Ecosystem Dynamics

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 ______________________&

__________________________• Ecosystems are self-sustaining– what is needed?

capture energy transfer energy cycle nutrients

capture energy transfer energy cycle nutrients

biosphere

Ecosystem inputs

constant inputof energy

energy flowsthrough

nutrients cycle

nutrients can only

cycleinputs energy nutrients

inputs energy nutrients

Matter cannotbe created or

destroyed

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

___________________: CO2 in atmosphere

___________________: photosynthesis =

carbon fixation in Calvin cycle

___________________: decomposition

___________________: respiration combustion

___________________: CO2 in atmosphere

___________________: photosynthesis =

carbon fixation in Calvin cycle

___________________: decomposition

___________________: 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 cycle _____________________: N in atmosphere

_____________________: nitrogen fixation by soil & aquatic bacteria_____________________: decomposing &

nitrifying bacteria animal wastes

_____________________: denitrifying bacteria

_____________________: N in atmosphere

_____________________: nitrogen fixation by soil & aquatic bacteria_____________________: decomposing &

nitrifying bacteria animal wastes

_____________________: 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

_____________________: rocks, minerals, soil

_____________________: erosion releases

soluble phosphate uptake by plants

_____________________: decomposing bacteria

& fungi_____________________: loss to ocean sediment

_____________________: rocks, minerals, soil

_____________________: erosion releases

soluble phosphate uptake by plants

_____________________: decomposing bacteria

& fungi_____________________: loss to ocean sediment

Lakes

Runoff

Percolation in soil

Evaporation

Transpiration

Precipitation

Oceans

Solar energy

AquiferGroundwater

Water cycle

Water vapor

_____________________: surface & atmospheric

water_____________________: precipitation & plant uptake_____________________: transpiration_____________________: evaporation & runoff

_____________________: surface & atmospheric

water_____________________: precipitation & plant uptake_____________________: transpiration_____________________: evaporation & runoff

TranspirationRemember

transpiration?

Breaking the water cycle• Deforestation breaks the __________________– groundwater is not transpired to the atmosphere, so

precipitation is not created

forest desert

desertification

Repairing the damage• The Greenbelt Movement

– planting trees in Kenya– restoring a _______________ecosystem– establishing democracy– empowering women

Wangari MaathaiNobel Peace prize 2004Nobel Peace prize 2004

Studying ecosystemsHubbard Brook Experimental Forest

7800 acres

38 acre deforestation

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?

Energy flows through ecosystems

sun

producers (plants)producers (plants)

loss of energy

loss of energy

secondary consumers(carnivores)

secondary consumers(carnivores)

primary consumers(herbivores)

primary consumers(herbivores)

Food chains• Trophic levels– feeding relationships– start with

____________________– captured by __________• 1st level of all food chains

– food chains usually go up only 4 or 5 levels• inefficiency of energy transfer

– all levels connect to ____________________ 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

Inefficiency of energy transfer• Loss of energy between levels of food chain– To where is the energy lost? _______________________

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

1,000,000,000

100,000

100

1

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?

Food webs• Food chains are linked

together into __________________

• Who eats whom?– a species may weave

into web at more than one level• bears• humans– eating meat?– eating plants?