Ecosystems: What Are They and How Do They Work?

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Ecosystems What Are They and How Do They Work?

• Chapter 3

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Core Case Study Tropical Rain Forests Are
Disappearing

• Cover about 2 of the earths land surface
• Contain about 50 of the worlds known plant and
  animal species
• Disruption will have three major harmful effects
• Reduce biodiversity
• Accelerate global warming
• Change regional weather patterns

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Natural Capital Degradation Satellite Image of
the Loss of Tropical Rain Forest
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3-1 What Is Ecology?

• Concept 3-1 Ecology is the study of how
  organisms interact with one another and with
  their physical environment of matter and energy.

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Cells Are the Basic Units of Life

• Cell Theory All living things are composed of
  cells
• Eukaryotic Cell Surrounded by a membrane and
  has a distinct nucleus (DNA), organelles
  surrounded by membrane
• Prokaryotic Cell Surrounded by a membrane, no
  distinct nucleus, no internal parts surrounded by
  membranes
• Bacteria

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Structure of a Eukaryotic Call and a Prokaryotic
Cell
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Animation Prokaryotic and eukaryotic cells
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Species Make Up the Encyclopedia of Life

• Species Set of individuals that can mate and
  produce fertile offspring
• Estimated 4 100 million species
• 10 14 million
• 1.75 Million species identified
• Insects make up most of the known species

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Ecologists Study Connections in Nature

• Ecology Study of how organisms interact with
  their living and non-living environment
  connections in nature
• Levels of Organization
• Population Group of individuals of the same
  species, living in the same place at the same
  time
• Genetic Diversity
• Community All of the populations of different
  species that live in a particular place
• Ecosystem Community of different species
  interacting with one another and environment
• Biosphere All the parts of Earths air, water,
  and soil

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Stepped Art
Fig. 3-3, p. 52
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Active Figure Levels of organization
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3-2 What Keeps Us and Other Organisms Alive?

• Concept 3-2 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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The Earths Life-Support System Has Four Major
Components

• Atmosphere Thin spherical envelope of gases
  surrounding Earths surface
• Troposphere majority of air we breathe,
  nitrogen and oxygen 1 greenhouse gases
• Stratosphere Ozone which filters out UV
  radiation
• Hydrosphere All water on Earths surface
  liquid, ice, vapor
• Geosphere Core, mantle, crust
• Biosphere Where life exists

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Vegetation and animals
Atmosphere
Biosphere
Soil
Rock
Crust
Lithosphere
Mantle
Biosphere (living organisms)
Atmosphere (air)
Core
Crust (soil and rock)
Mantle
Hydrosphere (water)
Geosphere (crust, mantle, core)
Fig. 3-6, p. 55
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Life Exists on Land and in Water

• Biomes Large regions such as forests, deserts,
  and grasslands distinct climates and certain
  species
• Aquatic life zones
• Freshwater life zones
• Lakes and streams
• Marine life zones
• Coral reefs
• Estuaries
• Deep ocean

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Average annual precipitation
100125 cm (4050 in.) 75100 cm (3040
in.) 5075 cm (2030 in.) 2550 cm (1020
in.) below 25 cm (010 in.)
Denver
Baltimore
San Francisco
St. Louis
Appalachian Mountains
Coastal mountain ranges
Sierra Nevada
Great American Desert
Rocky Mountains
Great Plains
Mississippi River Valley
Deciduous forest
Coastal chaparral and scrub
Coniferous forest
Desert
Coniferous forest
Prairie grassland
Fig. 3-7, p. 55
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Three Factors Sustain Life on Earth

• One-way flow of high-quality energy beginning
  with the sun
• Cycling of matter or nutrients
• Gravity

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What Happens to Solar Energy Reaching the Earth?

