The Arnhem Land tropical savanna is a

tropical and subtropical grasslands, savannas, and shrublands Tropical and subtropical grasslands, savannas, and shrublands is a terrestrial biome defined by the World Wide Fund for Nature. The biome is dominated by grass and/or shrubs located in semi-arid to semi-humid climate regions of subtropical and t ...

ecoregion An ecoregion (ecological region) or ecozone (ecological zone) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of ...

Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country by ...

Northern Territory The Northern Territory (commonly abbreviated as NT; formally the Northern Territory of Australia) is an Australian territory in the central and central northern regions of Australia. The Northern Territory shares its borders with Western Aust ...

Geography

The ecoregion occupies the peninsula of

Arnhem Land Arnhem Land is a historical region of the Northern Territory of Australia, with the term still in use. It is located in the north-eastern corner of the territory and is around from the territory capital, Darwin. In 1623, Dutch East India Compa ...

and its offshore islands, including the

Tiwi Islands The Tiwi Islands ( tiw, Ratuati Irara meaning "two islands") are part of the Northern Territory, Australia, to the north of Darwin adjoining the Timor Sea. They comprise Melville Island, Bathurst Island, and nine smaller uninhabited islands, w ...

Groote Eylandt Groote Eylandt ( Anindilyakwa: ''Ayangkidarrba'' meaning "island" ) is the largest island in the Gulf of Carpentaria and the fourth largest island in Australia. It was named by the explorer Abel Tasman in 1644 and is Dutch for "Large Island" i ...

, and the Wessel Islands. Western Arnhem land has rugged sandstone plateaus and gorges. The rest of the peninsula has gentler topography, and includes broad river floodplains and coastal lowlands. Arnhem Land is bounded on the northwest by the

Timor Sea The Timor Sea ( id, Laut Timor, pt, Mar de Timor, tet, Tasi Mane or ) is a relatively shallow sea bounded to the north by the island of Timor, to the east by the Arafura Sea, and to the south by Australia. The sea contains a number of reefs ...

, on the north by the

Arafura Sea The Arafura Sea (or Arafuru Sea) lies west of the Pacific Ocean, overlying the continental shelf between Australia and Western New Guinea (also called Papua), which is the Indonesian part of the Island of New Guinea. Geography The Arafura S ...

, and on the east by the

Gulf of Carpentaria The Gulf of Carpentaria (, ) is a large, shallow sea enclosed on three sides by northern Australia and bounded on the north by the eastern Arafura Sea (the body of water that lies between Australia and New Guinea). The northern boundary i ...

. The Kimberley tropical savanna ecoregion lies to the southwest, and the Carpentaria tropical savanna to the southeast.

IBRA regions

The ecoregion includes six IBRA regions – Arnhem Coast, Arnhem Plateau,

Central Arnhem The Central Arnhem, an interim Australian bioregion, is located in the Northern Territory,

, Darwin Coastal, Pine Creek, and Tiwi Cobourg.

Climate

The ecoregion has a

tropical savanna climate Tropical savanna climate or tropical wet and dry climate is a tropical climate sub-type that corresponds to the Köppen climate classification categories ''Aw'' (for a dry winter) and ''As'' (for a dry summer). The driest month has less than of ...

. Rainfall is strongly seasonal, with a summer wet season from November to March, and a mostly rainless dry season during the rest of the year. Average annual rainfall ranges from 1200 mm in the south to 1800 mm in the Tiwi Islands in the northwest. Average monthly maximum temperatures are vary from 27º to 33º C.

Flora

The predominant vegetation is woodland of Darwin stringybark (''Eucalyptus tetrodonta'') and

Darwin woollybutt ''Eucalyptus miniata'', commonly known as the Darwin woollybutt or woolewoorrng, is a species of medium-sized to tall tree that is endemic to northern Australia. It has rough, fibrous, brownish bark on the trunk, smooth greyish bark above. Adul ...

(''Eucalyptus miniata''). The trees are evergreen and form an open canopy up to 20 metres high. The open canopy supports an understory of tall grass, mostly species of ''

Sorghum ''Sorghum'' () is a genus of about 25 species of flowering plants in the grass family (Poaceae). Some of these species are grown as cereals for human consumption and some in pastures for animals. One species is grown for grain, while many other ...

'' growing up to 2.5 metres high. Areas of monsoon rainforest are found in enclaves with fertile soils, protection from fire, and dry-season water from shallow aquifers or perennial rivers or streams. The rainforest flora is distinct from the predominant eucalyptus-dominated woodlands. The rainforest flora includes evergreen, semi-evergreen, and deciduous trees, and the species mix varies with conditions. Woody vines are abundant, and climb into the tree canopy. '' Allosyncarpia ternata'' is a characteristic tree of the Arnhem Land rainforests. Tall-canopied littoral forests and vine thickets are found near the coast. Further inland, evergreen gallery forests grow along rivers, and evergreen forest patches are found at the base of escarpments.Bowman, D. M. J. S., G. K. Brown, M. F. Braby, J. R. Brown, L. G. Cook, M. D. Crisp, F. Ford, S. Haberle, J. Hughes, Y. Isagi, L. Joseph, J. McBride, G. Nelson and P. Y. Ladiges (2010). "Biogeography of the Australian monsoon tropics". ''Journal of Biogeography'', February 2010. DOI: 10.1111/j.1365-2699.2009.02210. Heathlands grow in areas of the sandstone plateaus with thin, acidic soils, and are home to many endemic species. Other plant communities include floodplain sedgelands and grasslands, swamp forests dominated by species of ''

