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PI: Dennis Baldocchi - University of California, Berkeley
DataManager: Joe Verfaillie - University of California, Berkeley
Technician: Daphne Szutu - UC Berkeley
Lat, Long: 38.4309, -120.9660
Elevation(m): 177
Network Affiliations: AmeriFlux, Phenocam
Vegetation IGBP: WSA (Woody Savannas: Lands with herbaceous and other understory systems, and with forest canopy cover between 30-60%. The forest cover height exceeds 2 meters.)
Climate Koeppen: Csa (Mediterranean: mild with dry, hot summer)
Mean Annual Temp (°C): 15.8
Mean Annual Precip. (mm): 559
Flux Species Measured: CO2, H2O
Years Data Collected: 2001 - Present
Years Data Available:

AmeriFlux BASE 2001 - 2023   Data Citation

AmeriFlux FLUXNET 2001 - 2021   Data Citation

Data Use Policy:AmeriFlux CC-BY-4.0 Policy1
Located in the lower foothills of the Sierra Nevada Mountains, the Tonzi Ranch site is classified as an oak savanna woodland on privately owned land. Managed ...
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Research Topics:
The research approach of the University of California, Berkeley Biometeorology Laboratory involves the coordinated use of experimental measurements and ...
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Acknowledgment: This research was supported by the US Department of Energy Terrestrial Carbon Program, grant No. DE-FG03-00ER63013 and DE-SC0005130
This research was supported in part by the Office of Science (BER), U.S. Department of Energy, Grant No. DE-FG02-03ER63638
Site Tasks
  1. This site’s data can also be used under the more restrictive AmeriFlux Legacy Policy.
    The AmeriFlux Legacy Policy must be followed if this site’s data are combined with data from sites that require the AmeriFlux Legacy Policy.
Site Photo More Site Images
Image Credit: Dennis Baldocchi, 03/01/2006
Copyright preference: Open use
Site Publication More Site Publications
Ma, S, Baldocchi, D.D., Wolf, S., Verfaillie, J. 2016. Slow ecosystem responses conditionally regulate annual carbon balance over 15 years in Californian oak-grass savanna, Agricultural and Forest Meteorology, , 252-264.

Use the information below for citation of this site. See the Data Policy page for more details.

DOI(s) for citing US-Ton data

Data Use Policy: AmeriFlux CC-BY-4.0 License

This site’s data can also be used under the more restrictive AmeriFlux Legacy Policy.
The AmeriFlux Legacy Policy must be followed if US-Ton data are combined with data from sites that require the AmeriFlux Legacy Policy.

  • AmeriFlux BASE:
    Citation: Siyan Ma, Liukang Xu, Joseph Verfaillie, Dennis Baldocchi (2024), AmeriFlux BASE US-Ton Tonzi Ranch, Ver. 20-5, AmeriFlux AMP, (Dataset).
  • AmeriFlux FLUXNET:
    Citation: Siyan Ma, Liukang Xu, Joseph Verfaillie, Dennis Baldocchi (2023), AmeriFlux FLUXNET-1F US-Ton Tonzi Ranch, Ver. 3-5, AmeriFlux AMP, (Dataset).

Find global FLUXNET datasets, like FLUXNET2015 and FLUXNET-CH4, and their citation information at

To cite BADM when downloaded on their own, use the publications below for citing site characterization. When using BADM that are downloaded with AmeriFlux BASE and AmeriFlux FLUXNET products, use the DOI citation for the associated data product.

