1. Chapter 6 Humans in the Biosphere

2. 6-1 Changing Landscape Earth as an Island All Organisms that live on Earth: Share Limited resources Depend on these for long term survival Rely on natural ecological processes to keep these resources

3. Human participate in food webs & chemical cycles Ecosystems provide: 1.Breathable air 2.Drinkable water 3.Fertile soil 4.Storage & recycling of nutrients

4. Human activities are the most important source of environmental change on the planet These include: 1.Hunting & Gathering – led to mass extinction of animals 2.Agriculture – practice of farming Benefits of the Green Revolution a. Greatly increased the world’s food supply b. Plant breeders developed new varieties of crops c.Use of chemical fertilizers Challenges for the Future a.Large scale monoculture – can lead to insect pests & disease b.Chemical pesticides can harm beneficial insects & can contaminate water supplies c.Need to find enough water for irrigation

5. 3.Industrial Growth & Urban Development Industrial revolution : Industrial revolution : –added machines & factories –Led to industrial productivity & scientific knowledge –Gave us mobility –Provides modern convenience Adverse effects: –Need for energy –Waste –Pollution –Suburban growth consumes farmland & natural habitats –Stresses plant & animal populations

6. 6-2 Renewable and Nonrenewable Resources Environmental goods may be classified as renewable or nonrenewable Renewable: 1.Can be regenerated if they are alive 2.If not alive, can be replenished by chemical cycles 3.Not necessarily unlimited 4.Examples: fresh water, trees

7. Nonrenewable: 1.A resource that can not be replenished by natural processes 2.Once (depleted) used up → gone forever 3.Examples: fossil fuels

8. Sustainable development → is a way of using natural resources w/out depleting them → of providing for human needs w/out causing long-term environmental harm To work well, sustainable development must: 1.Take into account both: Functions of ecosystems & Ways that human economic systems operate Ways that human economic systems operate 2.Must enable people to live comfortably & improve their situation

9. Land Resources Land – resources that provides space (humans) & raw materials for industry If managed properly it is a renewable resource Fertile soil = a mixture of sand, clay, rock particles & humus Topsoil- uppermost layer of the soil Good topsoil absorbs & retains moisture –Allows excess water to drain –Is rich in nutrients –Low in salts –Produced by long-term interactions between soil & its plants

10. Problems: –Soil erosion – wearing away of surface soil by wind & water –Desertification – one productive area turned into deserts by farming, overgrazing & drought Sustainable development practices include: –Contour plowing – fields plowed across slope –Leaving stems & roots to help hold the soil in place

11. Forest Resources Important resource because: –They provide products Examples: –Wood –Paper –Fuel –They perform services Examples: –Lungs- remove CO 2 & Produces O –Lungs- remove CO 2 & Produces O 2 –Store nutrients –Provide habitats –Moderate climate –Limit soil erosion –Protect freshwater supplies

12. Temperate forest are considered renewable resources Old-growth forests are forests never cut before –A nonrenewable resource –When logged, they may lose the rich variety of species Problem = Deforestation – loss of forests –Leads to severe erosion –Grazing or plowing causes permanent changes to local soils & microclimates Sustainable development practices include: 1.Harvest selectively 2.Replant tree farms 3.Breeding new varieties that grow faster

13. Fishery Resources Fish are a valuable source of food Problem – Over-fishing – catching fish faster then they can reproduce They were providing food, but the population of fish species were shrinking No one took responsibility for maintaining this resource It is a renewable resource Sustainable development practices include: US Fisheries Service developed guidelines for commercial fishing: Specifies how many fish & of what size Aquaculture – raising aquatic animals for food Problems: can pollute water & damage aquatic ecosystems

14. Air Resources Common resource that we use to breathe Problem: Smog – mixture of chemicals that occurs as a gray – brown haze Mostly due to automobile exhaust & industrial emissions Is considered a pollutant – harmful material that enters the biosphere Comes from burning fossil fuels Contains toxic chemicals ex: nitrates & sulfates Also have particles – microscopic particles of ash & dust Putting the nitrates & sulfates into air → changes to acid Acid rain – kills plants & changes chemistry of soil & standing water Sustainable development practices include: Industry uses smokestack technology Autos have strict emission standards Clean air regulations

