Humans and The Environment. Human Activities that have changed the biosphere include may have once...

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

Interest Grabber continued

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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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