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Title: ENVIRONMENTAL SCIENCE


1
ENVIRONMENTAL SCIENCE
CHAPTER 3Ecosystems What Are They and How Do
They Work?
2
Core Case Study Tropical Rainforests Are
Disappearing
  • Found near the equator
  • At one time covered 14 land surface, now covers
    only 2
  • 50 worlds known terrestrial plant and animal
    species
  • 50 destroyed or disturbed by humans
  • Cutting trees
  • Growing crops
  • Grazing cattle
  • Building settlements

3
Core Case Study Tropical Rainforests Are
Disappearing
  • Consequences of disappearing tropical rainforests
  • Decreased biodiversity as species become extinct
  • Accelerated global warming fewer trees to remove
    carbon dioxide from the atmosphere
  • Changes regional weather patterns can lead to
    increase in tropical grasslands

4
Sect. 3.1What Keeps Us and Other Organisms Alive?
  • Concepts to learn in 3.1
  • 1. The four major components of the earths
    life-support system are the atmosphere (air), the
    hydrosphere (water), the geosphere (rock, soil,
    sediment), and the biosphere (living things).
  • 2. Life is sustained by the flow of energy from
    the sun through the biosphere, the cycling of
    nutrients within the biosphere, and gravity.

5
Earth Has Four Major Life-Support Components
  • 1. Atmosphere Thin layer of gases, surrounding
    earths surface. Consists of
  • a. Troposphere contains the air we breathe
    (look up mixture) greenhouse gases
  • b. Stratosphere contains ozone, which filters
    UV rays, allowing for life to exist
  • Hydrosphere contains all of the water on or
    near the earths surface
  • a. Which water source makes up the largest
    component?

6
Earth Has Four Major Life-Support Components
  • Geosphere 3 parts
  • a. Core (extremely hot, mostly liquid rock)
  • b. Mantle (mostly rock)
  • c. Crust (thin outer layer)
  • Biosphere includes all the parts of the
    atmosphere, hydrosphere geosphere where life is
    found.
  • a. ecology focuses on this area
  • b. It is a very thin layer of the earth
    atmosphere

7
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

8
Solar Energy Reaching the Earth (one way energy
flow)
  • Suns energy reaches us as electromagnetic waves,
    seen as
  • 1. Visible light
  • 2. UV radiation
  • 3. Heat
  • Natural greenhouse effect What effect does it
    have on the earths energy?

9
Solar Energy Reaching the Earth (one way energy
flow)
  • The flow of energy in from the sun will equal
    the flow of energy out into the environment /
    atmosphere
  • 1. Group discussion
  • a. How does this happen?
  • b. Is this energy recycled?

10
Sect. 3.2 What Are the Major Components of an
Ecosystem?
  • Some organisms produce the nutrients they need.
  • Some get the nutrients they need by consuming
    other organism.
  • Some recycle nutrients back to producers by
    decomposing the wastes and remains of organisms.

11
Ecology
  • Ecology How organisms interact with biotic
    (living) and abiotic (non-living) environments
  • Ecology focuses on levels of matter ranging from
    the atomic level to the entire biosphere. 5
    levels
  • 1. Organisms
  • 2. Populations
  • 3. Communities
  • 4. Ecosystems
  • 5. Biosphere

12
Nonliving Components of Ecosystems
  • Abiotic non-living components of ecosystems,
    which includes
  • Water
  • Air
  • Nutrients
  • Solar energy
  • Rocks
  • Heat

13
Living Components of Ecosystems
  • Biotic living components of ecosystems,
    including
  • Plants
  • Animals
  • Microbes
  • Dead organisms
  • Waste products of dead organisms
  • Waste products of living organisms

14
Trophic Levels
  • Trophic Levels feeding levels assigned to
    every organism in an ecosystem
  • 1. Producers- called autotrophs
  • a. Produce food thru photosynthesis
  • 2. Consumers called heterotrophs
  • a. Primary consumers herbivores (eat plants)
  • b. Secondary consumers carnivores that eat
    herbivores
  • Third-level consumers carnivores that eat
    carnivores
  • Omnivores eat both plants and animals

