ENERGY
FLOW THROUGH ECOSYSTEMS
THE FLOW
OF ENERGY
HEAT ENERGY
(Lower Energy,
Longwave)
INPUT ENERGY
(Higher Energy,
Shortwave)
WORK ENERGY
(Higher – Lower Energy)
ENERGY CONVERSION PROCESS
(Physical or Chemical)
Dr. Jeffrey R. Corney, Managing Director
of the University of Minnesota’s Cedar Creek Ecosystem Science Reserve
ENERGY FLOW
Global Net Primary Productivity
NASA
ENERGY FLOW
Key to Productivity: Energy & Water
(…and Nutrients)
Wikipedia
Annual Mean Solar Energy Intercepting Surface of Earth
NASA
ENERGY FLOW
Eco-Regions of Earth
OCEAN
LAND
ENERGY FLOW
Total Global Net Productivity
Ecosystem Type
OPEN OCEAN
TROPICAL RAIN FOREST
TEMPERATE DECIDUOUS FOREST
SAVANNA
BOREAL CONIFEROUS FOREST
CONTINENTAL SHELF
AGRICULTURAL LAND
TEMPERATE GRASSLAND
WOODLAND & SHRUBLAND
ESTUARIES
SWAMPS & MARSHES
DESERT SCRUB
LAKES & STREAMS
TUNDRA (ARCTIC & ALPINE)
EXTREME DESERT
per R.H. Whittaker
Average Global Net Primary Productivity
(billion kcal/yr)
ENERGY FLOW
Global Net Productivity per Unit Area
Ecosystem Type
ESTUARIES
SWAMPS & MARSHES
TROPICAL RAIN FOREST
TEMPERATE DECIDUOUS FOREST
BOREAL CONIFEROUS FOREST
SAVANNA
AGRICULTURAL LAND
WOODLAND & SHRUBLAND
TEMPERATE GRASSLAND
LAKES & STREAMS
CONTINENTAL SHELF
TUNDRA (ARCTIC &
ALPINE)
OPEN OCEAN
DESERT SCRUB
EXTREME DESERT
per R.H. Whittaker
Average Net Primary Productivity
(kcal/m2/yr)
ENERGY FLOW
THE BIG IDEA: Solar Energy…
How Stuff Works
…Builds Organisms, Powers Life Functions, and Drives
Earth’s Water, Carbon, Oxygen & Nutrient Cycles
ENERGY FLOW
Food “Chain” vs. “Food Web”
Science Bob
ENERGY FLOW
Trophic Levels
ENERGY FLOW
Trophic Levels as “Food Web”
ENERGY FLOW
Trophic Level Pyramids
ENERGY FLOW
U of Virginia
Trophic Pyramid to Eltonian
Energy Transfer Pyramid
The starting point is
PHOTOSYNTHESIS
ENERGY FLOW
Photosynthesis Cellular Level
World Book Encyclopedia
ENERGY FLOW
Photosynthesis in Chloroplasts
ENERGY FLOW
Site of Photosynthesis: Chlorophyll
ENERGY FLOW
The Calvin Cycle
The Simple Home School
ENERGY FLOW
Product of Photosynthesis
ENERGY FLOW
Transfer of Energy from Sun to Cell
From here…
…to here!
