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 Use the CANVEG Model to Ask Ecophysiological and Micrometeorological Questions Relating to Trace Gas Fluxes

Classes of Model Complexity The 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.

ESPM 111 Ecosystem Ecology System Complexity: Interconnection of Key Ecosystem Processes

Processes and Linkages: Roles of Time and Space Scales

ESPM 111 Ecosystem Ecology 3-d Representation of Canopy Qi Chen and D. Baldocchi

ESPM 111 Ecosystem Ecology Geometrical Abstraction of the Canopy One-Dimensional –Big-Leaf –Dual Source, Sun-Shade –2-Layer Vegetation and soil –Multi-Layered Two-Dimensional –Dual source sunlit and shaded Vegetated vs Bare Soil Three-Dimensional –Individual Plants and Trees After Hanson et al Ecol Appl 2004

Big-Leaf Model

2-Layer/Dual Source Models

Dual Source Model: Discrete Form Whole Canopy

ESPM 111 Ecosystem Ecology Role of Proper Model Abstraction

Sunlit Leaf Area and Sun Angle

Multi-Layer Models

CANOAK Schematic

ESPM 111 Ecosystem Ecology Basics of Ecosystem Models

Quantifying Sources and Sinks Biology: a(z), C i, r s Physics: r b, C(z)

Weight Source/Sink by Fraction of Sunlit and Shaded Leaves and Their Environment

Random Spatial Distribution: Poisson Prob Distr. Prob of Beam Penetration Prob of Sunlit Leaf

Sources of Spatial Heterogeneity Vertical Variations in: –Leaf area index –Leaf inclination angles –Leaf Clumping –Leaf N + photosynthetic capacity –Stomatal conductance –Light, Temperature, Wind, Humidity, CO 2

Vertical Profiles in Leaf Area

Vertical Variation in Sunlight

Carboxylation Velocity Profiles

Profiles of Ci/Ca

Turbulence Closure Schemes Lagrangian Eulerian –Zero Order, c(z)=constant –First Order, F=K dc/dz –Second Order and ++ (dc/dt, dw’c’/dt)

ESPM 228 Adv Topics Micromet & Biomet Higher Order Closure Equations and Unknowns

Lagrangian Near- and Far-Field Theory ESPM 228 Adv Topics Micromet & Biomet

Dispersion Matrix ESPM 228 AdvTopics Micromet & Biomet

Turbulent Mixing

Vertical Gradients in CO 2

Vertical Gradients in q and T

13 C Profiles

Physiology Photosynthesis Stomatal Conductance Transpiration Micrometeorology Leaf/Soil Energy Balance Radiative Transfer Lagrangian Turbulent Transfer CANOAK MODEL

Examples: Non-Linear Biophysical Processes Leaf Temperature Transpiration Photosynthesis Respiration

Why Non-linearity is Important?

ESPM 129 Biometeorology35 Leaf Energy Balance R: is shortwave solar energy, W m -2 L: is Longwave, terrestrial energy, W m -2  E: Latent Heat Flux Density, W m -2 H: Sensible Heat Flux Density, W m -2

ESPM 129 Biometeorology36 Leaf Energy Balance, Wet, Transpiring Leaf Net Radiation is balanced by the sum of Sensible and Latent Heat exchange

ESPM 129 Biometeorology37 Derivation 1: Leaf Energy Balance 2: Resistance Equations for H and E 3: Linearize T 4 and e s (T)

ESPM 129 Biometeorology38 Linearize with 1 st order Taylor’s Expansion Series

ESPM 129 Biometeorology39 Linearize the Saturation Vapor Pressure function

ESPM 228, Advanced Topics in Micromet and Biomet W c, the rate of carboxylation when ribulose bisphosphate (RuBP) is saturated W j, the carboxylation rate when RuBP regeneration is limited by electron transport. W p carboxylation rate with triose phosphate utilization

ESPM 228, Advanced Topics in Micromet and Biomet If W c is minimal, then: If W j is minimal, then If W p is minimal, then

ESPM 228, Advanced Topics in Micromet and Biomet Analytical Equation for Leaf Photosynthesis Baldocchi 1994 Tree Physiology

ESPM 228, Advanced Topics in Micromet and Biomet Seasonality in V cmax Wilson et al Tree Physiol

Results and Discussion

Model Test: Hourly to Annual Time Scale

Model Test: Hourly Data

Time Scales of Interannual Variability

Spectra of Photosynthesis and Respiration

Model Test: Daily Integration

Interannual Variability

ESPM 111 Ecosystem Ecology Hansen et al, 2004 Ecol Monograph Model Validation: Who is Right and Wrong, and Why? How Good is Good Enough?

Decadal Power Spectrum of CO 2 and Water Vapor Fluxes

NEE and Growing Season Length

GPP

Component C Fluxes

Light Use Efficiency and Net Primary Productivity NPP=  f Q p

LUE and Leaf Area

LUE and Ps Capacity

Emergent Processes: Impact of Leaf Clumping on Canopy Light Response Curves

Role of Leaf Clumping on Annual C and H 2 O Fluxes

Interaction between Clumping and Leaf Area

How Sky Conditions Affect NEE?

Knohl and Baldocchi, JGR Biogeosci 2008

Knohl and Baldocchi, 2008 JGR Biogeosci

Potential Impact of Aerosols/Clouds on NEE

Oxygen and NEE: Paleoclimates

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

Leaf Temperature and Isoprene Emission?

Leaf size, CO 2 and Temperature: why oak leaves are small in CA and large in TN

Physiological Capacity and Leaf Temperature: Why Low Capacity Leaves Can’t Be Sunlit::or don’t leave the potted Laurel Tree in the Sun

Below Canopy Fluxes

Below Canopy Fluxes and Canopy Structure and Function

Impact of Thermal Stratification

Impact of Litter

Conclusions Biophysical Models that Couple Aspects of Micrometeorology, Ecophysiology and Biogeochemistry Produce Accurate and Constrained Fluxes of C and Energy, across Multiple Time Scales Models can be used to Interpret Field Data –LUE is affected by LAI, Clumping, direct/diffuse radiation, Ps capacity –NEE is affected by length of growing season –Interactions between leaf size, Ps capacity and position help leaves avoid lethal temperatures –Below canopy fluxes are affected by T stratification and litter