Transcript File

CHAPTER 24
HUMAN
AWARENESS
E10 HUMAN PRACTICES CAN
LEAD TO MAJOR CHANGES
IN COMMUNITIES
E10.1 GIVE EXAMPLES OF SPECIES’
EXTINCTION THAT HAVE BEEN BROUGHT
ABOUT BY HUMAN ACTIVITIES
Extinct- no longer found in the wild and not
seen for many years (~ 50)
Extinction is normal to a degree- current
loss is greater than ever before
Australia has suffered its greatest loss in
50 years
Read quote pg. 222/225 LB- in which
destruction of habitat is listed as the major
cause of extinction
EVERY HOUR….
(HUMAN ACTIVITY)
• Around 8 species become extinct around the
world
• 10,000 times the normal extinction rate
• Of 144 marsupials, 10 HAVE BECOME EXTINCT
and 19 endangered in Australia since the 18th
century
• European settlement-species that require large
areas have died out (Tasmanian Tiger)
• Some animals restricted to small areas- died out
• Those with specialised habitat needs- died out
(Rufus Hare Wallaby)
• Some rare habitats cleared for agriculture and
pasture or urban settlement- more species
extinct
HUMAN ACTIVITY
Human activity has impacted species survival in a number of
ways…most of which you will know
Climate change
Pollution
Introduced
species
Mining
SPECIES
DIVERSITY
Harvesting
Habitat clearance
INTRODUCED SPECIES
• Many species been introduced since
European settlement
• They compete with natural species for
resources
• Or feed on those species
• Cats, dogs, foxes, carp, rabbits, pigs
donkeys, goats, cane toads, sparrows,
starlings, trout and salmon
• Cats were introduced to control mice and
rats??? Successful?
CONT:
•
1850- established populations of feral cats in
the wild- eat small mammals, birds and reptiles
•
Rabbits used to be their food which was
helpful/kept a balance/ but with the Myxoma
viruses etc. less rabbits so more native species
being targeted
•
Rabbits were introduced in 1859- destroyed
much vegetation/compete for resources/take
over native animal burrows like the bilby’s and
bandicoots
•
Feral pigs damage the habitat as they wallow
at swamp edges and destroy vegetation
HERBIVORES
•
Large herbivores like Kangaroos have evolved
in the nutrient poor ecosystems and exert little
pressure ion the environment
•
Its introduced species like goats that stress the
fragile environment
INTRODUCED PLANTS
•
CAN BE A MAJOR ECOLOGICAL PROBLEMovertaking native species, poisonous to other
species, competes with native vegetation ,
difficult to remove, chokes waterways
•
See table page 223 or 226 LB
POLLUTION
• HUMAN LIFESTYLE HAS DIRECTLY
CREATED A POLLUITON PROBLEM
• Pesticides/insecticides-DDT
accumulated in tissues, interferes
with calcium metabolism in birds
causing eggs to be produced which
break
• Oil tankers- spillage/fish and
aquatic life dies
ACID RAIN
• Accumulation of sulfur and nitrogen
oxides form burning fossils fuels
• These chemicals react with water
vapour-sulfuric acid and nitric acid
• Rain fall then erodes buildings,
changes pH of lakes and waterways
poisons aquatic life
• Human respiratory issues
CFC’S
Chlorofluorocarbons
• Widely used in aerosol sprays and
refrigerants- react with the chemical
ozone
• Significant destruction of ozone in the
upper regions of the Earth’s atmosphere
– led to ozone hole over Antarctica
• Ozone provides life on earth with
protection form UV rays
HEAVY METAL POISON/SEWAGE
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Industry-produces heavy metal pollutantsmercury, cadmium and arsenic
These kill soil organisms and disrupt marine
ecosystems
Stormwater drains into the oceans taking with it
a cocktail of oil, fertilizers and many other
chemicals
Sewage:
• Organic wastes for untreated
sewage/intensive animal farming can lead to
pollution of the waterways
• Nitrates/phosphates choke lakes and rivers
with excess algae growth and damage
marine ecosystems
FERTILISERS/DETERGENTS
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Run off with fertilisers and detergents
headed into lakes and rivers leads to
excess algae growth
Stifles waterways
Destroys other forms of life
Nitrates and phosphate- essential for
healthy growth BUT in EXCESS destroys
Eutrophication-occurs with excess nutrients
like nitrates
Excludes all growth except bacteria in the
waterways
RADIOACTIVE WASTES
• Chernobyl nuclear incident-Ukraine 1986
• Explosion occurred due to a nuclear reactor
blowing up-plume 5 km high
• Radioactive wastes travelled across Europe
form Scandinavia to Greece
• 70,000 deaths plus over time
• Poisons found in Lichens, animals fed on
them- 100km form the explosion site
AUSTRALIA-AND NUCLEAR
WASTE
• The outback has been identified as a
suitable dumping ground
• Much debate has ensued
• Our high cost of living/lifestyle comes with a
greater cost- wastes that must be dealt with
• And we must minimise damage to the
environment in the process of disposal
MINING
• Mining removes vegetation and topsoils
• Disrupts ecosystems
• Pollutants and minerals bought to the
surface
• These end up in run off in rivers etc.
