environmental science
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13e. ENVIRONMENTAL SCIENCE. CHAPTER 3: Ecosystems: What Are They and How Do They Work?. Rainforest. http://www.youtube.com/watch?v=Ws6m46AAbQQ. Core Case Study In class assignment. Tropical Rainforests are Disappearing Where are tropical rainforests found? - PowerPoint PPT PresentationTRANSCRIPT
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ENVIRONMENTAL SCIENCE 13e
CHAPTER 3:Ecosystems: What Are They and How Do They Work?
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Rainforest
• http://www.youtube.com/watch?v=Ws6m46AAbQQ
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Core Case StudyIn class assignment
• Tropical Rainforests are Disappearing• Where are tropical rainforests found?• How much of the earth’s land surface do they cover?
Studies indicate they contain up to ______ of the world’s known terrestrial plant and animal species
• Define ecosystems• About ________ of these forests have been destroyed by
humans
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Core Case Study: Tropical Rainforests Are Disappearing (2)
• Consequences of disappearing tropical rainforests1. __________ as species become extinct
2. ______________: fewer trees to remove carbon dioxide from the atmosphere
3. _______________: can lead to increase in tropical grasslands
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• Define Ecological Tipping Point-
• What is the ecological tipping point for this case study?
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Fig. 3-1, p. 39
Satellite image of the loss of tropical rain forest near the Bolivian City of Santa Cruz. Why is this an example of Natural Capital degradation?
June 1975 May 2003
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3-1 What Keeps Us and Other Organisms Alive?
• Concept 3-1A The four major components of the earth’s life-support system are the atmosphere (air), the hydrosphere (water), the geosphere (rock, soil, sediment), and the biosphere (living things).
• Concept 3-1B Life is sustained by the flow of energy from the sun through the biosphere, the cycling of nutrients within the biosphere, and gravity.
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Earth Has Four Major Life-Support Components
• Atmosphere
• Hydrosphere
• Geosphere
• Biosphere
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Fig. 3-2, p. 41
RockCrust
Atmosphere
Vegetationand animals
Biosphere
Mantle
Lithosphere
Soil
Geosphere(crust, mantle, core)
Mantle
Core
Crust(soil and rock)
Biosphere(living organisms)
Atmosphere(air)
Hydrosphere(water)
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Three Factors Sustain Life on Earth
1) One-way flow of high-quality energy from the sun
2) Cycling of matter or nutrients through parts of the biosphere
3) Gravity
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Solar Energy Reaching the Earth
• Electromagnetic waves– Visible light
– UV radiation
– Heat
• Natural greenhouse effect
• Energy in = energy out
• Human-enhanced global warming
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Solarradiation
Radiated byatmosphereas heat
Reflected byatmosphere
Mostabsorbedby ozone
Absorbedby the earth
Greenhouseeffect
Visiblelight
UV radiation
Heat radiatedby the earthHeat
Troposphere
Lower Stratosphere(ozone layer)
Fig. 3-3, p. 41
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Greenhouse Effect Animation
• http://www.youtube.com/watch?v=CxUK2TizQ4g&feature=related
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3-2 What Are the Major Components of an Ecosystem?
• Concept 3-2 Some organisms produce the nutrients they need, others get the nutrients they need by consuming other organisms, and some recycle nutrients back to producers by decomposing the wastes and remains of organisms.
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Ecology
• How organisms interact with biotic (pertaining to life) and abiotic environment (non-living)
• Focuses on specific levels of matter:– Organisms– Populations– Communities– Ecosystems – Biosphere
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Smallest unit of a chemical element that exhibits its chemical properties
Atom
Molecule Chemical combination of two or more atoms of the same or different elements
CellThe fundamental structural and functional unit of life
Organism An individual living being
Population A group of individuals of the same species living in a particular place
Community Populations of different species living in a particular place, and potentially interacting with each other
Stepped Art
Ecosystem A community of different species interacting with one another and with their nonliving environment of matter and energy
Biosphere Parts of the earth's air,water, and soil where life is found
Fig. 3-4, p. 42
_______________________________
Which 5 levels does ecology focus on?
