This chapter discusses how human activities affect the biosphere and its resources. It covers topics like renewable and nonrenewable resources, including soil, forests, fisheries, air, and freshwater. It also addresses the importance of biodiversity and the threats it faces from habitat loss, pollution, invasive species, and more. The chapter explores the issues of ozone depletion and global climate change, and how understanding these problems helps chart a more sustainable course for managing the biosphere in the future.

1. Chapter 6
Humans in the Biosphere

7. 6 – 1 A Changing Landscape
• What type of human activities can
affect the biosphere?

8. 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

9. 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

10. Hunting and Gathering

11. Agriculture

12. Urban Development

13. The Tragedy of The
Commons

14. 6 – 2 Renewable and
Nonrenewable Resources
• How are environmental resources
classified?
• What effect does human activities
have on natural resources?

15. 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

16. Nonrenewable resource
• Cannot be replenished by natural
processes

17. 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

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

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

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

21. 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

23. 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

24. Deforestation
• Loss of forests
• Can lead to severe erosion

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

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

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

31. 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

32. 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

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

34. Pollutant
• A harmful material that can enter
the biosphere

35. • 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

37. 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

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

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

40. Water Treatment facilities

41. Drip irrigation

42. 6 – 3 Biodiversity
• What is the value of biodiversity?
• What are the current threats to
biodiversity?
• What is the goal of conservation
biology?

43. 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

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

45. 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

46. 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

47. Gum Tree

48. Rosy Periwinkle

49. Threats to Biodiversity
• Human activity can reduce
biodiversity by:

50. Altering habitats

51. Hunting species to extinction

52. Introducing toxic chemicals

53. Introducing foreign species

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

55. Extinct
• When a species disappears from
the biosphere

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

57. Habitat fragmentation
• When development split
ecosystems into pieces

58. 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

59. 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

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

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

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

64. Zebra mussel

65. Leafy Spurge

66. Mile-a-minute

67. Nutria

68. Phragmites

69. Purple loosestrife

70. 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”

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

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

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

77. 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

78. 6 – 4 Charting a Course
for the Future
• What are two types of global
change of concern to biologists

79. 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

80. Ozone Depletion

81. 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

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

85. 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

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

87. 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

88. • 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

89. Global Warming
• Increase in the average
temperature of the biosphere

90. 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

92. 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

93. 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

94. 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

95. 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