• Some companies engage in re-vegetation
• Need to preserve native flora
CLIMATE CHANGE
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•
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•
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By product of combustion- carbon dioxide in
the air
Atmospheric carbon dioxide increasing
Traps the heat in the atmosphere
Increases global temperatures- green house
effect
Temperatures expected to rise 3-4 degrees in
future (75 years)
Polar ice melting, expansion of sea water, rise
in sea levels, terrestrial habitats altered
Species move to their preferred habitats
HARVESTING
• Industry harvests natural
resources
• Fishing
• Can be sustainable if managed
well
• Trawling/dredging kills huge
numbers of other species thoughNOT HELPFUL
HABITAT CLEARANCE
• Extensive rainforests are destroyed to
support economies- South America,
South-East Asia and Central Africa
• Natural habitat destroyed, forests, vital
for absorbing Carbon dioxide also
destroyed
• Similar destruction occurred in last
200 years in Australia
• Read ex: page 227/230 Toolache
wallaby……
E10.2 EXPLAIN WHY THE BEST WAY TO
PRESERVE SPECIES IS TO PRESERVE
HABITAT
• Habitat destruction main cause of
extinction and endangerment of species
• Austrlai has a very high rate of native
vegetation clearance
• See table page 228/231
• Estimated 5 million hectares cleared
between 1983-1993
• Destroys native species habitat/them and
diversity is greatly reduced
REASONS TO MAINTAIN
NATURAL VEGETATION:
• Provide a range of habitats to maintain
species diversity
• Provide vegetation with deep roots to
maintain the water table and prevent salinity
• Maintain and protect soil form erosion
• Absorb carbon dioxide and produce oxygen
• Maintain regional rainfall patterns
• Reduce weeds and feral animals
TEMPERATE WOOD LANDS
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Most threatened
80 % have been cleared
High number of threatened species
Birds particularly impacted
Destroys nesting sites-chain reaction
Loss of food sources- and destruction can
create a succession environment- opportunistic
species then can be weeds, and feral organisms
that further destroy the environment- breaking
down the woodland environment
• Further loss of species diversity…. Read page
229/232
E11 THE LEVEL OF HUMAN
POPULATION IS A BIOLOGICAL AND
ETHICAL ISSUE
•
E11.1 Explain how the growth of the human
population is placing huge demands on the
resources of the biosphere
• Homo sapiens evolved on the planet 1
million years ago
• Current population over 6 billion
• This places a huge strain on the earths
resources
• Developed countries energy consumed per
person is 20-30 times more than someone
in a developing country
• As our standard of living improves the
demand for resources increases
FOSSIL FUELS E11
• Our demands for energy have been met
using fossil fuels- a finite resource (coal, gas
and oil)
• Scientists have been working to develop
alternative fuel sources like Sun/wind and
nuclear power
• Nuclear power as we know has other huge
potential issues
• Solar and wind hold huge promise- but need
technology to advance to harness it the full
potential
SOIL/LAND AVAILABILITY
• Huge number of humans means huge demand
for land to live on plus to farm on
• Nearly all land than be cultivated is being used
• Some land not productive long term
• Mineral content of the land depleted/eroded
• Poor quality fruit and veg being produced as a
result
• To feed more people need to be a continuation
of ecologically sustainable farming
• New wheat and rice varieties have been
developed to increase yields
• We need to double food production over the
next 40 years to sustain the population growth
worl wide
WATER
• Water important resource
• Essential for survival- yet many in the world
have difficulty accessing fresh water
supplies
• 3.4 billion people use around 50 litres of a
water a day-Australians use 250-300 litres a
day- way over the world average
• Three children die in India every minute form
disease carried in polluted water
• Water is a disappearing resource
BIODIVERSITY
• Most important resource for humans being
placed at risk is the biodiversity of animals
and plants on the biosphere
•
estimated that 20% of the world’s
biodiversity may be lost during the next 30
years
• Organisms offer food, medicine, new drugs,
clothing and help recycle the matter and
energy in ecosystems- a loss of this has
been discussed and has devastating effects
on life.
E11.2 EXPLAIN WHY THE EXPONENTIAL
GROWTH OF THE HUMAN POPULATION IS
NOT SUSTAINABLE
• For 99 % of human history- no growth
essentially
• Last 1 % human numbers have increased
exponentially- China and India having 40% of
the worlds population
• Usually the size of a population remains
constant- birth and death equal out
• populations reach a carrying capacity
• CYCLE IS- numbers grow as reproductive
capacity grows and resources are readily
available-then competition increases, resources
diminish, predators and disease keep numbers
in check, wastes accumulate- population size
stabilises or reaches its carrying capacity
HUMAN POPULATION
• Human population followed exponential
growth
• Expanding the carrying capacity with
increasing technological developmentagriculture and medicine
• There must be a slowing in the rate of
increase in the human population
• Our demands on the biosphere have been
discussed- its not sustainable
FINAL COMMENTS!!!
• It may seem doom and gloom…
• The planet is overpopulated and we are heading toward
extinction…
• We have the ability to change our course of action though..
• We have had a slowing of the human population growth since
the 1960’s
• contraception has been very helpful- especially in developing
countries
• Environmentalists and the “green movements” have been
heard and govts. have started to employ practices that work
more harmoniously with the environment
• Scientist continue to search for ways to improve farming
practices, increase yields, reduce the use of pesticides and
insecticides etc.
• The third millennium our biggest challenges …what will you do
to help???
• Ok you’re all done!!!! Happy revision 