A fresh framework for the ecology of arid Australia |
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| Authors: | SR Morton DM Stafford SmithCR Dickman DL DunkerleyMH Friedel RRJ McAllisterJRW Reid DA RoshierMA Smith FJ WalshGM Wardle IW Watson M Westoby |
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| Institution: | a CSIRO Ecosystem Sciences, PO Box 2111, Alice Springs, Northern Territory 0871, Australiab CSIRO Ecosystem Sciences, GPO Box 284, Canberra, Australian Capital Territory 2601, Australiac Institute of Wildlife Research, School of Biological Sciences, University of Sydney, New South Wales 2006, Australiad School of Geography and Environmental Science, Monash University, Victoria 3800, Australiae CSIRO Ecosystem Sciences, Queensland Bioscience Precinct, 306 Carmody Road, St. Lucia, Queensland 4067, Australiaf Fenner School of Environment and Society, Australian National University, Acton, Australian Capital Territory 0200, Australiag School of Life and Environmental Sciences, Deakin University, Geelong, Victoria 3217, Australiah Centre for Historical Research, National Museum of Australia, GPO Box 1901, Canberra, Australian Capital Territory 2601, Australiai Department of Agriculture and Food Western Australia, PO Box 483, Northam, Western Australia 6401, Australiaj Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia |
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| Abstract: | A revised set of propositions about ecology in arid Australia is presented, based on research literature since publication of Stafford Smith and Morton (1990). Fourteen propositions distil our argument that most features of the Australian deserts are explicable in terms of two dominant physical and climatic elements: rainfall variability, leading to extended droughts and occasional flooding rains; and widespread nutrient poverty. Different landscapes within the arid zone show these features to varying degrees, and so it is important to think about different places separately when considering our propositions. Plant life-histories strongly reflect temporal patterns of soil moisture; because Australian deserts receive more variable rainfall than most others, there is a distinctive spectrum of life-histories. Low levels of phosphorus (together with abundant soil moisture on irregular occasions) favour plants producing a relative excess of carbohydrate (C). In turn, C-rich plant products sometimes lead to fire-prone ecosystems, assemblages dominated by consumers of sap and other C-based products, and abundant detritivores (particularly termites). Fluctuations in production due to variable rainfall provide openings for consumers with opportunistic life-histories, including inhabitants of extensive but ephemeral rivers and lakes. Most consumer species exhibit some dietary flexibility or utilise more dependable resources; these strategies give rise to greater stability in species dynamics and composition of assemblages than might first be imagined under the variable rainfall regime. Aboriginal people have had long-standing ecological influence as they accessed resources. For each proposition we suggest the extent to which it is ‘different’, ‘accentuated’ or ‘universal’ in comparison with other deserts of the world, recognising that this categorisation is in need of critical testing. Further tests of each proposition are also suggested to fill the many gaps that still exist in our knowledge of the structure and functioning of Australia’s deserts. |
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| Keywords: | Animal life-histories Australian deserts Climate variability Infertile soils Plant life-histories |
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