1. Ecosystems: Components, Energy Flow, and Matter Cycling
“All things come from earth, and to earth they all return”—Menander

2. Ecology and the levels of organization of matter
Ecology—Greek 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

3. Ecosystem Organization
Biosphere
Ecosystems
Communities
Populations
Organisms
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; million likely
Populations
Genetic diversity
Communities
Ecosystems
Biosphere
Fig. 4.2, p. 66

4. Earth’s 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.
Atmosphere
Vegetation and animals
Soil
Rock
Biosphere
Crust
core
Mantle
Lithosphere
(crust, top of upper mantle)
Hydrosphere
(water)
(air)
(Living and dead
organisms)
(soil and rock)

5. 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
Biosphere
Carbon
cycle
Phosphorus
Nitrogen
Water
Oxygen
Heat in the environment
Heat

6. 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.

7. 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

8. The Source of High Quality Energy
Solar
radiation
Energy in = Energy out
Reflected by
atmosphere (34%)
UV radiation
Absorbed
by ozone
by the earth
Visible
light
Lower Stratosphere
(ozone layer)
Troposphere
Heat
Greenhouse
effect
Radiated by
atmosphere
as heat (66%)
Earth
Heat radiated
Energy of sun lights and warms the planet
Supports PSN
Powers the cycling of matter
Drives climate and weather that distribute heat and H2O

9. Fate of Solar Energy… Earth gets 1/billionth of sun’s output of energy
34% is reflected away by atmosphere
66% is absorbed by chemicals in atmosphere = 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

10. Primary Productivity
The conversion of light energy to chemical energy is called “gross primary production.”
Plants use the energy captured in photosynthesis for maintenance and growth.
The energy that is accumulated in plant biomass is called “net primary production.”
Primary Production in Plants
The total production of organic compounds by plants is referred to as primary productivity or production. This represents the total amount of light energy transformed into chemical energy through photosynthesis. Only about 1 – 5 % of the solar energy in any given location actually is captured for use or storage by plants. After the metabolic requirements of producers (plants or other photosynthetic organisms) are met, the total energy (accumulated as biomass) available to be passed through the food chain is called net primary productivity.
References:
Campbell, N.E., & Reece, J.B. (2002). Biology,(6th ed.). San Francisco: Benjamin Cummings.
Raven, P.H., & Johnson, G.B. (2002). Biology, (6th ed.). McGraw-Hill.
Image Reference:
Baylor College of Medicine, Center For Educational Outreach. (2004). Martha Young, Senior Graphic Designer.

11. Primary Productivity NPP=GPP-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? AP Lab Site
Most productive vs. least productive

12. What are the most productive Ecosystems?
Estuaries
Swamps and marshes
Tropical rain forest
Temperate forest
Northern coniferous forest (taiga)
Savanna
Agricultural land
Woodland and shrubland
Temperate grassland
Lakes and streams
Continental shelf
Open ocean
Tundra (arctic and alpine)
Desert scrub
Extreme desert
800
1,600
2,400
3,200
4,000
4,800
5,600
6,400
7,200
8,000
8,800
9,600
Average net primary productivity (kcal/m2/yr)

13. Fate of Primary Productivity and Some important questions…
Since producers are ultimate source of all food, why shouldn’t we just harvest the plants of the world’s marshes?
Why don’t we clear cut tropical rainforests to grow crops for humans?
Why not harvest primary producers of the world’s vast oceans?
Vitousek et al: Humans now use, waste, or destroy about 27% of earth’s total potential NPP and 40% of the NPP of the planet’s terrestrial ecosystems

14. Biotic Components of Ecosystems
Producers (autotrophs)
Source of all food
Photosynthesis
Consumers=heterotroph
Aerobic respiration
Anaerobic respiration
Methane, H2S
Decomposers
Matter recyclers…
Release organic compounds into soil and water where they can be used by producers
Heat
Abiotic chemicals
(carbon dioxide,
oxygen, nitrogen,
minerals)
Producers
(plants)
Decomposers
(bacteria, fungus)
Consumers
(herbivores,
carnivores)
Solar
energy

