Chapter 6 Resources and Conservation

1. Chapter 6Resources and Conservation

2. 6-2 Renewable and Nonrenewable Resources Classifying Resources • Renewable Resources – can regenerate if they are alive, or can be replenished by biochemical cycles if they are nonliving • Example: tree, water, air, solar • Nonrenewable Resources – cannot be replenished by natural processes • Once these fuels are depleted they are gone forever • Example: coal, oil, natural gas

3. Sustainable Development • Sustainable Development – a way of using natural resources without depleting them and causing long-term environmental harm

4. Forest Resources Earth’s forests are an important resource for the products they provide and for the ecological functions they perform. Provide wood for products and fuel. Remove carbon dioxide and produce oxygen. Store nutrients. Provide habitats and food for organisms. Moderate climate. Limit soil erosion. Protect freshwater supplies.

5. Whether a forest can be considered a renewable resource depends partly on the type of forest. Temperate forests of the Northeast are renewable because they have been logged and have grown back naturally. Old-growth forests, such as those in Alaska and the Pacific Northwest, are nonrenewable because it takes centuries to produce them.

6. Deforestation Loss of forests, or deforestation, has several effects: Erosion can wash away nutrients in the topsoil. Grazing or plowing can permanently change local soils and microclimates, which prevents the regrowth of trees. Forest Management  Mature trees can be harvested selectively to promote the growth of younger trees and preserve the forest ecosystem. Tree geneticists are breeding new, faster-growing trees that produce high-quality wood.

7. Fishery Resources Fishes and other animals that live in water are a valuable source of food. Overfishing  Harvesting fish faster than they can reproduce Has greatly reduced the amount of fish in parts of the world’s oceans Fisheries seemed to be a renewable resource, but overfishing has limited that resource U.S. National Fisheries Service has issued guidelines that specify how many fish, and of what size, can be caught

8. Air Resources • Smog – a mixture of chemicals that occurs as a gray-brown haze in the atmosphere • Is due to automobile exhausts and industrial emissions • Considered a pollutant because it threatens people’s health • Pollutant – a harmful material that can enter the biosphere through the land, air, or water • The burning of fossil fuels can release pollutants that cause smog and other problems in the atmosphere

9. Strict automobile emissions standards and clean-air regulations have improved air quality in many cities, but air pollution is still a problem. Acid precipitation – nitrogen and sulfur compounds in the atmosphere combine with water vapor and fall to the Earth in the form of rain, snow, sleet, or fog Acid precipitation kills plants by damaging their cells and interfere with plant growth

10. Freshwater Resources Although water is a renewable resource, the total supply of fresh water is limited and is threatened by pollution.

11. Sources of freshwater pollution include: Improperly discarded chemicals that enter streams and rivers. Wastes discarded on land that seep through soil and enter underground water supplies. Domestic sewage containing compounds that encourage growth of algae and bacteria. Sewage containing microorganisms that spread disease.

12. Sustainable Use of Water One way to ensure the sustainable use of water is to protect the natural systems involved in the water cycle that help purify water. Examples: wetlands forests rock layers Also, by conserving water in: home industry agriculture

13. The Fate of Spilled Oil • According to a well-known saying that oil and water don’t mix, it might be expected that spilled oil would float around until it was washed ashore • A single gallon of oil can spread enough to cover up to four acres of water • As soon as the oil is spilled in a marine environment, many changes begin to take place • Within days, 25% of the oil is lost through evaporation • The remaining oil sinks to the bottom of the ocean • It adheres to almost all objects that it encounters • After 3 months only 15% of the original oil remains

14. If a substantial oil spill occurred close to shore rather than at sea, the effects would be different because there would not be sufficient time available for the process described above to affect the total amount of oil involved

15. Effects of Oil Spills • Reduction of Light Transmission • Light intensity 2m below an oil slick can be reduced by 90% • Reduces the rate of photosynthesis so plants and protists die

16. Reduction in Dissolved Oxygen • Oil film blocks rate of oxygen uptake by water • DO is lower in oil contaminated water • Damage of Marine Birds • Birds covered with oil can drown • Oil causes bird feathers to mat together and reduces the birds ability to fly and float in water • Feathers lose their insulating ability • Birds die because of exposure to cold weather or inability to get food

17. Toxic Effects to Marine Environment • Oil contains benzene, toluene, xylene, which are toxic to plants and animals

18. Methods of Oil Spill Clean-Up • Booms or Barriers • Contain oil slick • Makes it easier to skim the oil off the surface

