Botanic Gardens Trust, Sydney, Australia

Dry rainforests

Not all rainforests grow in areas receiving evenly distributed, abundant supplies of rainfall. Lesser known are the tiny remnants of Dry Rainforests scattered across the Kimberley, Top End, Cape York and down the east coast of Australia. Since they occur in regions with a distinct wet and dry season, the more northerly monsoonal forests survive in sheltered gullies and along the banks of rivers. Under moister, past climatic conditions, their ancestors were widespread across the continent. As the climate became less suitable for rainforests, those species best fitted for the arid conditions survived. They replaced species less able to survive in the new conditions and evolved to deal with the changing environment.

Along the east coast, marginal rainfalls or poorer soils support Dry Rainforests in sheltered locations. They often grow on rocky sites that are rarely subject to fire. Because some Dry Rainforest trees have a greater tolerance of arid conditions, communities can be found up to 300 km inland where suitable shelter exists.

The ability of some species to shed leaves in dry conditions is an advantage for Dry Rainforest trees, enabling them to survive temporary water shortage. Common species include Lacebark (Brachychiton discolour), Australian Teak (Flindersia australis), Hoop Pine (Araucaria cunninghamii), and figs (Ficus species).

Characteristic features of dry rainforests:

  • small to large number of tree species forming the low to medium canopy layer
  • scattered larger trees or emergents rising above the canopy including semi-deciduous species or conifers
  • small average leaf size of canopy trees. Leaves are often hard and blunt-tipped
  • palms absent
  • large vines common and diverse
  • vascular epiphytes rare or common, but with few species
  • mosses and ferns scarce

Dry Rainforests
Features of Dry Rainforests