Eastern Australian temperate forests

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Temperate forest at Lake McKenzie, Fraser Island. Source: C.Michael Hogan

Reaching from central coastal New South Wales into southeast Queensland, the Eastern Australian temperate forests ecoregion encompasses a vast variety of substrates, microclimates, and vegetation communities. Eucalypt forests interspersed with patches of rain forest extend through much of the ecoregion, with heath and associated sandplain vegetation near the coast. The region contains three areas recognized internationally because of their biodiversity and landscape values. They include two centers of plant endemism, the sandstone area around Sydney and the Border Ranges, including the volcanic landscape of the Mount Warning Shield. Other areas of importance are the coastal sandmasses and high dunes of Fraser Island and the Great Sandy region in southern Queensland. However, European settlement has had significant impact on this region's orginal rich biota. Clearing for land and urban development still continues, and woody weeds have invaded native vegetation, subsequent to overgrazing and other land disturbance.

Location and general description

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A wide variety of substrates comprise this ecoregion, which runs along the central coast of eastern Australia, from near Sydney in New South Wales in the south to central Queensland and inland to Great Dividing Range. In coastal parts there are extensive sand deposits including high dunes and the great sandmass of Fraser Island. There are several major occurrences of Mesozoic sedimentary rocks, the most notable being the Sydney Basin in the south of the ecoregion. It is characterized by sandstones and shales, which were laid down by riverine sediments from the Late Permian to the Mid Triassic. Dissected plateaus are prominent. Much of the region is geologically complex with hills and ranges formed on acid to basic [[volcanic]s] and metamorphic rocks, interspersed with well-developed stream valleys. Volcanic activity during the Tertiary resulted in some extensive areas of basalt. The Border Ranges which form the boundary between Queensland and New South Wales are remnants of two ancient shield volcanoes, which are 20.5 to 23.5 million years old. The erosion caldera of the Tweed River Volcano is one of the world's largest. It is renowned for its size, its central mountain mass (Mount Warning), and its erosion patterns, which have worn the caldera floor down to basement Mesozoic and Palaeozoic rocks. In southeast Queensland there are also localized remnant Tertiary surfaces with duricrust and laterite. An elevated area dominated by a granite batholith lies on the western edge of the ecoregion south of the Queensland-New South Wales border. It is known as the New England Tableland.

Climate

300px-Aa0402 bluemountains.jpg Blue Mountains, Australia. Source: David Olson

The climate in the Blue Mountains region near Sydney is warm-temperate with summer maximum temperatures of 28?C in the lowlands, and winter minimum temperatures of three ?C recorded at approximately 1,000 meters (m) in elevation. In the central areas of the Blue Mountains, rainfall averages from 1,100 to 1,400 millimeters (mm) per year. Climate in the [[coastal] regions] is humid, with high rainfall (1,200 mm to 1,600 mm per annum). Rainfall decreases as one moves inland to the New England region, and Armidale receives approximately 800 mm of rain each year on average. Winters here are cold and wet and higher elevations receive snowfall most years. Further north in the Border Ranges, monthly summer temperatures vary from 21.5?C maximum to 19.7?C minimum. Corresponding winter temperatures from Mount Tamborine in the Border Ranges vary from 17.8?C maximum to 12.3?C minimum. Throughout the ecoregion, rainfall is concentrated in the summer. Towards the north of the ecoregion rainfall is lower (750 mm to 1,100 mm per annum) and more seasonal.

