1. Students:
Turn in to period box
Mark & Recapture Activity
Honor Code signatures
Costa Rica meeting slips? – return to me please
Mark & recapture make-ups
1st 2nd 4th
Adam F. Ryan L. Hank H.
Ayla S.
-Absent yesterday for LL check
1st 2nd 8th
Adam F. Aseel A. Andrea D.
Susie O. Ayla S.
-Early release tomorrow – bring your calculator
Cell phones in bin

2. Chapter 54: Ecosystems What is an ecosystem?
All the organisms living within an area & all the abiotic factors
they interact with
Energy flows through while chemicals cycle within an ecosystem

3. Figure 54.2 An overview of energy and nutrient dynamics in an ecosystem
Microorganisms
and other
detritivores
Detritus
Primary producers
Primary consumers
Secondary
consumers
Tertiary consumers
Heat
Sun
Key
Chemical cycling
Energy flow

4. Chapter 54: Ecosystems What is an ecosystem?
All the organisms living within an area & all the abiotic factors
they interact with
Energy flows through while chemicals cycle within an ecosystem
What is primary productivity?
Amount of light energy converted to chemical energy by autotrophs
What is the difference between Gross PP & Net PP?
GPP = total primary productivity
Amount of light energy converted to chemical energy
by photosynthesis
NPP = GPP – respiration (energy used by organisms)
Storage of chemical energy available to consumers

5. Figure 54.4 Net primary production of different ecosystems
Lake and stream
Open ocean
Continental shelf
Estuary
Algal beds and reefs
Upwelling zones
Extreme desert, rock, sand, ice
Desert and semidesert scrub
Tropical rain forest
Savanna
Cultivated land
Boreal forest (taiga)
Temperate grassland
Tundra
Tropical seasonal forest
Temperate deciduous forest
Temperate evergreen forest
Swamp and marsh
Woodland and shrubland 10 20 30 40 50 60
500
1,000
1,500
2,000
2,500 5 15 25
(a) Percentage of Earth’s surface area
(b) Average net primary production (g/m2/yr)
(c) Percentage of Earth’s net primary production
Key
Marine
Freshwater (on continents)
Terrestrial
5.2
0.3
0.1
4.7
3.5
3.3
2.9
2.7
2.4
1.8
1.7
1.6
1.5
1.3
1.0
0.4
125
360
3.0 90
2,200
900
600
800
700
140
1,600
1,200
1,300
250
5.6
1.2
0.9
0.04 22
7.9
9.1
9.6
5.4
0.6
7.1
4.9
3.8
2.3
65.0
24.4
Earth’s surface = 70% H2O

6. Figure 54.5 Regional annual net primary production for Earth
180
120W
60W 0
60E
120E
North Pole
60N
30N
Equator
30S
60S
South Pole

7. Chapter 54: Ecosystems What is an ecosystem?
All the organisms living within an area & all the abiotic factors
they interact with
Energy flows through while chemicals cycle within an ecosystem
What is primary productivity?
Amount of light energy converted to chemical energy by autotrophs
What is the difference between Gross PP & Net PP?
GPP = total primary productivity
Amount of light energy converted to chemical energy
by photosynthesis
NPP = GPP – respiration (energy used by organisms)
Storage of chemical energy available to consumers
What happens to energy at each trophic level?

8. Figure 54.10 Energy partitioning within a link of the food chain
Plant material
eaten by caterpillar
Cellular
respiration
Growth (new biomass)
Feces
100 J
33 J
200 J
67 J

9. Chapter 54: Ecosystems What is an ecosystem?
All the organisms living within an area & all the abiotic factors
they interact with
Energy flows through while chemicals cycle within an ecosystem
What is primary productivity?
Amount of light energy converted to chemical energy by autotrophs
What is the difference between Gross PP & Net PP?
GPP = total primary productivity
Amount of light energy converted to chemical energy
by photosynthesis
NPP = GPP – respiration (energy used by organisms)
Storage of chemical energy available to consumers
What happens to energy at each trophic level?
5. What does the “Pyramid of Net Production” look like?

10. Figure 54.11 An idealized pyramid of net production
Tertiary
consumers
Secondary
Primary
producers
1,000,000 J of sunlight
10 J
100 J
1,000 J
10,000 J
- <1% harnessed
by autotrophs
Rule of 10 = only 10% of stored energy reaches the next trophic level
Leads to the “Pyramid of Biomass”…..

