2005-2006 ecosystems chapter 54. 2005-2006 ecosystem community of organisms plus the abiotic factors...
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2005-2006 Ecosystems
Chapter 54
2005-2006
Ecosystem • Community of organisms plus the abiotic
factors that exist in a certain area
Relationships, I
• Trophic structure / levels~ feeding relationships in an ecosystem
• Primary producers~ the trophic level that supports all others; autotrophs
• Primary consumers~ herbivores
• Secondary and tertiary consumers~ carnivores
• Detrivores/detritus~ special consumers that derive nutrition from non-living organic matter
• Food chain~ trophic level food pathway
Energy Flow, I• Primary productivity (amount of light energy converted to chemical energy by autotrophs)
•Gross (GPP): total energy •Net (NPP): represents the storage of energy available to consumers •Rs: respiration
• NPP = GPP - Rs• Biomass: primary productivity reflected as dry weight of organic material • Secondary productivity: the rate at which an ecosystem's consumers convert chemical
energy of the food they eat into their own new biomass
Energy Flow, II• Ecological efficiency: % of E
transferred from one trophic level to the next (5-20%)
• Pyramid of productivity: multiplicative loss of energy in trophic levels
• Biomass pyramid: trophic representation of biomass in ecosystems
• Pyramid of numbers: trophic representation of the number of organisms in an ecosystem
Energy inefficiency
incompletedigestion
metabolism
Chemical Cycling• Biogeochemical cycles: the various nutrient circuits, which involve both abiotic and biotic
components of an ecosystem• Water• Carbon• Nitrogen• Phosphorus
2005-2006
Carbon cycleCO2 inatmosphere
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
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Birds
Herbivores
Plants
Amino acids
CarnivoresAtmosphericnitrogen
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
2005-2006Loss to deep sediment
Rocks andminerals
Soluble soilphosphate
Plants andalgae
Plants Urine
Land animals
Precipitates
Aquaticanimals
Animal tissueand feces
Animal tissueand feces
Decomposers(bacteria andfungi)
Decomposers(bacteria andfungi)
Phosphatesin solution
Loss indrainage
Phosphorus cycle
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Nutrient cycling
Decompositionconnects all trophic levels
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What have we done!
Human Impact• Biological magnification: trophic process
in which retained substances become more concentrated at higher levels
• Greenhouse effect: warming of planet due to atmospheric accumulation of carbon dioxide
• Ozone depletion: effect of chlorofluorocarbons (CFC’s) released into the atmosphere
• Acid Precipitation • Cause: Overpopulation?
2005-2006
Impact of ecology as a science• Ecology provides a scientific context for
evaluating environmental issues– Rachel Carson, in 1962,
in her book, Silent Spring,warned that use ofpesticides such as DDTwas causing populationdeclines in manynon-target organisms
2005-2006
Barry Commoner’s Laws of Ecology• Everything is connected to everything else• Everything must go somewhere
there is no such place as “away”• Nature knows best• There is no such thing as a free lunch
Laws of Unintended Consequences
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Acid Precipitation nitrogen oxides sulfur dioxide
• power plants• industry• transportation
2005-2006 Acid rain
2005-2006
BioMagnification
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BioMagnification• PCBs– General Electric
manufacturing plant on Hudson River
– PCBs in sediment– striped bass nesting
areas
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Carbon DioxideGlobal Warming
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CO2
NOx
methane
2005-2006
Ozone Depletion
protects from UV rays
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Ozone Depletion
2005-2006
Bad ozone vs. good ozone
2005-2006
Ozone Depletion• Loss of ozone above Antarctica