Looking at Biosphere-Atmosphere Interactions Differently: Roles of Switches, Lags and Pulses on Carbon, Water and Energy Fluxes with Data from a Global Network-Fluxnet Dennis Baldocchi ESPM/Ecosystem Sciences Div. University of California, Berkeley Toronto Seminar March 21, 2006

Why Pulses, Switches and Lags are Important? 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

C Dynamics of Pools and Fluxes: Leads, Lags and Oscillations

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

Scale Emergent Processes: Integrating Photosynthesis from Leaf to Canopy Scale

C Fluxes occur across a Spectrum of Time Scales, with Different Forcings at Each Scale

Switches, Pulses and Lags are Evident in Annual Time Series of Trace Gas Exchange

Complicating Dynamical Factors: Annual Time Course Pulses Switches Lags

Pulses: Volcanoes, Clouds and Aerosols –Photosynthesis Rain –Microbial Respiration –Evaporation Litterfall or Treefall –Respiration Fires –Carbon oxidation

Switches Time Phenological –LAI –Canopy Conductance –Albedo and Radiation Balance –PBL Growth –Photosynthesis Duration and Carbon Balance –Flowering and Respiration Climatic/Geophysical –Snow –Flood –Frost –Drought –Rain –day/night –Land Slide Space Land Use –Age –Roughness –Disturbance –Functional Type –evergreen vs deciduous –Tree vs grass

Lags Transpiration: – Xylem transport and Bole Capacitance Microbial respiration –phloem transport of photosynthate to roots feeds associated microbes –‘acclimation’ as labile pools are depleted and populations grow and change Photosynthetic Capacity: –Leaf chemistry depends on decomposition of previous year’s litter pool Soil respiration –soil temperature amplitude varies and phase angle shifts with depth Growth and Carbon Uptake – f(previous year’s growth)

Data Sources AmeriFlux –Oak Savanna, Ione, Ca –Annual Grassland, Ione, CA –Deciduous Forest, Oak Ridge, TN FLUXNET –Grass and Crops –Conifer Forests –Evergreen and Deciduous Broadleaved Forests

Oak-Grass Savanna: A Two Layer System and Model System for Studying Global Change

FLUXNET: From Sea to Shining Sea 300+ Sites, circa 2006

Eddy Covariance

Outline Pulses –Volcanoes, Aerosols + Photosynthesis –Rain + Respiration –Senescence + Respiration Switches –Phenology Growing Season Length Albedo PBL Development Reproduction + Respiration –Direct/Diffuse Light Use Efficiency Lags –Soil T and Respiration –VPD, Ps and Respiration –Interannual variability Interfaces –Grassland/Savanna

PULSES

Volcanoes, Aerosols + Canopy Photosynthesis

How does an array of biotic and abiotic factors interact to cause interannual variations in the breathing of the terrestrial biosphere?

Pinatubo Altered Radiation Direct-Diffuse Radiation Partitioning more than Global Radiation Measurements at Mauna Loa, Ellsworth Dutton  direct -130 W m -2  diffuse +100 W m -2

Anomaly Global CO 2 Trends after Pinatubo: Reduction (--) in CO 2 Growth Rate Data: Keeling and Whorf More Photosynthesis? Or Less Respiration?

Global Impact of Mt Pinatubo Eruption Rödenbeck, Houweling, Gloor and Heimann, 2003

How Sky Conditions Affect NEE? Baldocchi, 1997, Plant Cell Environ

CO 2 Flux and Diffuse Radiation Niyogi et al., GRL 2004; Gu et al, 2002, JGR; Hollinger et al, Xu et al; Flanagan et al

How do Changes in Diffuse Radiation affect Canopy Fluxes?: Case: Mt Pinatubo Explosion, ~ 10% of beam -> diffuse Gu et al, 2003, Science direct beam diffuse Solar radiation [W m -2 ] Solar elevation angle [°] Year of Mt. Pinatubo eruption

Impact on GPP Gu et al., Science, 2003 Theoretical Impact of 20% reduction in direct radiation is ~ +70 gC m -2 y -1 C uptake

Impact of rain pulses on ecosystem respiration:

Impact of rain pulse on ecosystem respiration: Fast response Baldocchi et al, JGR, Biogeosciences, in press

Rains Pulse do not have Equal Impacts Xu, Baldocchi Agri For Meteorol, 2004

Quantifying the impact of rain pulses on respiration: Assessing the Decay Time constant Xu, Baldocchi, Tang, 2004 Global Biogeochem Cycles

Respiration Enhancement Depends on Initial Condition Xu, Baldocchi, Tang Global Biogeochem Cycles 2004

Significance of rain pulse: Total C respired Xu, Baldocchi, Tang, 2004 Global Biogeochem Cycles

Impact of rain pulse on regional atmospheric CO 2

Coupled PBL-Sfc Energy CO 2 Model: al a McNaughton-Spriggs

Litter Fall Respiration Pulse Leaf Fall Wilson and Baldocchi, JGR, 2002; Granier et al. Functional Ecology, 2001

Switches

Ecohydrology: ET, Functional Type and Drought

Evaporation and Drought Baldocchi et al, 2004 AgForMet

Environmental Controls on Respiration Xu + Baldocchi, AgForMet 2004

Phenology, Growing Season Length and annual NEE Baldocchi et al, 2001, Bull Am Met Soc

Leaf Emergence and Onset of Photosynthesis

Predicting Phenology from Soil Temperature Baldocchi et al. Int J Biomet, 2005

Photosynthesis Switches Partitioning between dominance by Roots vs Microbes Stimulation of Autotrophic is much delayed after onset of photosynthesis Baldocchi et al, JGR, Biogeosciences, in press

Lags-Leads

Soil respiration: False Lags

Tonzi Open areas Tang, Baldocchi, Xu, GCB, 2005 Respiration and Temperature

Lags and Leads in Ps and Resp: Diurnal Tang et al, Global Change Biology 2005.

Soil Resp Lags Ps by about 5 to 6 hours

Other Ecosystem-Scale Lags: Residual Effects of Drought Data of Alex Knohl, ED Schulze and MPI-Jena

Role of Switches, Pulses and Lags on Interannual Variability of NEE? Data of Wofsy, Munger, Goulden et al., Harvard Univ

Sources of Interannual Variability

Landscape Switches

Albedo

Net Radiation

Conclusions Switches, Lags and Pulses are Components of Many Long Term Flux Records Toy Models Provide Insights on Complicated Dynamics and Help Interpret Field Data More Work is Needed to See if S/L/P induces Chaos and Unanticipated Consequences Papers: Nature.berkeley.edu/biometlab –Id: biomet_pubs –Password: cal_bears

Acknowledgements Funding –DOE/TCP, NASA, NIGEC/WESTGEC, Kearney, AES Students, Postdocs, Techs, Landowners Lianhong Gu, Eva Falge, Jianwu Tang, Liukang Xu, Ted Hehn, Tess Krebs, Alex Knohl, Siyan Ma, Matthias Falk Fluxnet Community Ranchers –Russell Tonzi, Fran Vaira