the Arnhem Land Plateau
  • Rivers, estuaries and internationally renowned wetlands
  • Spectacular escarpments and sandstone heathlands
  • Islands, coastal and sub-coastal landscapes
  • Monsoon rainforests and tropical savannas
  • More than 100 clans and 12 languages
  • 1000s of rock art sites

Environment and natural values

The Djelk and Warddeken Indigenous IPAs contain some of the most intact natural systems in Australia, as well as offering protection to the sources and catchments of some of northern Australia’s most important rivers  (Bawinanga Aboriginal Corporation 2009). The IPAs are a place of enormous biological diversity with a range of natural habitats including savannah woodlands, eucalypt and monsoon forests, rivers, billabongs, wetlands, heaths and scrublands, coastal beaches, mudflats and mangroves. These landscapes have been subjected to considerably less disturbance by European settlement than many other parts of the Australian continent. The significant natural values, the extent and integrity of the ecosystems represented and the enduring stewardship of Aboriginal traditional owners make these combined IPAs a treasure of Australia’s National Reserve System and a natural and cultural conservation initiative of international significance. The IPAs’ rugged and beautiful landscape and ecological values are considered to be at least the equal of the neighbouring World Heritage Area, Kakadu National Park.

Significant landscapes

Arnhem Plateau

The Arnhem Land Plateau covers over 32,000 square kilometres, with the greater part of the eastern section of the plateau being encompassed within the Warddeken IPA (Warddeken Land Management Limited 2009a). The Arnhem Land Plateau is widely regarded as ‘the crown jewel of Northern Territory biodiversity’, and an international site of biodiversity significance (Department of Natural Resources, Environment and the Arts 2006). The sandstone plateau is thought to contain the richest variety of reptiles in the world with 90 species recorded (Department of Sustainability, Environment, Water, Population and Communities 2009). The dominant ecological community of the Plateau is the endangered Arnhem Plateau Sandstone Shrubland Complex; the potential range of this vegetation type covers up to 70% of the Wardedeken IPA does not extend into the Djelk IPA (Environmental Resources Information Network, DSEWPC, 2011). The plateau also supports a high proportion of the Northern Territory’s rainforest estate, including almost all of the distinctive rainforest associations dominated by the endemic tree Allosyncarpia ternate (Centre for Aboriginal Economic Policy Research 2012).

Rivers and wetlands

The IPAs offer protection to the catchments of some of northern Australia’s most important rivers.  The area comprising these river basins remains untrammeled by western land uses such as clearing, agriculture or mining (Bawinanga Aboriginal Corporation 2009). Two major tropical rivers in their near entirety are located within the IPAs, the Blyth-Cadell and Liverpool-Tomkinson. Wetlands and riparian systems found in these catchments are exceptional both in their extent and ecological integrity. The Blyth-Cadell Floodplain and Boucaut Bay wetland system is listed in The Directory of Important Wetlands Australia as a nationally significant site.  These wetlands are extraordinarily productive, with seasonal floodplains supporting very high densities of key species. These fragile but productive ecosystems are important to both local Aboriginal people, broader Australia, and the international community. Healthy wetlands are critical for many migratory birds, they support major commercial fisheries and they provide rich and abundant hunting grounds for traditional owners.                                                                 

Offshore islands and coastal areas

The coastal region within the Djelk IPA is listed as internationally significant. There are many important breeding sites for marine turtles and seabirds, as well as roosting and feeding sites for many migratory shorebirds within the IPA. Over 44 migratory birds listed under international conventions and agreements utilize the IPAs.  Many of these have their breeding grounds thousands of kilometres away in the Northern Hemisphere. Boucaut Bay hosts some of the largest flocks of migratory shorebirds in the Top End, regularly supporting in excess of 20,000 birds.

Three coastal areas within the Djelk IPA are designated ‘Sites of Significance’ for wildlife within the Northern Territory, with each area satisfying one or more criteria for international conservation significance (Government Department of Natural Resources, Environment, The Arts and Sport, NRETAS, unpublished data). Approximately 10,000 seabirds were reported in the Haul Round Island colony in 1994, including 5,000 Bridled Terns and 5,000 Roseate Terns. This count of Roseate Terns is internationally significant (Chatto 2001). Birds Australia has also listed Haul Round Island as an Important Bird Area (IBA) in recognition of the importance of the island (Bawinanga Aboriginal Corporation 2009).

