Chapter 6Chapter 6

Humans in the BiosphereHumans in the Biosphere

6-1 Changing Landscape6-1 Changing Landscape

Earth as an IslandEarth as an Island

All Organisms that live on Earth:All Organisms that live on Earth:Share Limited resourcesShare Limited resources

Depend on these for long term survivalDepend on these for long term survival

Rely on natural ecological processes to keep Rely on natural ecological processes to keep these resourcesthese resources

Human participate in food webs & Human participate in food webs & chemical cycleschemical cycles

Ecosystems provide:Ecosystems provide:

1.1. Breathable airBreathable air

2.2. Drinkable waterDrinkable water

3.3. Fertile soilFertile soil

4.4. Storage & recycling of nutrientsStorage & recycling of nutrients

Human activities are the most important source Human activities are the most important source of environmental change on the planetof environmental change on the planetThese include:These include:1.1. Hunting & Gathering – led to mass extinction of Hunting & Gathering – led to mass extinction of

animalsanimals

2.2. AgricultureAgriculture – practice of farming – practice of farmingBenefits of the Green RevolutionBenefits of the Green Revolutiona. Greatly increased the world’s food supplya. Greatly increased the world’s food supplyb. Plant breeders developed new varieties of cropsb. Plant breeders developed new varieties of cropsc.c. Use of chemical fertilizersUse of chemical fertilizersChallenges for the FutureChallenges for the Futurea.a. Large scale monoculture – can lead to insect pests & Large scale monoculture – can lead to insect pests &

diseasediseaseb.b. Chemical pesticides can harm beneficial insects & can Chemical pesticides can harm beneficial insects & can

contaminate water suppliescontaminate water suppliesc.c. Need to find enough water for irrigationNeed to find enough water for irrigation

3.3. Industrial Growth & Urban DevelopmentIndustrial Growth & Urban Development Industrial revolution : Industrial revolution :

– added machines & factoriesadded machines & factories– Led to industrial productivity & scientific knowledgeLed to industrial productivity & scientific knowledge– Gave us mobilityGave us mobility– Provides modern convenienceProvides modern convenience

Adverse effects:Adverse effects:– Need for energy Need for energy – WasteWaste– PollutionPollution– Suburban growth consumes farmland & natural Suburban growth consumes farmland & natural

habitatshabitats– Stresses plant & animal populationsStresses plant & animal populations

6-2 Renewable and Nonrenewable 6-2 Renewable and Nonrenewable ResourcesResources

Environmental goods may be classified Environmental goods may be classified as renewable or nonrenewableas renewable or nonrenewable

RenewableRenewable::1.1. Can be regenerated if they are aliveCan be regenerated if they are alive2.2. If not alive, can be replenished by If not alive, can be replenished by

chemical cycleschemical cycles3.3. Not necessarily unlimitedNot necessarily unlimited4.4. Examples: fresh water, treesExamples: fresh water, trees

NonrenewableNonrenewable::

1.1. A resource that can not be A resource that can not be replenished by natural processesreplenished by natural processes

2.2. Once (Once (depleteddepleted) used up) used up→ → gone gone foreverforever

3.3. Examples: fossil fuelsExamples: fossil fuels

Sustainable developmentSustainable development→ → is a way of using natural resources w/out is a way of using natural resources w/out

depleting themdepleting them→ → of providing for human needs w/out causing of providing for human needs w/out causing

long-term environmental harmlong-term environmental harmTo work well, sustainable development must:To work well, sustainable development must:1.1. Take into account both: Take into account both:

Functions of ecosystems Functions of ecosystems &&

Ways that human economic systems operateWays that human economic systems operate2.2. Must enable people to live comfortably & Must enable people to live comfortably &

improve their situationimprove their situation

Land ResourcesLand ResourcesLand – resources that provides space Land – resources that provides space

