Transcript Energy flow in a community - Sonoma Valley High School

Energy transfer
Energy
sources
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The sun provides almost all the energy to sustain life.
Producers use Photosynthesis or Chemosythesis
acquire the energy needed to live.
Chemosythesis is the use of inorganic compound to
gain energy, only bacteria use this energy source.
Measuring productivity
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Biomass is the amount of organic matter in an ecosystem
 Producers make biomass
Gross primary productivity is the rate at which producer
use solar energy to make biomass and maintain the
producers metabolism.
Net primary productivity is the amount of biomass left for
consumers to eat.
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Productivity is measured in units of energy per unit area
per year.
Which biomes are the lest
productive? Which are the most?
Why do you think that is?
Consumers
primary consumers:
Herbivores – eat producers
secondary consumers:
Carnivores: meat eaters
Omnivores: eat producers & consumers
• Detritivore: eat dead plants and
animals & animal waste
• E.g. Voltures and dung beetles
• decomposers are detritivors that
break down organic matter into
nutrients
• e.g. bacteria and fungi
Energy flow
• Each level in the pyramid is called a trophic level.
• As levels increase energy is lost as heat or used for
growth.
• Only 1/10th of the energy is available for the next level in
the pyramid
Left side: Why do you think
there is no quaternary level?
Does it take more land to feed
a vegetarian or an omnivore?
With a growing human
population (7 billion +) what is
the best way to use our arable
land resources?
Energy use in a trophic pyramid
o Only 10% of
energy is
available from
one trophic
level to the
next.
o There is a
limit to the
number of
trophic levels
there can be.
Food chains & webs
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Food chain – a single
pathway fro energy to
move through the tropic
levels.
Food web - Several
food chains linked
together
Shows how energy
moves through a
community
A change to one part of
the web affects all the
others
Fresh water food web: Arrows mean “eaten by”
A forest food web
Antarctic
marine food
web is
supported by
krill, a small
crustacean
Krill feed on
algae & other
protozoans
Summary review
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What happens to a community if the number or output of the producers is
lowered, say in a drought?
What would happen if the decomposers died?
What happens if the top predators are killed by humans?
How are food chains and webs different? Which is the more accurate way
to show how energy moves through a community?