1. CHAPTER 9: BIOLOGICAL PRODUCTIVITY AND ENERGY FLOW

2. 9.1 HOW MUCH CAN WE GROW? Determining how much organic matter can be produced in any time period.  Farm production  Number of people on Earth  Whales in ocean Many factors limit growth  Ultimate limit is energy flow

3. 9.2 BIOLOGICAL PRODUCTION Biomass- the total amount of organic matter on Earth or in any ecosystem or area.  Usually measured as the amount per unit surface area Biological production- the capture of usable energy from the environment to produce organic compounds in which that energy is stored.

4. BIOLOGICAL PRODUCTION Change in biomass over a given time is called net production. Three measures used for biological production  Biomass  Energy stored  Carbon stored

5. Net production

6. TWO KINDS OF BIOLOGICAL PRODUCTION Autotrophs  Make their own organic matter from energy source and inorganic compounds  Primary production  Most photosynthesize, some chemoautotrophs Heterotrophs  Cannot make their own organic compounds and must feed on other living things  Secondary production

8. USE OF ENERGY Use of energy from organic matter by most heterotrophic and autotrophic organisms done by respiration.  Organic matter combines with oxygen  Releases energy, carbon dioxide and water Respiration- the use of biomass to release energy that can be used to do work.

9. GROSS AND NET PRODUCTION Production of biomass and its use as a source of energy  1. An organism produces organic matter w/in its body. (gross production)  2. It uses some of this new organic matter as a fuel for respiration.  3. It stores some of the newly produced organic matter for future use. (net production )

10. GROSS AND NET PRODUCTION Net production = Gross production – respiration

11. 9.3 ENERGY FLOW Most of the time energy is invisible to us  With infrared film we can see difference between warm and cold object  Warm object appear red  Cool objects appear blue

12. Birch forest in New Hampshire Regular filmInfrared film

13. A near by rocky outcrop Regular filmInfrared film

14. 9.3 ENERGY FLOW All life requires energy.  The ability to do work Ecosystem energy flow-  the movement of energy through an ecosystem from the external environment through a series of organisms and back to the external environment.

15. 9.3 ENERGY FLOW Energy enters an ecosystem by two pathways.  1. Energy fixed by organisms  2. Transfer of heat energy by air, water, soil and warm living things.

16. 9.4 THE ULTIMATE LIMIT ON THE ABUNDANCE OF LIFE Laws of thermodynamics First law = Law of conservation of energy  In any physical or chemical change, energy is neither created nor destroyed but merely changed from one form to another.

17. Impossible ecosystem because of 2 nd law of thermodynamics

18. 9.4 THE ULTIMATE LIMIT ON THE ABUNDANCE OF LIFE Energy must continually be added to an ecological system in a usable form.  Because inevitably degraded into heat  Net flow of energy is a one way flow Thermodynamic system  Energy source  Ecosystem (intermediate system)  Energy sink

19. ENERGY EFFICIENCY As energy flows through a food web, it is degraded, and less and less is useable. Energy efficiency- the ratio of output to input  The amount of useful work obtained from some amount of available energy

20. ENERGY EFFICIENCY AND TRANSFER EFFICIENCY Trophic-level efficiency- the ratio of production of one trophic level to the production of the next trophic level.  Never very high  1-3% in natural ecosystems  10% may be maximum  90% of all energy lost as heat

22. 9.5 ENERGY FLOW IN AN OLD-FIELD FOOD CHAIN Meadow mice feed on grasses and herbs. Weasels feed on mice. Most of the energy used in respiration  15% of vegetation gross production  68% of energy taken up by mice  93% of energy taken up by weasels

23. 9.5 ENERGY FLOW IN A STREAM OR RIVER The amount of organic matter produced by algae is small relative to amount of input by dead leaves and vegetation falling into stream.  Supports detritivores  Amazon Basin floodplain high production of herbivores fish

24. 9.5 ENERGY FLOW IN OCEAN ECOSYSTEMS Several ocean food chains start with phytoplankton. One continues near the surface  Variety of animals feed on those algae  Baleen whales and other animals spend much of their time in upper ocean. Other occurs deep in the ocean  Fecal matter and dead organisms sink to sea floor

25. 9.5 CHEMOSYNTHETIC ENERGY FLOW IN THE OCEAN Chemosynthetic organisms make their own food from energy in sulfur compounds.  Sulfur-laden water is emitted from hot water vents  Rich biological communities surround the vents  Clams, mussels, crabs, limpets, fish, octopuses and giant worms.