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  • http://www.fws.gov/Endangered/wildlife.html#Species http://www.endangeredspeciesinternational.org/overview1.html

Human ecology2012 Human ecology2012 Presentation Transcript

  • Human Ecology• The relationship between humans and their environment
  • Characteristics of Populations
  • • Location• Density• Growth Rate• What causes a population’s size to change? – Number of births – Number of deaths – Number of individuals that move in or out of population
  • Population Growth • Under ideal conditions populations grow exponentially – As population grows larger, it grows faster
  • Population Growth • In the natural world, populations show “logistic growth” – Populations growth slows or stops after a period of exponential growth – Population reaches a carrying capacity
  • Limiting Factors!!!• Density Independent • Density Dependent Limits limits – Limits that affect a – Limits that increase as population regardless of population size population size increases – temperature, storms, – disease, parasites, flood competition, predators
  • What about human populations? • World wide human population growth = exponential! • Why? – Humans can eliminate competition, increase food production, control disease, etc.
  • Biodiversity
  • Biodiversity • The variety of species in an area
  • high biodiversityMarine coral reef= lots of light benthos= deep ocean intertidal= lots of nutrients
  • high biodiversityTropical rainforest lots of rain, lots of sunlight, always warm many plants & animals
  • mid biodiversityGrasslands dry season/wet season, always warm frequent fires in dry season many herbivores
  • low biodiversityDesert very dry, hot in day & cold at night very few plants & only small animals: reptiles, insects, rodents, birds
  • low biodiversityTundra cold year round, dry, permafrost only lichens & mosses & mostly migrating animals
  • Why is Biodiversity Important?• Stability• Food source - removing organisms from the food chain will cause problems for its predator• Pharmaceutical drug development – Taxol – from Pacific Yew tree, breast cancer treatment – Periwinkle – flower used to treat leukemia – Willow bark – natural source for aspirin – Penicillium – mold that makes the antibiotic penicillin• Provides the world with beauty
  • What happens when biodiversity is threatened?• Threatened species – Population whose #’s are declining rapidly – sea otter, sea turtles• Endangered species – Population with very low numbers – ~ 1214 animals & ~750 plants – manatees, elephants• Extinction – ~ 905 species are extinct
  • Humans and the Ecosystem
  • • Disrupting ecosystems can threaten biodiversity. • Hunting & gathering • Agriculture • Animal domestication • Urbanization
  • What happens?1. Urbanization – movement to cities – Outcome • Increased runoff causing flooding & erosion • Use of nonrenewable natural resources
  • What happens?2. Deforestation – Human destruction of forests – building of malls, homes, farming – Outcome • Loss of biodiversity • Soil erosion – loss of topsoil
  • 3. Overfarming – When plants are harvested soil becomes less fertile – Outcome • Abandoned fields • Erosion of topsoil
  • 4. Overgrazing – Herds of cattle & sheep overgraze grasslands – Outcome • Land has no cover & topsoil is eroded
  • 5. Misuse of Pesticides – Contaminate air, water & soil – Kill many organisms that aren’t pests – “Safe” pesticides have been found to be dangerous • DDT
  • 6. Biomagnification – Process where chemical becomes highly concentrated in the bodies of upper level consumers – How does this happen? – E.g. DDT became concentrated in bald eagles causing thin-shelled eggs that did not survive
  • 7. Invasive species – Introduction of organisms that are not native (natural) to an area • E.g. Purple loosestrife • E.g. Zebra mussels • E.g. Japanese beetles – Outcompete native species & take over • No predators • Able to use available resources better
  • Pollution You Stink
  • • Adding anything to the environment or affecting the environment in a way that makes it less fit for living
  • 1. Land Pollution• Tons of solid waste (refuse) are produced everyday• Sanitary Landfill• Incineration
  • 2. Water Pollution• Organic wastes – fertilizer runoff, sewage, waste from factories – Waste acts as food for algae, algae become overpopulated and lead to death of other organisms – Causes “eutrophication” • accelerated aging process/ succession
  • Water Pollution• Inorganic chemicals – Poisonous wastes dumped into waterways from cities, farms & industry – Biological Magnification • Mercury poisoning in Japan
  • Water Pollution• Thermal Pollution. – Warm water can’t hold as much oxygen as cool water. Organisms will suffocate & die
  • 3. Air Pollution• Burning Fossil Fuels – Burning of coal & gas – Cars, factories, electrical plants – Release CO2, sulfur, & nitrogen into the atmosphere – Cause health problems, acid rain, etc.
