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6/23/2020
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© 2015 John Wiley & Sons, Inc. All rights reserved.
Website:
websites.rcc.edu/halama
© 2015 John Wiley & Sons, Inc. All rights reserved.
Lecture 2
Energy and Ecosystems
6/23/2020
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© 2015 John Wiley & Sons, Inc. All rights reserved.
Lecture 2
1. Ecology
• The Ecological Hierarchy
2. Energy
• Laws of Thermodynamics
• Photosynthesis and Cellular Respiration
3. Flow of Energy Through Ecosystems
• Producers, Consumers and Decomposers, etc
• Path of Energy Flow: Who Eats Whom
© 2015 John Wiley & Sons, Inc. All rights reserved.
Ecology
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© 2015 John Wiley & Sons, Inc. All rights reserved.
Popular vs. Scientific
Ecology
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Ecology
•A branch of the Biological Sciences
• Study of one’s house - “logy” study of, “eco”
house
1. The study of interactions among and between
organisms in their environment, or
2. Study of the structure and function of nature
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Ecology
Biotic - living environment
–Includes all organisms (plants, animals, etc.)
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EcologyAbiotic - non living or physical environment
–Includes: sunlight, soil, precipitation, water,
pollutants, etc.
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Ecology
• Organisms interact with
other biotic components,
but also effect many
physical and chemical
processes
• Physical – walking on
soil, digging burrows,
gnawing trees, etc.
• Chemical – CO2, O2,
wastes
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Ecology
Ecological Hierarchy
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© 2015 John Wiley & Sons, Inc. All rights reserved.
Ecology Hierarchy
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Ecology
•Autecology – study of the organism, physiology, natural history, genetics, etc.
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Ecology Hierarchy
• Species - similar organisms that can freely
interbreed to produce fertile offspring
• Currently – 1.2 million
• Estimates – 8.7 million +
• Maybe more????
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Ecology Hierarchy
• Population - A group of organisms of the same
species that live in the same area at the same
time
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© 2015 John Wiley & Sons, Inc. All rights reserved.
Ecology Hierarchy
• Community - All the populations of different
species that live and interact in the same area
at the same time
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© 2015 John Wiley & Sons, Inc. All rights reserved.
Ecology Hierarchy
• Community - All the populations of different
species that live and interact in the same area
at the same time
© 2015 John Wiley & Sons, Inc. All rights reserved.
Ecology Hierarchy
• Ecosystem - A community (biotic) and its
physical (abiotic) environment
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Ecology Hierarchy
• Landscape - Several interacting ecosystems
(ex: bear hunting for salmon in a river, living
in adjacent forest)
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Ecology Hierarchy• Biome - an area of the planet that can be classified according to the plants and
animals that live in it.
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Ecology Hierarchy
• Biosphere – all the areas of the earth that
contain living organisms; the global sum of
all ecosystems.
© 2015 John Wiley & Sons, Inc. All rights reserved.
Part of Earth that contains living organisms
Ecology Hierarchy
Community and physical environment
Individuals
Group of same species
All populations of species in an area
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Biodiversity• The variety of life on Earth at all its levels, from genes to
ecosystems, and can encompass the evolutionary, ecological,
and cultural processes that sustain life.
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Ecology
• Biosphere contains all earth’s ecosystems but
these systems interact with the three main
abiotic realms:
• Atmosphere- gaseous
envelope surrounding earth
• Hydrosphere- earth’s supply
of water
• Lithosphere- soil and rock of
the earth’s crust
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Ecology
Lithosphere
Hydrosphere
Atmosphere
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Energy
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Energy
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Energy of Life• The ability or capacity to do work
• Chemical, Thermal (Heat), Mechanical (Motion),
Nuclear, Electrical, and Radiant/Solar (below)
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Energy Basics
• Energy exists as:
–Potential energy
(stored energy)
–Kinetic energy
(energy of motion)
Potential energy is converted to kinetic energy as
arrow is released from bow
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Thermodynamics• Study of energy and its transformations
(potential energy to kinetic energy, etc.)
