Ecosystems: Components, Energy Flow, and Matter Cycling

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Ecosystems Components, Energy Flow, and Matter
Cycling

• APES ClassOctober 2004
• All things come from earth, and to earth they
  all returnMenander

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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?

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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

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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
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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.

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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

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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

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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

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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

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Ecosystem Boundaries Ecotones
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Principles of Ecological Factors

• Biotic vs. Abiotic Factors
• Law of Tolerance
• Limiting Factorsexamples on land in H2O

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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

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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.

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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

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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

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Detritivores vs Decomposers stop
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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

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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

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Energy Flow and Matter Cycling in Ecosystems

• Food Chains vs. Food Webs
• KEY There is little if no matter waste in
  natural ecosystems!

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Generalized Food Web of the Antarctic
Note Arrows Go in direction Of energy flow
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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

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Pyramids of Energy and Matter

• Pyramid of Energy Flow
• Pyramid of Biomass

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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?

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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

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What are the most productive Ecosystems?
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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

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How do ecologists learn about ecosystems?

• Field Research (stop)
• Descriptive
• Manipulative
• Remote Sensing
• GIS
• Laboratory Experiments
• Systems Analysis
• Develop models to simulate ecosystems

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GIS and Systems Analysis
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Ecosystem Services and Sustainability
Lessons From Nature!

• Use Renewable Solar Energy As Energy Source
• Recycle the chemical nutrients needed for life

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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