ENERGY FLOW
Biological Energy Storage & Release
PHOTOSYNTHESIS
ENERGY (in) + 6CO2 + 6H2O
C6H12O6 + 6O2
“Sugar”
Solar Energy > ATP
AEROBIC RESPIRATION
C6H12O6 + 6O2
“Sugar”
6CO2 + 6H2O + ENERGY (out)
Chemical Energy > ATP
J. Corney
ENERGY FLOW
Conversion of Photon Energy to Work
HEAT ENERGY
(Lower Energy,
Longwave)
INPUT ENERGY
(Higher Energy,
Shortwave)
WORK ENERGY
(Higher – Lower Energy)
ENERGY CONVERSION PROCESS
(Physical or Chemical)
ENERGY FLOW
Where It All Begins…
NOTE:
1 Watt = 1 Joule/second
1 Joule = 0.00024 kcal
1kcal = 1 Calorie
The Sun Radiates 63,000,000 W/m2 of Energy from Its Surface into Space
ENERGY FLOW
Then, On to Earth…
(93 Million Miles in about 8 Minutes)
1,367 W/m2 or 0.002% of the Sun’s Total Energy Output Reaches Earth’s Orbit
ENERGY FLOW
Earth’s Sphere Intercepting Energy
343 W/m2 or 0.0005% of the Sun’s Total Energy Output Enters Earth’s Atmosphere
ENERGY FLOW
Earth’s Gross Solar Insolation
Wikipedia
Annual Mean Solar Insolation Intercepting Top of Earth’s Atmosphere
ENERGY FLOW
Earth’s Energy Budget
49% REFLECTED
51% RE-RADIATED
51% ABSORBED
Jason Project
175 W/m2 or 0.00025% of the Sun’s Total Energy Output Is Absorbed by Earth’s Surface
ENERGY FLOW
Solar Spectrum Reaching Earth
343 W/m2
High energy, short
wavelength
Sun
REACHING EARTH
343 W/m2
LEAVING EARTH
Nonionizing radiation
Ionizing radiation
Cosmic
rays
Gamma
rays
Far
Near Visible
ultraviolet ultraviolet waves
waves
waves
X rays
10%
10-14
Wavelength
in meters
(not to scale)
10-12
W/m2
10-8
103
REFLECTED BY
ATMOSPHERE
& SURFACE
Low energy, long
wavelength
50%
10-7
Near
infrared
waves
Far
infrared
waves
microwaves
TV
waves
Radio
waves
40%
10-6
W/m2
10-5
175
ABSORBED BY
EARTH’S SURFACE
10-3
W/m2
10-2 10-1
65
ABSORBED BY
ATMOSPHERE
& CLOUDS
1
ENERGY FLOW
Net Solar Insolation at Surface
Wikipedia
Annual Mean Solar Insolation Intercepting Surface of Earth
ENERGY FLOW
Photosynthetically Active Radiation
(PAR)
Sun
High energy, short
wavelength
REACHING EARTH
LEAVING EARTH
Nonionizing radiation
Ionizing radiation
Cosmic
rays
Gamma
rays
Far
Near Visible
ultraviolet ultraviolet waves
waves
waves
X rays
10%
10-14
Wavelength
in meters
(not to scale)
10-12
10-8
Low energy, long
wavelength
50%
10-7
Near
infrared
waves
Far
infrared
waves
microwaves
TV
waves
Radio
waves
40%
10-6
10-5
10-3
10-2 10-1
1
AVAILABLE FOR PHOTOSYNTHESIS (PAR)
Global Annual Avg. = 70W/m2
[0.0001% of Total Solar Energy Output]
Range (latitude/season) = 0 - 240W/m2
[e.g. = mid-lat./summer = 160W/m2]
ENERGY FLOW
Cross-Section of Energy for 1-m2
(4-month Summer Growing Season)*
160 W/m2
Average PAR during Summer at 43oN = 160 W/m2
1 Watt = 1 Joule/second
1 Joule = 0.00024 kcal
160 W/m2
1 kcal = 1 Calorie
160 W/m2
160 W/m2
*Over a four-month summer season in a
Temperate Deciduous Forest at 43oN Latitude
(generalized from Hubbard Brook Experimental Forest study)
0.04
kcal/sec/m2
J. Corney
ENERGY FLOW
Energy Flow Into an Ecosystem
400,000 kcal/m2 *
(Summer Avg. = 160 W/m2)
SOLAR ENERGY POTENTIALLY
AVAILABLE FOR PHOTOSYNTHESIS
*Over a four-month summer season in a
Temperate Deciduous Forest at 43oN Latitude
(generalized from Hubbard Brook Experimental Forest study)
J. Corney
390,000 kcal/m2
Absorbed by Earth and
re-radiated as heat
ENERGY FLOW
Energy Flow Through an Ecosystem
ECOSYSTEM
PRODUCERS
6,000
700
10,000
kcal/m2
70
10
100
1o
2o
200
SOLAR
ENERGY
3,000
10,000
kcal/m2
CONSUMERS
1,000
7
3o
20
3
DECOMPOSERS
3,223
HEAT
ENERGY
J. Corney
ENERGY FLOW
Energy Flow Through a Trophic Level
AVAILABLE from
PRODUCERS
1,000 kcal
