Food Chains, Food Webs, Trophic

Levels, nutrient Cycles...

Ecosystem Ecology

Ecosystem• All the organisms in a community plus abiotic

factors–Transform energy & process matter

• Ecosystems are self-sustaining–what is needed?

capture energycapture energytransfer energytransfer energycycle nutrientscycle nutrients

capture energycapture energytransfer energytransfer energycycle nutrientscycle nutrients

biosphere

Ecosystem inputs

constant inputof energy

energy flowsthrough

nutrients cycle

inputsinputs energyenergy nutrientsnutrients

inputsinputs energyenergy nutrientsnutrients

How does energymove through

the ecosystem?

Energy flows through ecosystems

sun

producers (plants)producers (plants)producers (plants)producers (plants)

loss of energy

loss of energy

secondary secondary consumersconsumers(carnivores)(carnivores)

secondary secondary consumersconsumers(carnivores)(carnivores)

primary consumersprimary consumers(herbivores)(herbivores)

primary consumersprimary consumers(herbivores)(herbivores)

5

Primary Productivity

• What is primary productivity?• What is GPP?• What is NPP?• How does the light/dark bottle method allow you to calculate primary productivity?

5

Limiting Factors

What are some limiting Factors that can effect productivity?

Light

Nitrogen

Phosphorous

What is learned from this data?

• Trophic levels–Why do food chains usually go up only 4 or 5 levels?

–all levels connect to decomposers

Food chains

Fungi

Level 4Level 4

Level 3Level 3

Level 2Level 2

Level 1Level 1

Decomposers

Producer

Primary consumer

Secondary consumer

Tertiary consumer

top carnivore

carnivore

herbivore

Bacteria

autotrophsautotrophs

heterotrophsheterotrophs

Inefficiency of energy transfer• Loss of energy between levels of food chain

–Where is the energy that is not available to the next tropic level?

only this energymoves on to the

next level in the food chain 50%

waste (feces)

33%cellularrespiration

energy lost todaily living

energy lost todaily living

17% growth

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

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?

Humans in food chains• What has more energy a pound of hamburger or a pound of

peas?• What is the most efficient way for one person to eat?• What is the most efficient way for the human population to

eat?

13

Biological Magnification

Why do eggshellsbecome Fragile?

Where doesthe toxin

accumulate?

Let’s go to the video!

biosphere

Nutrients…

nutrients cycle

Don’t forgetthe laws of

Physics!

Matter cannotbe created or

destroyed

General Nutrient

Cycle

Decompositionconnects all

trophic levels

consumerconsumerss

decomposerdecomposerss

abioticabioticreservoireservoi

rr

nutrientsnutrientsmade availablemade availableto producersto producers

geologicgeologicprocesseprocesse

ss

consumerconsumerss

consumer

producer

decomposer

abioticreservor

nutrientsENTER FOOD CHAIN

= made availableto producers

geologicprocesse

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 atmosphereOther reservoirFossil fuelsenter food chain:photosynthesis = carbon fixation in Calvin cyclerecycle:decomposition return to abiotic:respirationcombustion

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

abiotic reservoir:N in atmosphereLocal reservoir N in soilenter food chain:nitrogen fixation by soil & aquatic bacteriarecycle:decomposing & nitrifying bacteriareturn to abiotic:denitrifying bacteria

Lakes

Runoff

Percolation in soil

Evaporation

Transpiration

Precipitation

Oceans

Solar energy

AquiferGroundwater

Water cycleWater cycle

Water vapor

abiotic reservoir:surface & atmospheric waterenter food chain:precipitation & plant uptakerecycle:transpirationreturn to abiotic:evaporation & runoff

Transpiration

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, soilenter food chain:erosion releases soluble phosphateuptake by plantsrecycle:decomposing bacteria & fungireturn to abiotic:loss to ocean sediment

Breaking the water cycle• Deforestation breaks the water cycle–groundwater is not transpired. Precipitation is not created.

forest forest →→desert desert

desertificationdesertification

Studying ecosystems

• Hubbard Brook Experimental Forest

7800 acres7800 acres

38 acre deforestation38 acre deforestation

Effects of deforestationC

on

cen

trat

ion

of

nit

rate

(m

g/l

)

1965 1966

Year

2

0

4

40

80

1967 1968

Deforestation

nitrate levels in runoffnitrate levels in runoff

40% increase in runoff40% increase in runoffloss of water

40% increase in runoff40% increase in runoffloss of water

60x loss in nitrogen60x loss in nitrogen10x loss in calcium10x loss in calcium

60x loss in nitrogen60x loss in nitrogen10x loss in calcium10x loss in calcium

loss into loss into surface watersurface water

loss out of loss out of ecosystemecosystem!!

Why is nitrogen so Important?

24

Rising CO2

Would this have happened

without us?

25

Ozone Depletion

What did we do this time?