ecosystems and energy - napa valley college 11… · · 2015-08-22biosphere contains earth’s...
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Ecosystems and Energy3
© 2015 John Wiley & Sons, Inc. All rights reserved.
Overview of Chapter 3
What is Ecology?
The Energy of Life
Laws of Thermodynamics
Photosynthesis and Cellular Respiration
Flow of Energy Through Ecosystems
Producers, Consumers and Decomposers
Path of Energy Flow: Who Eats Whom
Ecological Pyramids
Ecosystem Productivity
© 2015 John Wiley & Sons, Inc. All rights reserved.
Chesapeake Bay salt marshes
An estuary – semi-enclosed body of water
where freshwater drains into ocean
Tidal – gradual changed from fresh to salt water
Cordgrass dominates – brackish
Home to insects and birds,
nursery for fish
Very important buffer for
coasts against storms
© 2015 John Wiley & Sons, Inc. All rights reserved.
Ecology
Ecology
“logy” study of, “eco” house – study of one’s house
The study of interactions among and between
organisms in their abiotic environment
Biotic - living environment
Includes all organisms
Abiotic - non living or physical environment
Includes living space, sunlight, soil, precipitation,
etc.
© 2015 John Wiley & Sons, Inc. All rights reserved.
Ecology
Organisms interact
with biotic
components, but
also effect many
physical and
chemical processes
Physical – walking
on soil
Chemical – CO2, O2,
wastes
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Ecology
Ecologists are interested in the levels of life above that of organism
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Ecology Definitions
Species - A group of similar organisms whose members
freely interbreed to produce fertile offspring
Population - A group of organisms of the same species
that live in the same area at the same time
Community - All the populations of different species that
live and interact in the same area at the same time
Ecosystem - A community and its physical (abiotic)
environment
Landscape - Several interacting ecosystems (ex: bear
hunting for salmon in a river, living in adjacent forest)
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Part of Earth that contains living organisms
Ecology
Community and physical environment
Individuals
Group of same species
All populations of species in an area
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Ecology
Coral Reef communities – similar to rainforests
for number of species and productivity
Threatened with changing climate
How can communities
be protected from
warming waters?
What could loss mean?
© 2015 John Wiley & Sons, Inc. All rights reserved.
Ecology
Biosphere contains earth’s communities,
ecosystems and landscapes, and includes:
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 of Life
The ability or capacity to do work
Chemical, Thermal, Mechanical, Nuclear,
Electrical, and Radiant/Solar (below)
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Solar radiation is the primary source of energy
on planet
Energy of Life
Plants turn
solar radiation
into food
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Energy of Life
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
System- the object being studied
Closed System- Does
not exchange energy
with surroundings (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
Energy is absorbed by
water and plate, but
not lost
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Laws of Thermodynamics
Second Law of Thermodynamics
When energy is converted form one form to
another, some of it is degraded to heat
Heat is highly entropic (disorganized)
Water in sunlight will get
warmer
Engine converts chemical
energy of gasoline into
mechanical energy
inefficiently
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Photosynthesis
Biological process by which energy from the sun (radiant energy) is transformed into chemical energy of carbohydrate (sugar) molecules
6 CO2 + 12 H2O + radiant energy
C6H12O6 + 6 H2O + 6 O2
Chlorophyll in
plants
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Cellular Respiration
The process where the chemical energy
captured in photosynthesis is released within
cells of plants and animals
This energy is then used for biological work
C6H12O6 + 6 O2 + 6 H2O
6 CO2 + 12 H2O + energy
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Photosynthesis and Cellular
Respiration
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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
Passage of energy through an ecosystem
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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
Definition: An organism’s position in a food chain,
which is determined by its feeding relationships
First Trophic Level: Producers
Second Trophic Level: Primary Consumers
Third Trophic Level: Secondary Consumers
Decomposers are present at all trophic levels
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Food chains
Autotrophs = Producers
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
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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
Ex: fungus,
bacteria
Involved in
all aspects
of food
chains
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Food Web
Food web
visualizes
feeding
relationships
within a
community
More complex
than food chain
Still simplified
compared to
nature
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Humans and Antarctic food web
Base of web is algae, which
is eaten by krill
Krill are eaten by many
larger organisms
Wastes of whales resupply
nutrients for algae and krill
Ozone and climate change
are warming area
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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
Three main types
Pyramid of numbers
Pyramid of biomass
Pyramid of energy
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Pyramid of Numbers
Illustrates the number of organisms at each
trophic level
Fewer organisms
occupy each
successive level
Does not indicate:
biomass of organisms
at each level
amount of energy
transferred between
levels
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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.
Ecosystem Productivity
Gross Primary Productivity (GPP)
Total amount of energy that plants capture and
assimilate in a given period of time
Cellular respiration (R)
Plants use some energy of GPP to maintain
themselves
Plants respire too
Net Primary Productivity (NPP)
Productivity after respiration losses are subtracted
What is available as food for other organisms
© 2015 John Wiley & Sons, Inc. All rights reserved.
Ecosystem Productivity
GPP is similar to gross pay in paycheck
R is similar to taxes
NPP is similar to take home pay
Net Primary
Productivity
(plant growth per
area per time)
Gross Primary
Productivity (total
photosynthesis per
area per time)
Plant Cellular
Respiration
(per area per time)= -
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Variation in NPP by Ecosystem
Coral reefs are near
tropical rain forests
Humans consume a large
amount of global NPP
~30% but we make up
~0.5% of biomass
This represents a threat
to planet’s ability to
support both human and
non-human inhabitants
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Energy and Climate Change
Humans use a large portion of global NPP
If we use more biomass as energy rather than
fossil fuels, our use of NPP may increase
Corn as fuel, wood for heat
How can we balance our needs with other
organisms?
© 2015 John Wiley & Sons, Inc. All rights reserved.
ENVIRONEWS
Use of satellite imagery improves biomass
estimates of forests
Help protect tropic forests in developing countries
Developed countries pay to keep forests intact
Need to ground truth satellite models with
monitoring data from forest