(humans) & raw materials for industry(humans) & raw materials for industryIf managed properly it is a renewable If managed properly it is a renewable

resourceresource

Fertile soilFertile soil = a mixture of sand, clay, rock = a mixture of sand, clay, rock particles & humusparticles & humus

TopsoilTopsoil- uppermost layer of the soil- uppermost layer of the soilGood topsoil absorbs & retains moistureGood topsoil absorbs & retains moisture

– Allows excess water to drainAllows excess water to drain– Is rich in nutrientsIs rich in nutrients– Low in saltsLow in salts– Produced by long-term interactions Produced by long-term interactions

between soil & its plantsbetween soil & its plants

Problems: Problems: – Soil erosionSoil erosion – wearing away of surface soil – wearing away of surface soil

by wind & waterby wind & water– DesertificationDesertification – one productive area – one productive area

turned into deserts by farming, turned into deserts by farming, overgrazing & droughtovergrazing & drought

Sustainable development practices Sustainable development practices include:include:– Contour plowingContour plowing – fields plowed across – fields plowed across

slopeslope– Leaving stems & roots to help hold the soil Leaving stems & roots to help hold the soil

in placein place

Forest ResourcesForest ResourcesImportant resource because:Important resource because:

– They provide products They provide products Examples:Examples:

– WoodWood– PaperPaper– FuelFuel

– They perform servicesThey perform servicesExamples:Examples:

– Lungs- remove COLungs- remove CO22 & Produces O & Produces O2

– Store nutrientsStore nutrients– Provide habitatsProvide habitats– Moderate climateModerate climate– Limit soil erosionLimit soil erosion– Protect freshwater suppliesProtect freshwater supplies

Temperate forest are considered renewable Temperate forest are considered renewable resourcesresourcesOld-growth forestsOld-growth forests are forests never cut are forests never cut before before – A nonrenewable resourceA nonrenewable resource– When logged, they may lose the rich variety When logged, they may lose the rich variety

of speciesof speciesProblem = Problem = DeforestationDeforestation – loss of forests – loss of forests– Leads to severe erosionLeads to severe erosion– Grazing or plowing causes permanent Grazing or plowing causes permanent

changes to local soils & microclimateschanges to local soils & microclimatesSustainable development practices include:Sustainable development practices include:1.1. Harvest selectivelyHarvest selectively2.2. Replant tree farmsReplant tree farms3.3. Breeding new varieties that grow fasterBreeding new varieties that grow faster

Fishery ResourcesFishery ResourcesFish are a valuable source of foodFish are a valuable source of foodProblem – Problem – Over-fishingOver-fishing – catching fish faster – catching fish faster

then they can reproducethen they can reproduceThey were providing food, but the population of They were providing food, but the population of fish species were shrinkingfish species were shrinkingNo one took responsibility for maintaining this No one took responsibility for maintaining this resourceresourceIt is a renewable resourceIt is a renewable resource

Sustainable development practices include:Sustainable development practices include:US Fisheries Service developed guidelines for US Fisheries Service developed guidelines for

commercial fishing:commercial fishing:Specifies how many fish & of what Specifies how many fish & of what

sizesizeAquaculture Aquaculture – raising aquatic animals for food– raising aquatic animals for food

Problems: can pollute water & Problems: can pollute water & damage damage aquatic aquatic ecosystemsecosystems

Air ResourcesAir ResourcesCommon resource that we use to breatheCommon resource that we use to breatheProblem: Smog – mixture of chemicals that occurs as a Problem: Smog – mixture of chemicals that occurs as a

gray – brown hazegray – brown hazeMostly due to automobile exhaust & industrial Mostly due to automobile exhaust & industrial emissionsemissionsIs considered a pollutant – harmful material that Is considered a pollutant – harmful material that enters the biosphereenters the biosphereComes from burning fossil fuelsComes from burning fossil fuelsContains toxic chemicals ex: nitrates & sulfatesContains toxic chemicals ex: nitrates & sulfatesAlso have particles – microscopic particles of ash Also have particles – microscopic particles of ash & dust& dustPutting the nitrates & sulfates into air Putting the nitrates & sulfates into air → changes to → changes to acidacidAcid rain – kills plants & changes chemistry of soil & Acid rain – kills plants & changes chemistry of soil & standing waterstanding water

