Transcript Australia and Water - UGA Hydrology

Australia and Water
David Radcliffe
University of Georgia
Published in 1994
3-part series on Australian TV in
1998
www.abc.net.au/science/future/default.htm
Tim Flannery is Director of South
Australia Museum
Future Eaters
• Part One – An Infinity Before Man
– Geology and ecology of Australia before man
arrived
• Part Two – Arrival of the Future Eaters
– What happened when the aborigines arrived
• Part Three – The Last Wave
– What happened when the Europeans arrived
Early Geology
• Australian continent drifted north as the
Earth cooled
– Stable climate with very little glaciation
– “Did you have a good ice age?”
• Did not collide with other continents
– Little volcanic activity or mountain building
• Long stable period (60 million years)
produced nutrient-poor soils
www.lonelyplanet.com
Uluru
www.photoway.com/fr/dest/AUST96_30.html
Nutrient-Poor Soils
• Tim Flannery, Taming of the Fire, Australian
Broadcast TV
– "If you wanna understand the history of this continent
there's no better place to come than here Uluru the
timeless rounded features of the rock show that it just
hasn't been disturbed for hundreds of millions of
years, there's been no volcanoes, no mountain
building, no ice age here to rejuvenate this place and
as a result the soil here is old, leeched and exhausted
all that's left really is just sand."
ENSO
• El Nino Southern Oscillation effect
• 2-7 year cycle of drought and rainfall
• Australia is the only continent where
overwhelming influence of climate is not
an annual cycle
Under normal conditions,
trade winds pile up ocean
water to the west and
upwelling occurs to the
east – warm air rises from
eastern Australian
Under El Nino conditions,
trade winds weaken, warm
water moves back east –
dry air descends on
eastern Australia
www.pmel.noaa.gov/tao/elnino
Biodiversity
• Theory: greatest biodiversity develops in
low-resource (water & soil), stable
environments
– Organisms survive better by cooperating
– Enough time for evolution of organisms that
find a “niche”
• Australia has greater biodiversity than
other larger continents
– Plant species in Austrlia: 25,000
– Plant species in Greater Europe: 17,500
Niche Ecology Examples
• Kangaroo
• Koala bear
• Banded stilt
Kangaroo
• Kangaroo is world’s largest
marsupial
• Very efficient energy user
– No other animal this big hops
– Energy is recaptured in each
bound, in the tendons of its
legs – like a pogo-stick
– Each leap pushes its gut back,
drawing air into it’s lungs –
saving it from using chest
muscles to breath
• Female is fertile only during
periods of high rainfall
Eastern Grey Kangaroo
www.giftlog.com
Koala Bear
• Diet consists entirely of
Eucalyptus tree leaves
– Lives it’s life in these trees
– Leaves are filled with
chemicals to discourage
foraging animals
• Very energy efficient
– Slow moving like a sloth
– Low rate of reproduction
– Relatively small brain
• Brain is one of the greatest
energy users of all organs
• In man, the brain is 2% of
weight but uses 17% of
energy
www.giftlog.com
Banded Stilt
• Familiar bird along the
coast but never seen to
breed
• March 1989 banded stilts
disappeared from usual
haunts
• About 100,000 birds
found nesting near Lake
Eyre in South Australia
• Lake was filling to a 15year high as a result of a
period of ENSO rainfall
The Slater Field Guide to Australian Birds
www.lonelyplanet.com
Banded Stilt
• After hatching, the young
were tended by the males
– Hatchlings left the breeding
area and grew quickly on a
rich diet of brine shrimp
– After only 3 weeks the
young can fly
• Only 2 weeks after first
eggs were hatched, the
female was nesting again
• Breeding cycle adapted
to ENSO
– Can go a decade without
breeding
The Slater Field Guide to Australian Birds
Future Eaters
• Part One – An Infinity Before Man
– Geology and ecology of Australia before man
arrived
• Part Two – Arrival of the Future Eaters
– What happened when the aborigines arrived
• Part Three – The Last Wave
– What happened when the Europeans arrived
Aborigines
• Conventional view
– Primitive civilization
– Did not develop
agriculture of cities
– Nomadic
– Few tools
– Little impact
Aborigines
• Man evolved first in Africa and spread to other
continents
– Coevolved with megafauna species still seen today in
Africa
– Elephants, giraffes, rhinos, tigers, lions, etc.
– Predator-prey arms race
• Aborigines arrived in Australia at least 40,000
years ago
– Came by boat from South East Asia
• At the time they arrived there were a number of
megafauna species in Australia
Megafauna Extinction
• Megafauna disappeared from Australia
shortly after aborigines arrived
– Climate or man?