Plant communities

The ecoregion includes contains a wide variety of vegetation types, as a result of the varied substrates, altitudinal gradients, and microclimates. Temperate eucalypt forest dominates most of the region, with important rain forest communities found in the Border Ranges region as well as other parts of the region. Eucalypt communities along the coast are normally tall 'wet' forests, ranging from 30 percent to 70 percent closed canopy cover. Common species in wet eucalypt forests of southern Queensland and northern New South Wales include tallowwod (E. microcorys), blackbutt (E. pilularis), brush box (Lophostemon confertus), flooded gum (E. grandis), and Gympie messmate (E. cloeziana) which is restricted to southern Queensland. The complex understory contains small broadleaved trees, vines, ferns, and shrubs. Wet eucalypt forests are relatively restricted in southeast Queensland, with drier forms of eucalypt forest predominant. Major species in these forests include spotted gum (Corymbia citriodora), bloodwoods (C. trachyphloia, C. intermedia), white mahogany (Eucalyptus acmenoides) and ironbarks (E. siderophloia, E. crebra). Queensland blue gum (E. tereticornis) is predominant in alluvial areas away from the coast. In the Queensland part of the region a chain of topographic isolates support taxa more characteristic of southern parts of the ecoregion while lower altitude areas contain many taxa at the northern and southern limits of their geographic distribution.

Further south in New South Wales, Sydney blue gum (E. saligna), ironbark (E. paniculata), and blackbutt are common. Thin-leaved stringybark (E. eugenioides) Southern coastal regions of this ecoregion. The New England Tableland region is dominated by ash, stringybark, peppermint, and box species, including E. andrewsii, E. caliginosa, E. nova-anglica, E. melliodora, and E. blakleyi. Further west, white box (E. albens) woodlands dominate. Rain forest vegetation is normally found in sheltered, well-watered sites with good soils (often derived from basic igneous rocks). The transition from eucalypt to rain forest vegetation is often complex and 'mixed' eucalypt forests with rain forest elements in the understory may occur.

The rain forest communities of this ecoregion have been extensively researched and described, and are included in the Central Eastern Rainforest Reserves World Heritage Site. Four distinct communities are found here: subtropical rain forest, dry rain forest, warm temperate rain forest, and cool temperate rain forest. Subtropical rain forest is the best developed community in New South Wales, growing in warm, fertile sites with rainfall greater than 1,300 mm per annum. Forest ranges from 30 m to 45 m in height, with two to three tree strata forming an uneven canopy. Emergent tree species include booyong (Argyrodendron trifoliolatum), black booyong (A. actinophyllum), figs (Ficus spp.), yellow carrabeen (Sloanea woollsi), and the red cedar (Toona ciliata), which is highly prized for its timber. Stranglers, palms, plank buttressing, woody vines, and large epiphytes are characteristic. A coastal variant of subtropical rain forest known as littoral rain forest is capable of withstanding high levels of airborne salt. On the sandmass of Fraser Island littoral rain forest over-topped by brush box and satinay (Syncarpia hillii) grows in the swales of giant sand dunes.

Dry rain forest is found in sites with lower rainfall, ranging from 600 mm to 1,100 mm annual rainfall. Scattered emergents include hoop pine (Araucaria cunninghamii), lacebark tree (Brachychiton discolor), and crow's ash (Flindersia australis). Woody vines and stranglers may be common, but there are no palms, large epiphytes, and plank buttresses are uncommon. Sapindaceae, Euphorbiaceae, Rutaceae, and Myrtaceae are all well represented in dry rain forest. Dry rain forest was widespread in southeastern Queensland where it occupied about half a million hectares. It has been extensively cleared for agriculture and hoop pine plantations.

Warm temperate rainforest is less diverse than dry or subtropical communities and grows on low-nutrient soils. It is largely restricted to the southern half of the ecoregion. This community grows in cool, moist areas where lichens and ground ferns are common. Typical tree species include coachwood (Ceratopetalum apetalum), sassafras (Doryphora sassafras), and lillypilly (Acmena smithii). Cool temperate rain forest is also found in areas with rainfall in excess of 1,750 mm per year and more fertile soil. Only several tree species are common here, including Eucryphia moorei and Antarctic beech (Nothofagus moorei), which can form extensive stands.

