Humans and The Environment
Dec 17, 2015
Humans and The Environment
HumanActivities
that have changed the biosphere include
may have once caused often relies on the methods of thehave resulted in
which increased
Food supply Pesticide use Monocultureuse
Hunting andgathering Agriculture
Industrial growth
Urbandevelopment
Extinctions oflarge animals
Greenrevolution
High standardof living
Increasedpollution
Section 6-1
Concept Map
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Leaving a Mark on the World
• Have you ever seen very old photographs of the town or city in which you now live? Has your area changed? Perhaps there are more buildings or roads than there were many years ago. Maybe your town or city has more trees and flowers now than it had years ago. Humans, like all organisms, have an effect on their environment.
Section 6-1
Interest Grabber
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• Earth is a kind of island• Limited resources• Nature must sustain the resources• Human populations is growing• The planet is not
• Demands on– Air– Water– Land– Living things
• We must protect these resources• What human activities do you think have an
impact on the earth’s natural resources?– Hunting and gathering– Agriculture– Industry– Urban development
• Recent study concluded that human activity uses as much energy as all of earth’s other multicellular species combined
• Humans are the most influential in changing the environments of the planet
• HUNTING AND GATHERING• Hunting and gathering has been the primary
means of human survival for most of human history
• Fished, gathered seeds, fruits, and nuts• Lived in small groups
• Early man– Built dams– burned grasslands to encourage growth of certain
plants
• Some scientists hypothesize that humans are responsible for the mass extinction of – woolly mammoths– giant ground sloths– sabertooth cats\– cheetahs– zebras– yaks
Agriculture
• Early humans learned how plants grew, which were edible, and which were good medicines
• They began to plant those that were important near their settlements
• 11,000 years ago, humans started farming (Agriculture)
Agriculture
• Agriculture spread• With dependable food supply, people started
living in larger settlements – towns and cities• Domestication of Animals• Over time, people started keeping herds of
domesticated animals
• List 3 reasons people keep animals
Agriculture
• Milk, meat, hides, wool, companionship, perform work
• Overgrazing changed grasslands ecosystems – eroded soils, large demand on water
• Human population grew at an increasing rate.
Green Revolution
• By 1950’s food supply was straining• Green Revolution – to increase food supply,
governments and scientists introduced new farming techniques to increase yields of crops (rice, wheat, corn)
• Relied on new, highly productive strains of crops
Green Revolution
• Monoculture – large fields plowed, and planted with a single crop year after year
• Irrigation, fertilization, and pesticides were relied on to sustain the crops
• Animal and human power was replaced with machine power
• Within 20 years, Mexican farmers increased production of wheat 10 times
Green Revolution
• Problems have been introduced by the green revolution. Can you name a few?
• Depletion of water supplies• Pollution of water by pesticides and fertilizers
Industrial growth and Urban Development
• Wastes from manufacturing and energy production have been poured into the air, water, and soil
• Tied to high standard of living that we all enjoy
• The question is: How do we control the harmful effects of human activity on the environment?
Tragedy of the Commons
• Resource is something that can be used to take care of a need
• When an environmental resource is owned by many people, or no one, but no one is responsible for it, it is called a “common resource”.
Tragedy of the Commons
• The Tragedy of the Commons – any resource open to everyone will eventually be destroyed because although everyone owns the resource, no one is responsible for it.
• Air, Water – shared by many countries, but no one is responsible.
• Whaling – if some countries attempt to protect whales, but others continue to hunt whales to extinction, what will eventually happen?
2 types of resources – Renewable and Nonrenewable
• Renewable resources can be regenerated (but not necessarily limitless)– Sunlight– Fresh water– A tree– Fish
2 types of resources – Renewable and Nonrenewable
• Nonrenewable – cannot be replenished by natural resources– Fossil fuels– Coal– Oil
• 1. Examine the list of natural resources shown below. Then, classify each natural resource as either renewable or nonrenewable.
a. Wood
b. Fossil fuels
c. Aluminum
d. Wool
e. Gold
• 2. Describe the impact that the loss of nonrenewable resources would have on the environment.
Section 6-2
Interest Grabber continued
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Where Do Natural Resources Come From?
• Natural resources are materials that are supplied by nature. A renewable resource is one that is replaceable. A nonrenewable resource is one that cannot be replenished by natural processes. Once a nonrenewable resource is used up, it is gone forever.
Section 6-2
Interest Grabber
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Land Resources
• Land is a resource• Provides space for living, raw materials for
building, and industry• Important for soils crops grow on
Land Resources
• Soil is a renewable resource that can be damaged by human activities
• Best fertile soil is a mixture of humus, sand, clay, and rock particles
• Most of the humus is in the top layers called “Topsoil”– Absorbs and retains moisture, but allows drainage– Lots of nutrients– Low in salts
• Different plants add and use different amounts of nutrients
• Plowing the land removes the roots that prevent erosion
• Erosion – the wearing away of the surface soil by water and wind
• Combinations of farming, overgrazing, and drought can cause productive areas to become deserts
• Process is desertification
• Practices that can maintain the soil include– Contour plowing– Planting crops that maintain the soil while primary
crops are harvested – rye for example– Leaving roots and stems of previous year’s crops
Cover CropsLegumes, grasses, and othercover crops recycle soil nutrients,reduce fertilizer need, andprevent weed growth.
Controlled GrazingBy managing graze periods and herddensities, farmers can improve nutrientcycling, increase the effectiveness ofprecipitation, and increase the carryingcapacity of pastures.
