THE ARID ZONE ANDTHE ARID ZONE AND XERIC SHRUBLANDS XERIC SHRUBLANDS

Denise Noack 2009Denise 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.

• 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.

REFERENCESREFERENCES

• 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

REFERENCESREFERENCES

ONLINE RESOURCESONLINE RESOURCES

• http://www.cazr.csiro.au (Centre for http://www.cazr.csiro.au (Centre for Arid Zone Research, Alice Springs)Arid Zone Research, Alice Springs)

• http://www.australian-aridlands-http://www.australian-aridlands-botanic-garden.org botanic-garden.org

• http://worldwildlife.org/science/http://worldwildlife.org/science/ecoregions/australasia.cfmecoregions/australasia.cfm

(Ecoregions: Australasia; (Ecoregions: Australasia;

Deserts and Xeric Shrublands; Deserts and Xeric Shrublands;

AA1301-1310)AA1301-1310)

DEFINITIONSDEFINITIONS

• 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 shrublandsDeserts & xeric shrublands are are biomes characterized by dry climates biomes characterized by dry climates

ARID ENVIRONMENTARID ENVIRONMENT

"hot" deserts: evaporation >> precipitation "hot" deserts: evaporation >> precipitation physiological deserts "cold" deserts = physiological deserts "cold" deserts =

plants experience drought from ice plants experience drought from ice or osmotic stress (or osmotic stress (e.g.e.g. salinity) salinity)Characteristics of a Desert:Characteristics of a Desert:• Rainfall

– Average Annual : <250 Average Annual : <250 500 mm 500 mm– Variable and unpredictableVariable and unpredictable

• Temperature extremesTemperature extremes• SoilsSoils

– low nutrients, high salinitylow nutrients, high salinity– well-drained OR hard clays; little organic well-drained OR hard clays; little organic

mattermatter

Tanami Desert, NTTanami Desert, NT

DISTRIBUTION OF DESERTSDISTRIBUTION OF DESERTSWORLDWIDE DISTRIBUTIONWORLDWIDE DISTRIBUTION

Deserts have specific names & culture. Deserts have specific names & culture. • AFRICA AFRICA Namib,Namib, KalahariKalahari & 6 others& 6 others• S. AMERICA S. AMERICA AtacamaAtacama• N. AMERICA N. AMERICA Mojave, Sonoran, Mojave, Sonoran,

Chihuahuan, Great BasinChihuahuan, Great Basin • N. INDIA N. INDIA Takla-MakanTakla-Makan• AUSTRALIA AUSTRALIA Simpson, Sturt's Stony, Simpson, Sturt's Stony,

Gibson, Great Victoria, Great Sandy, Gibson, Great Victoria, Great Sandy, Tanami, Nullarbor Plains, Pilbara, Central Tanami, Nullarbor Plains, Pilbara, Central RangesRanges

WORLD DESERTSWORLD DESERTS

http://geology.com/records/largest-desert.shtml

Occur in the "temperate" band 30Occur in the "temperate" band 30oo N & S of equator N & S of equator

AUSTRALIAN ARID ZONEAUSTRALIAN ARID ZONE70% of continent is desert ("outback")70% of continent is desert ("outback")

AUSTRALIAN DESERTSAUSTRALIAN DESERTS

DESERT BIOMES / DESERT BIOMES / ECOREGIONSECOREGIONS

Arid Arid grasslandsgrasslands: used for grazing; : used for grazing; old culturesold cultures

• grasslands covered 40% of globe, grasslands covered 40% of globe, now only 25%now only 25%

• Eurasia:Eurasia: steppes steppes • N. America:N. America: prairies prairies • S. America:S. America: llanos, pampasllanos, pampas (high (high

productivity)productivity)

7 VEGETATION TYPES IN AUSTRALIA7 VEGETATION TYPES IN AUSTRALIA

Arid Arid grasslandsgrasslands

1.1. ““Spinifex” grasslands: Spinifex” grasslands: unique, Triodia! dunes & plains::

2.2. Mitchell grasslands,Mitchell grasslands, Astrebla spp. Astrebla spp. plains - grazed.plains - grazed.Also Also amongst amongst woodlandswoodlands short grass countryshort grass country,,

Austrostipa & Enneapogon spp.Austrostipa & Enneapogon spp.

