The tropical and subtropical savanna woodlands grasslands and dry forests of northern Australia and southern New Guinea...
Despite the similarity in appearance of tropical open woodlands around the world, the species composition is quite different. For example, the open tropical forest and savanna woodlands may be dominated by Acacia and elephants in southern Africa, and by Eucalyptus and kangaroos in Australia, but they both appear physically similar. The two images of savanna woodlands show this parallel development in similar conditions; on the left is India, on the right is Australia. (Or maybe it is the other way around?)
There are many different habitat structures and vegetation types that are within what I define as the ‘Tropical Woodlands”. The tropical open forest is the common default expression of the dry seasonal tropics on average land in northern Australia. The open canopy is usually dominated by Eucalypts, such as Eucalyptus miniata and E. tetradonta across much of northern Australia. The shrubby understorey can vary but includes various Acacia, Proteaceae species, or even cycads. And of course grasses dominate at the ground level. Savanna and Tropical Grasslands are the purest definition of savanna at an international level, based mainly on the well known grassland plains of Africa, which are somewhat modified by their very large herbivorous mammals and humans. In Australia, tropical grasslands can develop because of different situations, such as exposed and/or low nutrient sandy soils, or seasonally flooded plains.
The heaths and woodlands growing on the rocky plateaus, cliffs, and along ridges, are characterised by their challenging conditions; exposed aspects, shallow rocky soils, and slopes with loose sediment prone to wet season collapses and landslides. Ridges and cliffs support specifically rocky adapted Eucalyptus, several species of ‘Rock Fig’, and clumps of spinifex grass. The flatter plateaus are covered in a stunted heath habitat with species such as Calytrix.
Pandanus dominated grasslands can develop in sandy areas that may get water logged in the wet season. This habitat tends to be more common on islands and other coastal situations.
Waterways are the veins of life running through the seasonally dry savanna grasslands and woodlands. These beautiful rivers are oasis for humans as well. They are dominated by species such of Melaleuca along their banks, and may also have sections of obviously darker green monsoon rainforest.
Seasonal Freshwater Wetlands are inundated every wet season. The main trees here are Melaleuca and Pandanus. During the course of the dry they reduce in size and wildlife may congregate around their shrinking pools. In all seasons, they are the best areas for diversity and number of animals. This habitat is covered in the section on Australasian tropical freshwater wetlands.