• Electromagnetic Waves - UV, visible, and IR
  energy
• Radiation
• Absorbed by ozone
• Absorbed by the earth
• Reflected by the earth
• Radiated by the atmosphere as heat
• Natural greenhouse effect

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Solar radiation
Reflected by atmosphere
Radiated by atmosphere as heat
UV radiation
Lower Stratosphere (ozone layer)
Most absorbed by ozone
Troposphere
Visible light
Heat radiated by the earth
Heat
Absorbed by the earth
Greenhouse effect
Fig. 3-8, p. 56
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Active Figure Energy flow from the Sun to Earth
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3-3 What Are the Major Components of an
Ecosystem?

• Concept 3-3A Ecosystems contain living (biotic)
  and nonliving (abiotic) components.
• Concept 3-3B Some organisms produce the
  nutrients they need, others get their nutrients
  by consuming other organisms, and some recycle
  nutrients back to producers by decomposing the
  wastes and remains of organisms.

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Ecosystems Have Living and Nonliving Components

• Abiotic
• Water
• Air
• Nutrients
• Rocks
• Heat
• Solar energy
• Biotic
• Living and once living plants, animals, microbes
• Dead organisms, dead parts or organisms, waste

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Major Biotic and Abiotic Components of an
Ecosystem
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Range of Tolerance for a Population of Organisms

• INSERT FIGURE 3-10 HERE

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Several Abiotic Factors Can Limit Population
Growth

• Limiting factor principle
• Too much or too little of any abiotic factor can
  limit or prevent growth of a population, even if
  all other factors are at or near the optimal
  range of tolerance
• Population Control Scientific Principle of
  Sustainability is achieved

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Producers and Consumers Are the Living Components
of Ecosystems (1)

• Producers, autotrophs
• Photosynthesis
• Carbon Dioxide Water Solar Energy ? Glucose
  Oxygen
• Chemosynthesis
• Convert simple inorganic compounds into more
  complex nutrients without sunlight
• Consumers, heterotrophs
• Primary (Herbivores)
• Secondary (Carnivores feed on Herbivores)
• Third and higher level (Carnivores feed on
  Carnivores)
• Omnivores
• Decomposers
• Release nutrients from dead bodies to be reused
  by producers

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Active Figure Energy flow
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Animation Energy flow in Silver Springs
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Producers and Consumers Are the Living Components
of Ecosystems (2)

• Detritivores
• Feed on Waste or Dead Bodies
• Aerobic respiration Fueling Life Processes
• Glucose Oxygen ? Carbon Dioxide Water
  Energy
• Anaerobic respiration, fermentation
• Breakdown of glucose without oxygen
• End products are methane gas, ethyl alcohol,
  acetic acid, hydrogen sulfide

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Detritivores and Decomposers on a Log
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Energy Flow and Nutrient Cycling Sustain
Ecosystems and the Biosphere

• One-way energy flow
• Nutrient cycling of key materials
• Decomposers and detritus feeders break down
  organic matter into simpler nutrients that are
  reused by producers

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The Main Structural Components of an Ecosystem
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Science Focus Many of the Worlds Most
Important Species Are Invisible to Us

• Microorganisms
• Bacteria
• Protozoa
• Fungi

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Active Figure Roles of organisms in an ecosystem
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Active Figure Matter recycling and energy flow
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3-4 What Happens to Energy in an Ecosystem?

• Concept 3-4A Energy flows through ecosystems in
  food chains and webs.
• Concept 3-4B 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 Flows Through Ecosystems in Food Chains
and Food Webs

• Food chain
• Sequence of organisms, each which serves as a
  source of food or energy for the next
• How chemical energy and nutrients move from one
  organism to another
• Each use and transfer of energy results in loss
  of some energy as heat
• Food web
• Complex network of food chains

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A Food Chain
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Simplified Food Web in the Antarctic
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Usable Energy Decreases with Each Link in a Food
Chain or Web

• Biomass
• Dry weight of all organic matter contained in its
  organisms
• Transferred from one level to another in food web
• Ecological efficiency
• Percentage of usable chemical energy transferred
  as biomass from one level to another
• 2 to 40 - 10 Typical
• Pyramid of energy flow

