Queensland tropical rainforests

• Category: Forest Biomes.
• Geographic Location: Australia.
• Summary: This unique landform contains a World Heritage site with primitive flora of great scientific value—but faces a set of grave environmental threats.

The Queensland tropical rainforests biome covers an area of approximately 12,626 square miles (32,700 square kilometers), and is subject to two distinct climatic seasons, commonly known as the wet and the dry. Queensland tropical rainforests occur along narrow coastal plains, foothills, mountain ridges, and tablelands from sea level to 2,953 feet (900 meters), with mountain peaks rising to 5,322 feet (1,622 meters). The now-rare lowland coastal rainforests, such as that at Cape Tribulations, extend to the sea edge, where they may even abut the salt-tolerant mangrove forests.

The rainforest forests are highly varied, with uneven canopies ranging from 98 to 131 feet (30 to 40 meters) in height. There are three sections: the first, in the northern reaches of the biome, features a wet tropics regime; the second section extends from the Whitsunday group to Carmilia; and the third section, which includes the Wargunburra Peninsula, extends inland to include portions of the Normanby Range. The Queensland tropical rainforests are designated one of the World Wildlife Fund’s Global 200 ecoregions, and are the largest remnants of Australia’s rainforest flora.

Studies have shown that tropical rainforests are remnants of the oldest types of vegetation in Australia. Many species have ancestors dating back to the Cretaceous or early Tertiary period, more than 65 million years ago. Furthermore, the wet tropics microclimate here provides an unparalleled living record of the ecological and evolutionary processes that shaped the flora and fauna of Australia over the past 400 million years. For this reason, Queensland’s tropical rainforests have considerable historical and scientific importance.

The largest fragment—about 70 percent—of the tropical rainforest in Queensland (and Australia) occurs as a narrow strip along the east coast; it covers approximately 4.9 million acres (2 million hectares). Such is the biological significance of the region that a large part of this section was inscribed on the World Heritage List in 1988, as the Wet Tropics World Heritage Area. The Kulla (McIlwraith Range) National Park (jointly managed as Cape York Peninsula Aboriginal Land) is a recent outcome of the Cape York Tenure Resolution Program; it now protects one of the largest pristine tracks of rainforest left in Australia.

Biodiversity

The wet tropics portion of these rainforests have more plant taxa with primitive characteristics than perhaps any other area on Earth. Of the 19 angiosperm families described as the most primitive, 12 occur here. Some 600 to 800 tree species overall occur in Queensland’s tropical rainforests. The crowns of the largest forest trees interlock and form a closed canopy that shadows the middle canopy, subcanopy, and forest floor below. The upper canopy supports an aerial garden of climbing vines, as well as a full suite of epiphytes such as giant elkhorns, staghorns, bird’s-nest ferns, orchids, mosses, and lichens.

Lowland rainforests are characterized by robust woody lianas, epiphytic ferns, fan palms, and strangler figs. The leaves of the lowland forests generally are larger than those of the uplands, and more of the plants tend to be deciduous. Upland forests characteristically have woody lianas and epiphytic ferns, but tree ferns, climbing vines, and mosses appear to be more abundant. Buff alders, silkwood, crowsfoot elm, milky pine, and black bean trees are all found here, as well as a variety of palms, vines, and orchids.

The Wet Tropics zone reportedly contains the richest variety of animals and plants in Australia, including two-thirds of the butterfly species, half of the birds, and one-third of the mammals. A high proportion of fauna is endemic (found nowhere else) to the Wet Tropics bioregion, including 70 vertebrate species.

Mammals endemic to the Queensland rainforests include the Atherton antenchinus (a mouselike marsupial), green ring-tailed possum, mahogany glider, yellow-bellied glider, musky-rat kangaroo, and two species of tree kangaroo (Lumholtz’s and Bennett’s). Iconic rainforest birds include the golden bowerbird and cassowary. There also are many reptiles and amphibians, including the prickly rainforest skink, taipan, Boyd’s forest dragon, chameleon gecko, and giant tree frog.

Environmental Threats

It is estimated that only 50 percent of Australia's forests and bushlands remain intact compared to pre-European arrival. From 2013 to 2018, nearly 4 million acres (1.6 hectares) of forest and bushland were destroyed. According to a 2019 study by the Wilderness Society, 73 percent of the rainforest clearing is linked to beef production. The 2021-2022 Landcover and Trees Study (SLATS) report released by the Queensland Government in 2024 revealed that 323,676 hectares of land was impacted by land clearing during the reporting period, demonstrating the large impact deforestation has on the region. Logging and wildfires account for the remainder of the loss.

Other factors also place incredible pressure on the natural resources of this area and threaten its biodiversity, including stock grazing; mining; feral animals (such as pigs, dogs, cats, and cane toads); invasive plants (such as rubber vine and lantana); the plant pathogen Phytophthora cinnamomi, known to cause forest dieback; the chytrid fungus, a temperature-sensitive pathogen that kills frogs; cyclones; altered fire regimes; and global climate change, which is already exacerbating most if not all of these individual threats.

Climate change is also a threat to the Queensland rainforests. As global warming causes temperatures to rise, rainfall decreases. This makes the forest dryer and more vulnerable to wildfires, which destroy habitats. Extreme droughts and rising sea levels are also harming the area.

Bibliography

Accad, A., et al. Remnant Vegetation in Queensland. Analysis of Remnant Vegetation 1997–1999–2000–2001–2003–2005, Including Regional Ecosystem Information. Brisbane, Australia: Queensland Herbarium, Environmental Protection Agency, 2008.

“Deforestation in Queensland.” Wilderness, 2024, www.wilderness.org.au/protecting-nature/deforestation/qlddeforestation. Accessed 29 Dec. 2024.

Fratto, Avery. "The Queensland Rainforest." Arcgis, 12 Oct. 2021, storymaps.arcgis.com/stories/9fbd420b54244ab892e098965c0cd864. Accessed 29 Dec. 2024.

Keto, A. and K. Scott. Tropical Rainforests of North Queensland: Their Conservation Significance: A Report to the Australian Heritage Commission by the Rainforest Conservation Society of Queensland. Canberra: Australian Government Publishing Service, 1986.

Queensland Government. Building Nature’s Resilience. A Draft Biodiversity Strategy for Queensland. Brisbane, Australia: State of Queensland Department of Environment and Resource Management, 2010.

Sattler, P. S. and R. D. Williams, eds. The Conservation Status of Queensland Bioregional Ecosystems. Brisbane: Australia Environmental Protection Agency, 1999.

Stanton, J. P. and D. Stanton. Vegetation of the Wet Tropics of Queensland Bioregion. Cairns, Australia: Wet Tropic Management Authority, 2005.

Stork, N. E., et al. “Australian Rainforests in a Global Context.” In Living in a Dynamic Tropical Forest Landscape, edited by N. E. Stork and S. M. Turton. Oxford, UK: Blackwell Publishing, 2008.

Williams, S. E. and D. W. Hilbert. “Climate Change as a Threat to Biodiversity of Tropical Rainforests in Australia.” In Emerging Threats to Tropical Forests, edited by W. F. Laurance and C. Peres. Chicago: University of Chicago Press, 2006.