Kangaroo Island
Aerial photograph of Kangaroo Island shoreline. @ C.Michael Hogan
Kangaroo Island is a large island in the Indian Ocean off the coast of southern Australia. The island is under the national authority of Australia and within the state of South Australia. Ecologically it is within the Mount Lofty woodlands ecoregion, which has a mainland component as well. Flinders Chase National Park, on the extreme west coast of the island, comprises a significant part of Kangaroo Island. There are at least 36 endemic taxa present on Kangaroo Island. Approximately one third of the natural habitat on the island can be considered intact.
Kangaroo Island exhibits a mediterranean climate, influenced by southwesterly humid winds arriving over the Indian Ocean. Underlying strata date to the Late Cambrian period, and bear important Fossilcontent. The biodiversity is enhanced since the island is situated at the boundary of the western arid region and the southeastern wetter region of Australia, and hence the flora has elements of both biogeographical realms. The resident human population of the island was 4259 as of the 2006 census. Significant wildfires ravaged the island in 2007, but the woodlands are recovering at the current time.
Contents
Geography
Map of Kangaroo Island. Source: Berichard cc-3.0-sa unported Kangaroo Island, situated at the entrance to the Gulf of Saint Vincent in the Indian Ocean, has a land area of approximately 4406 square kilometres. The island is about thirteen kilometres from Cape Jervis on the Fleurieu Peninsula, which is the nearest point to the island on mainland Australia.
The total coastline of the island measures 540 kilometres and the east-west length of the island is about 150 kilometres; Kangaroo Island is the third largest island belonging to Australia. The highest elevation on the island is Prospect Hill, 307 metres above mean sea level.
Geology and soils
Beyeria Conservation Park, Dudley Peninsula. @ C.Michael Hogan A major soils association is the skeletal (shallow) limestone level landscape of Dudley Peninsula on the eastern drier side of the island, where KIngscote Mallee (Eucalyptus rugosa) and Soap Mallee (E. diversifolia) are dominant plants. The northeastern part of the island is dominated by ironstone solinised soils, a relatively flat terrain that hosts some very interesting scrub and grassland assemblies; the scrub communities are dominated by Kangaroo Island Narrow-leaf Mallee (Eucalyptus cneorifolia) and Broombush (Melaleuca uncinata); this substrate can also be found on the northern east-central portion of the island. The Beyeria Conservation Park on the Dudley Peninsula offers an excellent glimpse of well preserved Mallee/Broombush scrub.
A smaller unit of sandy soil substrate lies along the southern coast of the Dudley Peninsula, where plant communities were dominated by Eucalyptus rugosa, prior to massive agricultural conversion of the early 19th century.
Kangaroo Island's north coast manifests significant fossil-bearing deposits including Emu Bay Shale of the late Botomian (approximately 517 million years before present), within the late Lower Cambrian. A gamut of primordial marine arthropods have fossilised remains in this Burgess shale type unit.
Climate
The island is part of a region of South Australia that boasts a mediterranean climate, influenced by southwesterly humid winds arriving over the Indian Ocean. Austral winter (June to September) is typically the period of highest rainfall, and mild in temperature; conversely, the austal summer is normally warmer and more arid. Moderated by Indian Ocean influence, the peak maximum temperature usually is below 35 degrees Celsius (C), with average temperatures in the warmest month (February) ranging between 20 and 25 degrees C. Annual rainfall is lowest at Kingscote with around 45 centimetres, and highest atop the central plateau near Roo Lagoon with approximately 90 centimetres per annum.
Vegetative assemblies
Kangaroo Island manifests a range of vegetation types including sclerophyll woodlands, riparian woodland, chaparral and grassland. White Mallee (Eucalyptus diversifolia) is a prominent element of the mallee eucalypt woodlands.
Coastal riparian vegetation, Flinders Chase NP. @ C.Michael Hogan There is a pronounced endemism of plant species on Kangaroo Island, with approximately five percent of the taxa occurring nowhere else. Some of the prominent endemic vascular flora include Kangaroo Island Mallee Ash (Eucalyptus remota), Woolly Bush (Adenanthos sericeus), Kangaroo Island Conesticks (Petrophile multisecta) and the near-endemic Gland Flower (Adenanthos terminalis).
The Beyeria Conservation Park features an assembly of rare plants that thrive on the laterite soils in this location. Important endemics here include the Kangaroo Island Turpentine Bush (Beyeria subtecta), Rough Spider Flower (Grevillea muricata), Small-flowered Daisy-bush (Olearia microdisca), and the Kangaroo Island Spider Orchid (Caladenia ovata).
The western end of Kangaroo Island manifests more undulating terrain and is recipient of the highest precipitation on the island. The vegetation is chiefly dominated by a blend of open forest and woodlands. Vegetation communities feature stands of Sugar Gum (Eucalyptus cladocalyx) and Drooping Sheoak (Allocasuarina verticillata), along with other mixed eucalypt woodlands.
Fauna
The endemic Kangaroo Island Kangaroo in the wild, south Kangaroo Island. @ C.Michael Hogann The most notable mammal present is the endemic Kangaroo Island Kangaroo (Macropus fuliginosus fuliginosus), for whom the island was named upon European discovery in 1802. A smaller marsupial present on the island is the Tammar Wallaby (Macropus eugenii). An endemic dasyurid is the Critically Endangered Kangaroo Island Dunnart (Sminthopsis aitkeni), which is found only in the west of the island in Eucalyptus remota/E. cosmophylla open low mallee, E. baxteri low woodland or E. baxteri/E. remota low open woodland. The Common Brush-tailed Possum (Trichosurus vulpecula) is a widespread folivore native to Australia.
