Australia Lesson Activities - Environmental Studies

Last night, while biking through the night to Trephina Gorge, the bark of the gum trees stood out in contrast to the shadows, accented by the fullness of the moon. Red River and Ghost Gums are the predominate species in the area we are travelling through.

As a native species to Australia, gum trees create their own ecosystem. They can be found on the alluvial plain or in arid desert areas. They are quite adaptable to the environment based on the depth of their roots. The taller the tree, the more access to water it has. However, a stunted version may be found on rock ledges as seen in Trephina Gorge.

Gum trees can provide room and board to a variety of birds and insects. Insect secretions on the underside of leaves are sticky sweet and have provided Aboriginal children with a sweet lolly or candy treat. Honey from non-stinging bees, which make a hive in the termite-hollowed limbs of the gum, can be a tasty treat, as well.

When the gum trees blossom, their nectar is a draw for insects and some birds. The yellow necked miner bird feeds on insects found in the tree. His intimidating call wards off most other nectar- seeking birds. Insects attracted to the nectar of the gum blossom are prey to bats, birds and lizards, becoming another part of the food chain.

Suggested activity: Find a complete ecosystem in a tree or in vegetation where you live. Construct a part of the food chain, giving examples of the plants, animals or insects found in each stage.

Crister and April

2001 September 16, Derwent Station.

As we reached the flat lands to the north of the MacDonnel Ranges, the vegetation changed from a very native natural looking landscape, to farmed lands, with tall yellow daisies (camel weed), brown cattle, and windmills. While this is very pretty in a rural way, some of the unique native species we’ve encountered will now not be seen again for some time.

One remarkable example of the vegetation we have been amongst is the blackboy, or native grass tree, of the genus Xanthorrhoeaceae. Their distinctive fire-blackened trunks and skyline silhouettes of grass tufts accompanied us as we passed along the low ranges surrounding Gosse Bluff Crater.

Blackboys are the slowest developing plant in the world, growing just inches each century, and taking fifty years to appear above the ground after the germination of their seed. An interesting phenomenon is that the fastest growing flower in the world springs from the top of the tree in a lily-like spike – two amazing extremes in one plant.

Without regular burning, the growth of the blackboy can be stunted even further, and all of the large plants we saw showed signs of recent burning. Their extraordinary form protects them from being completely destroyed by the wildfires on which they thrive.

Another special plant which we saw amongst the xanthorrhoea is the poached egg daisy – the photograph speaks for itself.

Can you find a borderline in your local environment where the types of plants which can grow, change? Think about why they change – perhaps it’s the altitude, a different soil base, nearness to water, or more protection from the elements. Is it a natural border, or does it reflect the different ways in which humans use the land?

bel

2001 September 24. Rabbit Flat Roadhouse.

Around the turn of the century, rabbits, numbering in their millions, took Australia by storm, eating everything in their path. White settlers had brought them from Europe to be hunted for sport, in the same manner as foxes were introduced. Inevitably, many of these escaped the fate people had intended for them, and, once in the wild, both their numbers and the area they covered expanded phenomenally quickly – as our maths update explores.

Shrubs, seedlings, and when they were exhausted the bark of trees, were devastated, leaving no food for native animals. They also occupied the burrows of the natives, and dug their own, causing erosion. Eventually, they destroyed the ecosystem so effectively that there was not enough vegetation remaining to support their numbers, and populations dropped due to starvation.

Today, rabbits form the main food of both wedge tailed eagles and dingoes, as the native mammals which originally formed their diets have gone. The decline of the Rabbit-eared bandicoot (Bilby) is largely due to the introduction of rabbits.

Suggested learning activities: how do introduced animals in your country fit into the food chain? Are there rabbits where you live? See if you can find out the effect rabbits and similar feral animals have or have had on your local environment.

bel

2001 September 25, Tuesday. Twenty kilometres north of the Tanami Gold Mine, on the Lajamanu Track.

We’re one of the few creatures out here which are about in the day time. Because of the relentless solar radiation in daylight hours, most animals are active at night, and we can tell that we’re sharing their space only because of the pattern of footprints, tail prints, and belly prints left in the soft red sand.

These trails have captured our imaginations from the white silica sands of the Starcke mangrove swamps, through the riverbeds of the dividing range. They have been our entertainment when wading for miles through the deep sand of private station roads, and have made pleasant surprises when, after travelling on bitumen, we discover them amongst the brush during rest breaks.

We are able, by now, to match most of the tracks we encounter to their makers. The most exciting way to learn this is by having seen the animal actually making its trail, as with our close encounter with a long green snake today. But besides the interesting things to know about animals are living out here, tracks can be useful – to us, to native bush people, and to other animals.

Station owners can recognise foreign vehicle tracks and know strangers have been on their land. Chappie, the musterer we met one morning earlier in the trip told us that he had seen our tracks the night before, and “knew there were some crazy nutters on bikes out here.”

Mammal tracks can often be followed to a water source, as they cannot travel great distances in the desert without drinking regularly. To an animal with a less developed sense of sight than humans, tracks of another kind would be as obvious as footprints are to us.

Dingoes, for example, could follow a marsupial using scent or footprints, and sneak up upon it to hunt it as food. In the same way, a creature who sits much lower on the food chain, such as a rodent, could detect the presence of a threatening animal through it’s scent, and escape predation.

Suggestions: Some animals leave deliberate ‘trails’ of scent to mark their territories. Perhaps you have noticed your family pet doing this. What other trails could let you know there were animals about? Can you find any tracks in your local area which have been left by native or domestic animals? If so, try to find out who left them. Think about why that animal might have been going where it was. Think about the footprints you leave everywhere you go - how could you disguise these tracks to prevent being followed?

bel