Philip Ladd

During the late 19th and early 20th centuries, frustrated pastoralists in South Australia, New South Wales and Queensland fenced their properties to stop the Australian dingo (Canis lupus) killing their livestock. Eventually links formed between individual fences, creating a continuous barrier now covering over 5000 km. Known variously as the Dingo Fence ‘Dingo Barrier Fence or ‘Wild Dog Fence it is of wire mesh standing 1.8 in high, with a further 30cm buried. There is a 5 m wide cleared buffer on each side and the entire structure is well maintained. On the New South Wales side of the fence where sheep are the main livestock, dingoes are controlled and numbers are low, whereas on the South Australian side dingoes are tolerated alongside cattle husbandry. Unintentionally, the fence initiated a large-scale experiment, allowing biologists to assess the biological consequences of removing a large predator. Alan Newsome and his colleagues from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) studied vertebrate abundances on either side of the fence by counting animal tracks at stock watering points. One striking finding was that the introduced predator the red fox (Vulpes vulpes) was present on both sides, but in higher numbers in the absence of dingoes. Dingoes eat foxes and drive them away, explaining the differences in fox numbers across the fence. Foxes threaten several native Australian mammals (see Chapters 2 and 16), including many borrowers and diggers important in soil turnover, nutrient cycling and dispersing plants. It may be that, by regulating fox numbers, dingoes are protecting native fauna that in turn modify the environment to the benefit of many soil organisms. The case of the Dingo Barrier Fence shows how relationships between organisms determine the range and relative abundance of species.

In this chapter we describe the major factors influencing the Australian climate and how soil is formed, because these Factors determine the occurrence of plant and, in turn, animal species. We introduce the concept of biomes (climatically determined groups of plants and animals spread over wide areas) and describe the typical bionics of Australia developed from the biota provided by evolutionary history.

Granite rock formations are often prominent in Australian landscapes, for example in Girraween National Park in Queensland, Wilsons Promontory in Victoria and Mt Franklin in Western Australia. In arid areas waterholes in granite outcrops were significant in summer for Aboriginals (Plate 23.1). There are considerable similarities between granite outcrops across a wide range of climates. All have poor soils of restricted volume, severe fluctuations between wet and dry conditions, low levels of soil nutrients, high insolation (light intensity) and exposure to strong winds. However, as in any harsh environment, species with specialist adaptations survive and even thrive. Algae and lichens colonise the rock surface and may be overgrown by mosses. These plant forms and some ferns and flowering plants (such as the pincushion (Borya spp.) and the feather flower (Verticordia staminosa)) can desiccate completely in the dry season, but revitalise and function again hours after rewetting. More commonly, plants die down to seed or rootstock in the dry period. The insectivorous sundew (Drosera spp.), which catches and digests insects for extra nutrients, particularly nitrogen, survives summer as an underground tuber. Other plants such as the elbow orchid (Spiculea ciliata) are succulents, storing water to persist for some time into the summer. Shrubs and trees on granite outcrops use water conservatively most of the year and need access to rock cracks for water over the dry season. Many invertebrates flourish in temporary pools on rocks and survive the dry season as eggs in the sediment. Terrestrial invertebrates are often flattened to find protection under rock plates. Few vertebrates live in these dry conditions. One, the rock dragon (Ctenophorus ornatus), does not need to drink for 80 days. All these traits for survival under dry conditions are found in plants and animals occurring in the wider terrestrial landscape, but they are more accentuated in the harsh conditions on the rocks.

The 'sense of place' that a city and its inhabitants come to identify themselves by can have profound impacts on the way that urban landscapes develop. In the case of Perth, its icons are the Swan River, The sandy beaches of the Indian Ocean coastline, and Kings Park. While the first two have defined the way that the city is laid out and has grown, the latter has fostered the development of an Australian garden and landscape approach to urban design, and a strong native species conservation ethic.