1. Transfer of Energy Chapter 3-2
Ecology Notes 2
Transfer of Energy
Chapter 3-2

2. Ecosystem Inputs nutrients cycle inputs energy nutrients
biosphere
energy flows through
constant input of energy
nutrients cycle
Matter cannot
be created or destroyed
Don’t forget the laws of Physics!
nutrients can only cycle
inputs
energy
nutrients

3. 1. Energy Transfers In an ecosystem, energy flows in this manner:
SUN 
AUTOTROPHS(photosynthesis) 
AUTOTROPH PREDATORS 
OTHER PREDATORS
How much energy is cycled from organism to organism structures an ecosystem?

4. 2. The Producers
PRODUCER – an autotrophic organism; one capable of capturing energy to make its own food
Producers create BIOMASS (ORGANIC MATERIAL) in an ecosystem
Examples - on land, plants; in water photosynthetic bacteria
Energy Gathering processes
PHOTOSYNTHESIS - organisms capture energy from the sun
CHEMOSYNTHESIS – organisms get energy from inorganic molecules

5. 3. Productivity
Productivity is the rate at which producers convert solar energy into chemical energy
GROSS PRIMARY PRODUCTIVITY (GPP) – How quickly producers gather energy
Energy is used for cellular respiration and for reproduction (a process that creates biomass, organic stuff )
NET PRIMARY PRODUCTIVITY (NPP) – How quickly biomass accumulates
Non-autotrophic organisms can only access energy stored as biomass, not the energy producers use to stay alive
NPP = GPP – cellular respiration rate of producers
Unit = kilocalorie/meter2/year

6. 3. Productivity -Certain ecosystems are MORE productive than others
RAIN FORESTS account for 30% of the world’s primary productivity
Productivity depends on TEMPERATURE, PRECIPITATION and LIGHT
Water ecosystems depend on LIGHT and TEMPERATURE only

7. 4. The Consumers
-CONSUMER– heterotrophic organism; one that eats other organisms and waste products
HERBIVORES – Plant eaters
CARNIVORES – Meat eaters
OMNIVORES – Meat and plant eaters
DECOMPOSERS – Break down non-living organic matter
Scavengers: seek dead organisms for food
Detritivores: decompose and feed of dead organisms and organic waste products

8. 5. Food Chains vs. Food Webs
-FOOD CHAIN– a linear representation (line) of feeding relationships between organisms in an ecosystem
Example – GrassZebraLion
Grass = PRODUCER
Zebra = PRIMARY CONSUMER
Lion = SECONDARY CONSUMER

9. Food Chains sun Trophic levels feeding relationships
Tertiary consumer
top carnivore
Level 3
Secondary consumer
Trophic levels
feeding relationships
start with energy from the sun
captured by plants
1st level of all food chains
food chains usually go up only 4 or 5 levels
inefficiency of energy transfer
all levels connect to decomposers
carnivore
Level 2
Primary consumer
heterotrophs
herbivore
Level 1
Producer
autotrophs
Fungi
Decomposers
Bacteria

10. 5. Food Chains vs. Food Webs
-FOOD WEB – a diagram of all interrelated food chains in an ecosystem
Example: The zebra eats the grass, but so does a mouse. Lions eat zebras, but mice are more worried about snakes than lions. The insects feeding off the grass have to worry about bird predators…get the idea?

11. 5. Food Chains vs. Food Webs
A sample food web…Can you pick out the individual food chains?

12. A sample food web…Can you pick out the individual food chains?

13. 6. Trophic Levels and Energy Pyramids
TROPHIC LEVEL – an animal’s position on an energy pyramid
ENERGY PYRAMID – a diagram showing how energy is transferred from producer to primary consumer to secondary consumer etc…
Typically, the amount of energy transferred from one level to the next is only 10% of the level below it.
There are typically MORE producers than consumers in an area because less energy is available for the higher-level consumers to sustain a large population.

14. Ecological Pyramid sun Loss of energy between levels of food chain
can feed fewer animals in each level
Numbers 1
100
100,000
1,000,000,000

15. Inefficiency of Energy Transfer
sun
Inefficiency of Energy Transfer
Loss of energy between levels of food chain
To where is the energy lost? The cost of living!
17%
growth
energy lost to daily living
only this energy moves on to the next level in the food chain
33%
cellular
respiration
50%
waste (feces)

16. 6. Trophic Levels and Energy Pyramids
Shows the relative amount of
energy available at each trophic
level. Organisms use about 10
percent of this
energy for
life processes.
The rest is lost
as heat.
Pyramid of Numbers
Shows the relative
number of individual
organisms at each
trophic level.
Biomass Pyramid
Represents the amount of
living organic matter at each
trophic level. Typically, the
greatest biomass is at the
base of the pyramid.

17. Energy Pyramid

18. Energy Pyramid
On your Energy pyramid, label these items: Primary Producers, Primary Consumers, Secondary Consumers, and Tertiary Consumers.
What do you notice about the secondary vs. tertiary consumers?
What is the difference in energy between the producers and the primary consumers?
How about the difference between the producers and the tertiary consumers?
List the food chain present in this diagram starting with the producer.