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Living and Nonliving Components (1)
• Abiotic – Water
– Air
– Nutrients
– Solar energy
– Rocks
– Heat
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Living and Nonliving Components (2)
• Biotic– Plants
– Animals
– Microbes
– Dead organisms
– Waste products of dead organisms
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Soluble mineralnutrients
Producers
Decomposers
Secondaryconsumer(fox)
Carbon dioxide (CO2)
Primaryconsumer(rabbit)
Producer
Oxygen (O2)Precipitation
Water
Fig. 3-5, p. 43
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Trophic Levels (feeding levels)(1)
• Producers – autotrophs–Photosynthesis
• Consumers – heterotrophs– Primary - herbivores– Secondary - carnivores– Third-level (tertiary)– quartenary
• Omnivores
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Trophic Levels (2)
• Decomposers (ex. bacteria and fungi)
– Release nutrients from the dead bodies of plants and animals
• Detrivores (ex. earthworms, some insects, vultures)
– Feed on the waste or dead bodies of organisms
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Time progression Powder broken down by
decomposers into plantnutrients in soil
MushroomWoodreducedto powder
Dry rotfungus
Termite andcarpenterant work
DecomposersDetritus feeders
Carpenterant galleriesBark beetle
engravingLong-hornedbeetle holes
Fig. 3-6, p. 44
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Production and Consumption of Energy
• Photosynthesis• Carbon dioxide + water + solar energy
glucose + oxygen
6CO2 + 6H2O + solar E C6H12O6 + 6O2
• Aerobic respiration (opposite)
• Glucose + oxygen carbon dioxide + water + energy
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Energy Flow and Nutrient Recycling
• Ecosystems sustained through:– One-way energy flow from the sun
– Nutrient recycling
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Abiotic chemicals(carbon dioxide,
oxygen, nitrogen,minerals)
Decomposers(bacteria, fungi)
Consumers(herbivores,carnivores)
Producers(plants)
Solarenergy
Heat
Heat Heat
Heat Heat
Fig. 3-7, p. 45
Main components ofan ecosystem
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3-3 What Happens to Energy in an Ecosystem?
• Concept 3-3 As energy flows through ecosystems in food chains and webs, the amount of chemical energy available to organisms at each succeeding feeding level decreases.
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Energy Flow in Ecosystems
• Trophic levels
• Food chain – Sequence of organisms, each of which
serves as a source of food for the next
• Food web – Network of interconnected food chains
– More complex than a food chain
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Fourth TrophicLevel
Third TrophicLevel
Second TrophicLevel
First TrophicLevel
Heat
Heat
HeatHeatHeat
Tertiaryconsumers
(top carnivores)
Secondaryconsumers(carnivores)
Primaryconsumers(herbivores)
Producers(plants)
Solarenergy
Heat
Heat
Decomposers and detritus feeders
Fig. 3-8, p. 46
Food chain
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Humans
Squid
Herbivorouszooplankton
Phytoplankton
Krill
Fish
Petrel
Adeliepenguin
Sperm whale
Emperorpenguin
Leopardseal
Killerwhale
Crabeaterseal
Elephantseal
Blue whale
Carnivorousplankton
Fig. 3-9, p. 46
AntarcticFood Web
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Usable Energy by Trophic Level
• Energy flow follows the second law of thermodynamics – energy lost as heat
• Biomass decreases with increasing trophic level
• Ecological efficiency – typically 10%
• Pyramid of energy flow
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Tertiaryconsumers(human)
Secondaryconsumers(perch)
Producers(phytoplankton)
Primaryconsumers(zooplankton)
Usable energy availableat each trophic level
(in kilocalories)
HeatDecomposers
10
100
1,000
10,000
Heat
Heat
Heat
Heat
Fig. 3-10, p. 47
What happens to amount of usable energy as you go up each level?
