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Ecosystems: Components, Energy Flow, and Matter Cycling

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Title: Ecosystems: Components, Energy Flow, and Matter Cycling


1
Ecosystems Components, Energy Flow, and Matter
Cycling
  • APES ClassOctober 2004
  • All things come from earth, and to earth they
    all returnMenander

2
Key Questions
  • What is ecology?
  • What are the major parts of the earths life
    support systems?
  • What are the major components of an ecosystem?
  • What happens to matter and energy in ecosystems?
  • How do we study ecosystems?
  • What are ecosystem services?
  • How do they affect the sustainability of the
    earths life support systems?

3
Ecology and the levels of organization of matter
  • EcologyGreek oikos meaning house
  • Study of how organisms interact with one another
    and their non-living environment (biotic and
    abiotic components)
  • Studies connections in nature on the thin life
    supporting membrane of air, water, and soil
  • Levels of Organization of Matter
  • Subatomic to biosphere

4
Ecosystem Organization
  • Organisms
  • Made of cells
  • Eukaryotic vs Prokaryotic
  • Species
  • Groups of organisms that resemble one another in
    appearance, behavior, and genetic make up
  • Sexual vs Asexual reproduction
  • Production of viable offspring in nature
  • 1.5 million named 10-14 million likely
  • Populations
  • Genetic diversity
  • Communities
  • Ecosystems
  • Biosphere

Fig. 4.2, p. 66
5
Earths Life Support Systems
  • Troposphere
  • To 11 miles
  • Air is here
  • Stratosphere
  • 11 to 30 miles
  • Ozone layer
  • Hydrosphere
  • Solid, liquid, and gaseous water
  • Lithosphere
  • Crust and upper mantle
  • Contains non-renewable res.

6
Sustaining Life on Earth
  • One way flow of high quality energy
  • The cycling of matter (the earth is a closed
    system)
  • Gravity
  • Causes downward movement of matter

7
The Source of High Quality Energy
  • Energy of sun lights and warms the planet
  • Supports photosyn.
  • Powers the cycling of matter
  • Drives climate and weather that distribute heat
    and H2O

8
Fate of Solar Energy
  • Earth gets 1/billionth of suns output of nrg
  • 34 is reflected away by atmosphere
  • 66 is absorbed by chemicals in atm re-radiated
    into space
  • Visible light, Infrared radiation (heat), and a
    small amount of UV not absorbed by ozone reaches
    the atmosphere
  • Energy warms troposphere and land
  • Evaporates water and cycles it along with gravity
  • Generates winds
  • A tiny fraction is captured by photosynthesizing
    organisms
  • Natural greenhouse effect vs. Global Warming

9
Ecosystem Concepts
  • Biomes
  • Land regions characterized by a specific climate
    with species adapted to it
  • Role of Climate
  • Main factor in determining what types of life
    will thrive in a given land area
  • Climate vs. Weather
  • Aquatic vs. Terrestrial life zones

10
Ecosystem Boundaries Ecotones
11
Principles of Ecological Factors
  • Biotic vs. Abiotic Factors
  • Law of Tolerance
  • Limiting Factorsexamples on land in H2O

12
Limiting Factors on Land in H2O
  • Terrestrial
  • Sunlight
  • Temperature
  • Precipitation
  • Soil nutrients
  • Fire frequency
  • Wind
  • Latitude
  • Altitude
  • Aquatic/Marine
  • Light penetration
  • Water clarity
  • Water currents
  • Dissolved nutrient concentrations
  • Esp. N, P, Fe
  • Dissolved Oxygen concentration
  • Salinity

13
Major Ecosystem Components
  • Abiotic Components
  • Water, air, temperature, soil, light levels,
    precipitation, salinity
  • Sets tolerance limits for populations and
    communities
  • Some are limiting factors that structure the
    abundance of populations
  • Biotic Components
  • Producers, consumers, decomposers
  • Plants, animals, bacteria/fungi
  • Biotic interactions with biotic components
    include predation, competition, symbiosis,
    parasitism, commensalism etc.