Short Beaked Echidna, southern Kangaroo Island. @ C.Michael Hogan Monotremes are also represented on the island. There is also an introduced population of the Duck-billed Platypus (Ornithorhynchus anatinus) in the western part of the island in Flinders Chase National Park. The Short-beaked Echidna (Tachyglossus aculeatus) is also found moderately widespread on Kangaroo Island.
Chiroptera species on Kangaroo Island include the Yellow-bellied Pouched Bat (Saccolaimus flaviventris), which species is rather widespread in Australia and also occurs in Papua New Guinea. Australia's largest molossid, the White-striped Free-tail Bat (Tadarida australis) is found on Kangaroo Island. Another bat found on the island is the Southern Forest Bat (Eptesicus regulus), a species endemic to southern Australia (including Tasmania).
Several anuran species are found on Kangaroo island: Brown Tree Frog (Litoria ewingii), Spotted Marsh Frog (Limnodynastes tasmaniensis), Painted Spadefoot Frog (Neobatrachus pictus), Brown Toadlet (Pseudophryne bibroni) and Brown Froglet (Crinia signifera).
The Heath Monitor (Varanus rosenbergi ) is a lizard that grows up to a metre in length, preying on smaller reptiles, juvenile birds and eggs; it is frequently observed on warmer days basking in the sunlight or scavenging on roadkill. The Black Tiger Snake (Notechis ater) is found on Kangaroo Island. Another reptile particularly associated with this locale is the Kangaroo Island Copperhead (Austrelaps labialis).
The Glossy Black Cockatoo (Calyptorhynchus lathami) is found on the island, especially in the western part, where its preferred food, fruit of the Drooping Sheoak, is abundant. The Kangaroo Island Emu (Dromaius baudinianus) became extinct during the 1820s from over-hunting and habitat destruction due to burning.
Marine mammals that are observed on the island include the Australian Sea Lion (Neophoca cinerea) and New Zealand Fur Seal (Arctocephalus forsteri), each species of which is native to Kangaroo Island, and abundant at Admiral's Arch as well as at Seal Bay.
Kangaroo Island is not so adversely impacted by alien species grazers as parts of the mainland. No rabbit species are present on the island, and introduced (but escaped) Domestic Goats (Capra hircus) and pigs (Sus scrofa) have generated only minor issues. However, a Koala (Phascolarctos cinereus) population introduced to the island in the 1920s has caused significant damage to certain woodland communities, especially to Manna Gum trees.
Agriculture
Ligurian Bees on the hive, Kangaroo Island. @ C.Michael Hogan The earliest agriculture practised in the European settlement era was sheep farming commencing in the early 1800s, chiefly for wool production. In the early nineteenth century settlers cleared the native scrub and woodland but cutting and burning to make way for introduced domesticated sheep. As cropping technology improved, eventually soil amendments were added to make the land suitable for grain production, notably barley. In 1885 the first colony of Ligurian Honey Bees was introduced. Presently production of honey from this variety of bee is an important commercial agricultural activity on the island. Wine production began on the island in 1985, and currently there are 28 vineyard operations under cultivation.
Prehistory
Aboriginal peoples inhabited Kangaroo Island at least as early as 16,000 years before present, as evidenced by stone tools and shell middens left on the island; however, sea level rise accompanying glacial melt inundated the connection to the Australian mainland, and sometime during the middle Holocene, human habitation ceased, possibly as late as the first millennium BC. The island also bears the aborigine name Karta, meaning island of the dead. Not until European discovery in 1802 did human presence begin anew with the arrival of European settlers.
Conservation
False colour satellite image, with 2007 burn areas in red. Source: NASA There are a number of protected areas on the island, the largest being Flinders Chase National Park at the western end. Additionally, there are other smaller conservation areas, especially to preserve specialised plant assemblies such as the Beyeria Conservation Park on the Dudley Peninsula, established to protect a numerous rare plant taxa adapted to the ironstone soils. In 2007, major wildfires occurred in the west of the island, mainly within Flinders Chase National Park; these lightning generated events severely damages the woodlands of the west, although at current time, these habitats are slowly recovering.
Other key protected areas on the island are:
- Cape Gantheaume Conservation Park
- Cape Bouguer Wilderness Protection Area
- Ravine des Casoars Wilderness Protection Area
- Seal Bay Conservation Park
References
- Barrett. 2010. The Immigrant Bees, Volume 5. Caloundra, Queensland
- N.C.W. Beadle. 1981. The Vegetation of Australia. Cambridge University Press, Cambridge, United Kingdom. ISBN: 0521241952
- R. J. P. Davies. 1992. Threatened plant species of the Murray Mallee, Mount Lofty Ranges, and Kangaroo Island regions of South Australia. Nature Conservation Society of South Australia, Adelaide, Australia.
- M.F. Glaessner. 1979. Lower Cambrian Crustacea and annelid worms from Kangaroo Island, South Australia. Alcheringa: an Australasian Journal of Palaeontology (Taylor & Francis) 3 (1): 21–31
- J.M. Oades. 1986. Water and soils. pp. 44-53 in H.R.Wallace, ed. The ecology of the forests and woodlands of South Australia. Woolman Goverment Printer, Adelaide, Australia.
- S.Parker. 1984. The extinct Kangaroo Island Emu, a hitherto-unrecognised species. Bulletin of the British Ornithologists' Club 104: 19–22.
- Rebe Taylor. 2002. Unearthed: The Aboriginal Tasmanians of Kangaroo Island. Kent Town. Wakefield Press. ISBN1-86254-552-9.
- World Wildlife Fund. 2007. Mount Lofty woodlands.