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Pyramid of Energy Flow
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Some Ecosystems Produce Plant Matter Faster Than
Others Do

• Gross primary productivity (GPP)
• Rate at which an ecosystems producers convert
  solar energy into chemical energy as biomass in
  their tissues
• Energy production per unit area over given time
• Net primary productivity (NPP)
• Producers must use own chemical energy in biomass
  for respiration
• Rate at which producers use photosynthesis to
  produce and store chemical energy rate at which
  they use stored energy through aerobic
  respiration
• Ecosystems and life zones differ in their NPP

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Estimated Annual Average NPP in Major Life Zones
and Ecosystems
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3-5 What Happens to Matter in an Ecosystem?

• Concept 3-5 Matter, in the form of nutrients,
  cycles within and among ecosystems and the
  biosphere, and human activities are altering
  these chemical cycles.

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Nutrients Cycle in the Biosphere

• Biogeochemical cycles, nutrient cycles
• Hydrologic
• Carbon
• Nitrogen
• Phosphorus
• Sulfur
• Connect past, present , and future forms of life

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Water Cycles through the Biosphere

• Natural renewal of water quality three major
  processes
• Evaporation
• Precipitation
• Transpiration
• Alteration of the hydrologic cycle by humans
• Withdrawal of large amounts of freshwater at
  rates faster than nature can replace it
• Clearing vegetation
• Increased flooding when wetlands are drained

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Hydrologic Cycle Including Harmful Impacts of
Human Activities
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Global warming
Condensation
Condensation
Ice and snow
Evaporation from land
Evaporation from ocean
Transpiration from plants
Precipitation to land
Surface runoff
Increased flooding from wetland destruction
Precipitation to ocean
Runoff
Reduced recharge of aquifers and flooding from
covering land with crops and buildings
Lakes and reservoirs
Point source pollution
Infiltration and percolation into aquifer
Surface runoff
Groundwater movement (slow)
Ocean
Aquifer depletion from overpumping
Processes
Processes affected by humans
Reservoir
Pathway affected by humans
Natural pathway
Fig. 3-17, p. 66
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Science Focus Waters Unique Properties

• Properties of water due to hydrogen bonds
  between water molecules
• Exists as a liquid over a large range of
  temperature
• Changes temperature slowly
• High boiling point 100C
• Adhesion and cohesion
• Expands as it freezes
• Solvent
• Filters out harmful UV

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Carbon Cycle Depends on Photosynthesis and
Respiration

• Link between photosynthesis in producers and
  respiration in producers, consumers, and
  decomposers
• Additional CO2 added to the atmosphere
• Tree clearing
• Burning of fossil fuels

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Natural Capital Carbon Cycle with Major Harmful
Impacts of Human Activities
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Carbon dioxide in atmosphere
Respiration
Photosynthesis
Burning fossil fuels
Forest fires
Animals (consumers)
Diffusion
Deforestation
Plants (producers)
Carbon in plants (producers)
Transportation
Respiration
Carbon in animals (consumers)
Carbon dioxide dissolved in ocean
Carbon in fossil fuels
Decomposition
Marine food webs Producers, consumers, decomposers
Carbon in limestone or dolomite sediments
Compaction
Processes
Reservoir
Pathway affected by humans
Natural pathway
Fig. 3-18, p. 68
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Nitrogen Cycles through the Biosphere Bacteria
in Action (1)

• Nitrogen fixed
• Lightning
• Nitrogen-fixing bacteria
• Nitrification
• Denitrification

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Nitrogen Cycles through the Biosphere Bacteria
in Action (2)

• Human intervention in the nitrogen cycle
• Additional NO and N2O
• Destruction of forest, grasslands, and wetlands
• Add excess nitrates to bodies of water
• Remove nitrogen from topsoil