15. 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

16. Detritivores vs Decomposers stop
Fig. 4.15, p. 75
Mushroom
Wood
reduced
to powder
Long-horned
beetle holes
Bark beetle
engraving
Carpenter
ant
galleries
Termite and
carpenter
work
Dry rot fungus
Detritus feeders
Decomposers
Time progression
Powder broken down by decomposers
into plant nutrients in soil

17. Energy Flow and Matter Cycling in Ecosystems…
Food Chains vs. Food Webs
KEY: There is little if no matter waste in natural ecosystems!
Heat
First Trophic
Level
Second Trophic
Third Trophic
Fourth Trophic
Solar
energy
Producers
(plants)
Primary
consumers
(herbivores)
Tertiary
(top carnivores)
Secondary
(carnivores)
Detritvores
(decomposers and detritus feeders)

18. Generalized Food Web of the Antarctic
Fig. 4.18, p. 77
Humans
Blue whale
Sperm whale
Crabeater seal
Killer
whale
Elephant
seal
Leopard
Adélie
penguins
Petrel
Fish
Squid
Carnivorous plankton
Krill
Phytoplankton
Herbivorous
zooplankton
Emperor
penguin
Note: Arrows
Go in direction
Of energy flow…

19. 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?)

20. 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, use 10% as a rule of thumb)
Thus, the more trophic levels or steps in a food chain, the greater the cumulative loss of useable energy…

21. Food Webs and the Laws of matter and energy
Ecological Efficiency:
The % of usable energy transferred as biomass from one trophic level to the next (ranges from 5-20% in most ecosystems, use 10% as a rule of thumb)
Thus, the more trophic levels or steps in a food chain, the greater the cumulative loss of useable energy…

22. Pyramids of Energy and Matter
Pyramid of Energy Flow
Pyramid of Biomass
Heat 10
100
1,000
10,000
Usable energy
Available at
Each tropic level
(in kilocalories)
Producers
(phytoplankton)
Primary
consumers
(zooplankton)
Secondary
(perch)
Tertiary
(human)
Decomposers

23. Ecological Pyramids of Energy
Energy in ecosystems flows from producers (photosynthetic organisms) to consumers (herbivores and carnivores). Ecological pyramids of energy usually depict the amount of living material (or its energetic equivalent) that is present in different trophic levels. In this diagram, energy is depicted in kilocalories.
Primary producers convert only about 1% of the energy in available sunlight. The average amount of energy that is available to the next trophic level is about 10%. Because so much energy is utilized in building and maintaining organisms, food chains (series of feeding relationships) are usually limited to just three or four steps. Pyramids of energy can not be inverted.
References:
Campbell, N.E., & Reece, J.B. (2002). Biology,(6th ed.). San Francisco: Benjamin Cummings.
Holligan, P.M., Harris,R.P., Newell, R.C., Harbour, D.C., Head, R.N., Linley, E.A.S., Lucas, M.I., Tranter, P.R.G., Weekly, C.M. (1984). Vertical distribution and partitioning of organic carbon in mixed, frontal, and stratified waters of the English Channel. Marine Ecology Progress Series, 14,
Raven, P.H., & Johnson, G.B. (2002). Biology, (6th ed.). McGraw-Hill.
Image Reference:
Baylor College of Medicine, Center For Educational Outreach. (2004). Martha Young, Senior Graphic Designer.

