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Biology - Chp 6 - Humans In The Biosphere - PowerPoint


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Biology - Chp 6 - Humans In The Biosphere - PowerPoint

  1. 1. Chapter 6Humans in the Biosphere
  2. 2. 6 – 1 A Changing Landscape• What type of human activities can affect the biosphere?
  3. 3. Earth as an Island• All of the organisms, including humans that live on Earth share a limited resource base and depend on it for their long term survival• To protect these resources we need to understand how humans interact with the biosphere
  4. 4. Human Activities• Since we depend on the ecosystem for resources we must be aware that human activities can change the local and global environments• Among human activities that affect the biosphere include
  5. 5. Hunting and Gathering
  6. 6. Agriculture
  7. 7. Urban Development
  8. 8. The Tragedy of The Commons
  9. 9. 6 – 2 Renewable andNonrenewable Resources• How are environmental resources classified?• What effect does human activities have on natural resources?
  10. 10. Renewable resource• Can regenerate if they are alive or be replenished if they are non- living• A renewable resource is not necessarily unlimitedEx.) water
  11. 11. Nonrenewable resource• Cannot be replenished by natural processes
  12. 12. Sustainable development• A way of using natural resources without depleting them and without causing long-term environmental harm• Human activities can affect the quality and supply of renewable resources such as land, forests, fisheries, air, and fresh water
  13. 13. Land Resources• If managed properly, soil is a renewable resource• Soil, however can be permanently damaged if it is mismanaged
  14. 14. Soil erosion• The wearing away of surface soil by water or wind
  15. 15. Desertification• When once productive areas are turned into deserts• Caused by:• Farming• Overgrazing• Drought
  16. 16. Sustainable Solutions to guard against these practices• Contour plowing• Leaving stems and roots of the previous years crop in place• Planting an unused field with rye
  17. 17. Forest Resources• Forests are important because they• Provide wood • Moderate climate• Are considered • Limit soil erosion the lungs of the • Protect earth freshwater• Store nutrients supplies• Provide habitats• Provide food
  18. 18. Deforestation• Loss of forests• Can lead to severe erosion
  19. 19. Sustainable Solutions for Forest Management• Harvest mature trees selectively• Tree farms• Tree geneticists
  20. 20. Fishery Resources• Fishes and other animals that live in water are a valuable source of food for humanity
  21. 21. Overfishing• Harvesting fish faster than they can be replaced by reproduction
  22. 22. Sustainable Solutions for Fisheries• The US National Marine Fisheries Service uses data on fish populations to create guidelines for commercial fishing• Aquaculture – raising aquatic animals for human consumption
  23. 23. Air Resources• Air is a common resource that we use every time we breathe• The condition of air affects peoples health• The preservation of air quality remains a challenge to modern society
  24. 24. Smog• A mixture of chemicals that occurs as a gray-brown haze in the atmosphere
  25. 25. Pollutant• A harmful material that can enter the biosphere
  26. 26. • Many combustion processes, such as the burning of fossil fuels, releases nitrogen and sulfur compounds• When these compounds combine with water in the atmosphere they produce nitric and sulfuric acids - which fall to the earth as acid rain
  27. 27. Freshwater Resources• Americans use billions of liters of freshwater everyday• Although water is a renewable resource, the total supply of freshwater is limited• For this reason, protection of water supplies from pollution is a major priority
  28. 28. Sustainable Solutions• Protect natural systems involved with the water cycleEx.) wetlands and forests• Water treatment facilities• Drip irrigation
  29. 29. Protect natural systemsinvolved with the water cycleEx.) Wetlands and Forests
  30. 30. Water Treatment facilities
  31. 31. Drip irrigation
  32. 32. 6 – 3 Biodiversity• What is the value of biodiversity?• What are the current threats to biodiversity?• What is the goal of conservation biology?