Savanna woodlands

The eucalypt savanna provides niche environments for a broad range of honeyeaters, hollow-nesting parrots, cockatoos, raptors and kingfishers. Granivores are a predictably large group here with doves, pigeons and finches being common. Notably, the northern savannas are a stronghold for many woodland birds that have been lost from other areas of Australia. Reptiles in savannas are also diverse with large numbers of skinks, geckos, monitors, dragons and snakes (Bawinanga Aboriginal Corporation 2009).

Plants

The floristic diversity in the IPAs is extremely high, with 1085 plant species being recorded for the Djelk IPA and 1251 for the Warddeken IPA.  Of the 1251 plant species listed as occurring within the Warddeken IPA region, there are 22 naturalised non-native plant species included in this tally, a proportion (1.8%) of exotic flora that is extraordinarily small compared with other areas in Australia. This tally comprises about 40% of that of the Top End as a whole (3186 species) (Bawinanga Aboriginal Corporation 2009, Warddeken Land Management Limited 2009b). Thirty four mangrove species are recorded for the region, making these some of the richest mangrove communities in Australia (Duke 1992). 

Animals

Nineteen frog, 65 reptile, 200 bird and 20 mammal species are recorded for the Djelk IPA.  20 frog, 48 reptile, 141 bird and 30 mammal species are recorded for the Warddeken IPA (Bawinanga Aboriginal Corporation 2009, Warddeken Land Management Limited 2009b). These figures are based on very sparse sampling efforts and undoubtedly substantially underestimate the actual tally of species present. They also do not include fish or invertebrates.  Although the IPAs have not been well surveyed for invertebrates, 46 new species of spider have been collected and described from this area indicating that there is likely to be a diverse invertebrate population (Bawinanga Aboriginal Corporation 2009). Furthermore, over the past few years 24 native species of frog have been recorded including including one undescribed species (Warddeken Land Management Limited 2010).

Threatened species

At least 36 plant species found within the IPAs are either restricted to the Northern Territory or have otherwise limited distributions. Many of these are entirely endemic to the IPAs (Warddeken Land Management Limited 2009b). Six of these plant species are listed as threatened under national or Northern Territory legislation. There are also some cases of notable biogeographic disjunctions.  For example, the tree Podocarpus grayae is known in the Northern Territory only from a few small gorge systems in the Warddeken area, and is otherwise found only in north Queensland.  This is the only representative of the ancient conifer family Podocarpaceae in the Northern Territory (Warddeken Land Management Limited 2009b).

There is an unusually rich aggregation of threatened animal species known for the area. The NRETAS databases list 20 threatened animal species for the IPAs, which includes 6 birds, 7 reptiles, 6 mammals and 1 fish species. Eleven of these are also listed on the international IUCN Red List for threatened species of international concern (Table 1). This includes four threatened species of marine turtle, the green turtle, olive ridley turtle, flatback turtle and the leatherback turtle, the northern quoll, the narrow sawfish, the northern hopping mouse and Arnhem Land rock rat. Forty four species of migratory birds listed under the bilateral conservation agreements utliize the area and are listed under international conventions (CAMBA, JAMBA and ROKAMBA) such as the black-tailed godwit, brown booby and lesser frigatebird (Bawinanga Aboriginal Corporation 2009).

References

Bawinanga Aboriginal Corporation (2009). Djelk Indigenous Protected Area - Central Northern Arnhem Land Management Plan 2009.

Centre for Aboriginal Economic Policy Research. (2012). http://caepr.anu.edu.au/sites/default/files/cck_project_partners/2010/04/Warddeken.pd

Chatto, R. (2001). The distribution and status of colonial breeding seabirds in the Northern Territory. Technical Report 70, Parks and Wildlife Commission of the Northern Territory, Darwin.

Department of Natural Resources, Environment and the Arts (2006). Northern Territory Parks and Conservation Masterplan.

Department of Sustainability, Environment, Water, Population and Communities (2009). Djelk Indigenous Protected Area Fact Sheet.

Duke, N. C. (1992). Mangrove floristics and biogeography, In A.I, Robertson, and D.M. Alongi, Tropical Mangrove Ecosystems. Coastal and Estuarine Studies.

Warddeken Land Management Limited (2010). Warddeken Annual Report 2010 – 2011

Warddeken Land Management Limited (2009a). Warddeken Indigenous Protected Area Arnhem Land Plateau, Northern Territory Management Plan 2009-2013.

Warddeken Land Management Limited (2009b). Warddeken Indigenous Protected Area Arnhem Land Plateau Technical Information Document.