Energy and Flow
Energy
• Energy runs ecosystems
– It can typically be though of as food, or as
materials used to make food.
– Nearly all energy related to ecosystems ultimately
comes from our sun
• Energy Flow: transfer of energy between the
organisms of a community
Capturing Energy
• Energy enters ecosystems when organisms
capture it.
• What type of organism captures energy?
• Autotrophs (producers)- 2 types:
– Photoautotrophs- capture sunlight to construct
simple carbohydrates
• Photosynthesis
– Chemoautotrophs- harvest energy from chemical
bonds of inorganic moleucles
• chemosynthesis
Obtaining Energy
• After the energy is captured by the producers,
it can be transferred/acquired by other
organisms called….
• Heterotrophs or Consumers
– Obtain their energy by eating other organismseither producers or other consumers
• Energy flows from the sun to producers, the to
various consumers
• The steps in which organisms transfer energy
through a community is called a Food Chain
Food chains
 Feeding relationships
Level 4 Tertiary consumer
Sun
Top
carnivore
Level 3 Secondary consumer
 all food chains
start with energy from the sun
Carnivore
 first level of all food chains is
plants- producers
Level 2 Primary consumer
 Then herbivores/ omnivores
 Followed by omnivores/
Herbivore
carnivores
Level 1 Producer
 most food chains go up
only 4 - 5 levels
 all levels connect to
decomposers
Decomposers
Bacteria
Fungi
Flow of Matter and Energy in
Ecosystems
• Each feeding step in a food chain,
or web is referred to as a trophic
level
• Producers make up the first trophic
level (base)- primary producers
• Consumers make up the higher
levels.
–
–
–
–
Primary consumers
secondary consumers
tertiary consumers
quaternary consumers
• Each level relies on the one before
it
– berries → mice → black bear
Trophic levels represent links in the chain
Food webs
• In most ecosystems, there
are networks of complex,
interconnecting food
chains
– It is a more realistic view of
the trophic structure of an
ecosystem than a food chain
Energy Flow- not perfect
• When a zebra eats the grass, it does not obtain all of the
energy the grass has (much of it is not eaten)
• When a lion eats a zebra, it does not get all of the energy from
the zebra (much of it is lost as heat)
• The two (2) previous examples of energy transfer show that
no organism EVER receives all of the energy from the
organism they just ate
• Only 10% of the energy from one trophic level is transferred
to the next – this is called the 10% law
Energy and trophic levels= Ecological
pyramids
• show how energy flows
through an ecosystem.
• Pyramids illustrate that the
amount of available energy
decreases at each succeeding
trophic level.
• The total energy transfer from
one trophic level to the next is
only about 10% because
organisms fail to capture
and/or eat all the food energy
available at the trophic level
below them.
• Biomass is the total weight of
living matter at each trophic
level
Loss of energy
 Loss of energy between levels of food chain
 To where is the energy lost? The cost of living!
10-20%
growth
only this energy
moves on to the
next level in
the food chain
energy lost to
daily living
30%
cellular
respiration
50%
waste (feces)
Energy pyramid
• Loss of energy between levels of food chain
– fewer animals can live in each higher level
– There are always fewer animals in a level than the one
previous
Numbers
1
100
100,000
1,000,000,000
Biomass Pyramids
• Biomass= total
amount of living
tissue within a
given trophic
level
• Represent the
amount of
potential food in
a particular level
• Resemble energy
pyramids
Biomass Pyramid
But what about matter?
 Energy flows through but
nutrients and matter cycle
 nutrients must be recycled
to be available for the next
generation
n
u
t
r
i
e
n
t
s
 decomposers return
nutrients to the soil after
creatures die
 fungi
 bacteria
decomposers
Nutrients cycle around…
through decomposers
consumers
decomposers
producers
potassium
phosphorus
iron
carbon
nitrogen
calcium
soil
magnesium
Biogeochemical Cycles
• Hydrologic Cycle
• Phosphorus Cycle
• Nitrogen Cycle
• Carbon Cycle
Hydrologic (Water) Cycle
Nitrogen Cycle
Nitrogen Cycme
Nitrogen Cycle
Phosphorous Cycle