AP Biology
Ecosystems
Studying Organisms In Their Environment
organism
population
community
ecosystem
AP Biology
biosphere
Essential questions
 What limits the production in ecosystems?
 How do nutrients move in the ecosystem?
 How does energy move through the ecosystem?
AP Biology
Ecosystem
 All the organisms in a community plus abiotic
factors

ecosystems are transformers of energy
& processors of matter
 Ecosystems are self-sustaining

what is needed?
 capture energy
 transfer energy
 cycle nutrients
AP Biology
Ecosystem inputs
constant
energy flows
input
of
through
energy
nutrients cycle
Matter
cannot
Don’t forget
laws of or
bethe
created
Physics!
destroyed
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nutrients
can only
cycle
biosphere
inputs
 energy
 nutrients
Generalized
Nutrient
cycling
consumers
producers
consumers
decomposers
nutrients
nutrients
ENTER FOOD
CHAIN
made
available
= made available
to producers
to producers
Decomposition
connects all
trophic levels
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return to
abiotic
reservoir
abiotic
reservoir
geologic
processes
Carbon cycle
CO2 in
atmosphere
Diffusion
Respiration
abiotic reservoir:
 CO2 in atmosphere
enter food chain:
Combustion
of fuels =
 photosynthesis
carbon fixation in
Industry and home
Calvin cycle
Photosynthesis recycle:

return to abiotic:
 respiration
Plants
 combustion
Animals
Dissolved CO2
Bicarbonates
Photosynthesis
Animals
Plants and algae
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Carbonates in sediment
Deposition of
dead material
Deposition
of dead
material
Fossil fuels
(oil, gas, coal)
Nitrogen cycle
Carnivores
abiotic reservoir:
 N in atmosphere
enter food chain:
 nitrogen fixation by
soil & aquatic bacteria
recycle:
Herbivores
 decomposing &
nitrifying bacteria
return to abiotic:
 denitrifying bacteria
Birds
Plankton with
nitrogen-fixing
bacteria
Atmospheric
nitrogen
Plants
Death, excretion, feces
Fish
excretion
Decomposing bacteria
amino acids
Ammonifying bacteria
loss to deep sediments
Nitrogen-fixing
bacteria
(plant roots)
Nitrogen-fixing
bacteria
(soil)
Nitrifying bacteria
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soil nitrates
Denitrifying
bacteria
Phosphorus cycle
Plants
Land
animals
Soluble soil
phosphate
Loss in
drainage
fungi)
Rocks and
minerals
Decomposers Phosphates
(bacteria & fungi) in solution
Animal tissue
and feces
abiotic reservoir:
 rocks, minerals, soil
enter food chain:
 erosion releases
soluble phosphate
 uptake by plants
recycle:
 decomposing bacteria
Animal
tissue
&
fungi
Urine and feces
return to abiotic:
 loss toDecomposers
ocean
(bacteria and
sediment
Aquatic
animals
Plants and
algae
Precipitates
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Loss to deep sediment
abiotic reservoir:
 surface & atmospheric
water
enter food chain:
 precipitation & plant
uptake
Solar energy
recycle:
 transpiration
return to abiotic:
Evaporation
 evaporation & runoff
Water cycle
Transpiration
Water vapor
Precipitation
Oceans
Runoff
Lakes
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Percolation in soil
Groundwater
Aquifer
Transpiration
Remember
transpiration?
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Breaking The Water Cycle
 Deforestation breaks the water cycle

groundwater is not transpired to the
atmosphere, so precipitation is not
created
forest  desert
desertification
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Repairing the Damage
 The Greenbelt Movement




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planting trees in Kenya
restoring a sustainable ecosystem
establishing democracy
empowering women
Wangari Maathai
Nobel Peace prize 2004
Studying Ecosystems
Hubbard Brook
Experimental Forest
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7800 acres
38 acre deforestation
Effects of Deforestation
40% increase in runoff

loss of water
 60x loss in nitrogen
 10x loss in calcium
loss into
surface water
Concentration
of nitrate (mg/l )
80 nitrate levels in runoff
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40
loss out of
ecosystem!
4
Deforestation
2
Why is
0
nitrogen
1965 so
important?
1966
1967
Year
1968
Ecosystem Inputs
energy flows
through
nutrients cycle
AP Biology
biosphere
inputs
 energy
 nutrients
Energy Flows Through Ecosystems
sun
secondary
consumers
(carnivores)
primary consumers
(herbivores)
producers (plants)
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loss of
energy
loss of
energy
Food chains
 Trophic levels
feeding relationships
 start with energy from
the sun
 captured by plants



1st
sun
top carnivore
Level 3
Secondary consumer
carnivore
Level 2
Primary consumer
heterotrophs
herbivore
level of all food chains
food chains usually go Level 1
Producer
up only 4 or 5 levels
 inefficiency of energy
transfer

Level 4
Tertiary consumer
all levels connect to
decomposers
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autotrophs
Decomposers
Bacteria
Fungi
Inefficiency of Energy Transfer
sun
 Loss of energy between levels of food
chain

To where is the energy lost? The cost of living!
17%
growth
only this energy
moves on to the
next level in
the food chain
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energy lost to
daily living
33%
cellular
respiration
50%
waste (feces)
Ecological Pyramid
 Loss of energy between levels of food
chain

can feed fewer animals in each level
1
100
100,000
1,000,000,000
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sun
Humans In Food Chains
 Dynamics of energy through ecosystems have
important implications for human populations
 how much energy does it take to feed a human?
 if we are meat eaters?
 if we are vegetarian?
What is your
ecological
footprint?!
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Food Webs
 Food chains are

linked together into
food webs
Who eats whom?

a species may
weave into web at
more than one level
 bears
 humans
 eating meat?
 eating plants?
AP Biology
Any
Questions??
We’re working
on a lot
of them!
AP Biology
2006-2007