Download Lecture 13

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
• 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.
• 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
• 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.
• If grass obtained it’s
energy from the sun,
where did it acquire
it’s matter from?
Direction of Matter Flow
Matter to Matter
• Where is the matter?
• CO2 H20 C6H12O6 O2
• Where does it come from?
• Atmosphere
Light energy
Carbon
dioxide
Water
Photosynthesis
Glucose
Oxygen
gas
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?
Estimated major stores of carbon on the Earth.
Sink
Atmosphere
Soil Organic Matter
Ocean
Marine Sediments and
Sedimentary Rocks
Terrestrial Plants
Fossil Fuel Deposits
Amount in Billions of
Metric Tons
578 (as of 1700) - 766 (as
of 1999)
1500 to 1600
38,000 to 40,000
66,000,000 to
100,000,000
540 to 610
4000
Energy and Elements within a biological system
Oxygen Cycle
Largely tied
to the
carbon cycle
Generalized scheme for biogeochemical
cycles
Consumers
Producers
Detritivores
Nutrients
available to
producers
Abiotic
reservoir
Geologic
processes
Other biologically important cycles
•
•
•
•
•
Nitrogen
Phosphorous
Hydrogen
Sulfur
etc.
These are the basic elemental building
blocks of biological organisms
(CHONPS)
Nitrogen Cycle
Atmospheric N2
Denitrifying bacteria
Nitrogen fixing
bacteria
Soil Nitrogen
Clays, rocks,
sediment
Detritivores
Plants
Consumers
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.