• System- the object being studied
• Closed System- Does not
exchange energy with
surroundings (very rare in
nature)
• Open System- exchanges
energy with surroundings
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Laws of Thermodynamics
• First Law of Thermodynamics
–Energy cannot be created or destroyed; it can
change from one form to another
– a.k.a. Conservation of Energy
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Laws of Thermodynamics
• Second Law of Thermodynamics
–When energy is converted form one form to
another, some of it is lost as heat
• E.g. - Engine converts the
chemical energy of gasoline
into mechanical energy
• inefficiently…
mechanical energy + heat
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Energy Basics
• Solar radiation is the primary source of
energy on planet
• Powers ALL life on the planet (99%)
Plants turn solar
radiation into food
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All energy on this planet…
Mr. Sun
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Photosynthesis (in Plants)
• A biological process - energy from the sun (radiant energy) is transformed into chemical energy of carbohydrate (sugar) molecules (potential energy)
6 CO2 + 12 H2O + radiant energy
C6H12O6 + 6 H2O + 6 O2
Chlorophyll in plants
Potential Energy
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Photosynthesis (in Plants)
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Photosynthesis (in Plants)
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Cellular Respiration
• The process where the chemical energy captured in
photosynthesis (PE) is released (KE) within cells of
plants and animals
• This energy is then used for biological work
C6H12O6 + 6 O2 + 6 H2O
6 CO2 + 12 H2O + energy (kinetic energy)
© 2015 John Wiley & Sons, Inc. All rights reserved.
Photosynthesis and Cellular
Respiration
Represent an Open System
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Life without Sun
• 1970s – discovered hydrothermal vents in deep
ocean (200oC or 392oF)
• Rich ecosystem supported without light
• Bacteria perform
chemosynthesis
• Similar to
photosynthesis, but
use chemical (H2S)
not sunlight
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Energy Flow Through
Ecosystems
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Food Chain• A hierarchical sequence of organisms through
which matter and energy pass as one organism
eats another.
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Food Chains
The Path of Energy Flow
• Energy from food passes from one organism to
another based on their Trophic Level
Trophic Level - An organism’s position in a
food chain, which is determined by its feeding
relationships
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Energy Flows Through Ecosystems
• Passage of energy through an ecosystem
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Food Chains
The Path of Energy Flow
• First Trophic Level- Producers (plants)
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Food Chains
The Path of Energy Flow
• Second Trophic Level- Primary Consumers
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Food Chains
The Path of Energy Flow
• Third Trophic Level- Secondary Consumers
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Food Chains
The Path of Energy Flow
• Fourth Trophic Level- Tertiary Consumers
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Food Chains
The Path of Energy Flow
• Decomposers are present at all trophic levels
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Food Chains• Autotrophs = Producers (First Trophic Level)
–Auto “self ” and tropho “nourishment”
–Produce own food from inorganic material
–Ex: plants via photosynthesis and hydrothermal vent
bacteria via chemosynthesis
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Food Chains
• Heterotrophs = Consumers
–heter “different” and tropho “nourishment”
–Uses bodies of other organisms as food
• Omnivores – eat both plants and animals
• Carnivores – eat other animals
• Herbivores – eat plants
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© 2015 John Wiley & Sons, Inc. All rights reserved.
Food Chains
• Consumers of detritus (detritivores)
–Eat dead material such as leaves, carcasses, feces
–Ex: crabs, worms, millipedes, snails
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Food Chains• Decomposers or saprotrophs
– sapro “rotten” and tropho “nourishment”
–Breakdown dead organic material
–Release inorganic molecules (CO2 and nutrients) that
producers can use
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Food Web
• Food Web - feeding
relationships within a
community
–More complex than food
chain
–Still simplified compared
to nature
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Ecological Pyramids• Graphically represent the relative energy value
of each trophic level
–Important feature - large amount of energy is lost
as heat between trophic levels
–Only 10% of the energy available to the next level
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Pyramid of Numbers
• Illustrates the number of organisms at each
trophic level
• Fewer organisms occupy
each successive level
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Pyramid of Biomass
• Illustrates the total biomass at each successive
trophic level
• Biomass: measure of
the total amount of
living material
• ~90% reduction in
biomass through
trophic levels
• 100 to 10
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Pyramid of Energy
• Illustrates how much energy is present at each trophic
level and how much is transferred to the next level
• Most energy dissipates
between trophic levels
• Lost as heat and energy
to maintain each level
• Explains why there are
so few trophic levels
© 2015 John Wiley & Sons, Inc. All rights reserved.
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