Shrublands, shrubby woodlands (heaths), and associated sandplain vegetation are characteristic of coastal parts of the region. They are species-rich with the families Epacridaceae, Myrtaceae, Rutacaea, Fabaceae, Proteaceae, and Cyperaceae well-represented. Banksia spp., and Eucalyptus racemosa form woodlands in places and paper-barked teas-tree (Melaleuca quinquenervia) is present in swampy areas. The coastal heaths and low fertility substrates further inland such as the Sydney sandstones and elevated areas of rhyolite and granite share many genera and even some species.

A highly specialised plant community is found on Fraser Island, the site of the largest expanse of forest in the world occurring on pure sand substrate. This temperate forest is the locale of numerous diverse flora and fauna, and it is also the location of specialised geological formations known as window lakes, situated at the interior of the island.

Biodiversity features

300px-Aa0402 koala aus.jpg Koala (Phascolarctos cinereus), Australia. (Photograph by Howard Buffett)

This ecoregion contains two outstanding areas for plant endemism and diversity, the sandstone cliffs around Sydney and the Border Ranges region. The Border Ranges harbor more than 1,200 vascular plants, reflecting the variety of local habitats and the refugia role this region likely played during the continental aridity of the late Tertiary and the climatic fluctuations of the Quaternary. The rainforest communities found in this ecoregion demonstrate floristic links to other locations: the cool temperate rain forest is allied to that found in Tasmania, the warm temperate rain forest has links to the North Island of New Zealand, and the subtropical and dry communities are also found further north in the Queensland tropical rainforest ecoregion.

In the Border Ranges, approximately 140 dicotyledon genera are Gondwanan in origin, including rain forest genera (Nothofagus, Ceratopetalum, Akania) and non-rainforest genera such as Cassinia, Bauera, Hibbertia, and Leucopogon. More than 70 plant species are restricted to the Border Ranges region, and the area is also rich in mammals, reptiles, amphibians, birds, and invertebrates. The Border Ranges are the center of distribution for the pouched frog (Assa darlingtoni) and harbor a number of restricted range birds, including the black-breated buttonquail (Turnix melanogaster VU). Rainforests outside of the Border ranges include dry rain forest types which also contain many taxa with highly localized distributions. For example the only known population of the southern Queensland dry rain forest species Alectryon ramiflorus consists of approximately 40 individuals.

The Blue Mountains World Heritage Area contains 90 eucalypt taxa, or 13 percent of the global distribution. Nearly 130 nationally threatened plants are found in the Blue Mountains World Heritage Area, and 115 taxa are exclusively or predominantly found only with the World Heritage Area. Many of the rare and endemic plants have small ranges, restricted to specialized habitats such as clifftops and healthlands. Several relic taxa are represented (Wollemia, Microstrobos, Acrophyllum), including the recently discovered Wollemi pine (Wollemia nobilis). A wide variety of Australian fauna occurs here, although few species are endemic. The broad-headed snake (Hoplocephalus bungaroides VU) is an exception, largely restricted to the later, quartz-rich Hawkesbury sandstone. In total, over 60 reptiles, 65 mammals, and 275 birds have been recorded in the Blue Mountains. Among the birds, honey-eaters are especially well-represented, with 25 species found in the World Heritage Area.

Dingowildfraserisland.jpg Dingo in the wild, Fraser Island. Source: C.Michael Hogan The coastal sandplains and montane shrublands support a large number of taxa endemic to the region. The sandmasses of Fraser Island and Cooloola in Queensland, known collectively as the Great Sandy region, are contained within a World Heritage Area in recognition of the area's unique landscapes and biodiversity values.

