1. Role of Flux Networks in Biogeosciences
Dennis Baldocchi
ESPM/Ecosystem Science Div.
University of California, Berkeley
AGU Biogeosciences, May 22, 2007

2. Acknowledgements Co-Authors Data Preparation Networks and Scientists
Dario Papale, Markus Reichstein
Data Preparation
Dario Papale, Markus Reichstein, Tom Boden, Bob Cook, Susan Holliday, Catharine Van Ingen, Deb Agarwal +++
Networks and Scientists
AmeriFlux, CarboEurope, AsiaFlux, ChinaFlux, Fluxnet Canada, OzFlux, +++
Agencies
NSF/RCN, ILEAPS, DOE/TCP, NASA, Microsoft, ++++

3. Eddy Covariance
Direct and Quasi-Continuous

4. FLUXNET: From Sea to Shining Sea 400+ Sites, circa 2007

6. Global distribution of Flux Towers with Respect to Climate

7. Network Representativeness
Sundareshwar et al, 2007 Science

8. Evolution of FLUXNET
Co-Development of Eddy Covariance Theory, Instrumentation and Microcomputers
1980s
Measure Annual Cycle and Budget of NEE
1990s
Flux Partitioning: NEE into GPP and Reco
2000s
Measure NEE over multiple Land-Use and Disturbance Classes
2000+
Measure Inter-annual variations of NEE
2005+

9. Technical Developments: Evolution of FLUXNET
Instrumentation and Computational Issues
Fast Response Instrumentation (10 Hz) and Data Storage
Micromet issues
Detrending Time Series
Corrections due to Advection on non-ideal Terrain
Corrections due to Spectral Filtering by Sensors
DataBase Issues
DataSharing, Trust and Collaboration
Gap-filling
Error Assessment
QA/QC and Distribution

10. LaThuile Fluxnet Workshop, Feb. 2007
New Gap-Filled, Qa/Qc Dataset
180 Sites; 600 Site-years of Data

11. Recent Results and Advances:
Statistical Representation
Processes
Canopy-Scale Response Functions
Emergent Processes
Flux Partitioning, NEP=GPP-Reco
Acclimation
Carbon-Water Coupling
Time
Daily/Seasonal Dynamics
Pulses, Lags, Switches
Intra- + Interannual Variability
Stand Age/Disturbance
Space
Climate/Structure/Function
Coherence/Gradients
Upscaling with Remote Sensing

12. Annual Time Series of Trace Gas Exchange
Xu and Baldocchi, AgForMet, 2004

13. Can we Integrate C Fluxes, Probabilistically, and Globally, driven with Spatially-Gridded Climate Data?
Fluxnet Database

14. Potential and Real Rates of Gross Carbon Uptake by Vegetation:
Most Locations Never Reach Upper Potential
GPP at 2% efficiency and 365 day Growing Season
tropics
GPP at 2% efficiency and day Growing Season
FLUXNET 2007 Database

15. Light and Photosynthesis: Emergent Processes at Leaf and Canopy Scales

16. Emergent Scale Process: CO2 Flux and Diffuse Radiation
We are poised to see effects of Cleaner/Dirtier Skies and Next Volcano
Niyogi et al., GRL 2004

17. Optimal NEE: Acclimation with Temperature
E. Falge et al 2002 AgForMet; Baldocchi et al 2001 BAMS

18. GPP has a Cost, in terms of Ecosystem Respiration
LaThuile, Fluxnet 2007 Dataset

19. Environmental Controls on Respiration
Xu + Baldocchi, AgForMet 2004

20. Understory Respiratory Efflux Scales with GPP
Misson et al., 2007, AgForMet

21. Linking Water and Carbon: Potential to assess Gc with Remote Sensing
Xu + DDB, 2003 AgForMet

22. Normalized Evaporation Scales with Surface Resistance
Surface Resistance = f(LAI, soil moisture, Ps Capacity, Ps Pathway)

23. Temporal Dynamics of C Fluxes
Hour
Day
Month
Season
Year
Multiple Years
Pulses
Lags
Switches

24. Decadal Plus Time Series of NEE: Flux version of the Keeling’s Mauna Loa Graph
Data of Wofsy, Munger, Goulden, et al.

