Using a Global Flux NetworkFLUXNET to Study the Breathing of the Terrestrial BiosphereDennis BaldocchiESPM/Ecosystem Science Div.University of California, BerkeleyCEFE/CNRS- Montpellier, Dec. 7, 2007

Contemporary CO2 Record

Methods To Assess Terrestrial Carbon Budgets at Landscape to Continental Scales, and Across Multiple Time ScalesGCM InversionModelingRemote Sensing/MODISEddy Flux Measurements/FLUXNETForest/Biomass InventoriesBiogeochemical/Ecosystem Dynamics ModelingPhysiological Measurements/Manipulation Expts.

Eddy Covariance Technique

ObjectivesNetwork BackgroundTimeDaily and Annual IntegrationSeasonal DynamicsInter-Annual VariabilityDisturbance/ChronosequenceProcessesPhotosynthesis = f(Q,T,functional type)Respiration = f(T, growth, ppt, q)SpaceOther Uses and ApplicationEcosystem Modeling

FLUXNET: From Sea to Shining Sea400+ Sites, circa 2007

Network RepresentativenessSundareshwar et al, 2007 Science

Global distribution of Flux Towers with Respect to Climate

Institutional Memory:Evolution of FLUXNETMeasure Annual Cycle of NEEMicromet issues of Detrending, Transfer Functions, Flux Sampling and Measurements, Gap-filling, Error AssessmentMeasure and Interpret Intra-annual Variation of NEEFlux partitioning (GPP & Reco); assessment of metadata,e.g. Vcmax, soil respiration, LAI, biomass inventories. Quantifying Biophysical Controls on FluxesMeasure and Interpret Inter-annual variations of NEEMeasure NEE over multiple Land-Use Classescrops, grasslands, deciduous and evergreen broadleaf and conifer forestsDisturbance, logging, biodiversity and fireManipulative StudiesNitrogen and H2O additionsMeasure NEE over Representative AreasScaling Flux Information of Footprint to MODIS pixelWorkshopsLaThuile Italy, 1995Flathead Lake MT, 1997Marconi CA, 2000Orvieto Italy, 2002Lake Tahoe CA, 2003Firenze Italy, 2004LaThuile, 2007

FLUXNET Successes

Mountains of data from a spectrum of canopy roughness and stability conditions, functional types and climate spaces have been collectedA Model for Data SharingFLUXNET Web Site, a venue for distributing Primary, Value-added and Meta-Data productsValue-Added Products have been producedDevelopment of Gap-Filling TechniquesProduction of Gap-Filled Daily and Annual SumsMany New Findings on Emergent Processes, Environmental Controls and Seasonality and Annual C fluxesData for Validating and Improving SVAT models used for weather, climate, biogeochemistry and ecosystem dynamicsCollaboration & Synthesis through Workshops and Hosting VisitorsBuilding a Collaborative, Cooperative, Multi-Disciplinary & International Community of ResearchersTraining New and Next Generation of Scientists, Postdocs, Students

LaThuile Fluxnet Workshop, Feb. 2007New Gap-Filled, Qa/Qc Dataset250 Sites; 930 Site-years of Datawww.fluxdata.org

Failures/Un-resolved IssuesNot Measuring Night-time Fluxes WellImPerfect U* correction Not Measuring Fluxes over Complex terrain and during Advection WellImPerfect Flux PartitioningWorks Better on Longer Time ScalesImPerfect Energy Balance ClosureCould be red-herring based limited Rn and G fetchNeed Better Outreach and TrainingBeing Rectified at LaThuile with Participation of New Generation of Fluxnet Scientists

Temporal Dynamics of C FluxesHourDayMonthSeasonYearMultiple YearsPulsesLagsSwitches

Annual Time Series of Trace Gas ExchangeXu and Baldocchi, AgForMet, 2004

Complicating Dynamical FactorsSwitchesPhenologyDroughtFrost/FreezePulsesRainLitterfallEmergent ProcessesDiffuse Light/LUEAcclimationLags Stand Age/Disturbance

Baldocchi, Austral J Botany, submittedProbability Distribution of Published NEE Measurements, Integrated Annually

FLUXNET Database: n ~ 300 in 2003; n ~ 430 in 2005Does pdf change with Time and/or as the Network Grows?

Baldocchi, Austral J Botany, submittedDoes Net Ecosystem Carbon Exchange Scale with Photosynthesis?Ecosystems with greatest GPP dont necessarily experience greatest NEE

Baldocchi, Austral J Botany, submittedEcosystem Respiration Scales Tightly with Ecosystem Photosynthesis, But Is with Offset by Disturbance

Baldocchi, Austral J Botany, submittedNet Ecosystem Carbon Exchange Scales with Length of Growing Season

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

Interannual Variation and Long Term Trends in Net Ecosystem Carbon Exchange (FN), Photosynthesis (FA) and Respiration (FR)Urbanski et al 2007 JGR

Baldocchi, Austral J Botany, submittedInterannual Variations in Photosynthesis and Respiration are Coupled

