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Ecosystems
Essential Questions: What limits the production in ecosystems?
How do nutrients move in the ecosystem?
How does energy move through the ecosystem?
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 energycycle nutrients
capture energy transfer energycycle nutrients
biosphere
Ecosystem inputs
constant inputof energy
energy flowsthrough
nutrients cycle
nutrients can only
cycle
inputsenergynutrients
inputsenergynutrients
Don’t forgetthe laws of
Physics!
Matter cannotbe created or
destroyed
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
Food chains
Fungi
Level 4
Level 3
Level 2
Level 1
Decomposers
Producer
Primary consumer
Secondary consumer
Tertiary consumer
top carnivore
carnivore
herbivore
Bacteria
autotrophs
heterotrophs
sun
Energy flows through food chains
sun
producers (plants)producers (plants)
loss of energy
loss of energy
secondary consumers(carnivores)
secondary consumers(carnivores)
primary consumers(herbivores)
primary consumers(herbivores)Energy is
incorporated into a
community by what group?
Inefficiency of energy transfer Loss of energy between levels of food chain
To where is the energy lost? The cost of living!
only this energymoves on to the
next level in the food chain
17%growth
50%waste (feces)
33%cellularrespiration
energy lost todaily living
energy lost todaily living
sun
Ecological pyramid
Loss of energy between levels of food chain can feed fewer animals in each level
sun
Notice only 1% of sunlight energy
converted by plants
Average of 10% energy
available for next level
Humans in food chains Energy dynamics of ecosystems have important
implications for human populations How much energy is available if we are:
carnivores? vegetarians?
Seems to be easier/cheaper to support a large population on grain than on
beef!
Productivity Primary productivity: Term for the rate
which producers photosynthesize organic compounds in an ecosystem.
Gross primary productivity: total amount of photosynthetic biomass production in an ecosystem
Net Primary Productivity = GPP – respiration cost
Ecosystems with greater productivity have more sunlight, water and nutrients.
What you need to be able to do: Using the laws of conservation of matter
and energy to do some basic accounting and determine different aspects of energy and matter usage in a community.
Remember: Inputs have to equal outputs
Sample problem #1 Total energy output?
.75 kcal
How much is used to build biomass or Secondary Production? .05 kcal
What % is not being efficiently used for biomass? 93%
Sample problem #2 A caterpillar consumes 100 kcal of
energy. It uses 35 kcal for cell respiration, and loses 50 kcal as waste. Determine the trophic efficiency for its creation of new biomass. Total energy consumed = 100 kcal Lost and Respired: 35 + 50 = 85 kcal Total energy for growth: 15 kcal
Efficiency (%) = 15/100 = .15 or 15%
consumers
decomposers
abioticreservoir
nutrientsmade availableto producers
geologicprocesses
Generalized Nutrient cycling
consumers
consumers
producers
decomposers
abioticreservoir
nutrientsENTER FOOD CHAIN
= made availableto producers
geologicprocesses
Decompositionconnects all
trophic levels
return toabiotic
reservoir
Carbon cycleCO2 in
atmosphere
Diffusion RespirationPhotosynthesis
Photosynthesis
Plants and algae
PlantsAnimals
Industry and home
Combustion of fuels
Animals
Carbonates in sediment
Bicarbonates
Deposition ofdead material
Depositionof deadmaterial
Fossil fuels(oil, gas, coal)
Dissolved CO2
abiotic reservoir: CO2 in atmosphere
enter food chain: photosynthesis =
carbon fixation in Calvin cycle
recycle:
return to abiotic: respiration combustion
abiotic reservoir: CO2 in atmosphere
enter food chain: photosynthesis =
carbon fixation in Calvin cycle
recycle:
return to abiotic: respiration combustion
Birds
Herbivores
Plants
amino acids
CarnivoresAtmospheric
nitrogen
loss to deep sediments
Fish
Plankton withnitrogen-fixingbacteria
Nitrogen-fixingbacteria
(plant roots)
Nitrogen-fixingbacteria
(soil)
Denitrifyingbacteria
Death, excretion, feces
Nitrifying bacteria
soil nitrates
excretion
Decomposing bacteria
Ammonifying bacteria
Nitrogen cycleabiotic reservoir:
N in atmosphereenter food chain:
nitrogen fixation by soil & aquatic bacteriarecycle:
decomposing & nitrifying bacteriareturn to abiotic:
denitrifying bacteria
abiotic reservoir: N in atmosphere
enter food chain: nitrogen fixation by soil & aquatic bacteria
recycle: decomposing & nitrifying bacteria
return to abiotic: denitrifying bacteria
Phosphorus cycle
Loss to deep sediment
Rocks andminerals
Soluble soilphosphate
Plants andalgae
Plants Urine
Land animals
Precipitates
Aquaticanimals
Animal tissueand feces
Animal tissueand feces
Decomposers(bacteria and
fungi)
Decomposers(bacteria & fungi)
Phosphatesin solution
Loss indrainage
abiotic reservoir: rocks, minerals, soil
enter food chain: erosion releases
soluble phosphate uptake by plants
recycle: decomposing
bacteria & fungireturn to abiotic:
loss to ocean sediment
abiotic reservoir: rocks, minerals, soil
enter food chain: erosion releases
soluble phosphate uptake by plants
recycle: decomposing
bacteria & fungireturn to abiotic:
loss to ocean sediment
Lakes
Runoff
Percolation in soil
Evaporation
Transpiration
Precipitation
Oceans
Solar energy
AquiferGroundwater
Water cycle
Water vapor
abiotic reservoir: surface & atmospheric water
enter food chain: precipitation & plant uptake
recycle: transpiration
return to abiotic: evaporation & runoff
abiotic reservoir: surface & atmospheric water
enter food chain: precipitation & plant uptake
recycle: transpiration
return to abiotic: evaporation & runoff
Transpiration
We will discuss process in detail soon!
Why does water flow
into, up and out of a plant?
Breaking the water cycle Deforestation breaks the water cycle
groundwater is not transpired to the atmosphere, so precipitation is not created
forest desert
desertification
Effects of deforestationC
on
cen
trat
ion
of
nit
rate
(m
g/l
)
1965 1966Year
2
0
4
40
80
1967 1968
Deforestation
nitrate levels in runoff
40% increase in runoff loss of water
40% increase in runoff loss of water
60x loss in nitrogen 10x loss in calcium
60x loss in nitrogen 10x loss in calcium
loss into surface water
loss out of ecosystem!
Why isnitrogen soimportant?