1 UIUC ATMOS 397G Biogeochemical Cycles and Global Change Lecture 10: Carbon Cycle Don Wuebbles...
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Transcript of 1 UIUC ATMOS 397G Biogeochemical Cycles and Global Change Lecture 10: Carbon Cycle Don Wuebbles...
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ATMOS 397GATMOS 397GBiogeochemical Cycles and Global ChangeBiogeochemical Cycles and Global Change
Lecture 10: Carbon CycleLecture 10: Carbon Cycle
Don WuebblesDon Wuebbles
Department of Atmospheric SciencesDepartment of Atmospheric Sciences
University of Illinois, Urbana, ILUniversity of Illinois, Urbana, IL
February 4, 2003February 4, 2003
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Per capita
Honduras – CO2 Emissions
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Why are plants green?Why are plants green?
Absorption spectrum of isolated chlorophyll and carotenoid species.
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PhotosynthesisPhotosynthesis
Photosynthesis occurs in organelles called
CHLOROPLASTS
2 Stage Process
Water vapor split high energy molecules formed
— 2H2O 4H+ + O2 (note production of O2)
— NADP NADPH and ADP ATP
Reduction of CO2 by H atoms
— The Calvin Cycle
Net:
6 CO2 + 6H2O --------> C6H12O6 + 6 O2
(glucose)
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Photosynthesis: The Calvin cyclePhotosynthesis: The Calvin cycle
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PhotosynthesisPhotosynthesis
Overview of photosynthetic processes as they occur in plants, algae, and cyanobacteria.
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Flow Chart for PhotosynthesisFlow Chart for Photosynthesis
Photosynthesis (Flow Chart)
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At nightAt night
The light reactions of photosynthesis stop
when the sun goes down.
However, CO2 fixation can continue as
long as ATP and NADPH is available.
In cacti and other succulents CO2 uptake
by the plant occurs primarily at night.
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April 2001
September 2000
December 2000
0 0.90.5
MODIS FPAR(Fraction of absorbed Photosynthetically Active Radiation)
FPAR is defined as the fraction of incident photosynthetically active radiation (0.4 - 0.7 m) absorbed the vegetation canopy.
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RespirationRespiration
Respiration: oxidation of carbohydrate to CO2
and H20 in living cells is generally termed
respiration Reverse reaction mechanism
Approx. half of the gross carbon fixation by photosynthesis is used by the plants.
As a result, actual rate of photosynthesis is about twice that which is measured by plant growth
Respiration Photosynthesis
Energy Released Stored
Reactants Glucose CO2 and H2O
Products CO2 and H2O Glucose
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Gross Primary Productivity – Europe (Jan 25 – Feb 1, 2001Gross Primary Productivity – Europe (Jan 25 – Feb 1, 2001
From MODIS satellite instrument
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Net Primary ProductionNet Primary Production
NPP = Uptake of carbon by photolysis – autotrophic respiration losses by vegetation
NPP = Gross Primary Production – plant respiration
or
NPP = GPP - Rp
Annual accumulation of organic matter per unit of land is a measure of NPP
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Net Ecosystem ProductivityNet Ecosystem Productivity
NEP = NPP – Respiration losses from soil
NEP is an estimate of the carbon fluxes between the ecosystem and the atmosphere.
The soil respiration losses are caused by the heterotrophic decomposition of soil organic litter.
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Major Terrestrial Biomes Major Terrestrial Biomes
Savannah –Cabazo, Venezuala
Desert – New Mexico
Boreal Forest - Finland
<>
Tropical Forest - Malaysia
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Average annual Net Primary Productivity of the Average annual Net Primary Productivity of the
Earth's major biomesEarth's major biomes
Ecosystem Type Net Primary Productivity
(kilocalories/meter-2/year) Tropical Rain Forest 9000
Estuary 9000
Swamps and Marshes 9000
Savanna 3000
Deciduous Temperate Forest
6000
Boreal Forest 3500
Temperate Grassland 2000
Polar Tundra 600
Desert < 200
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Factors Limiting NPPFactors Limiting NPP
All plants require sunlight, carbon dioxide, and water for photosynthesis. Photosynthesis is also dependent on temperature and soil nutrients. Temperature (heat) controls the rate of plant metabolism which in turn determines the amount of photosynthesis that can take place. Most biological metabolic activity takes place within the range 0 to 50 degrees Celsius. There is little activity above or below this range. The optimal temperatures for productivity coincide with 15 to 25 degrees Celsius optimal range of photosynthesis. Shown is the relationship between the net primary productivity of forests with annual air temperature and precipiatation.
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IBIS Model – from Jon Foley
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