Publication(s) for citing site characterization



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Year Publication
2021 Baldocchi, D., Ma, S., Verfaillie, J. (2021) On The Inter‐ And Intra‐Annual Variability Of Ecosystem Evapotranspiration And Water Use Efficiency Of An Oak Savanna And Annual Grassland Subjected To Booms And Busts In Rainfall, Global Change Biology, 27(2), 359-375.
2020 Ma, S., Eichelmann, E., Wolf, S., Rey-Sanchez, C., Baldocchi, D. D. (2020) Transpiration And Evaporation In A Californian Oak-Grass Savanna: Field Measurements And Partitioning Model Results, Agricultural And Forest Meteorology, 295, 108204.
2020 Baldocchi, D. D., Ryu, Y., Dechant, B., Eichelmann, E., Hemes, K., Ma, S., Sanchez, C. R., Shortt, R., Szutu, D., Valach, A., Verfaillie, J., Badgley, G., Zeng, Y., Berry, J. A. (2020) Outgoing Near‐Infrared Radiation From Vegetation Scales With Canopy Photosynthesis Across A Spectrum Of Function, Structure, Physiological Capacity, And Weather, Journal Of Geophysical Research: Biogeosciences, 125(7), .
2021 Chu, H., Luo, X., Ouyang, Z., Chan, W. S., Dengel, S., Biraud, S. C., Torn, M. S., Metzger, S., Kumar, J., Arain, M. A., Arkebauer, T. J., Baldocchi, D., Bernacchi, C., Billesbach, D., Black, T. A., Blanken, P. D., Bohrer, G., Bracho, R., Brown, S., Brunsell, N. A., Chen, J., Chen, X., Clark, K., Desai, A. R., Duman, T., Durden, D., Fares, S., Forbrich, I., Gamon, J. A., Gough, C. M., Griffis, T., Helbig, M., Hollinger, D., Humphreys, E., Ikawa, H., Iwata, H., Ju, Y., Knowles, J. F., Knox, S. H., Kobayashi, H., Kolb, T., Law, B., Lee, X., Litvak, M., Liu, H., Munger, J. W., Noormets, A., Novick, K., Oberbauer, S. F., Oechel, W., Oikawa, P., Papuga, S. A., Pendall, E., Prajapati, P., Prueger, J., Quinton, W. L., Richardson, A. D., Russell, E. S., Scott, R. L., Starr, G., Staebler, R., Stoy, P. C., Stuart-Haëntjens, E., Sonnentag, O., Sullivan, R. C., Suyker, A., Ueyama, M., Vargas, R., Wood, J. D., Zona, D. (2021) Representativeness Of Eddy-Covariance Flux Footprints For Areas Surrounding Ameriflux Sites, Agricultural And Forest Meteorology, 301-302, 108350.
2020 Braghiere, R. K., Quaife, T., Black, E., Ryu, Y., Chen, Q., De Kauwe, M. G., Baldocchi, D. (2020) Influence Of Sun Zenith Angle On Canopy Clumping And The Resulting Impacts On Photosynthesis, Agricultural And Forest Meteorology, 291, 108065.
2019 Sadeghi, M., Tuller, M., Warrick, A. W., Babaeian, E., Parajuli, K., Gohardoust, M. R., Jones, S. B. (2019) An Analytical Model For Estimation of Land Surface Net Water Flux From Near-Surface Soil Moisture Observations, Journal of Hydrology, 570, 26-37.
2019 Novick, K. A., Konings, A. G., Gentine, P. (2019) Beyond Soil Water Potential: An Expanded View On Isohydricity Including Land–Atmosphere Interactions And Phenology, Plant, Cell & Environment, 42(6), 1802-1815.
2019 Zhang, Q., Ficklin, D. L., Manzoni, S., Wang, L., Way, D., Phillips, R. P., Novick, K. A. (2019) Response Of Ecosystem Intrinsic Water Use Efficiency And Gross Primary Productivity To Rising Vapor Pressure Deficit, Environmental Research Letters, 14(7), 074023.
2016 Novick, K. A., Ficklin, D. L., Stoy, P. C., Williams, C. A., Bohrer, G., Oishi, A., Papuga, S. A., Blanken, P. D., Noormets, A., Sulman, B. N., Scott, R. L., Wang, L., Phillips, R. P. (2016) The Increasing Importance Of Atmospheric Demand For Ecosystem Water And Carbon Fluxes, Nature Climate Change, 6(11), 1023-1027.
