Carbon Cycle at Global, Ecosystem and Regional Scales

Dennis BaldocchiUniversity of California, Berkeley

Bev LawOregon State University, Corvallis

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)

• 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

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

Barnola et alVostok Ice Core

Y ears before Present0 100000 200000 300000 400000

CO2 (p

pm)

160

180

200

220

240

260

280

300

320

Vostok Ice CorePetit et al. 1999 Nature

Y ears Before Present0 100000 200000 300000 400000

Tem

pera

ture

Var

iatio

n

-12

-10

-8

-6

-4

-2

0

2

4

CO2 => 280 ppm during Inter-Glacial, over 10k yearsCO2 => 180 ppm during Glaciation, over 100k years

Barnola et alVostok Ice Core

Y ears before P resent0 100000 200000 300000 400000

CO 2 (ppm

)

160

180

200

220

240

260

280

300

320

Vostok Ice CorePetit et al. 1999 Nature

Years Before Present0 100000 200000 300000 400000

Tem

pera

ture

Var

iatio

n

-12

-10

-8

-6

-4

-2

0

2

4

Vostok Ice Core, Chapallez et al.

Time, ka bpe

0 100 200 300 400M

etha

ne, p

pb200

300

400

500

600

700

800

Dust, Life, Oceans, CO2 and CH4 Amplify Feedbacks on Climate

VegetationDecreases

Climate Cools

More Dustto Ocean

[CO2]Decreases

Ocean NPPIncreases

Ice Expands/Sea Level

Drops

MethaneHydratesReleased

fromContinentalShelf/ CH4Increases

ClimateWarms

VegetationDenser

C4 PlantsExpand/ SoilC pools Grow

Less Dust toOcean

Ocean NPPDecreases

[CO2] Rises

Terrestrial RespirationOutpaces Photosynthesis

TerrestrialPhotosynthesis

Increases

Solar Forcing

Solar Forcing

CO2Solubilityin Ocean

Increases/DIC Stored

in DeepOcean

Ice Melts/ SeaLevel Rises/

Freshwater inOcean

CO2Solubilityin OceanDecrease

Contemporary CO2 RecordMauna LoaKeeling data

year

1950 1960 1970 1980 1990 2000 2010

CO

2 (pp

m)

300

310

320

330

340

350

360

370

380 Sources:Fossil Fuel CombustionDeforestationCement ProductionSoil and Plant RespirationVolcanoes

Sinks:Photosynthesis, Land/OceanC Burial in Wetlands

Global Carbon Cycle: Gross Fluxes and Pools

[~38,000 PgC]

Atmosphere[843 PgC @ 385 ppm]

88 P

gC/y

120

PgC

/y

Soil[~1500 PgC]

Vegetation[~600 PgC]

90 P

gC/y

60 P

gC/y

60 P

gC/y

7.6

PgC

/y

1.5

PgC

/y

OceanFossil Fuel

Combustion

Deforestation

How much is C in the Air?

• Mass of Atmosphere– F=Pressure x Area=g x Mass– Surface Area of the Globe = 4p R2

– Matmos = 101325 Pa 4p (6378 103 m)2/9.8 m2 s-1=– 5.3 1021 g air

• Compute C in Atmosphere @ 380 ppm

M M pPmm

mm

gCc atmosc co

a

c

co

2

2

15833 10

M P Rgatmos

4 2p

/ ( ) 2.19cc

pMP

Pg/ppm

CO2 in 50 years with Business as Usual

• Current Anthropogenic C Emissions– 7 GtC/yr, (1 GtC = 1015 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 CO2 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 .

C Fluxes Across the World

Schulze, 2006 Biogeosciences

• NBP• NEP• GPP• NPP• Rh

• Ra

FLUXNET: From Sea to Shining Sea500+ Sites, circa 2009

Probability Distribution of Published NEE Measurements, Integrated Annually

FLUXNET Database

NEE (gC m-2 y-1)

-1600 -1400 -1200 -1000 -800 -600 -400 -200 0 200 400 600

pdf

0.00

0.02

0.04

0.06

0.08

0.10

mean= -225 +/- 227 gC m-2 y-1

n=254

day

0 50 100 150 200 250 300 350 400

Rec

o (k

gC h

a-1 d-1 )

0

20

40

60

80

100

Harvard Forest, 1992-2002

day

0 50 100 150 200 250 300 350 400

GPP

(kgC

ha

-1 d-1 )