Arid Arid shrublandsshrublandsRangelands Rangelands - grazedgrazed

3.3. Chenopod shrublandsChenopod shrublands: : Atriplex, Atriplex, Maireana, SclerolaenaMaireana, Sclerolaena

Also amongst woodlands: mixed xeric shrubs Also amongst woodlands: mixed xeric shrubs e.g.e.g. Eremophila, Senna Eremophila, Senna ((CassiaCassia))

ARID ZONE BIOMESARID ZONE BIOMES

LessLessAridArid

Nullarbor PlainNullarbor Plain

Savanna/woodland:Savanna/woodland:

Scattered trees over grasslandScattered trees over grassland

4.4. AcaciaAcacia shrublands shrublands: widespread, Mulga: widespread, Mulga ((Acacia aneuraAcacia aneura))

5.5. Arid Mallee shrublandsArid Mallee shrublands: Small eucalypts : Small eucalypts with many stems, lignotuber; with many stems, lignotuber; e.g.e.g. S.A. S.A.

6.6. Arid and semi-arid low woodlands Arid and semi-arid low woodlands Nth Aust. • Tropical grasses, Tropical grasses, Sorghum, Sorghum,

Heteropogon, AstreblaHeteropogon, Astrebla

7. Semi-arid shrub woodlands7. Semi-arid shrub woodlands• Eucalyptus, Casuarina, CallitrisEucalyptus, Casuarina, Callitris

ARID ZONE BIOMESARID ZONE BIOMES

LessLessArid,Arid,Trees Trees tallertaller

ARID ZONE BIOMESARID ZONE BIOMES

Open shrublandOpen woodland

Shrubland

grassland

AUSTRALIAN AUSTRALIAN CONDITIONSCONDITIONS• Old landscape - Soils Old landscape - Soils

weatheredweathered poor nutrientspoor nutrients sorted by windsorted by wind

• RainfallRainfall LowLow UnreliableUnreliable

- El Nino – dryEl Nino – dry- La Niña – rain & flooding-shapes landscape, recharge La Niña – rain & flooding-shapes landscape, recharge

aquifersaquifers• Australia most variable continent in worldAustralia most variable continent in world Longer Longer

more intense dry periodsmore intense dry periods

Great Victoria DesertGreat Victoria Desert

DESERT BIOTADESERT BIOTA

Cope with LOW WATER accessCope with LOW WATER access by being Endurers (tolerate) or Avoidersby being Endurers (tolerate) or Avoiders

BUT BUT Hyperarid regions Hyperarid regions e.g.e.g. rocky deserts and rocky deserts and sand dunes – little biota adapted to thissand dunes – little biota adapted to this

Species in deserts show convergent Species in deserts show convergent evolutionevolution

• AFRICAAFRICA Namib Namib succulents succulents• S. AMERICA S. AMERICA AtacamaAtacama stunted, alpine stunted, alpine

vegetationvegetation• AUSTRALIA AUSTRALIA Nullarbor Nullarbor chenopodchenopod

Thorny DevilThorny Devil

DESERT BIOTADESERT BIOTA

AVOID byAVOID by– Avoid heat Avoid heat e.g.e.g. dormant dormant

OR TOLERATE dry conditionsOR TOLERATE dry conditions– Persist- slow metabolismPersist- slow metabolism

AustralianAustralian

• Live with cycles of floods and droughtsLive with cycles of floods and droughts Dramatic changes in animal community Dramatic changes in animal community

with rainfallwith rainfall

DESERT BIOTA:DESERT BIOTA: ANIMALSANIMALS

Water not an issue- adaptedWater not an issue- adapted- - Behavioural and physiologicalBehavioural and physiological

– DormancyDormancy– NocturnalNocturnal e.g. e.g. wombat wombat – Aquatic e.g. snails – Dalhousie Mound Springs. Aquatic e.g. snails – Dalhousie Mound Springs. – Rain Rain life; whole lifecycle or just reproduction life; whole lifecycle or just reproduction – Low metabolismLow metabolism– Mobile Mobile e.g.e.g. birds fly birds fly– Gain all moisture from foodGain all moisture from food

Number of species that need to drink water in arid Number of species that need to drink water in arid Aust.Aust.– Mammals: 4/ 95Mammals: 4/ 95– Birds: 25/ 230Birds: 25/ 230– Reptiles: 0/ 210Reptiles: 0/ 210

(Morton and Landsberg 2006, p. 240)

DESERT BIOTA: DESERT BIOTA: PLANTSPLANTS

Desert plants = xerophytes Desert plants = xerophytes e.g.e.g. succulent, succulent, sclerophyllous and annualssclerophyllous 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

PEOPLE IN ARID AUSTRALIAPEOPLE IN ARID AUSTRALIA

Influenced byInfluenced by

• Aboriginal settlement for > 40,000 yrsAboriginal settlement for > 40,000 yrs– Burning, hunting & harvesting food, dingoBurning, hunting & harvesting food, dingo

Indigenous words for arid zone systems and taxa (Anangu)Indigenous words for arid zone systems and taxa (Anangu) Rocky range and outcropsRocky range and outcrops pulipuliMulga shrublandsMulga shrublands putiputiRiverbed and riverbanksRiverbed and riverbanks karukaruSand plainSand plain pilapilaDunefieldsDunefields talitaliSaltlakes or claypansSaltlakes or claypans Pantu or tjintjiraPantu or tjintjira