2013 Barr, A., Richardson, A., Hollinger, D., Papale, D., Arain, M., Black, T., Bohrer, G., Dragoni, D., Fischer, M., Gu, L., Law, B., Margolis, H., McCaughey, J., Munger, J., Oechel, W., Schaeffer, K. (2013) Use Of Change-Point Detection For Friction–Velocity Threshold Evaluation In Eddy-Covariance Studies, Agricultural And Forest Meteorology, 171-172, 31-45.
2014 Matheny, A. M., Bohrer, G., Stoy, P. C., Baker, I. T., Black, A. T., Desai, A. R., Dietze, M. C., Gough, C. M., Ivanov, V. Y., Jassal, R. S., Novick, K. A., Schäfer, K. V., Verbeeck, H. (2014) Characterizing The Diurnal Patterns of Errors in The Prediction of Evapotranspiration by Several Land-Surface Models: An Nacp Analysis, Journal Of Geophysical Research: Biogeosciences, 119(7), 1458-1473.
2019 Sullivan, R. C., Kotamarthi, V. R., Feng, Y. (2019) Recovering Evapotranspiration Trends From Biased CMIP5 Simulations And Sensitivity To Changing Climate Over North America, Journal Of Hydrometeorology, 20(8), 1619-1633.
2019 Sullivan, R. C., Cook, D. R., Ghate, V. P., Kotamarthi, V. R., Feng, Y. (2019) Improved Spatiotemporal Representativeness And Bias Reduction Of Satellite-Based Evapotranspiration Retrievals Via Use Of In Situ Meteorology And Constrained Canopy Surface Resistance, Journal Of Geophysical Research: Biogeosciences, 124(2), 342-352.
2018 Baldocchi, D., Penuelas, J. (2018) The Physics And Ecology Of Mining Carbon Dioxide From The Atmosphere By Ecosystems, Global Change Biology, .
2018 Chu, H., Baldocchi, D. D., Poindexter, C., Abraha, M., Desai, A. R., Bohrer, G., Arain, M. A., Griffis, T., Blanken, P. D., O'Halloran, T. L., Thomas, R. Q., Zhang, Q., Burns, S. P., Frank, J. M., Christian, D., Brown, S., Black, T. A., Gough, C. M., Law, B. E., Lee, X., Chen, J., Reed, D. E., Massman, W. J., Clark, K., Hatfield, J., Prueger, J., Bracho, R., Baker, J. M., Martin, T. A. (2018) Temporal Dynamics Of Aerodynamic Canopy Height Derived From Eddy Covariance Momentum Flux Data Across North American Flux Networks, Geophysical Research Letters, 45, 9275–9287.
2017 Liu, Y., Hill, M. J., Zhang, X., Wang, Z., Richardson, A. D., Hufkens, K., Filippa, G., Baldocchi, D. D., Ma, S., Verfaillie, J., Schaaf, C. B. (2017) Using Data From Landsat, Modis, Viirs And Phenocams To Monitor The Phenology Of California Oak/Grass Savanna And Open Grassland Across Spatial Scales, Agricultural And Forest Meteorology, 237-238, 311-325.
2017 Filippa, G, Cremonesea, E, Migliavacca M., Galvagno, M., Sonnentag, O., Humphrey, E., Hufkens,K., Ryu, Y. Verfaillie, J., Morra di Cella, U., Richardson, A. (2017) NDVI derived from near-infrared-enabled digital cameras: Applicability across different plant functional types, Agricultural and Forest Meteorology, .
2010 Baldocchi, D., Chen, Q., Chen, X., Ma, S., Miller, G., Ryu, Y., Xiao, J., Wenk, R., Battles, J. (2010) The Dynamics Of Energy, Water, And Carbon Fluxes In A Blue Oak (Quercus Douglasii) Savanna In California, Ecosystem Function In Savannas, 135-151.
2017 Ma, S., Osuna, J. L., Verfaillie, J., Baldocchi, D. D. (2017) Photosynthetic Responses To Temperature Across Leaf–Canopy–Ecosystem Scales: A 15-Year Study In A Californian Oak-Grass Savanna, Photosynthesis Research, 132(3), 277-291.
2015 Dennis Baldocchi, Cove Sturtevant (2015) Does day and night sampling reduce spurious correlation between canopy photosynthesis and ecosystem respiration?, Agricultural and Forest Meteorology, 207, 117-126.