Knohl et al Max Planck, JenaLag Effects Due to 2003 European Drought/Heat Stress

Emerging Processes

Light and Photosynthesis:Emergent Processes at Leaf and Canopy Scales

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

FLUXNET 2007 DatabaseGPP at 2% efficiency and 365 day Growing SeasonPotential and Real Rates of Gross Carbon Uptake by Vegetation:Most Locations Never Reach Upper PotentialtropicsGPP at 2% efficiency and 182.5 day Growing Season

E. Falge et al 2002 AgForMet; Baldocchi et al 2001 BAMSOptimal NEE: Acclimation with Temperature

Linking Water and Carbon:Potential to assess Gc with Remote SensingXu + DDB, 2003 AgForMet

Processed by M. FalkGc Scale Invariance?Task to Expand with New Database

Environmental Controls on RespirationXu + Baldocchi, AgForMet 2004

Quantifying the impact of rain pulses on respirationXu, Baldocchi, Tang, 2004 Global Biogeochem Cycles

Soil Respiration Lags Photosynthesis onHourly ScaleTang et al. 2006, GCB

Data of Pilegaard et al.Soil Temperature: An Objective Indicator of Phenology??

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

Spatial Variations in C Fluxes

Baldocchi, unpublishedSpatialize Phenology with Transformation Using Climate Map

White, Baldocchi and Schwartz, GRL, submittedFlux Based Phenology Patterns with Match well with data from Phenology Network

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

Heinsch et al. 2006 RSEMODIS GPP Algorithm Test

Limits to Landscape Classification by Functional TypeStand Age/DisturbanceBiodiversityFireLoggingInsects/PathogensManagement/PlantationsKyoto Forests

Time Since Disturbance Affects Net Ecosystem Carbon ExchangeBaldocchi, Austral J Botany, submittedData of teams lead by Amiro, Dunn, Paw U, Goulden

Effects of Stand Age:After LoggingLaw et al. 2003 Global Change Biology

Northern Manitoba: Black Spruce chronosequence (Goulden et al.)SINKSOURCE

Other Activities and Uses of Fluxnet DataEcosystem ModelingEcoHydrologyBiodiversityClimate

Kucharik et al., 2006 Ecol ModelingEcosystem Model Testing and Development

Friend et al 2007, GCBNet ecosystem exchange of CO2 (NEE) predicted by different terrestrial biosphere models compares favourably with FLUXNET observations at diurnal and seasonal timescales.

Seasonality of Photosynthetic CapacityWang et al, 2007 GCB

Optimizing Seasonality of Vcmax improves Prediction of FluxesWang et al, 2007 GCB

Biodiversity and EvaporationBaldocchi, 2004: Data from Black, Schmid, Wofsy, Baldocchi, Fuentes

Mean Soil Temperature Scales with Mean Air Temperature

Current and Future Scientific DirectionsNEE in Urban and Suburban, Africa, India, Latin America and High Arctic EnvironmentsQuantifying and Understanding the controls on Interannual Variability of C and energy FluxesMonitoring the Metabolism of Ecosystems as we undergo Global ChangeCoupling CO2, Trace Gas Deposition/Emission (O3, voc) and Methane FluxesAdopting New Technology (TDL, wireless networks) to embellish flux measurementsCouple tower data with Real-time Data Assimilation Models.Boundary Layer Budgets using Fluxes and High Precision CO2 measurementsSpectral reflectance measurements and Digital Photos across the network for phenology and dynamics of structure and functionSpatial-Temporal Network-Scale AnalysisReal-time Data AssimilationMatching Footprints of Tower and PixelsModel Lags, Switches and PulsesUsing Fluxnet data to assess problems inEcology, Ecohydrology, Biogeochemistry, Biogeography, Remote Sensing, Global Modeling, BiodiversityTesting Maximum Entropy, Ecosystem Ecology, Biogeography and EcoHydrology Theories

AcknowledgementsData PreparationDario Papale, Markus Reichstein, Catharine Van Ingen, Deb Agarwal, Tom Boden, Bob Cook, Susan Holliday, Bruce Wilson, +++Networks AmeriFlux, CarboEurope, AsiaFlux, ChinaFlux, Fluxnet Canada, OzFlux, +++AgenciesNSF/RCN, ILEAPS, DOE/TCP, NASA, Microsoft, ++++

FLUXNET 2007++New Issues/Questions RaisedProduction of New, Expanded DataBaseUse of New Software Tools to Facilitate DataBase Navigation & ExplorationBroader representation of vegetation types and climates on NEE, GPP and Reco. Roles of natural and human induced disturbance on C FluxesImpacts of climate and ecosystem factors on inter-annual variations of carbon, water and energy fluxes. Use FLUXNET data to provide ground-truth information to validate and anchor NPP and fpar products being produced by MODIS LAND Perform geostatistical analyses with the FLUXNET database to examine the scales of spatial coherence of net carbon, water and energy fluxes across landscapes, regions and continents and to quantify the network connectivity among groups of sites. Revisit many basic tenets of bio- & micrometeorologyData are being collected from a spectrum of land surface types (short grasses and crops, through open heterogeneous canopies to tall, closed forests) on flat to moderately undulating terrain over a wide range of atmospheric stability conditions Intermittent Turbulence

Testbed for Ecohydrological TheoryMiller et al, Adv. Water Research, on-line

*******************R2 = 0.16***************************Check out Schulze, Wirth, Knohl**************