14
Biotic Components of Ecosystems
  • Producers (autotrophs)
  • Source of all food
  • Photosynthesis
  • Consumersheterotroph
  • Aerobic respiration
  • Anaerobic respiration
  • Methane, H2S
  • Decomposers
  • Matter recyclers
  • Release organic compounds into soil and water
    where they can be used by producers

15
Trophic Levels
  • Each organism in an ecosystem is assigned to a
    feeding (or Trophic) level
  • Primary Producers
  • Primary Consumers (herbivores)
  • Secondary Consumer (carnivores)
  • Tertiary Consumers
  • Omnivores
  • Detritus feeders and scavengers
  • Directly consume tiny fragments of dead stuff
  • Decomposers
  • Digest complex organic chemicals into inorganic
    nutrients that are used by producers
  • Complete the cycle of matter

16
Detritivores vs Decomposers stop
17
Biodiversity 101
  • Renewable resourcenatures insurance policy
    against disaster!
  • Many forms all encompassed under the term
    Biodiversity
  • Species Diversity the variety of different
    species
  • Genetic Diversity genetic variability among
    individuals within each species
  • Ecological Diversity the variety of different
    ecosystems
  • Functional Diversity ecosystem services such as
    matter cycling, pollination, waste recycling,
    pest control, purification etc needed for the
    survival of species and communities

18
Loss of Biodiversity? Who cares?
  • Gives us food, fibers, energy, raw materials,
    chemicals, medicines
  • Essential to economy and our well-being!
  • Every species here today
  • Contains genetic information that represents
    thousands to millions of years of adaptation to
    the earths changing conditions
  • Is the raw material for all future adaptations
  • Loss of species reduces the availability of
    ecosystem services and decreases the ability of
    species, communities, and ecosystems to adapt.
  • Biodiversity is natures insurance policy against
    disasters

19
Energy Flow and Matter Cycling in Ecosystems
  • Food Chains vs. Food Webs
  • KEY There is little if no matter waste in
    natural ecosystems!

20
Generalized Food Web of the Antarctic
Note Arrows Go in direction Of energy flow
21
Food Webs and the Laws of matter and energy
  • Food chains/webs show how matter and energy move
    from one organism to another through an ecosystem
  • Each trophic level contains a certain amount of
    biomass (dry weight of all organic matter)
  • Chemical energy stored in biomass is transferred
    from one trophic level to the next
  • With each trophic transfer, some usable energy is
    degraded and lost to the environment as low
    quality heat
  • Thus, only a small portion of what is eaten and
    digested is actually converted into an organisms
    bodily material or biomass (WHAT LAW ACCOUNTS FOR
    THIS?)
  • Ecological Efficiency
  • The of usable nrg transferred as biomass from
    one trophic level to the next (ranges from 5-20
    in most ecosystems)
  • Thus, the more trophic levels or steps in a food
    chain, the greater the cumulative loss of useable
    energy

22
Pyramids of Energy and Matter
  • Pyramid of Energy Flow
  • Pyramid of Biomass

23
Implications of Pyramids.
  • Why could the earth support more people if the
    eat at lower trophic levels?
  • Why are food chains and webs rarely more than
    four or five trophic levels?
  • Why do marine food webs have greater ecological
    efficiency and therefore more trophic levels than
    terrestrial ones?
  • Why are there so few top level carnivores?
  • Why are these species usually the first to suffer
    when the the ecosystems that support them are
    disrupted?

24
Primary Productivity
  • NPPGPP-respiration rate
  • GPP RATE at which producers convert solar energy
    into chemical energy as biomass
  • Rate at which producers use photosynthesis to fix
    inorganic carbon into the organic carbon of their
    tissues
  • These producers must use some of the total
    biomass they produce for their own respiration
  • NPP Rate at which energy for use by consumers is
    stored in new biomass (available to consumers)
  • Units Kcal/m2/yr or g/m2/yr
  • How do you measure it?
  • Most productive vs. least productive

25
What are the most productive Ecosystems?
26
Fate of Primary Productivity and Some important
questions
  • Since producers are ultimate source of all food,
    why shouldnt we just harvest the plants of the
    worlds marshes?
  • Why dont we clear cut tropical rainforests to
    grow crops for humans?
  • Why not harvest primary producers of the worlds
    vast oceans?
  • Vitousek et al Humans now use, waste, or
    destroy about 27 of earths total potential NPP
    and 40 of the NPP of the planets terrestrial
    ecosystems

27
How do ecologists learn about ecosystems?
  • Field Research (stop)
  • Descriptive
  • Manipulative
  • Remote Sensing
  • GIS
  • Laboratory Experiments
  • Systems Analysis
  • Develop models to simulate ecosystems

28
GIS and Systems Analysis
29
Ecosystem Services and Sustainability
Lessons From Nature!
  • Use Renewable Solar Energy As Energy Source
  • Recycle the chemical nutrients needed for life

30
Matter Cycles
  • You are responsible for knowing the water,
    carbon, nitrogen, sulfur, and phosphorus cycles
  • Know major sources and sinks
  • Know major flows
  • Know how human activities are disrupting these
    cycles
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