25. Decadal Plus Time Series of GEE and Reco:
Data of Wofsy, Munger, Goulden et al.

26. Complicating Dynamical Factors
Switches/Pulses
Rain
Phenology/Length of Season
Frost/Freezing
Emergent Processes
Clouds & LUE
Acclimation
Lags
Stand Age/Disturbance
Baldocchi and Valentini, SCOPE

27. NEE and Length of Growing Season:
Coherent response among sites, impact of length of growing season. Does not account for interannual variability at a site, due to snow cover, drought, cloudy vs clear summers etc.
Baldocchi et al 2001, BAMS

28. An Objective Indicator of Phenology??
Soil Temperature:
An Objective Indicator of Phenology??
Data of Pilegaard et al.; Baldocchi et al. Int J. Biomet, 2005

29. An Objective Measure of Phenology, part 2
Soil Temperature:
An Objective Measure of Phenology, part 2
Baldocchi et al. Int J. Biomet, 2005

30. Sources of Interannual Variability

31. Lag Effects Due to 2003 European Drought/Heat Stress
Knohl et al Max Planck, Jena

32. Respiration Lags Photosynthesis, v1: Hourly Scale
Tang et al. 2006, GCB

33. Continuous Measurements Enable Use of Inverse Fourier Transforms to Quantify Lag Times
Tang et al. 2006, GCB

34. Quantifying the impact of rain pulses on respiration
Xu, Baldocchi, Tang, 2004
Global Biogeochem Cycles

35. Spatial Variations in C Fluxes

36. Spatialize Phenology with Flux-Based Transformation & Climate Map

37. Flux Based Phenology Patterns with Match well with data from Phenology Network
White, Baldocchi and Schwartz, GRL, submitted

38. Do Snap-Shot C Fluxes, inferred from Remote Sensing, Relate to Daily C Flux Integrals?
Sims et al 2005 AgForMet

39. MODIS GPP Algorithm Test
Heinsch et al RSE

40. Limits to Landscape Classification by Functional Type
Stand Age/Disturbance
Biodiversity
Fire
Logging
Insects/Pathogens
Management/Plantations

41. Use of Chronosequences to Study Disturbance and Succession
SINK
SOURCE
Goulden et al.

42. Ecosystem Model Testing and Development
Kucharik et al., 2006 Ecol Modeling

43. Seasonality of Photosynthetic Capacity
Wang et al, 2007 GCB

44. Optimizing Seasonality of Vcmax improves Prediction of Fluxes
Wang et al, 2007 GCB

45. FLUXNET Successes
Mountains of data from a spectrum of canopy roughness and stability conditions, functional types and climate spaces have been collected
A Model for Data Sharing
FLUXNET Web Site, a venue for distributing Primary, Value-added and Meta-Data products
Value-Added Products have been produced
Development of Gap-Filling Techniques
Production of Gap-Filled Daily and Annual Sums
Many New Findings on Emergent Processes, Environmental Controls and Seasonality and Annual C fluxes
Data for Validating and Improving SVAT models used for weather, climate, biogeochemistry and ecosystem dynamics
Collaboration & Synthesis through Workshops and Hosting Visitors
Building a Collaborative, Cooperative, Multi-Disciplinary & International Community of Researchers
Training New and Next Generation of Scientists, Postdocs, Students

46. Current and Future Scientific Directions
NEE in Urban and Suburban, Africa, India, Latin America and High Arctic Environments
Quantifying and Understanding the controls on Interannual Variability of C and energy Fluxes
Monitoring the Metabolism of Ecosystems as we undergo Global Change
Coupling CO2, Trace Gas Deposition/Emission (O3, voc) and Methane Fluxes
Adopting New Technology (TDL, wireless networks) to embellish flux measurements
Couple tower data with Real-time Data Assimilation Models.
Boundary Layer Budgets using Fluxes and High Precision CO2 measurements
Spectral reflectance measurements and Digital Photos across the network for phenology and dynamics of structure and function
Spatial-Temporal Network-Scale Analysis
Real-time Data Assimilation
Matching Footprints of Tower and Pixels
Model Lags, Switches and Pulses
Using Fluxnet data to assess problems in
Ecology, Ecohydrology, Biogeochemistry, Biogeography, Remote Sensing, Global Modeling, Biodiversity
Testing Maximum Entropy, Ecosystem Ecology, Biogeography and EcoHydrology Theories