More than 2,300 woody species (trees, shrubs and vines) have been recorded in Australian rainforests, with many more species occurring as ferns, orchids, sedges, palms, mosses, lichens and bryophytes.
In some locations, such as lowland parts of the Nightcap National Park in northern New South Wales, woody plant diversity can be as high as 125 species in an area equivalent to a suburban house block!
Australia’s rainforests have often been described as an archipelago of high biodiversity ‘green’ islands in a sea of drier (fire prone) vegetation. Those ‘island’ patches retained high diversity because they remained climatically stable through time. However, more generally, rainforest species are not just constrained to small and isolated island patches.
Some rainforest tree species are distributed continuously along the east coast and have acted as a link between the high diversity patches, allowing the movement of other plants, and animals.
Large areas of the lowland Australian rainforest has been cleared or degraded and what remains is fragmented and vulnerable. Other highly disturbed and cleared types of ‘rainforest’ in Australia include:
- Dry ‘Vine Thickets’ that can occur hundreds of kilometres inland and sometimes include emergent species such as Bottle-trees (Brachychiton rupestris) and Hoop Pine (Araucaria cumminghamii)
- Acacia dominated Brigalow.
The Brigalow, Hoop Pine, Bottle-tree and Drier Vine Thickets once formed a semi-continuous forest distributed west of the Great Dividing Range from Charters Towers in Northern Queensland down to Moree and parts of Central NSW. These drier vine forests can share many lineages with the wetter forests of the coast. In contrast, larger areas of the steeper uplands of the east coast were spared from clearing and are now protected in conservation areas such as National Parks that can include World Heritage listed locations.
- Kooyman, R.M., Rossetto, M., Cornwell, W. and Westoby, M. 2011. Phylogenetic tests of community assembly across regional to continental scales in tropical and sub-tropical rainforests. Global Ecology and Biogeography 20: 707-716.
- Kooyman, R.M., Rossetto M., Sauquet, H. and Laffan, S.W. 2013. Landscape patterns in rainforest phylogenetic signal: isolated islands of refugia or structured continental distributions? PLoS ONE 8(12): e80685.