11. Figure 54.12 Pyramids of biomass (standing crop)
Trophic level
Dry weight
(g/m2)
Tertiary consumers
1.5
Secondary consumers 11
Primary consumers 37
Primary producers
809
(a) Most biomass pyramids show a sharp decrease in biomass at successively higher trophic levels, as illustrated by data from a bog at Silver Springs, Florida.
(b) In some aquatic ecosystems, such as the English Channel, a small standing crop of primary producers (phytoplankton) supports a larger standing crop of primary consumers (zooplankton).
Trophic level
Primary producers (phytoplankton)
Primary consumers (zooplankton)
Dry weight
(g/m2) 21 4
Pyramids of net productivity & biomass give rise to…..”pyramid of numbers”

12. Figure 54.13 A pyramid of numbers
Trophic level
Number of individual organisms
Primary producers
Tertiary consumers
Secondary consumers
Primary consumers 3
354,904
708,624
5,842,424

13. Fig. 54.14 Relative food energy available to the human population at different trophic levels
Secondary
consumers
Primary
producers
- more energy is available to vegetarians than carnivores

14. Chapter 54: Ecosystems What is an ecosystem?
All the organisms living within an area & all the abiotic factors
they interact with
Energy flows through while chemicals cycle within an ecosystem
What is primary productivity?
Amount of light energy converted to chemical energy by autotrophs
What is the difference between Gross PP & Net PP?
GPP = total primary productivity
Amount of light energy converted to chemical energy
by photosynthesis
NPP = GPP – respiration (energy used by organisms)
Storage of chemical energy available to consumers
What happens to energy at each trophic level?
What does the “Pyramid of Net Production” look like?
Let’s consider chemical cycling within an ecosystem….

15. Figure 54.17 Nutrient Cycles
Transport
over land
Solar energy
Net movement of
water vapor by wind
Precipitation
over ocean
Evaporation
from ocean
Evapotranspiration
from land
Percolation
through
soil
Runoff and
groundwater
CO2 in atmosphere
Photosynthesis
Cellular
respiration
Burning of
fossil fuels
and wood
Higher-level
consumers
Primary
Detritus
Carbon compounds
in water
Decomposition
THE WATER CYCLE
THE CARBON CYCLE

16. THE NITROGEN CYCLE THE PHOSPHORUS CYCLE
N2 in atmosphere
Denitrifying
bacteria
Nitrifying
Nitrification
Nitrogen-fixing
soil bacteria
bacteria in root
nodules of legumes
Decomposers
Ammonification
Assimilation
NH3
NH4+
NO3
NO2 
Rain
Plants
Consumption
Decomposition
Geologic
uplift
Weathering
of rocks
Runoff
Sedimentation
Plant uptake
of PO43
Soil
Leaching
THE NITROGEN CYCLE
THE PHOSPHORUS CYCLE

17. Chapter 54: Ecosystems What is an ecosystem?
What is primary productivity?
What is the difference between Gross PP & Net PP?
What happens to energy at each trophic level?
What does the “Pyramid of Net Production” look like?
Let’s consider chemical cycling within an ecosystem….
What happened at the Hubbard Brooks Experimental Forest?
- Nutrients stayed within an ecosystem due to plants

18. Nitrate concentration in runoff
Figure Nutrient cycling in the Hubbard Brook Experimental Forest: an example of long-term ecological research
(a) Concrete dams and weirs built across streams at the bottom of watersheds enabled researchers to monitor the outflow of water and nutrients from the ecosystem.
Nitrate concentration in runoff
(mg/L)
Deforested
Control
Completion of
tree cutting
1965
1966
1967
1968
80.0
60.0
40.0
20.0
4.0
3.0
2.0
1.0
The concentration of
nitrate in runoff from the
deforested watershed
was 60 times greater
than in a control
(unlogged) watershed.
(c)
One watershed was clear
cut to study the effects of
the loss of vegetation on
drainage and nutrient
cycling.
(b)

19. Chapter 54: Ecosystems What is an ecosystem?
What is primary productivity?
What is the difference between Gross PP & Net PP?
What happens to energy at each trophic level?
What does the “Pyramid of Net Production” look like?
Let’s consider chemical cycling within an ecosystem….
What happened at the Hubbard Brooks Experimental Forest?
Nutrients stayed within an ecosystem due to plants
What is biological magnification?
- Concentration of toxins increase in higher trophic levels

20. Fig. 54.23 Biological magnification of PCBs in a Great Lakes food web
Concentration of PCBs
Herring
gull eggs
124 ppm
Zooplankton
0.123 ppm
Phytoplankton
0.025 ppm
Lake trout ppm
Smelt
1.04 ppm