integrating fluxes of carbon dioxide and water vapor from leaf to canopy scales

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Integrating Fluxes of Carbon Dioxide and Water Vapor From Leaf to Canopy Scales. Dennis Baldocchi Ecosystem Science Division/ESPM UC Berkeley. Outline. Overview Leaf-Canopy Scaling and Integration Concepts Show Tests of Such Models over Multiple Time Scales - PowerPoint PPT Presentation


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Integrating Fluxes of Carbon Dioxide and Water Vapor From Leaf to Canopy ScalesDennis BaldocchiEcosystem Science Division/ESPMUC Berkeley

1OutlineOverview Leaf-Canopy Scaling and Integration ConceptsShow Tests of Such Models over Multiple Time ScalesUse the CANVEG Model to Ask Ecophysiological and Micrometeorological Questions Relating to Trace Gas Fluxes

2Classes of Model ComplexityThe breadth and linkage of functional components that describe the biophysics of trace gas exchange. How driving variables are defined and used as inputs to non-linear model algorithms. The geometric abstraction of the canopy.

3ESPM 111 Ecosystem Ecology

System Complexity: Interconnection of Key Ecosystem Processes4

Processes and Linkages:Roles of Time and Space Scales5ESPM 111 Ecosystem Ecology

3-d Representation of CanopyQi Chen and D. Baldocchi6ESPM 111 Ecosystem EcologyGeometrical Abstraction of the CanopyOne-DimensionalBig-LeafDual Source, Sun-Shade2-LayerVegetation and soilMulti-LayeredTwo-DimensionalDual sourcesunlit and shadedVegetated vs Bare SoilThree-DimensionalIndividual Plants and Trees

After Hanson et al Ecol Appl 20047

Big-Leaf Model8

2-Layer/Dual Source Models9Dual Source Model:Discrete FormWhole Canopy

10ESPM 111 Ecosystem Ecology

Role of Proper Model Abstraction


Sunlit Leaf Area and Sun Angle12Multi-Layer Models


CANOAK Schematic14ESPM 111 Ecosystem EcologyBasics of Ecosystem Models


Quantifying Sources and SinksBiology: a(z), Ci, rsPhysics: rb, C(z)16Weight Source/Sink by Fraction of Sunlit and Shaded Leaves and Their Environment


Random Spatial Distribution:Poisson Prob Distr.Prob of Beam PenetrationProb of Sunlit Leaf18Sources of Spatial HeterogeneityVertical Variations in:Leaf area indexLeaf inclination anglesLeaf ClumpingLeaf N + photosynthetic capacityStomatal conductanceLight, Temperature, Wind, Humidity, CO2


Vertical Profiles in Leaf Area

20Vertical Variation in Sunlight

21Carboxylation Velocity Profiles

22Profiles of Ci/Ca

23Turbulence Closure SchemesLagrangian

EulerianZero Order, c(z)=constantFirst Order, F=K dc/dzSecond Order and ++ (dc/dt, dwc/dt)


ESPM 228 Adv Topics Micromet & BiometHigher Order Closure Equations and Unknowns25

Lagrangian Near- and Far-Field TheoryESPM 228 Adv Topics Micromet & Biomet26

Dispersion MatrixESPM 228 AdvTopics Micromet & Biomet27Turbulent Mixing


Vertical Gradients in CO229

Vertical Gradients in q and T3013C Profiles

31PhysiologyPhotosynthesisStomatal ConductanceTranspirationMicrometeorologyLeaf/Soil Energy BalanceRadiative TransferLagrangian Turbulent Transfer

CANOAK MODEL32Examples: Non-Linear Biophysical Processes

Leaf TemperatureTranspirationPhotosynthesisRespiration


Why Non-linearity is Important?34ESPM 129 Biometeorology35

Leaf Energy BalanceR: is shortwave solar energy, W m-2

L: is Longwave, terrestrial energy, W m-2

lE: Latent Heat Flux Density, W m-2

H: Sensible Heat Flux Density, W m-2

35ESPM 129 Biometeorology36Leaf Energy Balance, Wet, Transpiring Leaf

Net Radiation is balanced by the sum of Sensible and Latent Heat exchange

36ESPM 129 Biometeorology37

Derivation1: Leaf Energy Balance2: Resistance Equations for H and lE3: Linearize T4 and es(T)

37ESPM 129 Biometeorology38

Linearize with 1st order Taylors Expansion Series38ESPM 129 Biometeorology39

Linearize the Saturation Vapor Pressure function

39ESPM 228, Advanced Topics in Micromet and Biomet

Wc, the rate of carboxylation when ribulose bisphosphate (RuBP) is saturated Wj, the carboxylation rate when RuBP regeneration is limited by electron transport.

Wp carboxylation rate with triose phosphate utilization40ESPM 228, Advanced Topics in Micromet and BiometIf Wc is minimal, then:

If Wj is minimal, then

If Wp is minimal, then

41ESPM 228, Advanced Topics in Micromet and Biomet

Analytical Equation for Leaf PhotosynthesisBaldocchi 1994 Tree Physiology42ESPM 228, Advanced Topics in Micromet and Biomet

Seasonality in VcmaxWilson et al. 2001 Tree Physiol43Results and Discussion


Model Test: Hourly to Annual Time Scale45Stress need to use ensembles of flux data, not instantaneous data points, they have errors too, both sampling and bias

Model Test: Hourly Data46Time Scales of Interannual Variability

47Spectra of Photosynthesis and Respiration


Model Test: Daily Integration49Interannual Variability

50ESPM 111 Ecosystem Ecology

Hansen et al, 2004 Ecol MonographModel Validation: Who is Right and Wrong, and Why?How Good is Good Enough?51

Decadal Power Spectrum of CO2 and Water Vapor Fluxes52

NEE and Growing Season Length53

GPP54Component C Fluxes

55Light Use Efficiency and Net Primary Productivity

NPP=e f Qp


LUE and Leaf Area57

LUE and Ps Capacity58Emergent Processes: Impact of Leaf Clumping on Canopy Light Response Curves


Role of Leaf Clumping on Annual C and H2O Fluxes60Interaction between Clumping and Leaf Area


How Sky Conditions Affect NEE?62



Knohl and Baldocchi, JGR Biogeosci 200865

Knohl and Baldocchi, 2008 JGR Biogeosci66

Knohl and Baldocchi, 2008 JGR Biogeosci67Potential Impact of Aerosols/Clouds on NEE

68But what if clouds cause cooling and shorter growing season?Oxygen and NEE: Paleoclimates


Do We Need to Consider Canopy Microclimate [C] Feedbacks on Fluxes?70

Leaf Temperature and Isoprene Emission?71

Leaf size, CO2 and Temperature: why oak leaves are small in CA and large in TN72

Physiological Capacity and Leaf Temperature: Why Low Capacity Leaves Cant Be Sunlit::or dont leave the potted Laurel Tree in the Sun73

Below Canopy Fluxes74Below Canopy Fluxes and Canopy Structure and Function


Impact of Thermal Stratification76

Impact of Litter77ConclusionsBiophysical Models that Couple Aspects of Micrometeorology, Ecophysiology and Biogeochemistry Produce Accurate and Constrained Fluxes of C and Energy, across Multiple Time ScalesModels can be used to Interpret Field Data LUE is affected by LAI, Clumping, direct/diffuse radiation, Ps capacityNEE is affected by length of growing seasonInteractions between leaf size, Ps capacity and position help leaves avoid lethal temperaturesBelow canopy fluxes are affected by T stratification and litter78