(from ~1,000 plants/m2)
CONSUMED by
PRIMARY CONSUMERS (1o)
(for ~100 grasshoppers/m2)
10 kcal
Feces
2 kcal
7 kcal
Respiration
HEAT
1 kcal
DECOMPOSERS
J. Corney
Growth
AVAILABLE for
SECONDARY CONSUMERS (2o)
1 kcal X 100 grasshoppers = 100 kcal
(for ~10 birds/m2)
ENERGY FLOW
Primary Productivity
GROSS PRIMARY PRODUCTIVITY (GPP)
uses available (PAR) Solar Energy, Water,
and Carbon Dioxide to produce Glucose
Range = 0.01% - 5% of PAR (2.5% average)
[~ 0.00000005% of Total Solar Output]
Mr. G’s
NET PRIMARY PRODUCTIVITY (NPP) =
Glucose produced during photosynthesis (GPP) –
Glucose used during plant Respiration (R)
Range = 20% – 60% of GPP (40% average)
Mr. G’s
ENERGY FLOW
Secondary Productivity
GSP ranges from 20% to 90% of
Incoming Food Energy
Mr. G’s
NSP ranges from 1% to 40% of
Incoming Food Energy
Mr. G’s
ENERGY FLOW
Efficiency of Energy Transfer
INGESTION EFFICIENCY: Energy Consumed as Food
Herbivores = 5% - 50% (25% average)
Carnivores = 25% - 100% (60% average)
ASSIMILATION EFFICIENCY: Energy Digested & Absorbed (- feces)
Herbivores = 20% - 50% (30% average)
Carnivores = 70% - 90% (80% average)
PRODUCTION EFFICIENCY: Energy Used to Grow Biomass
Invertebrates = 30% - 40% (35% average)
Vertebrates: Ectotherms = 5% - 15% (10% average)
Vertebrates: Endotherms = 1% - 2% (1.5% average)
TROPHIC-LEVEL ENERGY TRANSFER EFFICIENCY: Available for Next Consumer
Trophic-Level Energy Transfers = 2% - 24% (10% average) > “The 10% Rule”
ENERGY FLOW
Energy Transfer Eltonian Pyramid
Tertiary
Consumers
0.0025% of PAR
0.010% of GPP available
Secondary
Consumers
0.025% of PAR
0.10% of GPP available
Primary
Consumers
0.25% of PAR
Primary
Producers
10% of GPP available
Net Primary Productivity (NPP) = 1.0% of PAR or 40% of GPP
Gross Primary Productivity (GPP) = 2.5% of PAR
Solar Energy Available for Photosynthesis (PAR) = 100%*
J. Corney
*Photosynthetically Active Radiation (PAR) = 40% of Net Surface Solar Insolation
ENERGY FLOW
Example from Actual Temperate Forest
McGraw Hill
ENERGY FLOW
Example from a Sub-tropical Ecosystem
Wadsworth
Click and Learn
Pearson
ENERGY FLOW
Examples from Other Ecosystems
Mr. G’s
Mr. G’s
ENERGY FLOW
Examples of Actual Efficiencies
SIDE BAR
A Human at Rest Uses…
1,200 Calories/day
or
5,000,000 Joules/day
or
60 Joules/second
…just for Respiration!
McGraw Hill
NUTRIENT CYCLING
Then There’s the Carbon Cycle…
Animals &
Dead Material
Dept. of Energy
N
UTRIENT
CYCLING
ENERGY
FLOW
Carbon Cycling Through an Ecosystem
ECOSYSTEM
CO2
CO2
PRODUCERS
OTHER
SOURCES
C6H12O6
1o
CONSUMERS
2o
CO2
3o
DECOMPOSERS
C6H12O6
SOIL “SINK”
J. Corney
N
UTRIENT
CYCLING
ENERGY
FLOW
Energy Flow & Carbon Cycling
J. Corney
FOR NEXT TIME…
Nitrogen Cycle Linked to Carbon Cycle
Dept. of Energy
Wikipedia
WHAT’S GOING ON IN THE SOIL?
Dr. Jeffrey R. Corney, Managing Director
University of Minnesota
Cedar Creek Ecosystem Science Reserve
2660 Fawn Lake Dr NE
East Bethel, MN 55005
(763) 434-5131
www.cedarcreek.umn.edu
jcorney@umn.edu
Trophic-Level Energy Transfer Eltonian Pyramid
Decomposers
Tertiary
Consumers
Secondary
Consumers
Primary
Consumers
Primary
Producers
Solar Energy Available for Photosynthesis (PAR)
J. Corney
ENERGY FLOW
PRODUCERS
CONSUMERS
1o
SOLAR
ENERGY
2o
3o
DECOMPOSERS
HEAT
ENERGY
J. Corney
ENERGY FLOW
PRODUCERS
6,000
700
10,000
kcal/m2
CONSUMERS
1,000
2o
200
SOLAR
ENERGY
70
100
1o
3,000
10,000
kcal/m2
20
10
3o
7
3
DECOMPOSERS
3,223
HEAT
ENERGY
J. Corney
CARBON CYCLE
CO2
CO2
PRODUCERS
OTHER
SOURCES
C6H12O6
2o
3o
DECOMPOSERS
C6H12O6
CO2
ATMOSPHERE
1o
CONSUMERS
SOIL “SINK”
J. Corney