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G3: Human Impact on Ecosystems

G3: Human Impact on Ecosystems . G.3.3 Why Biodiversity is a good thing (example: rainforests). Economic reasons Medicines and chemicals (pharmaceutical industry profits) Rainforest soil is nutrient poor (not good for farming)

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G3: Human Impact on Ecosystems

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  1. G3: Human Impact on Ecosystems

  2. G.3.3 Why Biodiversity is a good thing (example: rainforests) • Economic reasons • Medicines and chemicals (pharmaceutical industry profits) • Rainforest soil is nutrient poor (not good for farming) • Alleles from wild populations lost forever if species go extinct (no possibility of improving domesticated animals with alleles from the wild)

  3. G.3.3 Why Biodiversity is a good thing (example: rainforests) • Ecological reasons • Organisms are interdependent • Diverse ecosystems are less prone to alien species out-competing native species • Fewer plants means less photosynthesis (less CO2 is sequestered from the atmosphere) • Soil erosion happens when tree roots are no longer there to keep soil in place

  4. G.3.3 Why Biodiversity is a good thing (example: rainforests) • Ethical Reasons • Do we have the right? • indigenous populations are affected • Future generations will not be able to enjoy its beauty and diversity • Aesthetic Reasons • Ecotourism is a way for people to connect with nature • Artists and writers have been inspired by the beauty of rainforests and the natural world in general

  5. Alien Species • Species which are non-native to a particular ecosystem. • They often are able to out-compete native species (becoming invasive)

  6. G.3.4- Deliberate Release of Alien Species Example: Kudzu • Brought from Japan to America as an ornamental plant • Later advertised as a fast growing plant that could prevent soil erosion • Grows so quickly that it crushes or covers other plants (killing them) • $500 million dollars is lost annually due to destruction by kudzu

  7. The plant that ate the South!

  8. G.3.4- Accidental Release of Alien Species Example: Zebra Mussels • Thought to be released by a European cargo ship • Clog pipes because larvae stick to adults and form masses • One mussel can make up to 100,000 eggs/year • Predators have not stopped their spread • In the next 10 years it is estimated that the US will spend $500 billion to control it

  9. G.3.6- An Alien Species Under Control Example: Prickly Pear Cactus • Released in Australia and rapidly began to overtake the landscape • Biologists released Cactoblastic cactorum, a moth, that feeds on the prickly pear • Moths rapidly began to decrease the cactus populations until a balance was reached

  10. Australia

  11. G.3.6- An Alien Species Under Control Example: Rabbits in Australia • RHD and myxomatosis viruses were introduced to kill Rabbits • Combined approach is still necessary as some rabbits have become immune • Australians must also use warren destruction, poison, explosives, and predators to control populations

  12. G.3.5 Impacts of Alien Species • Causes a reduction in diversity due to three factors: • Interspecific competition: increased competition between species • Predation: eats native species • Species extinction: out-competing native species

  13. G.3.7 & G.3.8 Biomagnification • Definition: the process by which chemical substances become more concentrated at each trophic level • Causes: release of pollutants or chemicals into the environment (examples: DDT, mercury, PCBs) • Effects: DDT- thins shells of predatory birds, PCBs-cancerous, mercury-toxic

  14. DDT

  15. G.3.9 The effects of UV radiation • Living Tissues • Non lethal skin cancer • Lethal skin cancer • Mutation of DNA (causing the above cancers) • Sunburn • Cataracts • Biological Productivity • Plants are harmed (decreased photosynthesis and and damaged DNA impairing cell growth) • Phytoplankton particularly vulnerable (base of food chain in most aquatic ecosystems)

  16. G.3.10 CFCs and the Ozone layer • Chlorofluorocarbons catalytically destroy ozone molecules in the stratosphere (one CFC molecule can destroy millions of ozone molecules) • Used as a coolant, aerosol, and in foam packaging • Montreal protocol phased out their use • CFCs can survive in the atmosphere for many years (problem is not over yet)

  17. G.3.11 Ozone and UV radiation • Ozone in the stratosphere absorbs UV radiation (blocking it from entering the troposphere)

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