Central Australian Desert, Flora and Fauna
More than Meets the Eye
Contrary to what many people assume, Central Australia is anything but a flat monotonous desert. Alice Springs is located at the base of the MacDonnell Ranges which stretch for over 400km in an east-west direction in parallel ridges with flat valleys between. They were formed through massive earth movements some 300 million years ago, breaking up what was then a sea bed as fossil remains testify. Being so old and weathered, generally they extend up only around 300 metres from the valley floor but are a sensational sight and more importantly, facilitate a number of permanent water holes and provide sanctuary to a large number of plant and animal species.
Just south of the West MacDonnell Ranges are the Gardener and James Ranges and a little further south-east is the George Gill Range which is home to the infamous Kings Canyon at Watarrka National Park, the site where the cult movie 'Priscilla Queen of the Desert' was shot. Another 120km or so further south-east lie Uluru (Ayers Rock) and Kata Tjuta (The Olgas) which rise approximately 350 and 500 metres respectively from the desert floor. The greater area around these two icons is a sandy plain with low lying sand dunes.
Even though the region of Central Australia only receives between 100 – 300 mm of rain per annum, there is still a rich and diverse range of plants and animals. A large part of this diversity can be attributed to these mountain ranges and rock formations. They can assist this diversity in a number of ways, namely; they can influence and often increase local rainfall, provide permanent or semi-permanent water holes, moderate temperatures compared to sand environments and provide shelter and refuge in caves, overhangs and crevices.
Adapting to the Environment
Many species have had to adapt to the unpredictability of weather in Australian deserts, with periods of long dry spells punctuated with short blasts of rain.
Plants have adapted to the low and unreliable rainfall in two main ways – drought tolerance and drought avoidance. To help plants tolerate the desert many plants have features that aid water storage and minimise water loss. Some plants have small and / or very few leaves which are often hard with a waxy or hairy surface. The leaves often point downward so as to reduce the exposure to the sun. Others have succulent leaves or underground tubers for water storage while others have very deep root systems that enable them to tap into underground water supplies.
Other plants avoid drought by essentially remaining dormant throughout dry periods. For annuals and biennials they remain dormant as seeds until a major rainfall and then spring to life, and reproduce over a relatively short space of time. For perennials, they can lie dormant over long periods and then spring to life again when a decent rain comes. Many grasses display this trait while trees of this nature show more deciduous tendencies, sprouting new shoots and leaves after good rain.
For desert animals there are a number of responses to the high heat and lack of water. One of the easiest ways for animals to avoid the heat of the day is to be nocturnal and hunt at night. Almost all mammals in the desert are nocturnal and about half of reptiles, although most birds are not. Many animals have burrows underground which moderates the temperature and means the burrows are cooler during the day and warmer at night.
Many species also hibernate to get around extreme climatic conditions which lowers metabolic rate, conserving water, energy and lowering temperature. Some desert frogs lead a bizarre existence, burrowing underground on sandy watercourses and claypans when it's dry and can live like that for months or years in an inactive state. When the rains come, they spring to life burrowing to the surface to feed and mate and then burrow underground again when it dries out.
All Those Critters
Insects are by some margin the largest group of animals in the desert in terms of number and biomass. There is barely a square metre in the desert that doesn’t have ants roaming around. There is prolific reptile and lizard fauna in Central Australia including a large variety of snakes, geckos, goannas, skinks and dragons. It is also home to Australia's largest lizard, the Perentie, which can grow up to 2.5 metres in length. There are approximately 150 species of birds and of course, kangaroos and wallabies. Surprisingly, there is also a reasonable variety of freshwater fish, molluscs and crustaceans that occur in streams, waterholes and springs.
So if thinking about visiting outback Central Australia, expect a lot more than a barren and monotonous landscape. It changes regularly, has a host of interesting wildlife and will amaze at the sheer magnitude and timelessness of it.