AP Biology Ecosystems

AP Biologybiosphere

ecosystem

community

population

Studying organisms in their environment

organism

AP Biology

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

capture energy transfer energy cycle nutrients

AP Biologybiosphere

Ecosystem inputs

constant inputof energy

energy flowsthrough

nutrients cycle

nutrients can only

cycle

inputs energy nutrients

inputs energy nutrients

Don’t forgetthe laws of

Physics!

Matter cannotbe created or

destroyed

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Participants in an Ecosystem Primary producers-autotrophs that make

up the first trophic level of any ecosystem Ex-plants, phytoplankton, & some bacteria

Consumers-heterotrophs that feed on the tissues, products, and remains of other organisms Ex=herbivores, carnivores, omnivores,

parasites, detritivores, decomposers

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Decomposers vs Detritivores Detritivores eat particles of decomposing

matter(detritus) Types-

Scavengers-animals that feed on

carrion, dead plant matter, or refuse.

Ex-buzzards, ants, & vultures Decomposers break down organic remains and

wastes off all organisms and return nutrients to earth

Ex-bacteria, protists, and fungi

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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)

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Inefficiency of energy transfer Loss of energy between levels of food

chain(only 10% is transferred b/t trophic levels) 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

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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

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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?

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Types of Food Webs Grazing food web-energy flows mostly

into herbivores, carnivores, then decomposers

Detrital food web-energy from producers flows mainly into detritivores and decomposers.

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Biological Magnification in Food Webs In biological magnification, some chemical substance is passed

from organisms at one trophic level to those above and becomes increasingly concentrated in body tissues.

By 1995, people in the US were spreading more than 1.25 billion pounds of toxins per year! (insecticides, herbicides, fungicides…)

Example- The peregrine falcon almost became extinct as a result of biomagnification of DDT (a pesticide). DDT has been banned since the 70’s.

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Ecological pyramid Loss of energy between levels of food chain

1,000,000,000

100,000

100

1

sun

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Types of ecological pyramids Biomass pyramid-depicts the dry weight of all

of an ecosystem’s organisms at each tier Energy pyramid-illustrates how the amount of

usable energy diminishes as it is transferred through an ecosystem

Pyramid of numbers-shows how population size decreases as you go from producer to consumer

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AP Biology

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

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In a biogeochemical cycle , an essential element moves from the environment, through ecosystems, then back to the environment.

Ex: O2,H,C,N, & P

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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

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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 atmosphere

enter 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 bacteriarecycle: decomposing &

nitrifying bacteriareturn to abiotic: denitrifying bacteria

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Nitrogen fixation-bacteria convert gaseous nitrogen to ammonia

Denitrification-conversion of nitrate or nitrite to gaseous nitrogen or nitrogen oxide by certain bacteria in the soil

Human activities add nitrogen to ecosystems. Use of fertilizer and fossil fuel burning are examples

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AP Biology

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

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Lakes

Runoff

Percolation in soil

Evaporation

Transpiration

Precipitation

Oceans

Solar energy

AquiferGroundwater

Water cycle

Water vapor

abiotic reservoir: surface & atmospheric

waterenter food chain: precipitation & plant

uptakerecycle: transpiration

return to abiotic: evaporation & runoff

abiotic reservoir: surface & atmospheric

waterenter food chain: precipitation & plant

uptakerecycle: transpiration

return to abiotic: evaporation & runoff

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Transpiration

Remembertranspiration?

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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

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

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Repairing the damage The Greenbelt Movement

planting trees in Kenya restoring a sustainable ecosystem establishing democracy empowering women

Wangari MaathaiNobel Peace prize 2004Nobel Peace prize 2004

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Studying ecosystemsHubbard Brook Experimental Forest

7800 acres

38 acre deforestation

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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?

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A Global Water Crisis Most water on Earth is too salty to drink (around 75%) 2/3 of fresh water is used to irrigate fields About ½ of the US population taps into groundwater for

drinking water that can be contaminated. If the US population and water depletion continues, our

freshwater supply will be in danger. Important terms:

Salinization-a build up of salt in soil that stunts crop plants and decreases yields.

Desalination-removal of salt from sea water

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Greenhouse Gases, Global Warming

The greenhouse effect occurs when greenhouse gases trap heat in the lower atmosphere.

This makes Earth’s surface warm enough to support life. Natural processes and human activities are adding more

greenhouse gases to the atmosphere. Examples: carbon dioxide, CFCs, methane, & nitrous

oxide This results in a result in global warming and climate change.