Digging up an impact on the environment
But it has been worth every dusty, dirty minute, as far as he is concerned.Mr Garkaklis has been studying the impact of the woylie, a small and shy marsupial, on the ecosystem.There are about 8,000 woylies living in the wandoo-timbered area around Dryandra, although at one time the species was on the brink of extinction due to agricultural clearing and predation by introduced species such as foxes and the feral cat.Woylie numbers have risen again largely as a result of a WA Department of Conservation and Land Management predator-control program. But today the marsupials live in only in a few distinct pockets in the woodland area.It dawned on Mr Garkaklis that this unusual distribution pattern was the perfect set up to study the impact of the woylie on its habitat. The areas uninhabited by the woylie would act as a natural "control" experiment. The study would show the effect of removing an organism from its ecosystem."I think a lot of people are unaware of the complex diversity of our ecosystem," said Mr Garkaklis."We have problems in managing our ecosystem and we don't really know what the effect of removing an organism from the ecosystem will be."
So three years ago Mr Garkaklis began studying a subset of about 60 woylies, which he trapped by enticing with peanut butter and oats, before tagging and releasing them.Needless to say peanut butter and oats are not the usual diet of the woylie. The marsupial instead has a preference for truffles -- fungi which grow underground.The woylie makes between 20 to 100 diggings a night foraging for these truffles and in doing so churns up a lot of soil. In fact this tiny mammal, which weighs little more than a kilo, churns up more than six tonnes of soil each year!"Everybody knew they dug a lot but we didn't know how much," said Mr Garkaklis, "which highlights the need to sometimes ask obvious questions."How much soil the woylie churns is important because of the effect these diggings have on the character of the soil.In most areas across the southern third of WA, a condition called soil water repellency exists. Waxy residues produced by eucalyptus trees coat the soil surface causing water to either sit on the surface or run off.But Mr Garkaklis found that areas inhabited by the woylie had absorbent soils because the surface crust had been broken by woylie diggings.The results were very apparent, according to Mr Garkaklis."When we measured the water repellency, we found that the soils were severely water repellent around the edge of the digging and at the digging itself the water repellency disappeared completely.""You would suspect that water repellency intensified in the time when woylie numbers decreased," said Mr Garkaklis, indicating the obvious effect this would in turn have on agriculture.Furthermore, the woylie's appetite for truffles helps the ecosystem by spreading the fungi's spores around the woodland, an important contribution because truffles shunt about 25 per cent of the nutrient Australian trees get from the soil.Mr Garkaklis said that such studies highlighted the intricate nature of an organism with its environment and had obvious significance for land conservation and reclamation."What the example of the woylie highlights is that we should be trying to conserve areas as being as diverse as they originally were in order to preserve the stability of the system," he said.Mr Garkaklis said it would take much more study to yield definite and conclusive results of the impact of the woylie on its environment.He hoped to pursue his study of the woylie's impact and also hoped that it might spark further research study by other post graduates."It could take decades for the woodland ecosystem to change. I imagine I might be an old man and still be out in Dryandra still on my hands and knees," he said.Further information
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Mark Garkaklis Telephone (08) 9430 9215 email astronpe@starwon.com.au |