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Ecology
The scientific study of interactions among
organisms and their environment
Includes:
Biotic factors
(Living organisms)
Abiotic factors (Non-living factors)
Ecological Hierarchy (BECPO)
organism
population
community
ecosystem
biosphere
BECPO
Terms (from smallest to largest):
Organism/
Individual
Refers to one individual organism
Population
Refers to all members of one specific species
inhabiting a given location (many individuals)
Community
Refers to all interacting populations in a
given location
BECPO
Terms (from smallest to largest):
Ecosystem
Refers to the community (biotic) and the
physical environment (abiotic) functioning
together as an independent, self-sustaining,
relatively stable system
Biosphere
Refers to the portion of the earth where life
exists (composed of numerous complex
ecosystems)
BECPO
Terms (from smallest to largest):
Ecosystem
Refers to the community (biotic) and the
physical environment (abiotic) functioning
together as an independent, self-sustaining,
relatively stable system
Biosphere
Refers to the portion of the earth where life
exists (composed of numerous complex
ecosystems)
What is meant by “self-sustaining?”
Self-sustaining ecosystems
Requirements:
Constant Source Energy source is constant and individuals
are capable of incorporating this energy into
of Energy
organic molecules, and this energy can be
transferred to other individuals
Cycling of
Materials
Materials are continuously cycled between
individuals and their environment
Essential questions
 What limits the production in ecosystems?
 How do nutrients move in the ecosystem?
 How does energy move through the ecosystem?
Ecosystem inputs
constant
energy flows
input
of
through
energy
nutrients cycle
Matter
cannot
Don’t forget
laws of or
bethe
created
Physics!
destroyed
nutrients
can only
cycle
biosphere
inputs
 energy
 nutrients
Energy flows through ecosystems
sun
secondary
consumers
(carnivores)
primary consumers
(herbivores)
producers (plants)
loss of
energy
loss of
energy
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
abiotic
abiotic
reservoir
reservoir
(All non-living material)
geologic
processes
return to
abiotic
reservoir
Food chains
 Trophic levels
feeding relationships
 start with energy from
the sun
 captured by plants



1st
sun
top carnivore/
Apex predator
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
autotrophs
Decomposers
Bacteria
Fungi
sun
Inefficiency of energy transfer
 Loss of energy between levels of food chain

To where is the energy lost? The cost of living!
10%
growth
only this energy
moves on to the
next level in
the food chain
energy
energy lost
lost to
to
metabolism
daily living
40%
cellular
respiration
50%
waste (feces)
sun
Ecological pyramid
 Loss of energy between levels of food
chain

can feed fewer animals in each level
Food webs
 Food chains are linked

together into food webs
Who eats whom?
 A species may weave
into web at more than
one level
 Example: omnivores
eat both consumers &
producers
 bears
 humans
 eating meat?
 eating plants?
 Nutrients: provide source of energy for each trophic
level
secondary
consumers
(carnivores)
primary
consumers
(herbivores)
producers (plants)
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?!
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
Carbonates in sediment
Deposition of
dead material
Deposition
of dead
material
Fossil fuels
(oil, gas, coal)
Nitrogen cycle
Carnivores
abiotic reservoir:
 Nitrogen in
atmosphere
enter food chain:
 nitrogen fixation by
soil & aquatic bacteria
Herbivores
recycle:
 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
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
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
Percolation in soil
Groundwater
Aquifer
Transpiration
Breaking the water cycle
 Deforestation breaks the water cycle

groundwater is not transpired to the
atmosphere, so precipitation is not
created
forest  desert
desertification
Studying ecosystems
Hubbard Brook
Experimental Forest
7800 acres
38 acre deforestation
Effects of deforestation
40% increase in runoff
loss of water
loss into
surface water
80 nitrate levels in runoff
Concentration
of nitrate (mg/l )

 60x loss in nitrogen
 10x loss in calcium
40
loss out of
ecosystem!
4
Deforestation
2
Why is
0
nitrogen
1965 so
important?
1966
1967
Year
1968
Ecological Relationships
Types:
Competition
Refers to when two or more organisms rely on
the same environmental resource(s)
Predation
Refers to the behavior of one animal preying
upon (feeding on) another
Symbiosis
Refers to the close relationship of two
dissimilar organisms
Symbiotic Relationships
Types of Symbiosis:
Mutualism
A symbiotic relationship where both organisms
benefit
Commensalism A symbiotic relationship where one organism
benefits, and the other is neither benefited
nor harmed
Parasitism
A symbiotic relationship in which one organism
benefits, and the other is harmed