Queensland Tropical Rain Forests - Flora

Flora

The Queensland tropical rain forests are designated one of the Global 200 ecoregions. The ecoregion is the largest remnant of Australia's rain forest flora, home to ancient assemblage of plants, called the Antarctic flora, presently characteristic of New Zealand and southern Chile, and that once covered much of Australia and Antarctica until about 15 million years ago.

Conifers of the southern hemisphere family Araucariaceae are the characteristic tree species. In the northern section of the ecoregion, Kauri commonly form the forest canopy, with Agathis robusta most common at lower elevations, and A. microstachya and A. atropurpurea predominant at higher elevations. In the southern sections, Araucaria cunninghamii is predominant, with Araucaria bidwillii dominant in two small areas. Conifers in the family Podocarpaceae are also present, including genera Podocarpus and Sundacarpus. The forests are thick with vines, ferns, epiphytes, and palms.

These forests are limited to areas of high rainfall and good soils. In waterlogged soils, the rainforest flora gives way to Melaleuca thickets, and on poor soils and in drier areas Eucalyptus becomes dominant. The rainforest flora is intolerant of fire, and where periods of drought have allowed devastating fires, the rainforest flora has retreated, allowing fire-tolerant Eucalyptus to become established. If a relatively wet period persists, the rainforest flora may reestablish itself. It is thought that the land management practices of the aboriginal Australians, which involve setting regular fires to keep the eucalyptus woodlands open, may have encouraged the expansion of eucalyptus forests at the expense of the rainforest flora. These rainforests seem to have retreated considerably since the arrival of the aboriginals' ancestors 50,000 years ago, and are presently limited to isolated pockets comprising less than 2% of the continent's area.