Arnhem Plateau (24544)
Australia, Australasia

Site overview

KBA status: confirmed

Global KBA criteria: A1b, B1

Year of last assessment: 2009

National site name: Arnhem Plateau

Central coordinates: Latitude: -13.1912, Longitude: 133.1807

System: terrestrial

Elevation (m): 0 to 465

Area of KBA (km²): 21218.02403

Protected area coverage (%): 79.19

KBA classification: Global

Legacy site: Yes

Site details

Site description: The IBA follows the boundaries of suitable vegetation for White-throated Grasswrens (heathlands, mixed heathlands and eucalypt, and mixed heathlands and rainforest as mapped by Blake 2004 and Woinarski et al. 2006) within the known and predicted range of this species as mapped by Noske (1992). This is approximately bounded by East Alligator Ranger Station to the northwest, 'Table Hill' vicinity (south-west of Maningrida) to the north-east, following the Mann River in the east to its headwaters, thence the Katherine River (from its headwaters) to Katherine Gorge National Park in the south, thence NNW to Kambolgie Creek-Mount Callanan vicinity, thence following the western escarpment to East Alligator Ranger Station. This includes much of the raised Arnhem Plateau where the habitat is dominated by sandstone plateaux and escarpments. The most important habitat for grasswrens is bare rock and spinifex on flat, often sparsely vegetated, high plateaux; heavily dissected escarpments and outliers supports less dense populations. The plateau is otherwise vegetated with open monsoonal savanna woodland and it also supports a high proportion of the Northern Territory’s rainforest including almost all of the rainforest dominated by the endemic tree Allosyncarpia ternata. About 25% of the IBA is located within Kakadu National Park, an outlier to the south is located within Nitmiluk (Katherine Gorge) National Park and much of the remainder is to be incorporated within the proposed Wardekken Indigenous Protected Area. There are no major population centres or roads within this rugged area but much is still used by the Traditional Owners.

Rationale for qualifying as KBA: This site qualifies as a Key Biodiversity Area of international significance that meets the thresholds for at least one criterion described in the Global Standard for the Identification of KBAs.

Additional biodiversity: The endangered Gouldian Finch, near threatened Grey Falcon, restricted-range Hooded Parrot and biome-restricted White-browed Robin are rare on the Arnhem Plateau (Atlas of Australian Birds database). The plateau also supports three endemic subspecies of three more widespread species: Banded Fruit-Dove (P. c. alligator is wholly restricted to the plateau), Helmeted Friarbird (P. b. ammintophila is wholly restricted to the plateau) and Variegated Fairy-Wren (M. l. dulcis is largely restricted to Arnhemland but integrades with M. l. assimilis to the south). The near threatened Chestnut-backed Buttonquail has been recorded in open woodland on sandstone (Woinarski et al. 1989) while the near threatened Partridge Pigeon may occur in non-sandstone plateau habitat. Non-bird biodiversity: About 200 plant species are endemic to this massif and there is high endemicity of mammals, reptiles and invertebrates, including an endemic family of invertebrates (Woinarski et al. 2006; J. Woinarski in litt. 2007).

Other site values: Arnhem Land and Manyallalik ALT; Kakadu managed by Commonwealth government. Public access is restricted to areas of Kakadu National Park.

Habitats

Land use: hunting | nature conservation and research

IUCN Habitat	Coverage %	Habitat detail
Forest	5
Grassland	5
Rocky Areas(e.g., inland cliffs, mountain peaks)	80
Savanna	5
Shrubland	5

Threats

Summary of threats to biodiversity at KBA: Fires should be kept to a minimum frequency of once every five years. Local land-owners need to be empowered to better manage the land for biodiversity conservation.

Threat level 1	Threat level 2	Threat level 3	Timing
Natural system modifications	Fire & fire suppression	Increase in fire frequency/intensity	Ongoing
Invasive & other problematic species, genes & diseases	Invasive non-native/alien species/diseases	Named species	Ongoing

Additional information

References: Blake, G. (2004) An Object-Oriented Approach to Mapping the Distribution of Sandstone Heath Vegetation on the Arnhem Plateau. Honours Thesis. Charles Darwin University, Darwin. Harrison, L., McGuire, L., Ward, S. Fisher, A., Pavey, C., Fegan, M. and Lynch, B. (2009) An inventory of sites of international and national significance for biodiversity values in the Northern Territory. Department of Natural Resources, Environment, the Arts & Sport, Darwin, NT. Noske, R.A. (1992a) The Status and Ecology of the White-throated Grasswren Amytornis woodwardi. Emu 92: 39-51. Noske, R. (1992b) Do grasswrens have the numbers? Reply to Woinarski (1992) Northern Territory Naturalist 13, 5-8. Russell-Smith, J., Ryan, P.G., and Cheal, D.C. (2002) Fire regimes and the conservation of sandstone heath in monsoonal northern Australia: frequency, interval, patchiness. Biological Conservation 104: 91-106. Ward, S. and Harrison, L. (2009) Recognising sites of conservation significance for biodiversity values in the Northern Territory. Department of Natural Resources, Environment, the Arts & Sport, Darwin, NT. Woinarski, J.C.Z. (1992) The conservation status of the white-throated grass-wren Amytornis woodwardi, an example of problems in status designation. Northern Territory Naturalist 13: 1-5. Woinarski, J.C.Z., Press, A.J. and Russell-Smith, J. (1989) The bird community of a sandstone plateau monsoon forest at Kakadu National Park, Northern Territory. Emu 89: 223-231. Woinarski, J. C. Z., 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.