15
Additional Trophic Levels
  • Decomposers
  • Release nutrients from the dead bodies of plants
    and animals
  • Detrivores
  • Feed on the waste or dead bodies of organisms

16
Production and Consumption of Energy
  • Photosynthesis
  • Carbon dioxide water solar energy ?glucose
    oxygen
  • Aerobic respiration
  • Glucose oxygen ? carbon dioxide water energy

17
Energy Flow and Nutrient Recycling
  • Ecosystems are sustained through
  • 1. One-way energy flow from the sun
  • 2. Nutrient recycling

18
Science Focus Invisible Organisms
  • Microorganisms/Microbes
  • Bacteria
  • Protozoa
  • Fungi
  • Phytoplankton

19
Science Focus Invisible Organisms
  • Microbes can cause disease
  • Malaria
  • Athletes foot
  • Microbes are also beneficial
  • Intestinal flora
  • Purify water
  • Phytoplankton remove carbon dioxide from the
    atmosphere

20
Sect. 3.3 What Happens to Energy in an
Ecosystem?
  • As energy flows through ecosystems in food chains
    and webs, the amount of chemical energy available
    to organisms at each succeeding feeding level
    decreases.

21
Energy Flow in Ecosystems
  • The chemical energy stored in all organisms flows
    thru ecosystems from one trophic level to another
  • Food chain
  • Sequence of organisms, each of which serves as a
    source of food for the next
  • Includes food production, feeders, and
    decomposition
  • Food web
  • A more complex network of interconnected food
    chains.
  • Consumers feed on more than one organism
  • Organisms are eaten/decomposed by more than one
    organism

22
Usable Energy by Trophic Level
  • Energy flow thru food webs follows the second law
    of thermodynamics energy lost as heat
  • Biomass The dry weight of all organic matter
    contained in its organisms
  • 1. Each trophic level has one, but biomass
    decreases with increasing trophic level
  • Ecological efficiency of energy transferred
    thru food chains is typically 10.
  • See Pyramid of energy flow, fig. 3-10 pg 47
  • 1. shows variable energy transfer efficiency
    between trophic levels

23
Ecosystem efficiency in producing plant matter
  • The amount of biomass an ecosystem is capable of
    producing is determined by its efficiency in
    capturing solar energy and converting it to
    chemical energy in food.
  • Gross Primary Productivity (GPP) rate at which
    an ecosystems producers (mostly plants) convert
    solar energy into chemical energy (stored in
    biomass of their tissues)
  • 1. plants do use some of their produced energy
    for their own respiration

24
Two Kinds of Primary Productivity
  • Net primary productivity (NPP) rate at which
    producers use photosynthesis to produce store
    chemical energy minus the rate at which they use
    some energy thru aerobic respiration.
  • Planets NPP limits number of consumers
  • Humans use, waste, or destroy between 10-55 of
    earths total potential NPP
  • Human population is less than 1 of total biomass
    of earths consumers

25
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.

26
Biogeochemical Cycles
  • Also called Nutrient cycles
  • All cycles have a place where the nutrients
    accumulate, called reservoirs
  • These nutrient cycles connect all organisms
    through time!
  • Cycles are all driven by
  • 1. solar energy
  • 2. gravity

27
Hydrologic Cycle
  • Water cycle is powered by the sun. Involves 3
    processes
  • Evaporation (from bodies of water)
  • Precipitation (rain, snow, sleet)
  • Transpiration water evaporation from plant
    surfaces
  • Over bodies of water most water vapor comes
    from the oceans 84
  • Over land 90 of water reaching the atmosphere
    comes from transpiration

28
The Water Cycle
  • As water moves thru its cycle, some will
    temporarily stored in
  • 1. Living parts of the ecosystems
  • a. EX Plants roots pull water into plants,
    which is stored in chemical compounds, then moved
    thru the ecosystem by transpiration and by plants
    being consumed
  • 2. glaciers
  • 3. Aquifers stores of groundwater under
    layers of rock, sand gravel

29
The Water cycle
  • An important feature of the water cycle is that
    as water passes thru, there is a natural renewal
    of water quality.
  • 1. In a sense, it is like a water filter
    which filters out impurities.
  • Lots of water is visible. How much of it is
    available to us as freshwater, usable for
    consumption?
  • about 0.024 of the total volume of water