2017 Wharton, S., Ma, S., Baldocchi, D.D., Falk, M., Newman, J.F., Osuna, J.L, Bible, K. (2017) Influence of regional nighttime atmospheric regimes on canopy turbulence and gradients at a closed and open forest in mountain-valley terrain, Agricultural and Forest Meteorology, 237–238, 18-29.
2010 Baldocchi, D. D., Ma, S., Rambal, S., Misson, L., Ourcival, J., Limousin, J., Pereira, J., Papale, D. (2010) On The Differential Advantages Of Evergreenness And Deciduousness In Mediterranean Oak Woodlands: A Flux Perspective, Ecological Applications, 20(6), 1583-1597.
2010 Ryu, Y., Nilson, T., Kobayashi, H., Sonnentag, O., Law, B. E., Baldocchi, D. D. (2010) On The Correct Estimation Of Effective Leaf Area Index: Does It Reveal Information On Clumping Effects?, Agricultural And Forest Meteorology, 150(3), 463-472.
2006 Kim, J., Guo, Q., Baldocchi, D., Leclerc, M., Xu, L., Schmid, H. (2006) Upscaling Fluxes From Tower To Landscape: Overlaying Flux Footprints On High-Resolution (IKONOS) Images Of Vegetation Cover, Agricultural And Forest Meteorology, 136(3-4), 132-146.
2003 Xu, L., Baldocchi, D. D. (2003) Seasonal Trends In Photosynthetic Parameters And Stomatal Conductance Of Blue Oak (Quercus Douglasii) Under Prolonged Summer Drought And High Temperature, Tree Physiology, 23(13), 865-877.
2011 Ma, S., Baldocchi, D. D., Mambelli, S., Dawson, T. E. (2011) Are Temporal Variations Of Leaf Traits Responsible For Seasonal And Inter-Annual Variability In Ecosystem CO2 Exchange?, Functional Ecology, 25(1), 258-270.
2010 Curiel Yuste, J., Ma, S., Baldocchi, D. D. (2010) Plant-Soil Interactions And Acclimation To Temperature Of Microbial-Mediated Soil Respiration May Affect Predictions Of Soil CO2 Efflux, Biogeochemistry, 98(1-3), 127-138.
2013 Raz-Yaseef, N., Koteen, L., Baldocchi, D. D. (2013) Coarse Root Distribution Of A Semi-Arid Oak Savanna Estimated With Ground Penetrating Radar, Journal Of Geophysical Research: Biogeosciences, 118(1), 135-147.
2005 Sims, D. A., Rahman, A. F., Cordova, V. D., Baldocchi, D. D., Flanagan, L. B., Goldstein, A. H., Hollinger, D. Y., Misson, L., Monson, R. K., Schmid, H. P., Wofsy, S. C., Xu, L. (2005) Midday Values Of Gross CO2 Flux And Light Use Efficiency During Satellite Overpasses Can Be Used To Directly Estimate Eight-Day Mean Flux, Agricultural And Forest Meteorology, 131(1-2), 1-12.
2008 Chen, Q., Baldocchi, D., Gong, P., Dawson, T. (2008) Modeling Radiation And Photosynthesis Of A Heterogeneous Savanna Woodland Landscape With A Hierarchy Of Model Complexities, Agricultural And Forest Meteorology, 148(6-7), 1005-1020.
2010 Miller, G. R., Chen, X., Rubin, Y., Ma, S., Baldocchi, D. D. (2010) Groundwater Uptake By Woody Vegetation In A Semiarid Oak Savanna, Water Resources Research, 46(10), n/a-n/a.
2003 Tang, J., Baldocchi, D. D., Qi, Y., Xu, L. (2003) Assessing Soil CO2 Efflux Using Continuous Measurements Of CO2 Profiles In Soils With Small Solid-State Sensors, Agricultural And Forest Meteorology, 118(3-4), 207-220.
2005 Hibbard, K. A., Law, B. E., Reichstein, M., Sulzman, J. (2005) An Analysis Of Soil Respiration Across Northern Hemisphere Temperate Ecosystems, Biogeochemistry, 73(1), 29-70.
2008 Chen, X., Rubin, Y., Ma, S., Baldocchi, D. (2008) Observations And Stochastic Modeling Of Soil Moisture Control On Evapotranspiration In A Californian Oak Savanna, Water Resources Research, 44(8), n/a-n/a.
2007 Chen, Q., Gong, P., Baldocchi, D., Tian, Y. Q. (2007) Estimating Basal Area And Stem Volume For Individual Trees From Lidar Data, Photogrammetric Engineering & Remote Sensing, 73(12), 1355-1365.
