I haven't read Voss either, but I imagine the effect of the Australian landscape would be something very similar to the importance of the American West landscape to literature of that area in the era of gold rush, settlers heading West, and so forth.
It seems to me that the indigenous peoples, the landscape and harshness of life associated with the outback, and the food sources would be paramount to the survival of the people and thus reflected in the literature.
I am not aware of the book you are referring to, however, in the work of Peter Carey, the outback occupies an important place in the imagination of Australian literature. It is conceived as a place that offers possibilities for a new start and a new life, free from the restricting influences of life in society.
Is the Australian landscape really as gloomy as portrayed in White's Voss,or is it a mere fetish with the Australian writers?The Australian writers initially tried to depict the landscape as both harsh and an imminent threat ,according to several critics they focused on the grimmer aspects of the local flora and fauna as they were trying to create a literary myth.The antipodean inversion of seasons,the bare barked trees, the unrelenting bleak wilderness were initially only tamed by the white settlers .This image gave to the colonizers a feel of superiority that made them masters to the hapless slaves-the aboriginals;their firm belief that they bore the torch of Enlightenment was also justified and thus started evacuation of the indigenes who lived of the land unlike their capitalist masters.(i.e. the aboriginals held the view that land was sacred and couldn't be bought and sold)
The landscape in 'Voss' corresponds with the travails of Voss's expedition which begins from New South Wales and ends probably in the midst of the desert.Voss , the german explorer feels one with the landscape,even though it is alien .