Swan Coastal Plain Swan Coastal Plain scrub and woodlands | |
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Swan Coastal Plain from Darling Scarp | |
![]() Map of IBRA regions with the Swan Coastal Plain in red | |
Ecology | |
Realm | Australasian |
Biome | Mediterranean forests, woodlands, and scrub |
Borders | Southwest Australia woodlands |
Geography | |
Area | 15,280 km2 (5,900 sq mi) |
Country | Australia |
State | Western Australia |
Coordinates | 31°49′S115°50′E / 31.82°S 115.84°E |
Conservation | |
Conservation status | Critical/endangered [1] |
The Swan Coastal Plain in Western Australia is the geographic feature which contains the Swan River as it travels west to the Indian Ocean. The coastal plain continues well beyond the boundaries of the Swan River and its tributaries, as a geological and biological zone, one of Western Australia's Interim Biogeographic Regionalisation for Australia regions. [2] [3] It is also one of the distinct physiographic provinces of the larger West Australian Shield division. [4] [1]
The coastal plain is a 30-kilometre-wide (19 mi) strip on the Indian Ocean coast directly west of the Darling Scarp uplands running from Cape Naturaliste in the south to north of the city of Perth. The plain mainly consists of fairly infertile sandy soil along with coastal sand dunes, river estuaries, and a number of wetlands kept back from the sea by the dunes. A number of rivers cross the plain from east to west from the Darling Scarp towards the sea, including the Swan and its main tributary, the Canning.
The sediments of the Perth Basin are Tertiary and Quaternary in age immediately below Perth and include coquina, travertine, and sandy limestones with abundant shelly material. Perth is sited on a set of sand dunes formed during the Pliocene-Pleistocene during the last ice age. Offshore, the sand dune system and surficial deposits transition into a system of partly eroded limestones and sandy limestones. These form a series of drowned cuestas which today form submerged reefs.
Because of the steepness and orientation of the Darling Scarp, watercourses run off the scarp in a westerly direction. On reaching the Swan Coastal Plain, they encounter two obstacles: firstly, the high permeability of the soil results in the loss of much water. Much flow is lost, and some watercourses simply cease to flow, for example, Wungong Brook, Cardup Brook, and Manjedal Brook. Secondly, the sequence of north-to-south-oriented dunes create obstacles to further westerly flow. Many watercourses turn at right angles and flow south or north along the dune swales, and in some cases this allows multiple watercourses to coalesce. For example, on reaching the coastal plain, Ellen Brook runs south for around 30 kilometres (19 mi), picking up a number of watercourses along the way, before finally emptying into the Swan River. Another example is the Serpentine River, which runs west to less than 10 kilometres (6.2 mi) from the coast, then turns south, running parallel with the coast for nearly 20 kilometres (12 mi) before disgorging into Peel Inlet.
The dune topology also results in extensive north-to-south-oriented chains of wetlands, again located in the swales. For example, the chain of lakes north of Perth includes lakes of the Wanneroo wetlands including – Lake Pinjar, Jandabup Lake and Gnangara Lake. The large bodies of water in the estuary of the Swan River, Perth Water and Melville Water are also located in dune swales.
The Swan coastal plain is characterised by a series of sand dune systems, the Quindalup dunes, the Spearwood dunes, and the Bassendean dunes, which run from west to east (in increasing age) from the coastline to the major faults which form the eastern boundary of the plain. [5] The plain is bounded to the east by the Darling Scarp, to the north by a subsidiary fault running north-west from Bullsbrook, and to the south by the Collie-Naturaliste Scarp. [6] The Pinjarra plain lies between the Bassendean dunes and the eastern scarps. [7] Early work on all three dune systems considered them to have been formed at differing times by the deposition of sands carried by wind (aeolian and/or by river processes (fluviatile). [6] [8] More recently, later authors have argued that these sandplains are mostly the product of in situ weathering. [9] [10]
The carbonate material of all three dune systems has been completely leached, leaving dunes which consist solely of quartz sand. [8] Within the Spearwood dunes, the yellow or grey sand may be several metres thick. [8]
The dune systems have been much studied, as the water retained within them supplies much of Perth's water needs. (See Gnangara Mound).
In the southwest of Australia, the Nyoongar seasonal calendar includes six different seasons in a yearly cycle. These are Birak, Bunuru, Djeran, Makuru, Djilba and Kambarang. Each of the six seasons represents and explains the seasonal changes we see annually. The flowering of many different plants, the hibernation of reptiles and the moulting of swans are all helpful indicators that the seasons are changing.
The Nyoongar seasons can be long or short and are indicated by what is happening and changing around us rather than by dates on a calendar. Aligning Nyoongar seasons with Western calendar months can provide an overview of a typical year.
This six season calendar is extremely important to Nyoongar people, as it is a guide to what nature is doing at every stage of the year, as well as understanding respect for the land in relation to plant and animal fertility cycles and land and animal preservation.
