Location and General Description
The Cape York Peninsula is separated from New Guinea to the north by Torres Strait, which is only 100 km wide at its narrowest point. The Cape York Peninsula Tropical Savannas ecoregion includes the offshore islands of the Torres Strait, the largest of which are the Princes of Wales, Horn, Moa, and Badu Islands. The Peninsula is mostly low-relief, with undulating plains comprising three quarters of the region. The highest point occurs in the Coen/Iron Range area, reaching only 800 m in elevation.
Approximately 1 billion years ago, large deposits of fluviatile sediments covered much of the northern savannas of Australia, forming sandstone plateaus. On the western half of Cape York Peninsula, there are large amounts of red and yellow earths, as well as laterite soils with significant bauxite deposits (Biggs and Phillip 1995). Near the coast there are vast areas of alluvial soils (Tropical Savannas CRC undated).
The climate is strongly monsoonal, with most rain falling in the summer. The northern and eastern areas receive more rain than the south and southwest (Cape York Regional Advisory Group 1996). Dry season rainfall is normally associated with the influx of moist trade winds over the coast. Summers are hot and humid, and maximum temperatures reach 33? to 36?C in January. Rainfall varies greatly with proximity to the coast, with the north receiving an average of 2,400 mm of rain per annum, and falling to an average of 800 mm per year in the south. Winter, or dry season, temperatures in July fall to an average minimum of 21?C in the north and 15?C in the south (Tropical Savannas CRC undated).
This remote, northernmost portion of Queensland harbors some of the most pristine wilderness in Australia, and certainly the largest wilderness area in eastern Australia. Intact eucalypt woodland, heathland, riparian, and coastal ecosystems are all found here. Eucalypt woodlands comprise nearly two-thirds (64 percent) of the ecoregion, while low open-woodlands dominated by Melaleuca spp. occupy nearly 15 percent of the region, followed by grasslands (6 percent), rainforest (5.6 percent), and heathland communities (3.3 percent) in order of abundance (Neldner and Clarkson 1995). An estimated 20 percent of the national extent of rainforest occurs on the Cape York Peninsula, concentrated on the east coast. These rainforests are in nearly pristine condition. Extensive mangroves line both coasts of the Peninsula, and contain 36 mangrove species (Cape York Regional Advisory Group 1996).
Large areas of Cape York Peninsula are vegetated with eucalyptus woodland. Darwin stringybark (Eucalyptus tetrodonta) dominated communities cover 36.3 percent of the ecoregion. Other communities found in this ecoregion include Eucalyptus stockeri/E. tetrodonta woodlands (7.3 percent), bloodwood (Eucalyptus clarksoniana, E. novoguinensis) woodlands (5.6 percent), box woodlands (E. chlorophylla, E. microtheca) (5.0 percent), and ironbark woodlands (E. cullenii, E. crebra) (4.0 percent). Community structure varies considerably, with canopy heights ranging from 10 m to 32 m in height depending on the site conditions. Scattered subcanopy trees and shrubs are usually present, and the conspicuous ground layer is dominated by a variety of grasses (Neldner and Clarkson 1995).
The vascular flora of Cape York Peninsula comprises 3,338 species (Neldner and Clarkson 1995), which show a variety of influences. While Cape York Peninsula shares many widespread plant species with the northern Australian tropical savannas, it contains 39 unique vegetation types identifiable at the 1:1,000,000 map scale (Mackey et al. 2001). The flora is a combination of relict Gondwanan species, autochthonous Australian plants that arose after the breakup of Gondwana and drying of Australia, Indo-Malay plants introduced 15 million years ago when Australia collided with the Sundaland plate, and New Guinean species which made their way across the Torres Strait.
Over 100 Gondwanan species are found on the Cape York Peninsula, including members of the primitive angiosperm families Annonaceae and Lauraceae, as well as orchids of the Arthochilus, Corybas, and Calochilus genera, and members of the Araucariaceae and Podocarpaceae families. Gondwanan plants are largely concentrated in rainforest habitat, including the McIlwraith Range area. Much of the intrusive Indo-Malay element is also concentrated in rainforest, as are the species which recently migrated from New Guinea. However, endemism among plants extends to only three genera, Jedda (Thymelaeaceae), Normanbya (Arecaceae), and Wodyetia (Arecaceae). In total, 264 plants are endemic to Cape York Peninsula, with an additional 40 to 100 undescribed taxa that are also likely to be endemic (Abrahams et al. 1995).
