The tropical savannas of northern Australia are important for
many reasons, but one of the most notable may not be obvious to the
casual visitor: the savannas are a refuge for biodiversity of world
significance.
The tropical savannas are home to hundreds of species of native
plants, mammals, birds, reptiles and amphibians and tens of
thousands of different species of invertebrates. Many species in
all these groups are found nowhere else in the world.
For information on the frogs of northern Australia, visit the
comprehensive Frogwatch site (web link below). It has
information on most of the northern frog species, frog calls and
the latest sightings of the cane toad.
The tiny long-tailed planigale from the Barkly's
Mitchell Grasslands. It lives in cracks in the soil, its flattened
head helping it to squeeze into narrow places.
Photo: Alaric Fisher, NT DIPE
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Why so many native plants and animals?
Various explanations can be put forward here. The first is that
the tropics are generally found to have more biodiversity in a
given area than regions in higher latitudes. The reasons for this
are not straightforward but could include a number of factors: less
frost; higher energy levels from more intense sunshine sustain
tropical ecosystems; large areas of rainforest are found in the
tropics; the tropical temperatures and humidity don't vary as much
over time as they do in higher latitudes.
Dahl's aquatic frog (Litoria dahlii ) is
from Yellow Waters in Kakadu.
Photo: Martin Armstrong©
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Although the tropical savannas region excludes the large areas
of rainforest in North East Queensland, there are patches of
rainforest scattered throughout the region. Apart from rainforest
patches there are rocky gorges, arid regions, mangrove swamps,
other wetlands and river habitats throughout the north. These
variations in the landscape may be hidden from the visitor who
generally needs to stick to the major roads—which usually
avoid rock country and wetlands.
Development pressure
Clearly one factor contributing to the high biodiversity in the
savannas is that significant parts of the region have not been
intensively developed and still retain large areas of natural
habitat.
Compared to other tropical regions in the world, Australia's
tropical savannas are distinguished by sparse populations and a
relatively low pressure for development. The resident population of
slightly more than 400,000 is less than that for Tasmania. This
figure does not include the large number of tourists that visit the
region, but even allowing for this the population pressures in
north Australia are very low in relative terms.
Termite mounds
Termite mounds are a conspicuous feature in the scenery of the
tropical savannas. These structures range from small earthen mounds
to majestic sentinel-like structures scattered across the
landscape. While most people are aware of the existence of termite
mounds, very few understand the significance of these invertebrates
in the nutrient cycling processes of northern Australia.
Click on the "Invertebrates" link on the Navigation Bar at left,
to read more of the fascinating story of Australia's termites and
their mounds.