• “The greatest danger that a species faces
in a rapidly coevolving ecosystem is the
loss of contact with its competitors”
• Megafauna had no defenses against man
• Short rich period for aborigines followed by
disaster
Aborigine Adaptation
• Aborigines were the first Future Eaters
– Consumed resources more rapidly than they could be
replenished
• “The story of how the first future eaters
recovered from this disaster - is one of
humanities greatest triumphs”
• Long period (40,000 years) after megafauna
extinction for aborigines to adapt
– Developed complex relationship with ecosystem
Aborigine Adaptation
• Adapted to make it through the driest periods
and take advantage of the wet periods
– Did not develop agriculture because it was not
sustainable given ENSO climate
– Nomadism allowed aborigines to move to water and
animals
– Used fires to recycle nutrients and provide forage for
animals – “fire-stick farming”
– Few tools because they had to be mobile
– Low population density
– Social structure was small tribes
Aborigine Adaptation
• Challenge was genetics
– How to avoid inbreeding when your social unit is a
small tribe and potential partners are few
• Solution was great tribal meetings during wet
periods
– Gathered in areas where food would be available
– Marriages were arranged between members of
different tribes
– Elaborate ceremonies renewed bonds between tribes
– Exchanged information on resources
• Aborigine religion codified rules and was the
knowledge base
Aborigines
• Revised view
– Highly evolved
civilization
– Nomads because
agriculture was not
sustainable
– Few tools because
these reduced mobility
– Elaborate knowledge
of ecosystem
embodied in religion
– Large impact
Future Eaters
• Part One – An Infinity Before Man
– Geology and ecology of Australia before man
arrived
• Part Two – Arrival of the Future Eaters
– What happened when the aborigines arrived
• Part Three – The Last Wave
– What happened when the Europeans arrived
Arrival of Europeans
• First contact occurred in 1688 with large number
of Europeans arriving in early 1800’s
• Aborigines suffered massive die-offs
– Some killed in conflicts
– Most killed by European diseases
– Typhus, influenza, small pox, measles, etc.
• Why didn’t the reverse happen?
– Why didn’t Europeans die of aborigine diseases?
European Diseases
• Guns, Germs, and Steel by Jared Diamond
• Most powerful diseases develop where you
have:
–
–
–
–
High population densities
Contact with herding animals (source of diseases)
London a huge breeding ground for disease
Europeans developed some resistance to these
diseases and survived
• When Europeans arrived on other continents
locals had little resistance and died
European Development
• Australia was used first as a place to send
convicts from overflowing English debtor
prisons
– 1788 to 1868
– Farms were developed to feed prison
populations
• Gold was discovered in 1851 and largescale immigration from Europe began
European Development
• Second episode of “future eating” occurred
• English settlers first thought that Australia was a
rich “new land”
– Biodiversity
– Extensive forests
– Vast continent
• Applied European agricultural practices
• Extensive cutting of forests for timber and to
clear land for agriculture
– Led to erosion and loss of native species
European Development
• Settlers moved inland from the eastern coast in
search of better farm land and rivers
• Found some small areas of fertile soils where
limited volcanic activity occurred but no big
rivers
• Water supplies were limited by ENSO cycles
• Settlement expanded during wet years, failed
during dry years
European Development
• Introduced invasive species
– Rabbits (24) introduced in 1859 for hunting
purposes and exploded in number
– Same thing happened with foxes
– Only the wild dog (dingo) was a predator of
rabbits and foxes, but settlers saw the dingo
as a pest and killed it off
Agriculture Today
• Still trying to adapt to harsh conditions
• Extensive irrigation systems have been
developed that take water from rivers
• Results have been saline soils and rivers and
low stream flow
– Crops use less water (lower year-round ET) than
native vegetation
– Combination of irrigation and lower ET has raised
water tables
– Groundwater is high in salt and now poisons the soil
and rivers
Water Management Today
• Australia today is taking a hard-look at how it
manages water resources
– Discussing what the upper limit might be for country’s
human population (now 40 million)
– World leader in the science of “environmental flows”
– Set limits on salinity in rivers
• Searching for an alternative to the European
model of resource management
– Could the aborigine be the new model for living with a
harsh ecosystem?
Future Eating in America
• Many parallels with
Australia
– 2 cycles of predator
invasions
• Clovis point indians
• European settlers
– Megafauna & indian
extinction
• Important differences
– Resource rich continent
– Relatively short history
– Only now are we reaching
our limits (water)