Applications of eddy covariance measurements, Part 1:
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Applications of eddy covariance measurements, Part 1: Lecture on Analyzing and Interpreting CO 2 Flux Measurements. Dennis Baldocchi ESPM/Ecosystem Science Div. University of California, Berkeley. CarboEurope Summer Course, 2006 Namur, Belgium. Outline. Philosophy/Background Processing

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Applications of eddy covariance measurements, Part 1:Lecture on Analyzing and Interpreting CO2 Flux Measurements

Dennis Baldocchi

ESPM/Ecosystem Science Div.

University of California, Berkeley

CarboEurope Summer Course, 2006

Namur, Belgium


Outline

  • Philosophy/Background

  • Processing

  • Time Series Analysis

    • Diurnal

    • Seasonal

    • Interannual

  • Flux Partitioning

    • Canopy photosynthesis

    • Ecosystem Respiration

  • Processes

    • Photosynthesis

      • f(T,PAR, LAI, soil moisture)

    • Respiration

      • f(photosynthesis, soil C &N, T, soil moisture, growth)

    • Functional Type

    • Disturbance

  • Space

    • Cross-Site Analyzes


Philosophy/Background

  • Philosophy

    • What, How, Why, Will be?

  • BioPhysical Processes

    • Meteorology/Microclimate

      • Light, temperature, wind, humidity, pressure

    • Vegetation

      • Structure (height, leaf area index, leaf size)

      • Physiology (photosynthetic capacity, stomatal conductance)

    • Soil

      • Roots

      • Microbes

      • Abiotic conditions (soil moisture, temperature, chemistry, texture)

  • Spatial-Temporal Variability

    • Spatial

      • Vertical (canopy) and Horizontal (footprint, landscape, functional type, disturbance)

    • Temporal

      • Dynamics

      • Diurnal

      • Seasonal

      • Inter-annual


What a Tower Sees


What the Atmosphere Sees

Schulze, 2006 Biogeosciences


Eddy Covariance


Reality


From the Field to your Dissertation


Time Series Analysis: Raw Data


Time Series: FingerPrint


Time Series: Diurnal Pattern


Time Series: Mean Diurnal Pattern


Night time Biased Respiration


CO2 Storage ‘Flux’


Deciduous Broadleaved Forests


Fourier Transforms


Time Series: Spectral Analysis

Baldocchi et al., 2001 AgForMet


Stoy et al. 2005 Tree Physiol


Time Series: Interannual Variability

Data of Wofsy, Munger, Goulden, Harvard Univ


Intern-annual Lag Effects Due to Drought/Heat Stress

Knohl et al Max Planck, Jena


Processes

  • Canopy Photosynthesis

    • Light

    • Temperature

    • Soil Moisture

    • Functional Type

  • Ecosystem Respiration

    • Temperature

    • Soil Moisture

    • Photosynthesis


Concepts:

NEE and Environmental Drivers

From E. Falge


Pulses, Switches and Lags are Important too!

  • They are Features of Complex Dynamical Systems

  • Biosphere is a Complex Dynamical System

    • Constituent Processes are Non-linear and Experience Non-Gaussian Forcing

    • Possess Scale-Emergent Properties

    • Experiences Variability Across a Spectrum of Time and Space Scales

    • Solutions are sensitive to initial conditions

    • Solutions are path dependent

    • Chaos or Self-Organization can Arise


Light and Photosynthesis:Leaves, Canopies and Emerging Processes


CO2 uptake-Light Response Curve: Crops

Linear Function and High r2 (~0.90)


CO2 uptake-Light Response Curve: Forest

Function is Non-Linear and Low r2 (~0.50)


CO2 flux vs Sunlight at different LAI

Xu and Baldocchi, 2003, AgForMet


Use Theory to Interpret Complex Field Data Patterns


Ac vs Qp: Daily Sums Become Linear!?

Leuning et al. 1995, PCE


Role of Averaging Period:

Hourly vs Daily

Sims et al. AgForMet, 2005


Role of Averaging Period:

Snap Shot vs Daily Integral

Sims et al 2005, AgForMet


Canopy Light Response Curves: Effect of Diffuse Light


CO2 Flux and Diffuse Radiation

Niyogi et al., GRL 2004


C Fluxes and Remote Sensing: NPP and NDVI of a Grassland

Xu, Gilmanov, Baldocchi


Rahman et al 2005 GRL


Linking Water and Carbon:

Potential to assess Gc with Remote Sensing

Xu + DDB


Land Surface Water Index (LSWI) plotted with daily NEE for 2004/2005

Land Surface Water Index LSWI = (ρ860 - ρ1640)/(ρ860 + ρ1640)

PRI and NEE

PRI = (r531 - r570) / (r531 + r570)

Falk, Baldocchi, Ma


Partitioning Carbon Fluxes


Law and Ryan, 2005, Biogeochemistry


De-Convolving Soil Respiration

Kuzyakov, 2006


From E. Falge


Deconstructing NEP:Flux Partitioning into Recoand GPP

Falge et al

Xu and Baldocchi


Ecosystem Respiration

Is Q10 Conservative?

Xu + Baldocchi, AgForMet 2003


Environmental Controls on Respiration

Xu + Baldocchi, AgForMet 2003


Rains Pulse do not have Equal Impacts

Xu, Baldocchi Agri For Meteorol , 2004


Rain Pulses: Heterotrophic Respiration


Respiration time Constant & ppt

Xu + DDB


Respiration and Photosynthesis

Tonzi Open areas

Tang, Baldocchi, Xu, Global Change Biology, 2005


Lags and Leads in Ps and Resp: Diurnal

Tang et al, Global Change Biology 2005.


Cross-Site Analyses


What is Wrong with this Picture?

Valentini et al., 2000, Nature


Longitudinal Gradients across Continents in T and ppt

Break the Relationship


Falge et al., 2002


Law et al 2002 AgForMet


Temperature Acclimation

Falge et al; Baldocchi et al.


Respiration: Temperature and acclimation

Analyst: Enquist et al. 2003, Nature


Atkin


Spatial Gradients:NEE and Length of Growing Season


DRe vs DGPP


Soil Temperature:

An Objective Indicator of Phenology??

Data of Pilegaard et al.


Soil Temperature:

An Objective Measure of Phenology, part 2

Data of: ddb, Wofsy, Pilegaard, Curtis, Black, Fuentes, Valentini, Knohl, Yamamoto. Granier, Schmid

Baldocchi et al. Int J. Biomet, in press


Disturbance and Carbon Fluxes

Amiro et al., 2006


Coursolle et al. 2006


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