Australia and New Guinea have been connected for a large part of the last 1 million years, although the largely dry climate of the northern Cape York Peninsula has limited the flow of species from New Guinea, which are mostly rainforest- or wet-adapted species. The New Guinean plants, birds, and mammals found in Cape York Peninsula are all rainforest inhabitants, including Bennett’s tree-kangaroo (Dendrolagus bennettianus) and the spotted cuscus (Spilocuscus maculatus). In contrast, the herpetofauna shared between New Guinea and Australia are not rainforest species, and are often concentrated in heathlands habitat (Abrahams et al. 1995).
Due to the variety of vegetation types, the well preserved and natural landscapes, the region’s proximity with New Guinea, and the wide variety of substrates found here, the Cape York Peninsula is known for its rich, diverse, and endemic biota. There are 509 terrestrial vertebrates on the Peninsula, including one quarter of Australia’s frogs, one quarter of its reptiles, a third of all mammals, and half of its birds (Cape York Regional Advisory Group 1996). Richness in orchids has also been documented, with areas of greatest orchid diversity largely overlapping with rainforest communities. Orchid diversity is greatest at the genus level, with 62 genera recorded in the Cape York Peninsula, and the McIlwraith Range supporting over 16 percent of the entire Australian orchid flora. While there has been no systematic Peninsula-wide survey of invertebrates, nearly 60 percent of all Australian butterflies (223 species) occur on Cape York Peninsula, including the spectacular Cape York birdwing (Troides priamus pronomus). According to regional endangered species lists, nine fauna and ten flora species occurring on Cape York Peninsula are listed as endangered, 27 and 44 respectively as vulnerable, and 53 and 165 respectively as rare (Neldner 1999).
Restricted range and globally threatened birds present in Cape York Peninsula include the buff-breasted buttonquail (Turnix olivii EN), golden-shouldered parrot (Psephotus chrysopterygius EN), lovely fairywren (Malurus amabilis), white-streaked honeyeater (Trichodere cockerelli), and yellow-spotted honeyeater (Meliphaga notata). Two subspecies of widespread Australian birds have been identified as threatened, the Cape York Peninsula form of rufous owl (Ninox rufa meesi) and the white-bellied form of crimson finch (Neochmia phaeton evangelinae). The southern cassowary (Casuarius casuarius VU) is found here in rainforest habitat; its distribution extends to New Guinea and other regions of Australia (Hilton-Taylor 2000, Stattersfield et al. 1998).
Endangered mammals present include the spotted-tailed quoll (Dasyurus maculatus gracilis EN), which may be declining as a result of cane toad (Bufo marinus) expansion. The critically endangered Bramble Cay melomys (Melomys rubicola) is known only from a vegetated cay located 50 km from New Guinea. It is thought to be closely related to the endemic melomys (Melomys capensis) (Strahan 1998). Three species of endangered marine turtle are found on Cape York Peninsula (Neldner 1999).
Riparian corridors often harbor a different fauna than the dry eucalypt woodlands they cross. These strips of vegetation connect the extensive east coast rainforests to smaller rainforests on the west coast. The spotted cuscus (Spilocuscus maculatus), white-tailed rat (Uromys caudimaculatus), frugivorous birds, and the palm cockatoo (Probosciger aterrimus) all utilize these corridors (Abrahams et al. 1995). The Cape York Peninsula is an important area for bird migration due to the large areas of pristine habitat. The Peninsula and the Torres Strait are a major avian migration route for landbirds leaving and returning to Northern Australia (Stattersfield et al. 1998). Waterbirds also migrate within the Peninsula as smaller seasonal wetlands dry out and they return to larger wetlands elsewhere on the Peninsula.