• European settlement 200European settlement 200+ + yrs agoyrs ago– New managementNew management

• Type of animal & density changedType of animal & density changed• Artificial watering pointsArtificial watering points

– piosphere effectpiosphere effect

• Clearing - by ringbarkingClearing - by ringbarking• "improvement" by "improvement" by

subclover=nutrients/weedssubclover=nutrients/weeds

PEOPLE IN ARIDPEOPLE IN ARIDAUSTRALIAAUSTRALIA

Nigel Dickinson/StillPictures

HUMAN IMPACTSHUMAN IMPACTS

LICHENS AND MOSS: BIOLOGICAL SOIL CRUSTSLICHENS 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

http://www.powerhousemuseum.com/walkingthewall/index.php/2006/08/29/the-living-wall/

HUMAN IMPACTSHUMAN IMPACTS

– Associated effectsAssociated effects• Introduced feral animals Introduced feral animals e.g. goats, horses, e.g. goats, horses,

donkeys, rabbits, pigs, cats, foxes, camelsdonkeys, rabbits, pigs, cats, foxes, camels

• Introduced plants less of a problemIntroduced plants less of a problem– ImpactsImpacts

•Desertification of the semiaridDesertification of the semiarid•Erosion Erosion •SalinisationSalinisation•ExtinctionsExtinctions

EXTINCT AUSTRALIAN MARSUPIALSEXTINCT AUSTRALIAN MARSUPIALSSpecies

Thylacine, Thylacinus cynocephalusDesert Bandicoot, Perameles eremianaPig-footed Bandicoot, Chaeropus ecaudatusLesser Bilby, Macrotis leucuraBroad-faced Potoroo, Potorous platyopsDesert Rat-kangaroo, Caloprymnus campestrisEastern Hare-wallaby, Lagorchestes leporidesCentral Hare-wallaby, Lagorchestes asomatusCrescent Nailtail Wallaby, Onychogalea lunataToolache Wallaby, Macropus greyi

Subspecies

Western Barred Bandicoot (mainland), Perameles bougainville fasciataEastern Bettong, Bettongia gaimardi gaimardiBoodie (mainland), Bettongia lesueur graiiBrush-tailed Bettong (SE mainland), Bettongia penicillata penicillataRufous Hare-wallaby (SW mainland), Lagorchestes hirsutus hirsutusBanded Hare-wallaby (mainland), Lagostrophus fasciatus albipilis

http://www.environment.gov.au/biodiversity/threatened/publications/action/marsupials/9.html http://www.environment.gov.au/biodiversity/threatened/publications/action/marsupials/9.html

MANAGEMENT ISSUESMANAGEMENT ISSUES

• Management Management – Limits on agriculture- Goyders lineLimits on agriculture- Goyders line– Protection through enforcement of Protection through enforcement of

legislationlegislation– Control animal populations- exotic & nativeControl animal populations- exotic & native– Traditional land management- burningTraditional land management- burning– RehabilitateRehabilitate

• ImpedimentsImpediments– Financial security for pastoralistsFinancial security for pastoralists– Difficulty enforcing legislationDifficulty enforcing legislation– Political will- Ignorance of voting public, Political will- Ignorance of voting public,

living on coastliving on coast – Revegetation- difficult in arid zone Revegetation- difficult in arid zone

SUSTAINABLE DESERTSSUSTAINABLE DESERTS

• Deserts are models of how to cope with no water Deserts are models of how to cope with no water – Australia- dry country BUT one of the largest users of Australia- dry country BUT one of the largest users of

water per capita in the worldwater per capita in the world– Other organisms in Aust. adapted live with dry Other organisms in Aust. adapted live with dry

conditions. Why cant we conditions. Why cant we Minimise impacts, but how?Minimise impacts, but how?• ResearchResearch

– Support sustainable Aboriginal land management: Support sustainable Aboriginal land management: CSIRO- Desert Knowledge Cooperative Research CSIRO- Desert Knowledge Cooperative Research Centre’s Livelihoods in Land™ projectCentre’s Livelihoods in Land™ project

• ChangesChanges– e.g.e.g. different agriculture/ industry? different agriculture/ industry?– suggestions?suggestions?

JOBSJOBS

• Management Management – Government Government e.g.e.g. NPWS, NRM boards in NPWS, NRM boards in

Arid ZonesArid Zones• Community educationCommunity education

– Farmers - government advisorsFarmers - government advisors• ScientificScientific

– Research Research e.g.e.g. CSIRO CSIRO– Monitoring Monitoring e.g.e.g. DEH- surveys DEH- surveys