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

nutrientscan only

cycle

inputs

� energy

� nutrients

inputs

� energy

� nutrients

Don’t forgetthe laws of Physics!

Matter cannotbe created ordestroyed

AP Biology

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

AP Biology

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)

AP Biology

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

AP Biology

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.

AP Biology

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.

AP Biology

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

AP Biology

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 alltrophic levels

return toabiotic

reservoir

AP Biology

� In a biogeochemical cycle , an

essential element moves from the

environment, through ecosystems, then

back to the environment.

� Ex: O2,H,C,N, & P

AP Biology

Carbon cycleCO2 in

atmosphere

Diffusion RespirationPhotosynthesis

Photosynthesis

Plants and algae

Plants

Animals

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

AP Biology

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

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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

AP Biology

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

AP Biology

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

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Transpiration

Remembertranspiration?

AP Biology

Breaking the water cycle

� Deforestation breaks the water cycle

� groundwater is not transpired to the atmosphere, so precipitation is not created

forest →→→→ desert

desertification

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are needed to see this picture.

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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

AP Biology

Effects of deforestationC

on

ce

ntr

ati

on

of

nit

rate

(m

g/l

)

1965 1966

Year

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?

AP Biology

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

AP Biology

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.