Ecology: Biogeochemical Cycles

study of the interaction between abiotic and biotic components of……

Energy

• Energy passes through biological systems– Organisms transmit energy through food

chains/webs– 2nd Law of Thermodynamics means that

organisms that feed higher on the food chain have less energy available to them

• Therefore, as we move up food chain there is less and less energy and thus biomass

Movement of Matter

• Unlike photosynthetic organism which make their own chemical energy, non-photosynthetic organisms must use other energy transport mechanisms (e.g. conduction and convection) to gather matter.

• The food that they eat contains matter, but does matter move through food webs the same way that energy does?

Answer: Yes and No

• We’ve discussed energy movement but we also must discuss matter movement.

• Matter is anything that has mass and occupies space.– The matter that we observe most commonly takes the form of

compounds, polymers, alloys, or pure elements.

Matter to Matter

• Matter from one organism is moved and converted into matter in another organism in much the same was as we saw energy move in the food chain.

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• If grass obtained it’s energy from the sun, where did it acquire it’s matter from?

• Where is the matter? • CO2 H20 C6H12O6 O2

• Where does it come from?• Atmosphere

Light energyLight energy

Carbondioxide

WaterPhoto-

synthesis Glucose Oxygengas

Where does atmosphere get CO2?

• Respiration of living animal

• Respiration of plants

• But where did it come from?

• Well, a better question to ask may be, where did Carbon or Oxygen come from?

SinkAmount in Billions of

Metric Tons

Atmosphere578 (as of 1700) - 766 (as

of 1999)

Soil Organic Matter 1500 to 1600

Ocean 38,000 to 40,000

Marine Sediments and Sedimentary Rocks

66,000,000 to 100,000,000

Terrestrial Plants 540 to 610

Fossil Fuel Deposits 4000

Estimated major stores of carbon on the Earth.

Energy and Elements within a biological system

Oxygen Cycle

Largely tied Largely tied to the to the carbon cyclecarbon cycle

Consumers

Producers

Detritivores

Nutrients available to producers

Abiotic reservoir

Geologic processes

Generalized scheme for biogeochemical cycles

Other biologically important cycles

• Nitrogen

• Phosphorous

• Hydrogen

• Sulfur

• etc.

These are the basic elemental building blocks of biological organisms (CHONPS)

Nitrogen Cycle

Soil Nitrogen

Consumers

Plants

DetritivoresClays, rocks,

sediment

Nitrogen fixing bacteria

Denitrifying bacteria

Atmospheric N2

What you should be able to do:• Trace the flow of energy and/or matter

through food webs and biogeochemical cycles.

• Identify what happens to pools of matter when rates of change between pools change.

• Explain the effects (actual and potential) of man made changes in these rates.

• Identify and explain the biological, geological and chemical processes important to the Carbon and Nitrogen cycles.