The south west region of Western Australia was one of the first places on earth to experience the effects of human induced climate change, namely a significant decline in annual rainfall. The drying climate is expected to continue and exacerbate bushfires. The summer of 2021/22 has been the hottest on record, with many consecutive days over 40 degrees Celsius.
The Swan Coastal Plain is a specific botanical province. [11] [12]
Southwestern Australia is very rich in flora, with an estimated 8,000 species, a quarter of which can be found on this coastal strip. The traditional flora of the dunes and the fairly infertile plain was dense shrubby kwongan heathland adapted to the poor soils, dry summers, and regular fires. Kwongan vegetation contains a large number of endemic plant species, especially shrubs and wildflowers, including yellow flame and toothbrush grevilleas, fan-flowers, and cockies' tongues. The heath is scattered with woodland of Banksia and other trees including the red-blossomed quandong (desert peach) and firewood banksia. Going further inland, especially in river valleys where the soil is better, eucalyptus woodlands including tuart (Eucalyptus gomphocephala) occur. The wetlands meanwhile have been particularly important ecologically, supporting a rich habitat of many plant varieties.
The Swan Coastal Plain is a particularly important centre for certain types of plants, including Banksia, but also Caladenia orchids and Leucopogon shrubs, indeed some genera, such as the Dryandra series of Banksia and the Synaphea flowers are found nowhere else in the world. Other flora of the plain includes a type of mistletoe called the Christmas tree.
The coastal plains are home to a number of marsupials from the large western grey kangaroo to the very small southwestern pygmy possum and mouse-like honey possum. Remnant populations of some marsupials are found on offshore islands including the Tammar wallaby and the quokka, the latter particularly on Rottnest Island. The coastal plains skink, discovered in 2012, is endemic to sand dunes in the area, and is threatened by residential development.
Much of the plain has been cleared for agriculture and urban development, especially in and around Perth, where the heath has been almost entirely cleared as far as the Darling Scarp and the city is spreading up and down the coast. Although some areas are protected, clearance is going on while the plant disease Phytophthora dieback and changes to traditional fire regimens affect the heathland vegetation including the Banksia trees. Protected areas include Kings Park, Beeliar Wetlands, Star Swamp, Hepburn Heights Bushland, Canning River Regional Park, Bold Park, Whiteman Park, Kensington Bushland and Thomsons Lake.
Traditionally, this area was under the care and control of the Yued, Whadjuk, Binjareb, and Wardandi Noongar peoples, whose hunter-gathering firestick farming practices maintained the climax vegetations old growth forests observed at the time of first contact. At this time, the kwongan heathland was much more widespread along the coast.
In the 1830s, it was originally named Great Plain of Quartania or Plain of Quartania by James Stirling, the first governor of Western Australia, but those terms have fallen into disuse.
European settlement led to many of the wetlands areas being drained for land reclamation to take advantage of the fertile soil for farming enterprises, and for expansion of parks and recreation areas. The city of Perth sits on an area of reclaimed wetlands. Between 49% (Riggert, 1966) and 80% (Godfrey, 1989) of the wetlands on the coastal plain is thought to have been drained, filled, or cleared since 1832. Lake Monger and Herdsman Lake are the last two major wetlands remaining in close proximity to the city.
Lake Monger was originally part of a series of freshwater wetlands running north from the Swan River along the coastal plain for about 50 kilometres (31 mi). Lake Monger with Georgiana Lake and Lake Sutherland (both near Mitchell Freeway, near Sutherland and Newcastle streets) and Herdsman Lake made up what was known as "The Great Lakes District". Other lakes and swamps in the immediate northern vicinity of the early Perth township were Lake Kingsford (site of the current Perth railway station), Lake Irwin (Perth Entertainment Centre) and further north were Stone's Lake (Perth Oval), Lake Poullet (First Swamp, part of what is now Birdwood Square), Lake Thomson (Mews Swamp, between Lake, Brisbane, and Beaufort Streets) and Lake Henderson (parts of what is now Robertson Park and Dorrien Gardens). Further north still lay Second Swamp (Bulwer Street, east of Lake Street), Third Swamp (Hyde Park), and Three Island Lake and Smith's Lake (now Charles Veryard Reserve). Many of these lakes formed a natural interconnected drainage system which found its way into the Swan River at East Perth through Claise Brook. In 1833, water draining from Lakes Kingsford, Irwin, Sutherland, and Henderson was used to drive a water-driven mill located in Mill Street.
The Darling Scarp, also referred to as the Darling Range or Darling Ranges, is a low escarpment running north–south to the east of the Swan Coastal Plain and Perth, Western Australia. The escarpment extends generally north of Bindoon, to the south of Pemberton. The adjacent Darling Plateau goes easterly to include Mount Bakewell near York and Mount Saddleback near Boddington. It was named after the Governor of New South Wales, Lieutenant-General Ralph Darling.
Southwest Australia is a biogeographic region in Western Australia. It includes the Mediterranean-climate area of southwestern Australia, which is home to a diverse and distinctive flora and fauna.
