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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)
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Chapter 24Human 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 Harvesting Habitat clearance Pollution Introduced species Mining SPECIES DIVERSITY
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 PROBLEM-overtaking 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 • Industry-produces heavy metal pollutants-mercury, 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 • 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 • 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 though- NOT 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 • 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 development- agriculture 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