1. List three ways humans have impacted the environment.

2. Do you think humans have had a positive impact or negative impact? Explain your answer.

3. Do you think it is important to preserve our environment? What can we do to preserve our environment?

Section 6-3 Do Now

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Changing landscape• Past and present humans have had a powerful

influence on the physical and living world by modifying their environment.

• Our practices have changed the environment!– From deforesting to fishing

• We used the environment for food, medicine, wood, and fiber

• We introduced new species, predators, agriculture, industry, and disease

• The world is very different from what it was long ago.• Think of Earth as an island – all of the organisms that

live on Earth share limited resources and increasing population sizes place greater demands on the biosphere

Human ActivitiesHumans have advantages in competing with other

species for limited resources (food, energy, and space)

Humans are the most important source of environmental change on the planet, because we can change the flow of energy in an ecosystem and reduce the ability of ecosystems to recycle nutrients

Human activities that have transformed the biosphere include:Hunting and gatheringAgricultureIndustry and urban developmentTechnology

Human ImpactHunting and Gathering – the primary means of survival for most of human history, changed environment by diverting water, burning grasslands to grow certain plants, and causing major mass extinctions

Human ImpactAgriculture – farming began about 11,000 years

ago supplying a dependable food source and beginning civilization developmentDomestication of animals provides humans’

energy to do work overgrazing (changing ecosystem)

Human population growth strain on world’s food supply Green Revolution (new farming practices with increased yields and new hardier strains of plants)

Human ImpactIndustrial growth and Urban

development – added machines and factories to civilization during 1800s creating citiesIndustrial Revolution (increased productivity and scientific knowledge) increased energy use (coal, oil, gas) increased waste/pollution (air, water, soil) and stress on natural habitats

Quick ActivityClassify the following resources as renewable

or nonrenewable with your seat partner:Solar energyWind/airWater Fossil fuelsMetals Soil Plants Animals

} Biodiversity

ResourcesEnvironmental resources can be classified as:

Renewable = regenerate and replaceable (trees, water), but not necessarily unlimitedThe classification “renewable” depends upon

the context in which you use it. (For example, a forest is not renewable, because the climate would change if all trees were cut down, but individual trees are renewable)

Nonrenewable = cannot be replenished by natural processes (fossil fuels, coal, oil, natural gas)

Renewable resourcesHuman activities affect the supply and the quality

of renewable resources including:Land resources Forest resources Ocean resources Air resources Water resources

Land Resources• Provide space for cities and suburbs, raw materials for industry,

and fertile soil with nutrients and moisture to grow plants with roots to hold soil against rain and wind

Negative activities:Soil erosion = wearing away of surface soil by water and wind (usually results from removing roots that hold soil)Desertification = turning once productive areas into deserts (usually results from farming, overgrazing, and drought)

Positive activities:Sustainable agriculture = reduces soil erosion by conserving soil’s properties

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)

Provide wood for homes, paper, fuel and “lungs of the Earth” because they remove carbon dioxide and produce oxygen, store nutrients, provide habitats and food, moderate climates, limit soil erosion, and protect fresh water supplies

Negative activities:Deforestation = loss of forests leading to soil

erosion Positive activities:

Tree farms = plant, promote growth, manage, harvest and replant trees to preserve the ecosystem

Forest resources

Ocean resourcesProvides protein-rich food (cod and shrimp)

Negative activities:Overfishing = fish are being harvested

faster than they can reproduce Positive activities:

Limit the catch of fish populations

Aquaculture = farming of aquatic organisms

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 6-2Growth of Fish Catch

Larger fishing boats with better technology for locating and catching fish

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Used to breathe Negative activities:

Pollutant = harmful material that can enter the biosphere through the land/air/water Smog = mixture of chemicals that results in a

gray-brown haze in the atmosphere mostly due to car exhausts and industrial emissions causing respiratory conditions

Acid rain = mixture of acidic gases (nitrates and sulfates) from combustion with water vapor damaging plants, soil and water

Positive activities: Clean-air regulations and controlling emissions has

improved air quality

Air resources

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 The Formation of Acid Rain

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Billions of gallons of water are used daily by Americans for drinking, washing, watering crops and making steel (“everyday use”)Negative activities:

Our renewable water supply can be limited by drought, overuse, oil spills, improperly discarded chemicals and waste (sewage)

Positive activities: Protect natural cycles because plants naturally filter

and purify water = Fresh Water Wetlands Act Water conservation Clean Water Act

Water resources

Which would you rather swim in? Why?