Sustainable development practices include:Sustainable development practices include:Industry uses smokestack technologyIndustry uses smokestack technologyAutos have strict emission standardsAutos have strict emission standardsClean air regulationsClean air regulations

Freshwater ResourcesFreshwater ResourcesUses:Uses:1.1. DrinkingDrinking2.2. WashingWashing3.3. Watering cropsWatering crops4.4. Making SteelMaking SteelIs a renewable resource, but the supply is limitedIs a renewable resource, but the supply is limitedProblems:Problems:

Pollution is caused by Pollution is caused by – Improperly discarded chemicalsImproperly discarded chemicals– Domestic sewage – wastewater from sinks & toiletsDomestic sewage – wastewater from sinks & toilets

Contain microorganisms that can cause diseaseContain microorganisms that can cause diseaseN & P can cause growth of algae & bacteriaN & P can cause growth of algae & bacteria

Sustainable development practices IncludeSustainable development practices Include– Cities & towns treat wastewaterCities & towns treat wastewater– Water passing wetland Water passing wetland → purify water→ purify water– Reduce demand → conservationReduce demand → conservation

6-3 Biodiversity6-3 BiodiversityDiversityDiversity = variety = varietyBiodiversity Biodiversity – sum total of the genetically – sum total of the genetically

based variety of all organismsbased variety of all organismsEcosystem diversity – variety of habitats, Ecosystem diversity – variety of habitats,

communities & ecological processescommunities & ecological processesSpecies diversitySpecies diversity – # of different species in – # of different species in

the biospherethe biosphereGenetic diversityGenetic diversity – sum total of all the – sum total of all the

different forms of genetic information different forms of genetic information carried by all organisms on Earth todaycarried by all organisms on Earth today

One of earth’s greatest natural resources is One of earth’s greatest natural resources is biodiversitybiodiversity

Provide us with food , industrial products & Provide us with food , industrial products & medicinesmedicines

Threats to BiodiversityThreats to Biodiversity

ExtinctionExtinction - when a species disappears - when a species disappears from all of its rangefrom all of its range

Endangered speciesEndangered species – population of – population of species is low enough, it is in danger species is low enough, it is in danger of extinctionof extinction

As population numbers decline, species diversity As population numbers decline, species diversity is lostis lost

Caused by human activitiesCaused by human activities1.1. Habitat alterationHabitat alteration – when land is developed – when land is developed

a.a. Provides organisms’ needs which are a limited Provides organisms’ needs which are a limited resource.resource.

b.b. Developments can cause Developments can cause habitat fragmentationhabitat fragmentation – a – a process that splits ecosystems into pieces (islands)process that splits ecosystems into pieces (islands)

c.c. The habitat islands formed have fewer species, smaller The habitat islands formed have fewer species, smaller populations which make the species more vulnerable populations which make the species more vulnerable to any disturbanceto any disturbance

2.2. Demand for wildlife productsDemand for wildlife productsa.a. Hunting for food or other productsHunting for food or other products

b.b. Some body parts (horns) have “medicinal” propertiesSome body parts (horns) have “medicinal” properties

c.c. CITES bans international trade in products from CITES bans international trade in products from endangered speciesendangered species

3.3. PollutionPollutiona.a. Occurs when toxic compounds accumulate in Occurs when toxic compounds accumulate in

tissues of organismstissues of organismsb.b. Example = pesticide DDTExample = pesticide DDTc.c. Biological magnificationBiological magnification – harmful substance – harmful substance

concentrations in organisms at higher trophic level concentrations in organisms at higher trophic level in a food chain or webin a food chain or web

d.d. Those at highest risk are found top – level Those at highest risk are found top – level carnivorescarnivores