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Nitrogen Cycle in a Terrestrial Ecosystem with
Major Harmful Human Impacts
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Processes
Nitrogen in atmosphere
Reservoir
Pathway affected by humans
Natural pathway
Denitrification by bacteria
Electrical storms
Nitrogen in animals (consumers)
Nitrogen oxides from burning fuel and using
inorganic fertilizers
Volcanic activity
Nitrification by bacteria
Nitrogen in plants (producers)
Nitrates from fertilizer runoff and decomposition
Decomposition
Uptake by plants
Nitrate in soil
Nitrogen loss to deep ocean sediments
Nitrogen in ocean sediments
Bacteria
Ammonia in soil
Fig. 3-19, p. 69
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Annual Increase in Atmospheric N2 Due to Human
Activities
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300
Projected human input
250
200
Total human input
150
Nitrogen input (teragrams per year)
Fertilizer and industrial use
100
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Nitrogen fixation in agroecosystems
Fossil fuels
0
2050
2000
1980
1960
1940
1920
1900
Year
Fig. 3-20, p. 70
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Phosphorus Cycles through the Biosphere

• Cycles through water, the earths crust, and
  living organisms
• May be limiting factor for plant growth
• Impact of human activities
• Clearing forests
• Removing large amounts of phosphate from the
  earth to make fertilizers

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Phosphorus Cycle with Major Harmful Human Impacts
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Processes
Reservoir
Pathway affected by humans
Natural pathway
Phosphates in sewage
Phosphates in fertilizer
Plate tectonics
Phosphates in mining waste
Runoff
Runoff
Sea birds
Runoff
Phosphate in rock (fossil bones, guano)
Erosion
Ocean food webs
Animals (consumers)
Phosphate dissolved in water
Phosphate in shallow ocean sediments
Phosphate in deep ocean sediments
Plants (producers)
Bacteria
Fig. 3-21, p. 71
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Sulfur Cycles through the Biosphere

• Sulfur found in organisms, ocean sediments, soil,
  rocks, and fossil fuels
• SO2 in the atmosphere
• H2SO4 and SO4-
• Human activities affect the sulfur cycle
• Burn sulfur-containing coal and oil
• Refine sulfur-containing petroleum
• Convert sulfur-containing metallic mineral ores

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Natural Capital Sulfur Cycle with Major Harmful
Impacts of Human Activities
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Sulfur dioxide in atmosphere
Sulfuric acid and Sulfate deposited as acid rain
Smelting
Burning coal
Refining fossil fuels
Sulfur in animals (consumers)
Dimethyl sulfide a bacteria byproduct
Sulfur in plants (producers)
Mining and extraction
Uptake by plants
Decay
Sulfur in ocean sediments
Decay
Processes
Sulfur in soil, rock and fossil fuels
Reservoir
Pathway affected by humans
Natural pathway
Fig. 3-22, p. 72
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Active Figure Carbon cycle
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Active Figure Hydrologic cycle
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Animation Linked processes
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Active Figure Nitrogen cycle
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Animation Phosphorus cycle
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Active Figure Sulfur cycle
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3-6 How Do Scientists Study Ecosystems?

• Concept 3-6 Scientists use field research,
  laboratory research, and mathematical and other
  models to learn about ecosystems.

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Some Scientists Study Nature Directly

• Field research muddy-boots biology
• New technologies available
• Remote sensors
• Geographic information system (GIS) software
• Digital satellite imaging
• 2005, Global Earth Observation System of Systems
  (GEOSS)

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Some Scientists Study Ecosystems in the
Laboratory

• Simplified systems carried out in
• Culture tubes and bottles
• Aquaria tanks
• Greenhouses
• Indoor and outdoor chambers
• Supported by field research

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Some Scientists Use Models to Simulate Ecosystems

• Computer simulations and projections
• Field and laboratory research needed for baseline
  data

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We Need to Learn More about the Health of the
Worlds Ecosystems

• Determine condition of the worlds ecosystems
• More baseline data needed