Which would you rather live in? Why?

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 Do Now

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Biological diversity or “Biodiversity” = the sum total of the genetically based variety of all organisms in the biosphere

Our existence relies on a great variety of other organisms.

Some branches within biodiversity:Ecosystem diversity = variety of habitats,

communities, and ecological processes in the living world

Species diversity = number of different species in the biosphere (about 1.5 million discovered)

Genetic diversity = sum total of all the different forms of genetic information carried by all organisms living on Earth today

Biodiversity

Insects

BacteriaFungi

Plants

Protists Other Animals

54.4%

4.2%

18%

3.4%0.3%

19.7%

Section 6-3Species Diversity

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Value of BiodiversityBiodiversity is one of Earth’s greatest natural

resources providing us with food, industrial products, and medicines (painkillers, antibiotics, heart drugs, antidepressants, and anticancer drugs)

When biodiversity is lost, potential sources of material with significant value to the biosphere and to humankind may be lost.

Threats to BiodiversityHuman activities can reduce biodiversity by:

Habitat alterationHunting species to extinction

Extinction = occurs when a species disappears from all or part of its range

Endangered species = species in danger of extinction with declining population sizesAs the population declines, the species loses

genetic diversity, making it more vulnerable to extinction

Introducing toxic compounds (pollutants) into food webs

Introducing foreign species to new environments

Habitat AlterationWhen land is developed, natural habitats may

be destroyed and the species that live in those habitats may vanish

Habitat fragmentation = development of land that splits ecosystems into pieces resulting in biological “islands” with fewer species and smaller populations more vulnerable to further disturbances or climate changes

HuntingIn the past, hunting for meat, fur, hides or

other body parts caused the extinction of some species

Today, endangered species are protected from hunting by laws in most of the world

PollutionPollution can threaten biodiversity, because

toxic compounds accumulate in tissue of organisms

Biological magnification = increasing concentrations of harmful substances at higher trophic levels in a food chain/webEntire food web is affected, but top-level

carnivores are at highest risk

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

Biological Magnification of DDT

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Introducing Foreign SpeciesBiodiversity is also threatened by apparently

harmless plants and animals that humans transport around the world either accidentally or intentionally

Invasive species = organisms introduced into new habitats and reproduce rapidly lacking the parasites and predators that control population size in their native country They can displace native species driving them

close to extinctionEx. Zebra Mussels

Conserving BiodiversityConservation = wise management of natural resources

Preservation of habitats and wildlife to protect Earth’s biodiversity for future generations, however protected areas may not be enough

Current conservation efforts focus on protecting individual species as well as entire ecosystems (to ensure natural habitats and interactions among

different species are preserved).“Hot spots” = places around the world where everything possible is being done to conserve the ecosystem and species

Our FutureSince the human population is rapidly

increasing, we are creating greater environmental changes.

Two major concerns are:Ozone depletionGlobal warming

Ozone DepletionOzone layer = a layer of concentrated ozone

gas made up of three oxygen molecules (O3) between 20 and 50 kilometers above Earth’s surface absorbing harmful UV radiationOzone holes caused by CFCs

(chlorofluorocarbons) breaking down ozone molecules

Increased UV radiation can cause cancer, eye damage, decreased resistance to disease, and tissue damage to plants and animals

Global WarmingA 0.5°C increase in the average temperature of the

biosphere in the past 120 years (abiotic factor)Some scientists believe the rising temperature may be due

to natural variations in climateOthers believe it is caused by human activities adding

carbon dioxide and other greenhouse gases into the atmosphere, making the atmosphere retain more heat More carbon dioxide from burning fossil fuels, cutting

down trees and burning forestsIt may result in rising sea level causing more

frequent and more severe weather disturbancesEnvironmental changes benefit some species, but

greatly disturb others that may not survive

The Value of a Healthy BiosphereA healthy biosphere provides us with many

valuable goods and services (food, medicine, temperature control, water purification, soil formation, etc)

Make wise choices about resources used, disposal, recycling, and energy conservation

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

Ecosystem services are provided, but it’s your responsibility to help save the Earth!

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