1. Energy Flow Through the Ecosystem

2. Energy and matter
The Earth has internal (chemical) and external (solar) energy.
That energy is used to move matter through the Earth’s systems.
Energy changes the physical and chemical properties of matter.

3. Sustaining Life on Earth Requires Energy and Matter
One-way flow
of Energy
Sun
Chemicals
Cycling
of Matter

4. Energy in Living Systems
Living systems use energy
Energy used for growth, reproduction and metabolism
No organism can create energy
Can store it, but not create it

5. Ecosystem energy flow Energy enters an ecosystem in 2 ways:
Energy is “fixed” (stored in tissues) by organisms and moves through food webs.
Heat energy is transferred (air, water, soil convection) and warms life on Earth.

6. Sunlight is primary source of energy for most life on Earth
Exception: Chemicals used in deep sea vents

7. Primary Producers
Primary producers capture sunlight or chemicals and convert it into useable energy.
These organisms are called “autotrophs.”

8. Primary Producers
Primary producers use solar or chemical energy to make complex organic compounds out of inorganic materials.
Primary producers store energy.
Used for their own energy needs
Also used by organisms that consume them

9. Primary Producers
Primary producers include plants, algae and certain bacteria.
Use either
Photosynthesis: use solar energy to make carbohydrates; release oxygen
Phytoplankton (aquatic autotrophs) account for 50% of the oxygen produced
Chemosynthesis: use chemical energy to make carbohydrates

10. Consumers = heterotrophs
Consumers (heterotrophs) rely on other organisms for energy and nutrients.
Different types of consumers are classified by the way they get energy.

11. Types of Consumers: Carnivores
Carnivores kill and eat other animals.
The process of obtaining meat requires energy but meat is generally high in energy and nutrients and is easy to digest.

12. Types of Consumers: Herbivores
Herbivores obtain energy from plants: roots, leaves, stems, seeds or fruits.
Examples include koalas, cows, rabbits and deer.

13. Types of Consumers: Omnivores
Omnivores eat a variety of foods including both plants and animals.
Example: Bears eat other animals but also eat berries and other plant products.

14. What about the human diet?
Humans who are vegans (plant products only) can be considered _______________.
What about vegetarians who eat milk products? ___________________
Humans who eat meat and fat only can be considered
____________.
Humans who eat meat, vegetables and fruit can be considered ________________.

15. Types of Consumers: Scavengers
Scavengers eat animals that have been killed by other animals or have died of other causes.
Vultures are scavengers.

16. Types of Consumers: Detritivores
Detritivores help decompose organic matter by consuming detritus: dead animal and plant parts and organic wastes.
Commonly digest decomposers that live on or in detritus
Earthworms are detritivores.

17. Types of Consumers: Decomposers
Decomposers chemically break down organic matter and use it for energy.
Release inorganic compounds into soil
Decomposers include bacteria and fungi.
Mushrooms are types of fungi.

18. Decomposers and detritivores

19. Energy Flow in an Ecosystem: Food Chains and Food Webs
Energy flows through an ecosystem in one direction -- from producers to various levels of consumers.
Producers and consumers are linked through feeding relationships.

20. Energy Flows Through “Trophic Levels”
Each step of a food web or food chain is called a trophic level.
Energy flows up from one trophic level to the next.

21. Trophic Levels First Trophic Level Second Trophic Level
Third Trophic Level
Fourth Trophic Level
Producers (plants)
Primary consumers (herbivores)
Feed directly on producers
Secondary consumer (carnivores)
Feed on Primary Consumers
Tertiary consumer
Feed on other carnivores

22. Food Chains
Food chains are the series of steps through which organisms transfer energy by eating or being eaten.
Can be short or long

23. Food Webs Food Web = more complicated network of feeding interactions
Include interconnected food chains
Removal of one organism affects all other members of the web.
Remember: Decomposers and detritivores play an
important role by releasing organic nutrients that can
be used by the primary producers.

24. Identify three food chains within this food web.
Which is shortest?
______________
Which is longest?
Describe the
possible effects
of a grasshopper
extinction.
Note: Energy flows in the direction
of the arrow.

25. Ecological Pyramids
Diagrams used to show the relative amounts of energy or matter in each trophic level of a food chain or food web.
Three types:
Pyramids of Energy
Pyramids of Biomass
Pyramids of Numbers

26. Pyramid of Energy
Shows the relative amount of energy available at each trophic level of a food chain or food web

27. Pyramid of Energy: 10% Rule
As energy is transferred up to the next trophic level, 90% of the energy is lost.
Only 10% of the energy within one trophic level is transferred to the next level.

28. Pyramid of Energy: 10% Rule
Example: A bird (1st consumer) eats plant seeds (primary producer).
Only 10% of the energy in the grass will be stored in the tissues of the bird.
How much of the energy from the grass will be stored in the tissues of the hawk that eats the bird? ___________________

29. Pyramid of Biomass
The total dry mass of organisms in a trophic level is its “biomass”.
A pyramid of biomass shows the relative amount of organic matter at each level.
Most at primary producer level; least at the top trophic level

30. What does this say about the amount of primary producer
biomass required to support tertiary consumers?

31. Pyramid of Numbers
Shows the relative number of individual organisms at each trophic level
Generally follows the same pattern as the pyramid of biomass