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Carbon Cycle at Global, Ecosystem and Regional Scales Dennis Baldocchi University of California, Berkeley Bev Law Oregon State University, Corvallis

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Topics Concepts Stores, pools, fluxes, processes Carbon Stores and Fluxes Stores: Vegetation and Soil C = f(x,y,z) Fluxes: NEP = f(x,y,t) Global Fluxes Regional Fluxes (WA, OR, CA)

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How Does Contemporary Carbon Cycle Differ from Pre- Settlement Times? What types of landscapes are better or worse sinks for Carbon? How does Carbon Assimilation and Respiration respond to Environmental stresses, like drought, heatspells, pollution? Are Forests Effective Mitigators for stalling Global Warming? Big Questions

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Methods To Assess Terrestrial Carbon Budgets at Landscape to Continental Scales, and Across Multiple Time Scales Global Circulation Model Inversion Remote Sensing Eddy Flux Measurements/ Flux Networks Forest/Biomass Inventories Biogeochemical/ Ecosystem Dynamics Modeling Physiological Measurements/ Manipulation Expts. Ice Cores

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CO 2 => 280 ppm during Inter-Glacial, over 10k years CO 2 => 180 ppm during Glaciation, over 100k years

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Dust, Life, Oceans, CO 2 and CH 4 Amplify Feedbacks on Climate

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Contemporary CO 2 Record Sources: Fossil Fuel Combustion Deforestation Cement Production Soil and Plant Respiration Volcanoes Sinks: Photosynthesis, Land/Ocean C Burial in Wetlands

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Global Carbon Cycle: Gross Fluxes and Pools

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Net Global Carbon Fluxes, 10 15 gC y -1 1970-19991990-19992000-2006 Fossil Fuel Emission + Cement 5.66.57.6 Land use Change 1.51.61.5 Atmospheric Uptake 3.13.24.1 Ocean uptake 2.02.2 Land Uptake 2.02.72.8 Canadell et al. 2007 PNAS

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Perspective How big is 1 Peta (10 15 ) gram? 1 Giga-ton (Gt) Billion-Million grams Billion cars (@ 1 ton each) 1 10 15 gC/100 10 12 m -2 ~10g m -2 =10 cm 3 m -2 Equivalent to a 10 micron layer of water over a meter-squared surface across the land 1g = 1 cm 3 1 m 3 = 10 6 g = 1 Mt Water Reservoir, 1 km 3 = 1Gt

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How much is C in the Air? Mass of Atmosphere F=Pressure x Area=g x Mass Surface Area of the Globe = 4 R 2 M atmos = 101325 Pa 4 (6378 10 3 m) 2 /9.8 m 2 s -1 = 5.3 10 21 g air Compute C in Atmosphere @ 380 ppm Pg/ppm

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CO 2 in 50 years with Business as Usual Current Anthropogenic C Emissions 7 GtC/yr, (1 GtC = 10 15 g=1Pg) 45% retention in Atmosphere Net Atmospheric Efflux over 50 years 7 * 50 * 0.45 = 157 GtC Atmospheric Burden over 50 years 833 (@380 ppm) + 157 = 990 GtC, Conversion back to mixing ratio 451 ppm ( 2.19 Pg/ppm) or 1.6 x pre-industrial level of 280 ppm To keep atmospheric CO 2 below 450 ppm the World must add less than157GtC into the atmosphere PERIOD Natural Growth in Population and Economies has Anthropogenic emissions slated to grow to 16 GtC/y by 2050.

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C Fluxes Across the World

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Schulze, 2006 Biogeosciences NBP NEP GPP NPP R h R a

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FLUXNET: From Sea to Shining Sea 500+ Sites, circa 2009

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Probability Distribution of Published NEE Measurements, Integrated Annually

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Data of Wofsy et al; Urbanski et al. JGR 2008 Season Course in Daily GPP and Reco for a temperate deciduous forest

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Odum, 1969, Science Conceptual Paradigm: Net Ecosystem Productivity (P N ) is a function of age, in responses to changes in Biomass (B), gross primary productivity (P G ) and respiration (R) Years

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Urbanski et al. 2007, JGR C fluxes of a Middle-Age Temperate Deciduous Forest Continue to change with Stand Age Re-growth after 1938 Hurricane

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Baldocchi, Austral J Botany, 2008 Ecosystem Respiration (F R ) Scales with Ecosystem Photosynthesis (F A ), But with an Offset by Disturbance

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Baldocchi, Austral J Botany, 2008 Interannual Variations in Photosynthesis and Respiration are Coupled

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Law and Ryan, 2005, Biogeochemistry C Cycling, Below Ground

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Soil Respiration and Temperature, Adequate Soil Moisture Soil Respiration and Declining Soil Moisture

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Impact of Rain Pulse and Metabolism on Ecosystem respiration: Fast and Slow Responses Baldocchi et al, 2006, JGR Biogeosciences

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Regional Carbon Budget Approach Washington, Oregon, California Objectives: Reduce uncertainty in estimates Multiple modeling approaches Multiple observation datasets Effects of disturbance and climate on carbon balance (past 35 years)

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ORCA Top-Down Modeling Concept

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Diagnostic Carbon Flux Model (BioFlux)

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Oregon & California Carbon Budget (1996-2000 means) OR: C sequestered as NBP + accum. in forest products = 50% ff CA: 10% of equivalent fossil fuel emissions (NBP = NEP harvest fire; OR 17 - 10.7 0.4 = 5.9 TgC)

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Carbon Emission and Ecosystem Services US accounts for about 25% of Global C emissions 0.25*7.0 10 15 gC = 1.75 10 15 gC Per Capita Emissions, US 1.75 10 15 gC/300 10 6 = 5.833 10 6 gC/person= 5.833 mtC Ecosystem Service, net C uptake ~100-200 gC m -2 Land Area per Person 3.03 10 4 m 2 /person ~ 1.5- 3.0 ha/person US Land Area 9.1 10 8 ha 8.75 10 8 to 1.75 10 9 ha needed by US population to offset its C emissions Naturally!

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What is the Upper Bound of GPP? Bottom-Up: Counting Productivity on leaves, plant by plant, species by species Top-Down: Energy Transfer

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Upper-Bound on Global Gross Primary Productivity Global GPP is ~ 120 * 10 15 gC y -1 Solar Constant, S* (1366 W m -2 ) Ave across disk of Earth S*/4 Transmission of sunlight through the atmosphere (1-0.17=0.83) Conversion of shortwave to visible sunlight (0.5) Conversion of visible light from energy to photon flux density in moles of quanta (4.6/10 6 ) Mean photosynthetic photon flux density, Q p Fraction of absorbed Q p (1-0.1=0.9) Photosynthetic efficiency, a (0.02) Arable Land area (~ 110 * 10 12 m 2 ) Length of daylight (12 hours * 60 minutes * 60 seconds = 43200 s/day) Length of growing season (180 days) Gram of carbon per mole (12) GPP = 1366*0.83*0.5*4.6*0.9*0.02*110 10 12 *43200*180*12/(4 10 6 )=120.4 * 10 15 gC y -1

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Gifford, 1994, Australian J Plant Physiol The Ratio between Respiration and Photosynthesis is Constant: Regardless of Plant Size, Treatment etc Emerging and Useful Ecological Rules

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Luyssaert et al. 2007, GCB GPP and Climate Drivers Climate explains 70% of variation in GPP

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NEP and Climate Drivers Luyssaert et al. 2007, GCB Climate explains 5% of variation in NEP