  33. 33. 6 – 3 Biodiversity• Variety is the spice of life• But variety in the biosphere gives us more than just interesting things to look at• Human society takes place in local and global food webs and nutrient cycles• For that reason, out well being is closely tied to the well being of a great variety of other organisms
  34. 34. Biodiversity• (Biological diversity) – the sum total of the genetically based variety of all organisms in the biosphere
  35. 35. Types of Biodiversity• Ecosystem diversity – the variety of habitats• Species diversity – the variety of species• Genetic diversity – the variety of genetic info carried by all the organisms
  36. 36. The Value of Biodiversity• Biodiversity is one of Earth’s greatest natural resources• Species of many kinds have provided us with…• Food• Industrial products• medicines
  37. 37. Gum Tree
  38. 38. Rosy Periwinkle
  39. 39. Threats to Biodiversity• Human activity can reduce biodiversity by:
  40. 40. Altering habitats
  41. 41. Hunting species to extinction
  42. 42. Introducing toxic chemicals
  43. 43. Introducing foreign species
  44. 44. Endangered Species• A species whose population is declining and is in danger of becoming extinct
  45. 45. Extinct• When a species disappears from the biosphere
  46. 46. Habitat Alteration• When land is developed, natural habitats are destroyed
  47. 47. Habitat fragmentation• When development split ecosystems into pieces
  48. 48. Demand for Wildlife Products• Throughout history, humans have pushed some animal species to extinction by hunting them for food or other products• Today, endangered species are protected by laws• Unfortunately it is difficult to enforce laws in remote wilderness areas
  49. 49. Pollution• Many forms of pollution can threaten biodiversity• One of the most serious problems occurs when toxic compounds accumulate in the tissues of organismsEx.) DDT
  50. 50. Biological magnification• When concentrations of harmful substances increase in organisms at higher trophic levels in a food chain
  51. 51. Introduced species• One of the most important threats to biodiversity today is introduced species
  52. 52. Invasive species• Plants and animals that live in environments they are not native to
  53. 53. Zebra mussel
  54. 54. Leafy Spurge
  55. 55. Mile-a-minute
  56. 56. Nutria
  57. 57. Phragmites
  58. 58. Purple loosestrife
  59. 59. Q: Why do invasive speciesreproduce rapidly and quicklytake over their new habitat?A: Their new habitat lacks the predators and parasites that control their populations “back home”
  60. 60. Conservation• The wise management of natural resources including the preservation of habitats and wild life
  61. 61. Strategies for Conservation1. Managing of a single speciesEx.) captive breeding
  62. 62. Strategies for Conservation2. Protecting entire ecosystemsEx.) setting land aside
  63. 63. Conservation Challenges• Protecting resources for the future can require people to change the way they earn their living• The challenge is to maximize benefits while minimizing economic cost• But an ecological perspective tells us that if we don’t take some difficult steps today, some resources may disappear and jobs that depend of that resource will be lost permanently
  64. 64. 6 – 4 Charting a Course for the Future• What are two types of global change of concern to biologists
  65. 65. 6 – 4 Charting a Course for the Future• For most of human history, environmental change was a local affair• Today, most of Earth’s land surface has been altered by human activity• In order to plan a sound environmental strategy for the 21st century, we need data provided by research
  66. 66. Ozone Depletion
  67. 67. Ozone layer• Part of the atmosphere that contains a relatively high concentration of ozone gas (O3)• The ozone layer absorbs a good deal of harmful ultraviolet or UV radiation from sunlight before it reaches the Earth’s surface
  68. 68. • Over exposure to UV rays causes:• Sunburn• Cancer• Damage to eyes• Decreased resistance to disease
  69. 69. Early evidence• Satellite images in the 1970’s first showed the hole in the ozone layer over Antarctica• Evidence also showed that chlorofluorocarbons or CFC’s could change the ozone layer
  70. 70. One Solution• Reduce the use of CFC’s• Many CFC’s are now bannedEx.) Montreal Protocol signed 1987
  71. 71. Global Climate Change• All life on Earth depends on climate conditions such as temperature and rainfall• That’s why many ecologists are concerned about strong evidence that Earth’s climate is changing• Since the late nineteenth century, average atmospheric temperatures on Earth’s surface have risen about 0.6 degrees Celcius
  72. 72. • Since 1980 average temperatures have risen .2 and .3 degrees Celcius• The 1990’s were the warmest decade on record• 1998 was the warmest year since record keeping began
  73. 73. Global Warming• Increase in the average temperature of the biosphere
  74. 74. Evidence of Global Warming• If is believed that the current warming is related to human activities that are adding CO2 and other greenhouse gases to the atmosphere• The burning of fossil fuels combined with cutting and burning of forests worldwide is adding carbon dioxide to the atmosphere faster than the carbon cycle removes it• As a result, the atmosphere’s natural greenhouse effect is intensified causing the atmosphere to retain more heat
  75. 75. Possible Effects of Global Warming• Computer models based on the trends seen in the data suggest that average global surface temperatures will increase by 1 to 2 degrees Celsius by the year 2050
  76. 76. Q: What might this mean?A:• Sea levels may rise enough to flood some costal areas• More droughts in North America• New organisms will be able to live in places where they once could not• Other organisms may become threatened or extinct in areas they once thrived
  77. 77. The Value of a Healthy Biosphere• Human society depends on healthy, diverse and productive ecosystems because of the environmental and economic benefits they provide• People can help maintain the health of the biosphere without drastically changing their lifestyles if they make wise choices in the use and conservation of resources
  78. 78. The Future of the Biosphere• Studies of human impact on the environment are not about predicting disaster• You have seen how research has lead to action which is fixing the mistakes of the past• Remember, the biosphere is strong and we humans are clever. Both humans and natural ecosystems can adapt to change of different kinds