A number of globally threatened species inhabit this ecoregion. The avifauna includes red goshawk (Erythrotriorchis radiatus VU), swift parrot (Lathamus discolor EN), regent honeyeater (Xanthomyza phrygia EN), Albert's lyrebird (Menura alberti EN), and eastern bristlebird (Dasyornis brachypterus EN). The rare species of Dingo wild dog is also found in this ecoregion, particularly on Fraser Island. The superb lyrebird (Menura novaehollandiae) also inhabits this ecoregion and may have drastically affected vegetation and erosion rates: it turns over an estimated 63,000 kilograms (kg) of debris per hectare each year looking for food or nest-mound building materials. Threatened mammals include the brush-tailed rock-wallaby (Petrogale penicillata VU) and the Hastings River mouse (Pseudomys oralis EN). Among the herpetofauna, the broad-headed snake (Hoplocephalus bungaroides VU) and the stuttering frog (Mixophyes balbus VU) are both present in this ecoregion.

Current status

When Europeans first arrived, the Border Ranges area contained one of the largest expanses of rain forest in Australia. The 750 square kilometer (km2) 'Big Scrub' comprised the largest stand of lowland subtropical rain forest in Australia and one of the biggest in the world. Today the Big Scrub has been reduced to mere fragments. Important timber species found in this ecoregion include red cedar, hoop pine, and white beech (Gmelina leichardtii). The Border Ranges are also vital for water catchment. Rainforests in this region are largely protected within the 3,700 km2 Central Eastern Rain forest Reserves World Heritage Site. The Blue Mountains area is also protected in a 2,500 km2 World Heritage Site. An extensive network of National and State Parks are spread throughout New South Wales and Queensland, although the representation of habitats varies throughout the ecoregion.

Sustainable logging continues in state-held eucalyptus forests and woodlands, with tallowwod, Sydney blue gum, spotted gum, blackbutt, and flooded gum harvested. Logging of eucalyptus forest in state forests in southeast Queensland is gradually being phased out. Eucalypt woodlands and dry forests have also been cleared for development or to enhance grazing. This ecoregion contains several large population centers, most notably Sydney and Brisbane.

Types and severity of threats

Major threatening processes are continuing clearing and fragmentation of native vegetation, introduced species, and altered fire regimes. Water pollution and schemes for water use are also threats. Coastal development in New South Wales has greatly intensified over the last 20 years, and nearly the entire [[coast]line] is inhabited. Coastal development in southeastern Queensland has continued at a similar pace, with all coastal lowland vegetation affected by rapid urban expansion. One study found that a third of all bushland cover in coastal southeast Queensland had been lost, and predicated that if clearance continued unabated all vegetation would be gone by 2019.

Even within protected areas, there are a number of threats to native flora and fauna, including trampling by tourists, altered fire regimes, problems of sewage disposal, and the continued spread of weeds and exotic animals. The Central Eastern Rainforest Reserves comprises disjunct and fragmented sites, which presents management challenges. The Blue Mountains World Heritage Area actually includes an estimated 80,000 inhabitants, living in residential, tourist, and small farm development along the Great Western Highway which bisects the site. These inhabitants further contribute to erosion, waste disposal problems, the spread of exotic (Exotic species) plants, and development pressures. Invasive plant species include privet (Ligustrum spp.), camphor laurel (Cinnamomum camphora), and Lantana camara.

Justification of ecoregion delineation

The Eastern Australian temperate forests ecoregion is a transition zone between temperate southeastern Australia and the tropical climate of north and northeastern Australia. It includes five full Interim Biogeographical Regions of Australia (IBRAs): 'South Eastern Queensland', 'New England Tableland', 'Nandewar', 'NSW North Coast', and 'Sydney Basin'. This ecoregion includes the 'Border Ranges' Centre of Plant Diversity (CPD) and part of the 'Sydney Sandstone Region' CPD.

Further Reading

Disclaimer: This article contains some information that was originally published by, the World Wildlife Fund. Topic editors and authors for the Encyclopedia of Earth have edited its content and added new information. The use of information from the World Wildlife Fund should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.

Citation

Fund, W. (2014). Eastern Australian temperate forests. Retrieved from http://editors.eol.org/eoearth/wiki/Eastern_Australian_temperate_forests