4.4. Introduced Species – apparently harmless Introduced Species – apparently harmless plants & animals that humans transport to plants & animals that humans transport to new areasnew areas

a.a. In new habitats these become invasive speciesIn new habitats these become invasive speciesb.b. They reproduce rapidlyThey reproduce rapidlyc.c. New habitat lacks parasites & predatorsNew habitat lacks parasites & predatorsd.d. Zebra mussels – ( Missouri)-are driving native Zebra mussels – ( Missouri)-are driving native

species away species away

Conserving BiodiversityConserving BiodiversityConservation Conservation – wise management of natural – wise management of natural

resourcesresources

Strategies include:Strategies include:– Breeding programs at zoos which manage Breeding programs at zoos which manage

individual speciesindividual species– Protecting entire ecosystems protects habitats, Protecting entire ecosystems protects habitats,

species & species interactions by setting aside species & species interactions by setting aside land for park & reservesland for park & reserves

– Marine sanctuaries protect coral reefs & Marine sanctuaries protect coral reefs & marine mammalsmarine mammals

Conservation challenges: try to maximize Conservation challenges: try to maximize benefits while minimizing economic costsbenefits while minimizing economic costs

6-4 Charting a Course for the Future6-4 Charting a Course for the FutureOzone DepletionOzone Depletion

Ozone layerOzone layer – the part of the atmosphere that – the part of the atmosphere that contain relatively high concentration of contain relatively high concentration of ozone gas Oozone gas O33

A naturally occurring layer that is necessary to A naturally occurring layer that is necessary to absorb UV radiationabsorb UV radiation

Overexposure to UV rays causesOverexposure to UV rays causes

1. Sunburn1. Sunburn

2. Cancer2. Cancer

3. Damage eyes3. Damage eyes

4. Disease Resistance4. Disease Resistance

5. Damage Plant Tissue5. Damage Plant Tissue

Problem = holes in the natural layer over Problem = holes in the natural layer over Antarctica & ArcticAntarctica & Arctic

Holes caused by CFC’sHoles caused by CFC’s

CFC’s were widely used as coolant, aerosol CFC’s were widely used as coolant, aerosol propellant & production of plastic foampropellant & production of plastic foam

1987 use was banned; but there are still 1987 use was banned; but there are still effects because CFC molecules lingereffects because CFC molecules linger

Current data shows that the holes should Current data shows that the holes should shrink & disappear in ~ 50yearsshrink & disappear in ~ 50years

Global Climate ChangeGlobal Climate ChangeAll life depends on temperature & rainfallAll life depends on temperature & rainfall

Global warmingGlobal warming – increase in the average – increase in the average temperature of the biospheretemperature of the biosphere

Evidence: Two hypothesesEvidence: Two hypotheses

1.1. This is part of a larger natural cycle of This is part of a larger natural cycle of climate changeclimate change

2.2. Humans are causing the warming trendHumans are causing the warming trend

Data shows that COData shows that CO2 concentrations have been concentrations have been rising for 200 yearsrising for 200 years

Human activities that add more COHuman activities that add more CO2 by: by:1. Burning fossil fuels1. Burning fossil fuels2. Cutting & burning forests2. Cutting & burning forests

Possible effects of Global WarmingPossible effects of Global Warming– Effects are based on computer modelsEffects are based on computer models– Sea levels may rise and flood coastal areasSea levels may rise and flood coastal areas– North America may experience more North America may experience more

droughtdrought– Long term climate change will affect Long term climate change will affect

ecosystemsecosystems

Value of a Healthy BiosphereValue of a Healthy Biosphere

Ecosystems provide goods & servicesEcosystems provide goods & services

To maintain healthy systems, every To maintain healthy systems, every individual must make wise choices in individual must make wise choices in the use & conservation of resourcesthe use & conservation of resources

Examples:Examples:

1.1. Use less waterUse less water

2.2. Plant TreesPlant Trees

3.3. Dispose of waste properlyDispose of waste properly

4.4. RecycleRecycle