Whole river catchments of good quality are very rare on Australia, especially in the densely populated east. But Cape York Peninsula contains 16 complete drainage basins, including several large river systems in essentially natural condition: the Jardine, Jackson, Olive, and Holroyd systems. These rivers also hold exceptionally rich fish fauna, with the Wenlock River containing the richest freshwater fish fauna of any river in Australia. The Olive River also contains significant fish diversity for a river of its size (Abrahams et al. 1995).
Cape York Peninsula is sparsely populated, with 12 urban centers containing a population of 8,700, and the rest of the population (roughly 9,000 people) spread out in smaller towns, settlements, and cattle properties. The earliest recorded contact between Aborigines and European explorers in Australia took place on Cape York Peninsula in 1606. European business interests were not established until the 1800s, first concentrating on marine harvesting of beche-de-mer, trochus, and pearls, then shifting to pastoralism and mining. Mining initially concentrated on gold extraction, but today bauxite, silica, and kaolin are the major mineral products. Pastoralism remains the biggest land use, with roughly 60 percent of Cape York Peninsula held as cattle properties. Aboriginal and Torres Strait Islander holdings comprise approximately 20,000 km2, and more than 60 percent of Cape York Peninsula’s population belong to Aboriginal and Torres Strait Islands groups. The arrival of Europeans had profound consequences for Aboriginal communities and Torres Strait Islanders. Some Torres Strait Islanders relocated to the mainland, while Aboriginal groups on the mainland were often displaced by the pastoral industry.
This ecoregion has long been recognized as one of Australia’s largest and most important wilderness areas. Very little clearing has occurred with 99 percent of the area covered in remnant vegetation (Accad et al. 2001). Approximately 10 percent of the Peninsula is contained in a protected areas system including a number of large national parks: Lakefield (5,370 km2), Mungkan Kandju (4,570 km2), and Jardine River National Parks (2,530 km2).
The vast, high-quality areas of wilderness mean that there have been no documented plant or vertebrate extinctions in this ecoregion after European settlement. The region actually serves as a refuge for several birds that were originally widely distributed across Australia in low numbers, such as the pied oyster catcher (Haemotopus longirostris) (Abrahams et al. 1995).
Types and Severity of Threats
This region is very remote and retains its wilderness character, but inappropriate fire regimes associated with grazing management and invasive species are serious concerns (Neldner et al. 1997). The northern tropical savannas have experienced considerable degradation over the last 50 years as a result of extensive cattle raising (Mott and Tothill 1994). Exotic species are a serious concern, including invasive weeds, feral pigs (Sus scrofa), and the cane toad. Infrastructure development such as a proposed gas pipeline and bauxite mining as well as piecemeal decision making are threats to the natural heritage values of Cape York Peninsula (Mackey et al. 2001).
In 1990, Queensland and Commonwealth Governments jointly funded a major study on the land use and management of this region, the Cape York Peninsula Land Use Strategy (CYPLUS). This strategy aims to ensure that natural resources are safeguarded as plans for economic development are implemented. The Cape York Peninsula represents one of the last opportunities in Australia, and on Earth, to fully implement precautionary principles in planning new development in a tropical savannas environment (Mackey et al. 2001).
Justification of Ecoregion Delineation
The Cape York Peninsula Tropical Savannas ecoregion encompasses one IBRA, ‘Cape York Peninsula’ (Thackway and Cresswell 1995) and the ‘Cape York’ Endemic Bird Area (Stattersfield et al. 1998).
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Neldner, V.J., R.J. Fensham, J.R. Clarkson, and J.P. Stanton. 1997. The natural grasslands of Cape York Peninsula. Description, distribution and conservation status. Biological Conservation 81: 121-136
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Stattersfield, A.J., M.J. Crosby, A.J. Long, and D.C. Wedge. 1998. Endemic Bird Areas of the World. Priorities for biodiversity conservation. BirdLife Conservation Series No. 7. BirdLife International, Cambridge, United Kingdom.
Thackway, R. and I.D. Cresswell, editors. 1995. An Interim Biogeographic Regionalisation for Australia: a framework for establishing the national system of reserves, Version 4.0. Australian Nature Conservation Agency, Canberra.
Prepared by: Miranda Mockrin
Reviewed by: John Nelder