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Two Kinds of Primary Productivity
• Gross primary productivity (GPP): the rate at which an ecosystems producers convert solar E into chemical E in the form of biomass found in their tissues
• Net primary productivity (NPP)- rate at which producer’s use photosynthesis to produce and store chemical E minus the rate at which they use some of this stored E thru aerobic respiration
• Planet’s NPP limits number of consumers• Humans use, waste, or destroy 10-55% of earth’s total
potential NPP• Human population is less than 1% of total biomass of
earth’s consumers
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Temperate forest
Aquatic Ecosystems
Open ocean
Continental shelfLakes and streams
Estuaries
Terrestrial Ecosystems
Extreme desert
Desert scrub
Tundra (arctic and alpine)
Temperate grasslandWoodland and shrubland
Agricultural landSavanna
Northern coniferous forest (taiga)
Swamps and marshesTropical rain forest
Fig. 3-11, p. 48
Average net primary productivity (kcal/m2/yr)
800 1,600 2,400 3,200 4,000 4,800 5,600 6,400 7,200 8,000 8,800 9,600
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3-4 What Happens to Matter in an Ecosystem?
• Concept 3-4 Matter, in the form of nutrients, cycles within and among ecosystems and in the biosphere, and human activities are altering these chemical cycles.
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Biogeochemical Cycles
• Nutrient cycles• Reservoirs- temporary storage sites for nutrients
• Connect all organisms through time
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Hydrologic Cycle
• Water cycle is powered by the sun1. Evaporation
2. Precipitation
3. Transpiration - evaporates from plant surfaces
• Water vapor in the atmosphere comes from the oceans – 84%
• Over land, most of water reaching the atmosphere comes from transpiration
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Increasedfloodingfrom wetlanddestruction
Condensation
Evaporationfrom ocean
Climatechange
Infiltrationand percolationinto aquifer
Condensation
Ocean
Lakes andreservoirs
Ice andsnow
Surfacerunoff
Surface runoff
Aquiferdepletion fromoverpumping
Pointsourcepollution
Reduced recharge ofaquifers and floodingfrom covering land with crops and buildings
Groundwatermovement (slow)
Runoff
Precipitationto land
Precipitationto ocean
Transpirationfrom plants
Evaporationfrom land
Fig. 3-12, p. 49
Processes
Processes affected by humans
Reservoir
Pathway affected by humans
Natural pathway
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Science Focus: Water’s Unique Properties (1)
• Holds water molecules together – hydrogen bonding
• Liquid over a wide temperature range
• Changes temperature slowly
• Requires large amounts of energy to evaporate
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Science Focus: Water’s Unique Properties (2)
• Dissolves a variety of compounds
• Filters out UV light from the sun
• Adheres to a solid surface – allows capillary action in plants
• Expands as it freezes
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Carbon Cycle
• Based on carbon dioxide (CO2)• CO2 makes up 0.038% of atmosphere
volume • Major cycle processes
– Aerobic respiration– Photosynthesis– Fossil fuel combustion and deforestation
• Fossil fuels add CO2 to the atmosphere and contribute to global warming
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Respiration
Forest fires
Deforestation
Diffusion
Carbon dioxidedissolved in ocean
Carbonin limestone or
dolomite sediments
Marine food websProducers, consumers,
decomposers
Transportation
Carbon dioxidein atmosphere
Carbonin animals
(consumers)
Plants(producers)
Animals(consumers)
Decomposition
Respiration
Compaction
Carbonin fossil
fuels
Carbonin plants
(producers)
Burningfossil fuels
Photosynthesis
Fig. 3-13, p. 51
Processes
Reservoir
Pathway affected by humans
Natural pathway
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Nitrogen Cycle
• Multicellular plants and animals cannot utilize atmospheric nitrogen (N2)
• Nitrogen fixation
• Nitrification
• Ammonification
• Denitrification
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Nitrogenin atmosphere
Nitrogenloss to deepocean sediments
Nitrogen oxidesfrom burning fuel
Nitratesfrom fertilizer
runoff anddecomposition