30
Science Focus Waters Unique Properties
  • Holds water molecules together (called hydrogen
    bonding)
  • Water is liquid over a wide temperature range
  • It changes temperature slowly
  • Requires large amounts of energy to evaporate

31
Additional Unique Properties of Water
  • 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

32
Carbon Cycle
  • Based on carbon dioxide (CO2)
  • It circulates thru the biosphere, hydrosphere
    atmosphere
  • CO2 makes up 0.038 of atmospheres volume
  • Major cycle processes that carbon cycles thru
  • Aerobic respiration
  • Photosynthesis
  • Fossil fuel combustion and deforestation (both
    can lead to a build-up of CO2)
  • Fossil fuels add CO2 to the atmosphere will cause
    an increase in temperature (and a decrease in CO2
    will decrease surface temperatures)

33
Nitrogen Cycle
  • Multicellular plants and animals cannot directly
    absorb and use atmospheric nitrogen (N2), which
    makes up most of the atmosphere (78)
  • 1. Nitrogen is extremely important to the
    building of proteins, vitamins nucleic acids
  • 2. Bacteria are our friends, because they
    convert N2 to a form which can be absorbed
  • 3. There are 2 processes involved with this
    conversion Nitrogen Fixation and Nitrification
  • 4. There are 2 additional processes in the
    nitrogen cycle Ammonification and
    Denitrification

34
Nitrogen Cycle
  • Nitrogen fixation specialized bacteria in soil
    and green algae in aquatic environments combine
    N2 with H2 to produce ammonia (NH3)
  • 1. Some is converted to NH4 ions, and is
    absorbed by plants
  • Nitrification NH3 and NH4 is converted by
    special bacteria into nitrate ions (NO3-)
  • 1. plants will use it to make proteins (amino
    acids) nucleic acids vitamins

35
Nitrogen Cycle
  • Ammonification The process that decomposer
    bacterias accomplish when they eat decaying
    plants animals, converting their
    nitrogen-containing compounds into ammonia or
    ammonium ions.
  • Denitrification A specialized process of
    bacteria in watery soil sediments of lakes
    oceans, that convert ammonia ammonia ions back
    into N2 gas, to be returned back into the
    nitrogen cycle again.

36
Phosphorus Cycle
  • Does not cycle through the atmosphere
  • Its obtained mostly from terrestrial rock
    formations ocean floor sediments
  • 1. water runs over rocks, slowly eroding off
    phosphorus salts (containing phosphate ions
    PO43-)
  • It is the slowest moving of all the cycles
  • The presence of phosphorus is a limiting factor
    on land and in freshwater ecosystems
  • Biologically important for producers and
    consumers
  • 1. part of energy transfer molecules ADP ATP
  • 2. part of nucleic acids

37
Sulfur Cycle
  • Most sulfur stored in rocks and minerals, in
    ocean sediments
  • Enters atmosphere through
  • 1. Volcanic eruptions and processes
  • 2. Anaerobic decomposition in swamps,
    bogs, and tidal flats
  • 3. Sea spray
  • 4. Dust storms
  • 5. Forest fires

38
Sulfur Cycle
  • Biologically important to producers consumers
  • 1. sulfur is an essential part of proteins
  • 2. It is absorbed by plants thru their roots

39
3-5 How Do Scientists Study Ecosystems?
  • Scientists use field research, laboratory
    research, and mathematical and other models to
    learn about ecosystems.

40
Field Research
  • Collecting data in the field by scientists that
    are actively in the mud
  • Remote sensing devices are also used to
    detect/scan the earths surface
  • Geographic information systems (GIS) used to
    interpret display the information obtained thru
    remote sensing devices.

41
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?
  • Is best for doing controlled experiments!

42
Scientific Studies of Ecosystems
  • Models can be used
  • 1. Mathematical
  • 2. Computer simulations
  • Models need to be fed real data collected in the
    field- baseline data before any meaningful
    interpretations can take place.
  • Models must also determine relationships among
    the key variables

43
Baseline Data to Measure Earths Health
  • A baseline of data is needed in order to monitor
    any changes over time
  • Many ecosystems lack this baseline data
  • Call for massive program to develop baseline data
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