1. Humans in the Biosphere
Chapter 6
Humans in the Biosphere

6. 6 – 1 A Changing Landscape
What type of human activities can affect the biosphere?

7. 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

8. 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

9. Hunting and Gathering

10. Agriculture

11. Urban Development

12. The Tragedy of The Commons
The tragedy of the commons is a dilemma arising from the situation in which multiple individuals, acting independently and rationally consulting their own self-interest, will ultimately deplete a shared limited resource, even when it is clear that it is not in anyone's long-term interest for this to happen. This dilemma was first described in an influential article titled "The Tragedy of the Commons," written by ecologist Garrett Hardin and first published in the journal Science in 1968.

13. 6 – 2 Renewable and Nonrenewable Resources
How are environmental resources classified?
What effect does human activities have on natural resources?

14. Renewable resource
Can regenerate if they are alive or be replenished if they are non-living
A renewable resource is not necessarily unlimited
Ex.) water

15. Nonrenewable resource
Cannot be replenished by natural processes

16. 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

17. Land Resources If managed properly, soil is a renewable resource
Soil, however can be permanently damaged if it is mismanaged

18. Soil erosion
The wearing away of surface soil by water or wind

19. Desertification When once productive areas are turned into deserts
Caused by:
Farming
Overgrazing
Drought

20. 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

22. Forest Resources Forests are important because they Provide wood
Are considered the lungs of the earth
Store nutrients
Provide habitats
Provide food
Moderate climate
Limit soil erosion
Protect freshwater supplies

23. Deforestation
Loss of forests
Can lead to severe erosion

26. Sustainable Solutions for Forest Management
Harvest mature trees selectively
Tree farms
Tree geneticists

27. Fishery Resources
Fishes and other animals that live in water are a valuable source of food for humanity

28. Overfishing
Harvesting fish faster than they can be replaced by reproduction

30. 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

31. 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

32. Smog
A mixture of chemicals that occurs as a gray-brown haze in the atmosphere

33. Pollutant
A harmful material that can enter the biosphere

34. 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

36. 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

37. Sustainable Solutions
Protect natural systems involved with the water cycle
Ex.) wetlands and forests
Water treatment facilities
Drip irrigation

38. Protect natural systems involved with the water cycle
Ex.) Wetlands and Forests

39. Water Treatment facilities

40. Drip irrigation

41. 6 – 3 Biodiversity What is the value of biodiversity?
What are the current threats to biodiversity?
What is the goal of conservation biology?

42. 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

43. Biodiversity
(Biological diversity) – the sum total of the genetically based variety of all organisms in the biosphere

44. 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

45. 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

46. Gum Tree

47. Rosy Periwinkle

48. Threats to Biodiversity
Human activity can reduce biodiversity by:

49. Altering habitats

50. Hunting species to extinction

51. Introducing toxic chemicals

52. Introducing foreign species

53. Endangered Species
A species whose population is declining and is in danger of becoming extinct

54. Extinct
When a species disappears from the biosphere

55. Habitat Alteration
When land is developed, natural habitats are destroyed

56. Habitat fragmentation
When development split ecosystems into pieces

57. 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

58. Pollution Many forms of pollution can threaten biodiversity
One of the most serious problems occurs when toxic compounds accumulate in the tissues of organisms
Ex.) DDT

59. Biological magnification
When concentrations of harmful substances increase in organisms at higher trophic levels in a food chain

61. Introduced species
One of the most important threats to biodiversity today is introduced species

62. Invasive species
Plants and animals that live in environments they are not native to

63. Zebra mussel

64. Leafy Spurge

65. Mile-a-minute

66. Nutria

67. Phragmites

68. Purple loosestrife

69. Q: Why do invasive species reproduce rapidly and quickly take over their new habitat?
A: Their new habitat lacks the predators and parasites that control their populations “back home”

70. Conservation
The wise management of natural resources including the preservation of habitats and wild life

71. Strategies for Conservation
Managing of a single species
Ex.) captive breeding

72. Strategies for Conservation
2. Protecting entire ecosystems
Ex.) setting land aside

76. 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

77. 6 – 4 Charting a Course for the Future
What are two types of global change of concern to biologists

78. 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

79. Ozone Depletion

80. 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

83. Over exposure to UV rays causes:
Sunburn
Cancer
Damage to eyes
Decreased resistance to disease

84. 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

85. One Solution Reduce the use of CFC’s Many CFC’s are now banned
Ex.) Montreal Protocol signed 1987

86. 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

87. 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

88. Global Warming
Increase in the average temperature of the biosphere

89. 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

91. 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

92. 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

93. 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

94. 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