1. Biological Productivity and Energy Flow
Chapter 9
Biological Productivity and Energy Flow
Botkin and Keller
Environmental Science 5e

2. Biological Production
Biomass
- the total amount of organic matter on Earth or in any ecosystem.
Biological Production
- the capture of usable energy from the environment to produce organic compounds in which that energy in stored
Botkin and Keller
Environmental Science 5e

3. Two Kinds of Biological Production
Primary Production
Make their own organic matter from a source of energy and an inorganic compound
Carried out by autotrophs and chemoautothrophs
Ex) photosynthesis
2. Secondary Production
Cannot make their own organic compounds and therefore must feed on other living things
Carried out by heterotrophs
Botkin and Keller
Environmental Science 5e

4. Environmental Science 5e
The use of energy from organic matter by most heterotrophic and autotrophic organisms is accomplished through respiration.
Respiration:
the use of biomass to release energy that can be used to do work
Botkin and Keller
Environmental Science 5e

5. Environmental Science 5e
Botkin and Keller
Environmental Science 5e

6. Gross and Net Production
The production of biomass and it’s use as a source of energy by autotrophs includes three steps:
Gross Production: An organism produces organic matter within it’s body
It uses some of this new organic matter as a fuel in respiration
It stores some of the newly produced organic matter for future use
The amount left over after utilization is called Net Production
Net Production = Gross Production - Respiration
Botkin and Keller
Environmental Science 5e

7. Environmental Science 5e
Energy Flow
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
Botkin and Keller
Environmental Science 5e

8. Environmental Science 5e
Botkin and Keller
Environmental Science 5e

9. The Laws of Thermodynamics
1st Law of Thermodynamics
- (the law of conservation of energy)
Energy is neither created nor destroyed. It is merely changed from one form to another
2nd Law of Thermodynamics
- Energy always changes from a more useful, higher quality from to a less useful, lower quality form
Thermodynamic System
- Formed by an energy source, ecosystem and energy sink, where the ecosystem is said to be an intermediate system between the energy source and the energy sink
Botkin and Keller
Environmental Science 5e

10. Energy Efficiency and Transfer Efficiency
-the ratio of output to input, or the amount of useful work obtained by some amount of available energy.
Trophic-level efficiency
- a ecological measure of energy efficiency
- the ratio of production of one trophic level to the production of the next lower trophic level
Botkin and Keller
Environmental Science 5e

11. Environmental Science 5e
Some Example of Energy Flow:
Energy Flow in an Old-Field Food Chain
Energy Flow in a Stream or River
Energy Flow in Ocean Ecosystems
Chemosynthetic Energy Flow in the Ocean
Botkin and Keller
Environmental Science 5e