The Brixton Street Wetlands is an environmentally significant wetland area in the city of Perth, Western Australia. The wetlands are located in the suburb of Kenwick, in the south-east of the city not far from the foot of the Darling Scarp. The Brixton Street Wetlands occupies 126 hectares adjoining urban residential developments, schools and remnant semi-rural properties in an area which is rapidly urbanising. Roe Highway, a major transport artery, runs along one boundary of the wetlands, together with a parallel railway line.
Banksia ilicifolia, commonly known as holly-leaved banksia, is a tree in the family Proteaceae. Endemic to southwest Western Australia, it belongs to Banksia subg. Isostylis, a subgenus of three closely related Banksia species with inflorescences that are dome-shaped heads rather than characteristic Banksia flower spikes. It is generally a tree up to 10 metres (33 ft) tall with a columnar or irregular habit. Both the scientific and common names arise from the similarity of its foliage to that of the English holly Ilex aquifolium; the glossy green leaves generally have very prickly serrated margins, although some plants lack toothed leaves. The inflorescences are initially yellow but become red-tinged with maturity; this acts as a signal to alert birds that the flowers have opened and nectar is available.
Banksia menziesii, commonly known as firewood banksia, is a species of flowering plant in the genus Banksia. It is a gnarled tree up to 10 m (33 ft) tall, or a lower spreading 1–3 m (3.3–9.8 ft) shrub in the more northern parts of its range. The serrated leaves are dull green with new growth a paler grey green. The prominent autumn and winter inflorescences are often two-coloured red or pink and yellow, and their colour has given rise to more unusual common names such as port wine banksia and strawberry banksia. Yellow blooms are rarely seen.
Assemblages of plants and invertebrate animals of tumulus springs of the Swan Coastal Plain are ecological communities in Western Australia. They have been managed under a number of other, similar names, including Mound springs of the Swan Coastal Plain and Communities of Tumulus Springs . The tumulus mounds were common to a narrow range of groundwater discharge at the boundary of 'bassendean sand' and 'guildford clay', along the edge of the Gnangara Mound aquifer. The communities are critically endangered.
Coolgardie is an Australian bioregion consisting of an area of low hills and plains of infertile sandy soil in Western Australia. It has an area of 129,122.09 square kilometres (49,854.32 sq mi). It includes much of the Great Western Woodlands.
Western Australia occupies nearly one third of the Australian continent. Due to the size and the isolation of the state, considerable emphasis has been made of these features; it is the second largest administrative territory in the world, after Yakutia in Russia, despite the fact that Australia is only the sixth largest country in the world by area, and no other regional administrative jurisdiction in the world occupies such a high percentage of a continental land mass. It is also the only first level administrative subdivision to occupy the entire continental coastline in one cardinal direction.
The Jandakot Mound, or Jandakot Groundwater Mound, is an unconfined aquifer in south-western Western Australia. It is the smaller of the two main shallow aquifers near Perth that together supply about 40% of Perth's drinking water. Its highest point lies about 18 km (11 mi) south of Perth's central business district. It stretches from the Swan River in the north to the Serpentine River in the south, and from the Indian Ocean in the west to the Darling Scarp and Southern River in the east, covering an area of about 760 km2 (290 sq mi).
Thomsons Lake Nature Reserve is a lake nature reserve around Thomsons Lake in the City of Cockburn, Western Australia, approximately 25 kilometres (16 mi) south of the central business district of Perth, the state capital, and on the southern fringes of the Perth metropolitan area. It is in the suburb of Beeliar, 7 kilometres (4.3 mi) south-west of Jandakot Airport. It is a still largely natural wetland, with adjoining native vegetation, surrounded by land developed for housing and agriculture, that regularly supports large numbers of shorebirds and other waterbirds.
The Naracoorte woodlands is an ecoregion in southern Australia. It covers the Naracoorte coastal plain in southeastern South Australia and southwestern Victoria. It is coterminous with the Naracoorte Coastal Plain IBRA region. Only 10% of the ecoregion's area still has its original vegetation; most has been converted to agriculture and pasture.
The Wanneroo wetlands are a series of wetlands, swamps and lakes that occur on the Swan Coastal Plain of Perth, Western Australia. They are linked very closely to the Gnangara Mound.
Lake Gnangara is the most southerly of the Wanneroo wetlands in metropolitan Perth, Western Australia.
The Perth Wetlands, also known as the Perth Great Lakes or the Great Lakes District, was a collection of fresh-water wetlands, swamps and lakes located on the Swan Coastal Plain north of the city of Perth in Western Australia. Over a period of 80 years from the first British settlement in Western Australia in 1829 most of the wetlands were reclaimed for use as housing, parks and market gardens.
Kensington bushland reserve is a significant remnant of Swan Coastal Plain vegetation, that has been reserved in the suburb of Kensington, in Perth, Western Australia, by the state government.
The Banksia Woodlands of the Swan Coastal Plain is a protected sclerophyll community situated in the Swan Coastal Plain, Western Australia that predominantly consists of banksias. Listed as endangered under the Environment Protection and Biodiversity Conservation Act 1999, it was once a near-incessant band of large shrub patches around Perth and other nearby coastal areas.
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