15. Freshwater Resources Uses: 1.Drinking 2.Washing 3.Watering crops 4.Making Steel Is a renewable resource, but the supply is limited Problems: Pollution is caused by –Improperly discarded chemicals –Domestic sewage – wastewater from sinks & toilets Contain microorganisms that can cause disease N & P can cause growth of algae & bacteria Sustainable development practices Include –Cities & towns treat wastewater –Water passing wetland → purify water –Reduce demand → conservation

16. 6-3 Biodiversity Diversity = variety Biodiversity – sum total of the genetically based variety of all organisms Ecosystem diversity – variety of habitats, communities & ecological processes Species diversity – # of different species in the biosphere Genetic diversity – sum total of all the different forms of genetic information carried by all organisms on Earth today One of earth’s greatest natural resources is biodiversity Provide us with food, industrial products & medicines

17. Threats to Biodiversity Extinction - when a species disappears from all of its range Endangered species – population of species is low enough, it is in danger of extinction

18. As population numbers decline, species diversity is lost Caused by human activities 1.Habitat alteration – when land is developed a.Provides organisms’ needs which are a limited resource. b.Developments can cause habitat fragmentation – a process that splits ecosystems into pieces (islands) c.The habitat islands formed have fewer species, smaller populations which make the species more vulnerable to any disturbance 2.Demand for wildlife products a.Hunting for food or other products b.Some body parts (horns) have “medicinal” properties c.CITES bans international trade in products from endangered species

19. 3.Pollution a.Occurs when toxic compounds accumulate in tissues of organisms b.Example = pesticide DDT c.Biological magnification – harmful substance concentrations in organisms at higher trophic level in a food chain or web d.Those at highest risk are found top – level carnivores 4.Introduced Species – apparently harmless plants & animals that humans transport to new areas a.In new habitats these become invasive species b.They reproduce rapidly c.New habitat lacks parasites & predators d.Zebra mussels – ( Missouri)-are driving native species away

20. Conserving Biodiversity Conservation – wise management of natural resources Strategies include: –Breeding programs at zoos which manage individual species –Protecting entire ecosystems protects habitats, species & species interactions by setting aside land for park & reserves –Marine sanctuaries protect coral reefs & marine mammals Conservation challenges: try to maximize benefits while minimizing economic costs

21. 6-4 Charting a Course for the Future Ozone Depletion Ozone layer – the part of the atmosphere that contain relatively high concentration of ozone gas O 3 A naturally occurring layer that is necessary to absorb UV radiation Overexposure to UV rays causes 1. Sunburn 2. Cancer 3. Damage eyes 4. Disease Resistance 5. Damage Plant Tissue

22. Problem = holes in the natural layer over Antarctica & Arctic Holes caused by CFC’s CFC’s were widely used as coolant, aerosol propellant & production of plastic foam 1987 use was banned; but there are still effects because CFC molecules linger Current data shows that the holes should shrink & disappear in ~ 50years

23. Global Climate Change All life depends on temperature & rainfall Global warming – increase in the average temperature of the biosphere Evidence: Two hypotheses 1.This is part of a larger natural cycle of climate change 2.Humans are causing the warming trend

24. Data shows that CO concentrations have been rising for 200 years Data shows that CO 2 concentrations have been rising for 200 years Human activities that add more CO by: Human activities that add more CO 2 by: 1. Burning fossil fuels 2. Cutting & burning forests Possible effects of Global Warming –Effects are based on computer models –Sea levels may rise and flood coastal areas –North America may experience more drought –Long term climate change will affect ecosystems

25. Value of a Healthy Biosphere Ecosystems provide goods & services To maintain healthy systems, every individual must make wise choices in the use & conservation of resources Examples: 1.Use less water 2.Plant Trees 3.Dispose of waste properly 4.Recycle