24. Ecological Pyramids of Biomass
The total dry weight of organisms (standing crop) in a particular trophic level is referenced as biomass. Most pyramids follow the typical pattern of narrowing at each level, however in some aquatic ecosystems, the pyramid may be inverted. In the example, phytoplankton grow and reproduce so rapidly that they can support a large population of zooplankton even though at any one time, the biomass of phytoplankton is smaller than that of the zooplankton.
References:
Campbell, N.E., & Reece, J.B. (2002). Biology,(6th ed.). San Francisco: Benjamin Cummings.
Holligan, P.M., Harris,R.P., Newell, R.C., Harbour, D.C., Head, R.N., Linley, E.A.S., Lucas, M.I., Tranter, P.R.G., Weekly, C.M. (1984). Vertical distribution and partitioning of organic carbon in mixed, frontal, and stratified waters of the English Channel. Marine Ecology Progress Series, 14,
Raven, P.H., & Johnson, G.B. (2002). Biology, (6th ed.). McGraw-Hill.
Image Reference:
Baylor College of Medicine, Center For Educational Outreach. (2004). Martha Young, Senior Graphic Designer.

25. 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?

26. Ecosystem Services and Sustainability
Solar
Capital
Air
resources
and
purification
Climate
control
Recycling
vital
chemicals
Renewable
energy
Nonrenewable
mineral
Potentially
renewable
matter
Biodiversity
and gene
pool
Natural
pest and
disease
Waste
removal and
detoxification
Soil
formation
renewal
Water
Lessons
From
Nature!
Use Renewable Solar Energy As Energy Source
Recycle the chemical nutrients needed for life

27. 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

28. Carbon Cycle Carbon Cycle
Carbon, in the form of carbon dioxide, comprises about 0.03 percent of the atmosphere. Worldwide circulation of carbon atoms is called the carbon cycle. Since carbon becomes incorporated into molecules used by living organisms during photosynthesis, parts of the carbon cycle closely parallel the flow of energy through the earth’s living systems. Carbon is found in the atmosphere, the oceans, soil, fossil deposits and living organisms. Photosynthetic organisms create carbon-containing molecules (known as “organic” compounds), which are passed to other organisms as depicted in food webs. Each year, about 75 billion metric tons of carbon are trapped in carbon-containing compounds through photosynthesis. Carbon is returned to the environment through respiration (breakdown of sugar or other organic compounds), combustion (burning of organic materials, including fossil fuels), and erosion.
References:
Campbell, N.E., & Reece, J.B. (2002). Biology,(6th ed.). San Francisco: Benjamin Cummings.
Image Reference:
Baylor College of Medicine, Center For Educational Outreach. (2004). Martha Young, Senior Graphic Designer.

29. Nitrogen Cycle Nitrogen Cycle
A major component of the atmosphere, nitrogen is essential for all living things. However, most organisms are unable to use the gaseous forms of nitrogen present in the atmosphere. In order for nitrogen to be usable by most organisms, it must be “fixed,” in other words, combined with oxygen, hydrogen or carbon to form other molecules. Nitrogen fixation can happen during rainstorms, which yields nitrate and ammonium ions. Nitrogen also can be fixed biologically by free-living and symbiotic bacteria. Leguminous plants, for example, host nitrogen-fixing bacteria in root nodules allowing them to capture nitrogen and incorporate it into proteins and other molecules.
Unlike other organisms, nitrogen fixing bacteria are able to convert atmospheric nitrogen to ammonia, which then can serve as raw material for the incorporation of nitrogen into other molecules. The other four important steps in the nitrogen cycle are: (1) assimilation (reduction of nitrate ions [NO2-] inside plants to ammonium ions [NH4+], which are used to manufacture proteins and other molecules; this conversion requires energy); (2) ammonification (release of excess nitrogen in the form of ammonia [NH3] and ammonium ions [NH4+] by soil-dwelling bacteria and some fungi during the decomposition of complex organic compounds such as proteins, and nucleic acids); (3) nitrification (the oxidation of ammonium ions or ammonia by free-living, soil dwelling bacteria to nitrates [NO2-]; and (4) denitrification (the conversion of nitrate to gaseous nitrogen [N2 ] by free-living bacteria in soil; this conversion yields energy and occurs in conditions with low levels of oxygen).
References:
Campbell, N.E., & Reece, J.B. (2002). Biology,(6th ed.). San Francisco: Benjamin Cummings.
Image Reference:
Baylor College of Medicine, Center For Educational Outreach. (2004). Martha Young, Senior Graphic Designer.