Melaleuca ''Melaleuca'' () is a genus of nearly 300 species of plants in the myrtle family, Myrtaceae, commonly known as paperbarks, honey-myrtles or tea-trees (although the last name is also applied to species of ''Leptospermum''). They range in size f ...

'', and mangrove forests.

Fauna

Native mammals include the agile wallaby (''Macropus agilis''),

common wallaroo The common wallaroo (''Osphranter robustus''), also known as the euro, hill wallaroo, or simply wallaroo, is a species of macropod. The word ''euro'' is particularly applied to one subspecies (''O. r. erubescens'').WE Poole and JC Merchant (198 ...

(''Osphranter robustus''),

antilopine kangaroo The antilopine kangaroo (''Osphranter antilopinus''), also known as the antilopine wallaroo or the antilopine wallaby, is a species of macropod found in northern Australia: in Cape York Peninsula in Queensland, the Top End of the Northern Terri ...

(''Osphranter antilopinus''), northern quoll (''Dasyurus hallucatus''),

short-beaked echidna The short-beaked echidna (''Tachyglossus aculeatus''), also called the short-nosed echidna, is one of four living species of echidna and the only member of the genus ''Tachyglossus''. It is covered in fur and spines and has a distinctive snout ...

(''Tachyglossus aculeatus''),

northern brushtail possum The northern brushtail possum (''Trichosurus arnhemensis'') is a nocturnal marsupial inhabiting northern Australia. The northern brushtail possum is sometimes considered a species, however more often than not is considered a subspecies of the ...

(''Trichosurus arnhemensis''),

common brushtail possum The common brushtail possum (''Trichosurus vulpecula'', from the Greek for "furry tailed" and the Latin for "little fox", previously in the genus ''Phalangista'') is a nocturnal, semiarboreal marsupial of the family Phalangeridae, native to Aus ...

(''Trichosurus vulpecula''),

rock-haunting ringtail possum The rock-haunting ringtail possum (''Petropseudes dahli''), also known as the rock ringtail possum, is a species of Australian possum. It is found in rocky escarpments in the Kimberley, Arnhem Land and Gulf of Carpentaria across Western Austral ...

(''Petropseudes dahli''),

sugar glider The sugar glider (''Petaurus breviceps'') is a small, omnivorous, arboreal, and nocturnal gliding possum belonging to the marsupial infraclass. The common name refers to its predilection for sugary foods such as sap and nectar and its abili ...

(''Petaurus breviceps''),

dusky rat The dusky rat (''Rattus colletti'') is an indigenous species of rodent in the family Muridae found in Australia. Name Kunwinjku people of western Arnhem Land call this animal ''mulbbu'', a name also applied to other rodent species. It was first ...

(''Rattus colletti''), and pale field rat (''Rattus tunneyi''). Endemic species include the Arnhem shovel-nosed snake ''( Brachyurophis morrisi)'', the Kakadu dunnart (''Sminthopsis bindi''), Arnhem Land rock rat (''Zyzomys maini''), and the Kakadu pebble-mound mouse (''Pseudomys calabyi'').

Protected areas

A 2017 assessment found that 55,398 km², or 36%, of the ecoregion is in protected areas. Protected areas in the ecoregion include

Kakadu National Park Kakadu National Park is a protected area in the Northern Territory of Australia, southeast of Darwin. It is a World Heritage Site. Kakadu is also gazetted as a locality, covering the same area as the national park, with 313 people recorded liv ...

Djukbinj National Park Djukbinj National Park is a protected area in the Northern Territory of Australia located about east-south-east of the territory capital of Darwin. The national park was proclaimed on 3 April 1997 over land which has previous protected area st ...

, Nitmiluk National Park, Garig Gunak Barlu National Park, Mary River National Park, and

Litchfield National Park Litchfield National Park, covering approximately 1500 km2, is near the township of Batchelor, 100 km south-west of Darwin, in the Northern Territory of Australia. Each year the park attracts over 260,000 visitors. Proclaimed a nati ...

. Indigenous protected areas in the ecoregion include Anindilyakwa, Dhimurru, Djelk, Laynhapuy–Stage 1, Marthakal, Warddeken, and the northern portion of South-East Arnhem Land.UNEP-WCMC (2020). Protected Area Profile for Australia from the World Database of Protected Areas, September 2020. Available at: www.protectedplanet.net

External links

References

{{Interim Biogeographic Regionalisation for Australia (IBRA) Ecoregions of the Northern Territory Tropical and subtropical grasslands, savannas, and shrublands