Biological Pest ControlThe use of predators and parasitesto control destructive insectsminimizes pesticide use as well ascrop damage
Contour PlowingContour plowing reduces soil erosion from land runoff. On hilly areas, plowing is done across the hill rather than straight up and down.
Crop RotationDifferent crops use and replenish different nutrients. By rotating crops, the loss of important plant nutrientsis decreased.
A B C
Yr. 1
Yr. 2
Yr. 3
Section 6-4
Sustainable Agriculture
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corn
corn
corn
alfalfa
alfalfa
alfalfa
oats
oats
alfalfa (plowed in)
Forest Resources
• Forests provide– Wood– Paper– Fuel– Remove CO2 and add O2– Food– Sore nutrients– Moderate climate– Limit soil erosion– Protect fresh water supplies
Forest Resources
• Deforestation – Loss of forests• Soil erosion – topsoil and nutrients washed away• Grazing and plowing after deforestation can add
to problems• Sustainable use strategies• Harvesting mature trees selectively• Plant, manage, harvest, and replant tree farms• Geneticists breeding faster growing varieties
Ocean Resources
• Food• Fish catch has risen from 20 million tons/year to
over 90 million tons / year• As fish catches rose, fish stocks declined• Overfishing• Techniques to moderate include
– Limits– Aquaculture– Temporary closing of areas to fishing
World Fish Catch World Fish Catch per Person
Tot
al C
atch
(mill
ion
tons
)
Am
ount
of
Fis
h pe
r P
erso
n(k
ilogr
am
s)Year Year
Section 6-2
Growth of Fish Catch
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Air Resources
• Air is a resource – we breath it• Smog – smoke and fog• Auto and industrial exhaust include Nitrogen oxides and
sulfur dioxides that are transformed into nitric and sulfuric acids
• Cause acid rain• Pollutant – a harmful material that can enter the biosphere
through land, air, or water• Acid rain can kill plants, and cause soil chemistry to
change• May release Hg, or other dissolved toxic elements
Emissions to AtmosphereNitrogen oxidesSulfur dioxide
Chemical TransformationNitric acid
Sulfuric acid
PrecipitationAcid rain, fog,snow, and mist
Dry Fallout
Condensation
particulates, gases
Industry Transportation Ore smelting Power generation
Section 6-2
Figure 6-12 The Formation of Acid Rain
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Water Resources
• Water is a resource• Drinking, washing, watering crops, industry• 71% of the earth is covered by water• 97% of the water is sea water (salty)• 2% more is frozen• 1% of all water is liquid fresh water
Pollution
• Wastes discarded (on purpose or not) can• Seep into water supplies• Sewage
– Contains nitrogen and phosphorus– Cause algal and bacterial growth– Spread disease
Pollution
• Wetlands such as swamps and estuaries can help to protect water supplies
• Purifies water as it passes through• Holds soil in place
What Is Biodiversity?
• Biodiversity is the sum total of the variety of organisms in the biosphere. Sometimes humans can reduce biodiversity, which is considered a natural resource.
Interest Grabber
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Biodiversity
• 1.5 million species identified so far• Food• medicine – painkillers, heart drugs, antibiotics• industrial products
Insects
BacteriaFungi
Plants
Protists Other Animals
54.4%
4.2%
18%
3.4%0.3%
19.7%
Section 6-3
Species Diversity
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Biodiversity
• Human activity can reduce biodiversity• May cause extinction
Biological magnification
• Biological magnification– toxins may be concentrated from one trophic level to the next.
• DDT is an example• DDT is a pesticide that was used extensively• DDT is not biodegradable• Organisms do not eliminate it
Fish-Eating BirdsMagnification ofDDT Concentration
10,000,000
100,000
10,000
1,000,000
1
1000
LargeFish
Small Fish
Zooplankton
Producers
Water
Section 6-3
Figure 6-16 Biological Magnification of DDT
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Biological magnification
• Concentrates as herbivores eat plants sprayed with DDT, then carnivores eat the herbivores etc…
Introduced species
• Organisms transferred from one area to another that did not have them before
• Zebra Mussel, Phragmites, Japanese shore crab
• 1. Choose an animal other than a human and describe at least two ways in which it may change its environment.
• 2. What events might have led to the changes that occurred in your town or city?
• 3. What positive effect have humans had on their environment? What negative effect have humans had on their environment?
Section 6-1
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• 1. List three ways in which other organisms have proved to be a benefit to humans.
• 2. Compare biodiversity with other natural resources, such as wood and fossil fuels. Do you think biodiversity is a renewable or a nonrenewable resource? Explain your answer.
• 3. What can be done to preserve the biodiversity of organisms?
Section 6-3
Interest Grabber continued
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How Much Should It Cost?
• You may have read that when something becomes hard to obtain, its price usually increases. Such is the case for materials like gold and diamonds, which are nonrenewable resources. Using similar thinking, some researchers believe that all the valuable services provided by a healthy ecosystem should be assigned a dollar value.
Interest Grabber
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• Rank the following items in order of their importance to you. Then, next to each item, write down how much you would be willing to pay for it.
• 1. Fresh, clean drinking water• 2. Clean air to breathe• 3. An endangered plant containing a substance that can cure cancer• 4. Gas for your family car
Section 6-4
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Solar energy
Production of oxygen
Storage and recycling of nutrients
Regulation of climate
Purification of water and air
Storage and distribution offresh water
Food production
Nursery habits for wildlife
Detoxification of human andindustrial wasteNatural pest and disease controlManagement of soil erosionand runoff
Section 6-4 Figure 6-22 Ecosystem Services
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