-140

-120

-100

-80

-60

-40

-20

0

Data of Wofsy et al; Urbanski et al. JGR 2008

Season Course in Daily GPP and Reco for a temperate deciduous forest

Odum, 1969, Science

Conceptual Paradigm: Net Ecosystem Productivity (PN) is a function of age, in responses to changes in Biomass (B), gross primary

productivity (PG) and respiration (R)

Years

Harvard Forest

Year

1990 1992 1994 1996 1998 2000 2002 2004 2006

Car

bon

Flux

(gC

m-2

y-1

)

-600

-400

-200

01000

1200

1400

1600

1800

FNFAFR

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

FA (gC m-2 y-1)

0 500 1000 1500 2000 2500 3000 3500 4000

F R (g

C m

-2 y

-1)

0

500

1000

1500

2000

2500

3000

3500

4000

UndisturbedDisturbed by Logging, Fire, Drainage, Mowing

Baldocchi, Austral J Botany, 2008

Ecosystem Respiration (FR) Scales with Ecosystem Photosynthesis (FA), But with an Offset by Disturbance

Interannual Variability in FN

d FA/dt (gC m-2 y-2)

-750 -500 -250 0 250 500 750 1000

d F R

/dt (

gC m

-2 y

-2)

-750

-500

-250

0

250

500

750

1000Coefficients:b[0] -4.496b[1] 0.704r ² 0.607n =164

Baldocchi, Austral J Botany, 2008

Interannual Variations in Photosynthesis and Respiration are Coupled

Law and Ryan, 2005, Biogeochemistry

C Cycling, Below Ground

Soil Respiration and Temperature, Adequate Soil Moisture

Soil Respiration and Declining Soil Moisture

Regional Carbon Budget ApproachWashington, Oregon, California

Objectives:• Reduce uncertainty in

estimates• Multiple modeling

approaches• Multiple observation

datasets• Effects of disturbance

and climate on carbon balance (past 35 years)

ORCA Top-Down Modeling Concept

SO

UR

CE

SBiosphere

CO2 flux model

Fossil fuel CO2 inventories for

conterminous US

Bac

kgro

und

CO

2 (C

arbo

nTra

cker

)

Atmospheric CO2 observations:

- AmeriFlux data- 5 Monitoring

sites in Oregon

SIN

KS

SO

UR

CE

S

Atmospheric transport modelingAtmospheric transport modeling

Sur

face

dat

a m

aps

Spatial met data

MODIS fPAR

Initial and boundary met

Surface maps high res met fields

STILTStochastic Time

Inverted Lagrangian Transport Model

WRFWeather

Research and Forecasting

Initial and boundary met

Surface maps high res met fields

STILTStochastic Time

Inverted Lagrangian Transport Model

WRFWeather

Research and Forecasting

1km resolutionTimestep refined to

sub-daily (1hr)

fPARSWCTagefaR

fPARGPPTfaRSWCagecloudAPARVPDTfaGPP

soilH

A

,,,,,

,,,,,

3

2

1

25m - 1km resolutionMODIS in 8d bins

DisturbanceHistory

Ecoregion

Land covertype

Stand Age

MODIS fPAR

Surface information

DisturbanceHistory

Ecoregion

Land covertype

Stand Age

MODIS fPAR

Stand Age

MODIS fPAR

Surface information

Temperature

VPD

Radiation

Pressure

Precipitation

Meteorological data (SOGS)

Temperature

VPD

Radiation

Pressure

Precipitation

Meteorological data (SOGS)

A-priori parameter optimization

Reference Flux Data

Solve for optimized flux baserates

Compare to atmospheric data

Diagnostic Carbon Flux Model (BioFlux)

Oregon & California Carbon Budget(1996-2000 means)

OR: C sequestered as NBP + accum. in forest products = 50% ffCA: 10% of equivalent fossil fuel emissions(NBP = NEP – harvest – fire; OR 17 - 10.7 – 0.4 = 5.9 TgC)

Carbon Emission and Ecosystem Services

• US accounts for about 25% of Global C emissions– 0.25*7.0 1015 gC = 1.75 1015 gC

• Per Capita Emissions, US– 1.75 1015 gC/300 106 = 5.833 106 gC/person= 5.833 mtC

• Ecosystem Service, net C uptake– ~100-200 gC m-2

• Land Area per Person– 3.03 104 m2/person ~ 1.5- 3.0 ha/person

• US Land Area – 9.1 108 ha– 8.75 108 to 1.75 109 ha needed by US population to offset its

C emissions Naturally!

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

Luyssaert et al. 2007, GCB

GPP and Climate Drivers

Climate explains 70% of variation in GPP

NEP and Climate Drivers

Luyssaert et al. 2007, GCB

Climate explains 5% of variation in NEP