Post on 14-Feb-2022
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
AP Biology
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
AP Biology
� 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?
AP Biology
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
AP Biology
� 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
AP Biology
� 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
AP Biology
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
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
AP Biology
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
AP Biology
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.