1. list three ways humans have impacted the environment. 2. do you think humans have had a positive...
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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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