  • Air Pollution• Acid Rain – Occurs when sulfur & nitrogen combine with water – Forms in the rain, snow, & sleet – Lowers the pH of the water – Kills many producers Did you know that non- polluted rain is slightly acidic? The CO2 in the air forms carbonic acid when it rains…
  • Air Pollution• Smog – Produced from auto exhaust & industrial processes – Results in toxins that can be inhaled – Occurs when pollutants combine with sunlight
  • Air Pollution• Climate Change – Change in the climate (temp, precipitation, wind) last for an extended period of time. – Can occur naturally – Human activity & pollution can add to the effect
  • Air Pollution• Greenhouse effect Greenhouse effect – Occurs when sunlight passes through atmosphere gases • CO 2 , methane, H 2 O vapor – Gases trap & absorbs the sunlight resulting in an overall warming effect – Pollution can increase this effect The greenhouse effect is a natural and good process. Without it, the earth would be 30ºC cooler…
  • Air Pollution• Ozone Depletion (not global warming) – The ozone layer is made of ozone gas (O3) and is found between 20-50km above the Earth’s surface. – Absorbs harmful ultraviolet (UV) radiation from sunlight
  • • Ozone Depletion – CFCs (chlorofluorocarbons) cause ozone to break down • Found in aerosols, refrigerators, & air conditioners – Ozone holes form • UV light can enter atmosphere • Kills producers • Cause cancer Remember, ozone depletion does not cause the Earth’s temperature to increase!!!!
  • Natural Resources
  • Restoring the Environment – What can we do?• Nonrenewable natural • Renewable natural resource resources – coal, oil, natural gas, – air, water, soil, sunlight, metals, minerals living things – Can be taken from earth – Resources that are only once naturally replaced – Human activity can disrupt the natural events that replace the resources
  • Natural Resources• Conserving both renewable & nonrenewable natural resources is important – Sustainable use – use natural resources at a rate that does not deplete them.1. Recycling – Newspaper, glass, metal, plastic
  • 2. Conserving Soil• Soil is renewable, but the process is very slow, therefore it is important to conserve• Cover crops – Crops planted to cover a field to prevents erosion • Can also plant in between rows
  • Conserving Soil - HOW???• Crop rotation• Fertilizer• Strip cropping• Terracing• Contour Farming• Windbreaks
  • 3. Conserving Forests - WHY and HOW??? • Sustained-yield tree farming – Cutting down trees only in certain areas so surrounding areas are untouched. • Reforestation – Replace lost trees by planting new ones WHY???? • Forests provide wood, paper. • Soil holds large amts of water, prevent erosion. • Destruction takes a long time to replace
  • 4. Restoring the Environment - Conserving Wildlife • Cities & suburbs destroy natural habitats • Protection – Hunting/fishing laws – Game & bird preserves – Fish hatcheries breed fish & are restocked in heavily fished lakes – Pesticide & herbicide restrictions
  • Controlling Pests Biologically• More specific than chemical pesticides• Fewer adverse environmental effects• How ? – Import natural enemies • E.g. Ladybugs control aphids – Bacteria or virus that infect insect larvae • Gypsy moth caterpillars, mosquito larvae
  • Controlling Pests Biologically• Crop rotation – Remove favored food source…• Pheromones – Lure insect to trap & kill• Sterilization & release of male insects – Males become sterile by exposure to radiation – E.g. the screwworm fly only gets to mate once, so she is out of luck if she mates with a sterile males
  • 5. Controlling Pollution• Emission Controls for cars• Ban aerosol sprays• Control Industrial waste – Gas treated before released – Ban on dumping waste in water & land• Sewage treatment plants – Use bacteria to treat water before released• Reclaim strip mined land• Special sites for toxic waste
  • Restoring the Environment• Individual Actions – People can choose: • Not to pollute • Not to burn garbage • Change products that they use • Drive energy efficient cars – Car pool, use public transportation • Reduce, Reuse, Recycle
  • Restoring the Environment• Societal Actions – Cities, States, & governments can: • Pass laws against pollution • Fine or jail polluters • Hold public meetings & hearings about pollution • Give incentives - $$