Subtropical and temperate rainforests occur in discontinuous patches along the Great Dividing Range and Great Escarpment of southern Queensland and New South Wales (roughly 27°54′ S ─ 32°14′ S). It is believed these stands represent the forest that once covered almost all Australian parts of the ancient supercontinent of Gondwana. Many of these forest remnants are situated along the Queensland/New South Wales state border; important outliers occur in the New England range of eastern New South Wales. Western limits appear to be determined by aridity and frequent fires. They harbor relict plants and animals and others of primitive lineage.
Vegetation. Five variations of rainforest are recognized that reflect different climatic conditions related to latitude and elevation as well as differences in soil fertility. Characteristic of all are two Gondwanan genera of plants: Araucaria, primitive gymnosperms, and Nothofagus, the southern beeches.
- Warm subtropical rainforest is floristically the most diverse. It grows at elevations below 2,600 ft. asl on soils derived from basalt. Typical trees are the buttressed white boojong (Argyrodendron trifoliatum) and the tall yellow carbeen (Sloena woolsi), which can reach heights of 180 ft. The understory consists of palms and tree ferns; lianas and ferns are also abundant. The largest undisturbed site is in the so-called Shield Volcano Group in the McPherson and Tweed ranges.
- Cool subtropical rainforest grows at higher elevations than the warm variant, ranging from 2,600-3,600 ft. asl. Yellow carabeen continues to be common. Black booyong (A. actinophyllum), rose mahogany (Dysoxylum fraserianum), and coachwood (Ceratopetalum apetalum) are also prevalent. It requires deep, moist, fertile soils such as found at the heads of gulleys, as demonstrated in Washpool National Park.
- Warm temperate rainforests are dominated by Nothofagus growing in plant communities less diverse than subtropical counterparts. Typically there are two layers in the canopy comprised of 3-13 species, including crabapple (Schizomeria ovata) and corkwood (Ackama paniculata). Most trees lack buttresses. Ferns are abundant, but palms, lianas, and large epiphytes are rare.
- Cool temperate rainforest occurs on mist-shrouded slopes at higher elevations from the McPherson Range southward. Usually the only canopy tree is Antarctic beech (Nothofagus moorei). In some places, however, pinkwood (Eucrphyia moorei), myrtle beech (N. cunninghamii), sassafras (Doryphora sassafras) or coachwood may dominate. Tree ferns are abundant.
Gondwanan rainforest, Dorrigo National Park, New South Wales
Courtesy Andrea Schaffer from Sydney, Australia [CC BY 2.0 (https://creativecommons.org/licenses/by/2.0)]
Close to half of Australia’s native plant species are found in these subtropical and temperate rainforests, which cover only 0.25 percent of the land area. There are ferns and conifers from some of the oldest lineages on Earth and members of primitive families of flowering plants.
Red-necked pademelon
Courtesy Gaz ( Creative Commons Attribution-Share Alike 3.0 Unported)
Animal life. About 30 percent of Australian animal species inhabit these forests. among them are two monotremes (the short-beaked echidna, Tachglossus aculeata, and the platypus, Ornithorhyncus anatinus) and 32 marsupials. Among the marsupials are the red-necked pademelon (Thylogale thetis) and the red-legged pademelon (T. stigmatica). Bird families of ancient lineages include lyrebirds (Menuridae), scrub-birds (Atrichornithidae), and bowerbirds (Ptilonorhynchidae). Geckos, dragon lizards, skinks, and snakes number in total 140 species; frogs number 45 kinds, including some relicts.
Gondwana Rainforests of Australia World Heritage Site was inscribed by UNESCO in 1986 and expanded in 1994. It incorporates more than 50 separate protected areas, most of them in national parks. Increasing aridity and fire frequency as the global climate changes threaten these forests. Isolated forest fragments need to connected to preserve evolutionary processes.
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