Nitrogenin oceansediments Ammonia
in soil
Volcanicactivity
Electricalstorms Nitrogen
in animals(consumers)
Bacteria
Nitratein soil
Nitrogenin plants
(producers)
Nitrificationby bacteria
Denitrificationby bacteria
Uptake by plantsDecomposition
Fig. 3-14, p. 52
Processes
Reservoir
Pathway affected by humans
Natural pathway
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Phosphorus Cycle
• Does not cycle through the atmosphere• Obtained from terrestrial rock
formations• Limiting factor on land and in
freshwater ecosystems• Biologically important for producers
and consumers
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Seabirds
Phosphatein shallowocean sediments
Bacteria
Animals(consumers)
Plants(producers)
Runoff
Runoff Runoff
Phosphatesin fertilizer
Phosphatesin mining waste
Phosphatesin sewage
Phosphatedissolved inwater
Erosion
Phosphatein deep ocean
sediments
Oceanfood chain
Platetectonics
Phosphatein rock
(fossil bones,guano)
Fig. 3-15, p. 53
Processes
Reservoir
Pathway affected by humans
Natural pathway
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Sulfur Cycle
• Most sulfur stored in rocks and minerals• Enters atmosphere through:
– Volcanic eruptions and processes– Anaerobic decomposition in swamps, bogs,
and tidal flats– Sea spray– Dust storms– Forest fires
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Fig. 3-16, p. 54
Refiningfossil fuels
Sulfurin animals
(consumers)
Sulfurin plants
(producers)
Sulfur dioxidein atmosphere
Sulfurin soil, rock
and fossil fuels
Sulfurin oceansediments
Dimethylsulfide
a bacteriabyproduct
Processes
Reservoir
Pathway affected by humans
Natural pathway
Decay
Sulfuric acidand Sulfate
deposited asacid rain
Uptakeby plantsDecay
Mining andextraction
Burningcoal
Smelting
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3-5 How Do Scientists Study Ecosystems?
• Concept 3-5 Scientists use field research, laboratory research, and mathematical and other models to learn about ecosystems.
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Field Research
• Collecting data in the field by scientists
• Remote sensing devices
• Geographic information systems (GIS)
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Laboratory Research
• Simplified model ecosystems– Culture tubes– Bottles – Aquariums– Greenhouses– Chambers with controllable abiotic factors
• How well do lab experiments correspond with the greater complexity of real ecosystems?
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Scientific Studies of Ecosystems
• Models– Mathematical
– Computer simulations
• Models need to be fed real data collected in the field- baseline data
• Models must determine relationships among key variables
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Baseline Data to Measure Earth’s Health
• Needed to measure changes over time
• Lacking for many ecosystems
• Call for massive program to develop baseline data
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Core Case StudyIn class assignment
• Tropical Rainforests are Disappearing• Where are tropical rainforests found? Near equator• How much of the earth’s land surface do they cover? No more than 6%
Studies indicate they contain up to _50%__ of the world’s known terrestrial plant and animal species
• Define ecosystems: communities of organisms interacting with one another and with the physical environment of matter and energy in which they live
• About _half__ of these forests have been destroyed by humans
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Core Case Study: Tropical Rainforests Are Disappearing (2)
• Consequences of disappearing tropical rainforests1. Decreased biodiversity as species become
extinct
2. Accelerated global warming: fewer trees to remove carbon dioxide from the atmosphere
3. Changes regional weather patterns: can lead to increase in tropical grasslands
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• Ecological tipping point- Point in development of an environmental problem where a threshold level is reached, causing an irreversible shift in the behavior of a natural system.
• What is the ecological tipping point for this case study? Once the tropical rain forests are cleared, local weather patterns change so that rainforests can no longer be supported; areas become much less diverse tropical grasslands