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THE ARID ZONE AND XERIC SHRUBLANDS

THE ARID ZONE AND XERIC SHRUBLANDS. Denise Noack 2009. Morton, S. and Landsberg, J. (2003) The Ecology of Deserts. In Attiwill P. and Wilson B. (2003) Ecology, an Australian Perspective . Oxford University Press, Melbourne.

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THE ARID ZONE AND XERIC SHRUBLANDS

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  1. THE ARID ZONE AND XERIC SHRUBLANDS Denise Noack 2009

  2. Morton, S. and Landsberg, J. (2003) The Ecology of Deserts. In Attiwill P. and Wilson B. (2003) Ecology, an Australian Perspective. Oxford University Press, Melbourne. Thackway R. and I.D. Cresswell (eds) (1995) An Interim Biogeographic Regionalisation for Australia: a framework for establishing the national system of reserves, Version 4.0. Australian Nature Conservation Agency, Canberra. Groves R. (ed.)(1994) Australian Vegetation. Ch.17 Cambridge University Press, Oakleigh, Vic. Kirkpatrick J.B. (1994) A Continent Transformed: Human Impact on the Natural Vegetation of Australia. Oxford University Press, Melbourne. White M. (1997) Listen, Our Land is Crying. Reed Books. REFERENCES

  3. Morton, S.R. (1986). Land of uncertainty: the Australian Arid Zone. In: Recher et al. (eds). Ecology in Australia: A Natural Legacy. Pergamon Press, Sydney. Shephard, M. (1992).The Simpson Desert: Natural History and Human Endeavour. RGSSA, Adelaide. Vandenbeld, J. (1988).Nature of Australia: A Portrait of the Island Continent. Ch4. The Sunburnt Country. William Collins and ABC, Sydney. Journal of Arid Environments The Rangeland Journal REFERENCES

  4. ONLINE RESOURCES http://www.cazr.csiro.au (Centre for Arid Zone Research, Alice Springs) http://www.australian-aridlands-botanic-garden.org http://worldwildlife.org/science/ecoregions/australasia.cfm (Ecoregions: Australasia; Deserts and Xeric Shrublands; AA1301-1310)

  5. DEFINITIONS Arid “Zone" = a geographic distribution “Xeric”= living in a dry habit “Ecoregions” = biogeographic region (relating to plant & animal (bio) distribution (geo)) “Biome” = a biological subdivision- reflects biology “Deserts” = a biome characterised by low rainfall “Desertification” = converting semi-arid shrublands to deserts through human activities; UNEP (http://www.unep.org/desertification/) Deserts & xeric shrublands are biomes characterized by dry climates

  6. ARID ENVIRONMENT "hot" deserts: evaporation >> precipitation physiological deserts "cold" deserts = plants experience drought from ice or osmotic stress (e.g. salinity) Characteristics of a Desert: Rainfall Average Annual : <250  500 mm Variable and unpredictable Temperature extremes Soils low nutrients, high salinity well-drained OR hard clays; little organic matter Tanami Desert, NT

  7. DISTRIBUTION OF DESERTS WORLDWIDE DISTRIBUTION Deserts have specific names & culture. AFRICA Namib,Kalahari& 6 others S. AMERICA Atacama N. AMERICA Mojave, Sonoran, Chihuahuan, Great Basin N. INDIA Takla-Makan AUSTRALIA Simpson, Sturt's Stony, Gibson, Great Victoria, Great Sandy, Tanami, Nullarbor Plains, Pilbara, Central Ranges

  8. WORLD DESERTS Occur in the "temperate" band 30o N & S of equator http://geology.com/records/largest-desert.shtml

  9. AUSTRALIAN ARID ZONE 70% of continent is desert ("outback")

  10. AUSTRALIAN DESERTS

  11. DESERT BIOMES / ECOREGIONS Arid grasslands: used for grazing; old cultures grasslands covered 40% of globe, now only 25% Eurasia: steppes N. America: prairies S. America:llanos, pampas (high productivity)

  12. 7 VEGETATION TYPES IN AUSTRALIA Arid grasslands “Spinifex” grasslands: unique, Triodia! dunes & plains: Mitchell grasslands,Astrebla spp. plains - grazed. Also amongst woodlandsshort grass country,Austrostipa & Enneapogon spp. Arid shrublands Rangelands -grazed Chenopod shrublands: Atriplex, Maireana, Sclerolaena Also amongst woodlands: mixed xeric shrubs e.g.Eremophila, Senna (Cassia) ARID ZONE BIOMES Nullarbor Plain LessArid