2005 Tang, J., Baldocchi, D. D. (2005) Spatial–Temporal Variation In Soil Respiration In An Oak–Grass Savanna Ecosystem In California And Its Partitioning Into Autotrophic And Heterotrophic Components, Biogeochemistry, 73(1), 183-207.
2010 Ryu, Y., Sonnentag, O., Nilson, T., Vargas, R., Kobayashi, H., Wenk, R., Baldocchi, D. D. (2010) How To Quantify Tree Leaf Area Index In An Open Savanna Ecosystem: A Multi-Instrument And Multi-Model Approach, Agricultural And Forest Meteorology, 150(1), 63-76.
2012 Kobayashi, H., Baldocchi, D. D., Ryu, Y., Chen, Q., Ma, S., Osuna, J. L., Ustin, S. L. (2012) Modeling Energy And Carbon Fluxes In A Heterogeneous Oak Woodland: A Three-Dimensional Approach, Agricultural And Forest Meteorology, 152, 83-100.
2004 Baldocchi, D. D., Xu, L., Kiang, N. (2004) How Plant Functional-Type, Weather, Seasonal Drought, And Soil Physical Properties Alter Water And Energy Fluxes Of An Oak–Grass Savanna And An Annual Grassland, Agricultural And Forest Meteorology, 123(1-2), 13-39.
2007 Ma, S., Baldocchi, D. D., Xu, L., Hehn, T. (2007) Inter-Annual Variability In Carbon Dioxide Exchange Of An Oak/Grass Savanna And Open Grassland In California, Agricultural And Forest Meteorology, 147(3-4), 157-171.
2005 Gu, L., Falge, E. M., Boden, T., Baldocchi, D. D., Black, T., Saleska, S. R., Suni, T., Verma, S. B., Vesala, T., Wofsy, S. C., Xu, L. (2005) Objective Threshold Determination For Nighttime Eddy Flux Filtering, Agricultural And Forest Meteorology, 128(3-4), 179-197.
2004 Xu, L., Baldocchi, D. D., Tang, J. (2004) How Soil Moisture, Rain Pulses, And Growth Alter The Response Of Ecosystem Respiration To Temperature, Global Biogeochemical Cycles, 18(4), n/a-n/a.
2007 Baldocchi, D. D., Xu, L. (2007) What Limits Evaporation From Mediterranean Oak Woodlands – The Supply Of Moisture In The Soil, Physiological Control By Plants Or The Demand By The Atmosphere?, Advances In Water Resources, 30(10), 2113-2122.
2007 Fisher, J. B., Baldocchi, D. D., Misson, L., Dawson, T. E., Goldstein, A. H. (2007) What The Towers Don'T See At Night: Nocturnal Sap Flow In Trees And Shrubs At Two Ameriflux Sites In California, Tree Physiology, 27(4), 597-610.
2007 Chen, Q., Gong, P., Baldocchi, D., Xie, G. (2007) Filtering Airborne Laser Scanning Data With Morphological Methods, Photogrammetric Engineering & Remote Sensing, 73(2), 175-185.
2016 Wolf, S., Keenan, T.F., Fisher, J.B., Baldocchi, D.D., Desai, A.R., Richardson, A.D., Scott, R.L., Law, B.E., Litvak, M.E., Brunsell, N.A., Peters, W., van der Laan-Luijkx, I.T. (2016) Warm spring reduced carbon cycle impact of the 2012 US summer drought, Proceedings of the National Academy of Sciences, 113(21), 5880-5885.
2016 Wang, J., X. M. Xiao, P. Wagle, S. Y. Ma, D. Baldocchi, A. Carrara, Y. Zhang, J. W. Dong, and Y. W. Qin. (2016) Canopy and climate controls of gross primary production of Mediterranean-type deciduous and evergreen oak savannas., Agricultural and Forest Meteorology, 226, 132-147.
2016 Ma, S, Baldocchi, D.D., Wolf, S., Verfaillie, J. (2016) Slow ecosystem responses conditionally regulate annual carbon balance over 15 years in Californian oak-grass savanna, Agricultural and Forest Meteorology, 252-264.
2004 Xu, L., Baldocchi, D.D., Tang, J. (2004) How soil moisture, rain pulses, and growth alter the response of ecosystem respiration to temperature, Global Biogeochemical Cycles, 18(GB4002), 0-0.