19. Skimmers • Used to remove oil from the surface of the water • They are attached to ships or may be hand-held along shore • Skimming works best in calm waters

20. Sorbents • Materials used to soak up oil spills • Example: straw, powdered clay, sawdust, chopped corn cobs, pine bark

21. Chemical Dispersants, Detergents, and Solvents • Used to degrade the oil • Unfortunately most of these chemicals are toxic to animals

22. Flames • Used to burn the oil • The black smoke contains toxic components

23. Bioremediation • The oil spill cleanup methods listed above only recover 10-30% of the spilled oil • The most environmentally safe prospect for the cleanup of oil spills is the use of oil-degrading microbes • Bioremediation – the use of naturally occurring microorganisms that have been genetically engineered and that can be used to degrade petroleum products • A microorganism called petrophiles are spread across an oil spill and they degrade the oil and convert it into food

24. The microorganisms may be mixed with nutrients such as nitrogen, phosphorus, and cottonseed protein that not only enhance the microbial growth, but also absorb the oil and provide a matrix for the microorganisms to continue to degrade the absorbed oil • The treated oil slick begins to break up and turn into a yellowish substance that eventually diminishes in size

25. Case Study – The Exxon Valdez • In the spring of 1989, the largest oil spill in U.S. history occurred when an oil tanker named the Exxon Valdez hit a reef in Prince William Sound off the coast of Alaska • More than 10 million gallons of crude oil spilled • The oil slick covered more than 1,000 miles of coastline • Caused an estimated 5 billion dollars in environmental damages

28. The Exxon Valdez disaster killed more wildlife than any other environmental disaster in our nation’s history • 250,000 seabirds died • 2,800 sea otters died • 300 harbor seals died • 250 bald eagles died • 22 killer whales died

33. 6-3 Biodiversity The Value of Biodiversity Biodiversity – the number of species that live in a certain area A rain forest has the greatest amount of biodiversity. Why is biodiversity important? Food Medicines Industrial products

34. Threats to Biodiversity Human activity can reduce biodiversity by: altering habitats hunting species to extinction introducing toxic compounds into food webs introducing foreign species to new environments

35. Threatened species – when the population of a species begins declining rapidly • Endangered Species – when species numbers become so low that extinction is possible • Extinction – the disappearance of a species when the last of its members dies • Since 1980’s almost 40 species of plants and animals living in the United States have become extinct • Although extinction can occur as a result of natural processes, humans have been responsible for the extinction of many species

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40. Habitat Alteration • Habitat loss is the biggest threat to biodiversity • Habitat Fragmentation – the separation of wilderness areas from other wilderness areas • Presents problems for organisms that need large areas to gather food • Habitat Degradation – the damage to a habitat by pollution

43. Introduced Species Another threat to biodiversity comes from plants and animals that humans transport around the world either accidentally or intentionally. Exotic (Invasive) species – organisms that are not native to a particular area Reproduce rapidly because their new habitat lacks the predators that would control their population Example: zebra mussels, amur honeysuckle, kudzu, cane toad, European starling, mongoose in Hawaii

45. Conservation Biology • Conservation – the management of natural resources, including the preservation of habitats and wildlife • Many species are in danger due to the actions of humans, so working with people is an important part of conservation biology

46. Strategies for Conservation • Many conservation efforts are aimed at managing individual species to keep them from becoming extinct • U.S. Endangered Species Act – this law made it illegal to harm any species on the endangered or threatened species lists • Create more natural preserves • Reintroduction programs – release organisms into an area where their species once lived • Examples: California condor, wolves in Yellowstone, Black-footed ferret

48. 6-4 Charting a Course for the Future • Ozone Depletion • Ozone Layer – atmospheric layer in which ozone gas is relatively concentrated • The ozone layer absorbs a good deal of harmful ultraviolet or UV radiation from sunlight before it reaches Earth’s surface

49. Early Evidence • In the 1970’s, scientists discovered a hole in the ozone layer over Antarctica • In 1974, a research team published data showing that gases called chloroflurocarbons, or CFC’s could damage the ozone layer

50. CFC’s were once widely used: • As propellants in aerosol cans • As coolant in refrigerators, freezers, and air conditioners • In the production of plastic foams • The U.S. and other nations began reducing the use of CFC’s in 1987, and eventually banned them • Since the ban the level of CFC’s in the atmosphere had decreased, indicating that the ban will have positive, long-term effects on the global environment • Current data predict that the ozone holes should shrink and disappear within 50 years