  13. Savanna/woodland: Scattered trees over grassland Acacia shrublands: widespread, Mulga(Acacia aneura) Arid Mallee shrublands: Small eucalypts with many stems, lignotuber; e.g. S.A. Arid and semi-arid low woodlands Nth Aust. Tropical grasses, Sorghum, Heteropogon, Astrebla 7. Semi-arid shrub woodlands Eucalyptus, Casuarina, Callitris ARID ZONE BIOMES LessArid, Trees taller

  14. ARID ZONE BIOMES Shrubland Open woodland Open shrubland grassland

  15. AUSTRALIAN CONDITIONS Old landscape - Soils weathered poor nutrients sorted by wind Rainfall Low Unreliable El Nino – dry La Niña – rain & flooding-shapes landscape, recharge aquifers Australia most variable continent in world Longer more intense dry periods Great Victoria Desert

  16. DESERT BIOTA Cope with LOW WATER access by being Endurers (tolerate) or Avoiders BUT Hyperarid regions e.g. rocky deserts and sand dunes – little biota adapted to this Species in deserts show convergent evolution AFRICA Namib succulents S. AMERICA Atacama stunted, alpine vegetation AUSTRALIA Nullarbor chenopod Thorny Devil

  17. DESERT BIOTA AVOID by Avoid heat e.g. dormant OR TOLERATE dry conditions Persist- slow metabolism Australian Live with cycles of floods and droughts  Dramatic changes in animal community with rainfall

  18. DESERT BIOTA:ANIMALS Water not an issue- adapted - Behavioural and physiological Dormancy Nocturnal e.g. wombat Aquatic e.g. snails – Dalhousie Mound Springs. Rain  life; whole lifecycle or just reproduction Low metabolism Mobile e.g. birds fly Gain all moisture from food Number of species that need to drink water in arid Aust. Mammals: 4/ 95 Birds: 25/ 230 Reptiles: 0/ 210 (Morton and Landsberg 2006, p. 240)

  19. DESERT BIOTA: PLANTS Desert plants = xerophytes e.g. succulent, sclerophyllous and annuals Opportunistic: short-lived with rainfall (desert ephemerals) Aquatic e.g. Nardoo (Marsilea drummondii) Succulents: stores water (avoiders) Cell chemistry: endure concentrated salts Roots: surface, deep, storage organs for water Leaves: reduced area e.g. needles (also deter grazers), thick, shedding Slow growth e.g. Mulga, Mallee

  20. PEOPLE IN ARID AUSTRALIA Influenced by Aboriginal settlement for > 40,000 yrs Burning, hunting & harvesting food, dingo Indigenous words for arid zone systems and taxa (Anangu) Rocky range and outcrops puli Mulga shrublands puti Riverbed and riverbanks karu Sand plain pila Dunefields tali Saltlakes or claypans Pantu or tjintjira

  21. European settlement 200+ yrs ago New management Type of animal & density changed Artificial watering points piosphere effect Clearing - by ringbarking "improvement" by subclover=nutrients/weeds PEOPLE IN ARIDAUSTRALIA Nigel Dickinson/StillPictures

  22. HUMAN IMPACTS http://www.powerhousemuseum.com/walkingthewall/index.php/2006/08/29/the-living-wall/ • LICHENS AND MOSS: BIOLOGICAL SOIL CRUSTS • bind soil particles into a crust • fix nitrogen in the soil • improve soil’s resistance to wind and water erosion • vulnerable to damage from livestock

  23. HUMAN IMPACTS Associated effects Introduced feral animals e.g. goats, horses, donkeys, rabbits, pigs, cats, foxes, camels Introduced plants less of a problem Impacts Desertification of the semiarid Erosion Salinisation Extinctions

  24. EXTINCT AUSTRALIAN MARSUPIALS http://www.environment.gov.au/biodiversity/threatened/publications/action/marsupials/9.html

  25. MANAGEMENT ISSUES Management Limits on agriculture- Goyders line Protection through enforcement of legislation Control animal populations- exotic & native Traditional land management- burning Rehabilitate Impediments Financial security for pastoralists Difficulty enforcing legislation Political will- Ignorance of voting public, living on coast Revegetation- difficult in arid zone

  26. SUSTAINABLE DESERTS Deserts are models of how to cope with no water Australia- dry country BUT one of the largest users of water per capita in the world Other organisms in Aust. adapted live with dry conditions. Why cant we Minimise impacts, but how? Research Support sustainable Aboriginal land management: CSIRO- Desert Knowledge Cooperative Research Centre’s Livelihoods in Land™ project Changes e.g. different agriculture/ industry? suggestions?

  27. JOBS Management Government e.g. NPWS, NRM boards in Arid Zones Community education Farmers - government advisors Scientific Research e.g. CSIRO Monitoring e.g. DEH- surveys

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