BADM for This Site

Access the Biological, Ancillary, Disturbance and Metadata (BADM) information and data for this site.

BADM contain information for many uses, such as characterizing a site’s vegetation and soil, describing disturbance history, and defining instrumentation for flux processing. They complement the flux/met data.

* Online updates are shown on the Overview tab real time. However, downloaded BADM files will not reflect those updates until they have been reviewed for QA/QC.

Wind Roses

Click an image below to enlarge it, or use the navigation panel.
  • Image scale: 795m x 795m
  • Data Collected:
  • Wind roses use variables ‘WS’ and ‘WD’.
    Download Data Download Wind Rose as Image File (PNG)

    Wind Speed (m/s)

  • Graph Type
  • Wind Speed Scale
  • Wind Direction Scale (%)
  • Show Satellite Image
  • Show Wind Rose
  • Annual Average
    About Ameriflux Wind Roses
    Wind Rose Explanation
    wind rose gives a succinct view of how wind speed and direction are typically distributed at a particular location. Presented in a circular format, a wind rose shows the frequency and intensity of winds blowing from particular directions. The length of each “spoke” around the circle indicates the amount of time (frequency) that the wind blows from a particular direction. Colors along the spokes indicate categories of wind speed (intensity). Each concentric circle represents a different frequency, emanating from zero at the center to increasing frequencies at the outer circles
    This information can be useful to gain insight into regions surrounding a flux tower that contribute to the measured fluxes, and how those regions change in dependence of the time of day and season. The wind roses presented here are for four periods of the year, and in 16 cardinal directions. Graphics are available for all sites in the AmeriFlux network based on reported wind measurements at each site.
    Data from each site can be downloaded by clicking the ‘download’ button.
    Hover the cursor over a wind rose to obtain directions, speeds and intensities.
    Note that wind roses are not equivalent to flux footprints. Specifically, the term flux footprint describes an upwind area “seen” by the instruments measuring vertical turbulent fluxes, such that heat, water, gas and momentum transport generated in this area is registered by the instruments. Wind roses, on the other hand, identify only the direction and speed of wind.
    Where do these data come from?
    The wind roses are based on observed hourly data from the sites registered with the AmeriFlux Network.
    Parameters for AmeriFlux Wind Roses
    To use wind roses for a single AmeriFlux site, the following parameters may be most useful:
    • Wind Speed Scale: Per Site
    • Wind Direction Scale (%): Per Site
    To compare wind roses from more than one single AmeriFlux site, the following parameters may be most useful:
    • Wind Speed Scale: Non-Linear
    • Wind Direction Scale (%): AmeriFlux
    Mar - Jun; 6am - 6pm
    Mar - Jun; 6pm - 6am
    Jun - Sep; 6am - 6pm
    Jun - Sep; 6pm - 6am
    Sep - Dec; 6am - 6pm
    Sep - Dec; 6pm - 6am
    Dec - Mar; 6am - 6pm
    Dec - Mar; 6pm - 6am