International Journal of Biometeorology

, Volume 49, Issue 6, pp 377–387

Predicting the onset of net carbon uptake by deciduous forests with soil temperature and climate data: a synthesis of FLUXNET data


    • Ecosystem Science Division, Department of Environmental Science, Policy and ManagementUniversity of California
  • T. A. Black
    • Faculty of Agricultural SciencesUniversity of British Columbia
  • P. S. Curtis
    • Department of Evolution, Ecology & Organismal BiologyOhio State University
  • E. Falge
    • Bayreuth University
  • J. D. Fuentes
    • Department of Environmental SciencesUniversity of Virginia
  • A. Granier
    • INRA
  • L. Gu
    • Environmental Science DivisionOak Ridge National Laboratory
  • A. Knohl
    • Max Planck Institute for Biogeochemistry
    • Present address: ESPMUniversity of California
  • K. Pilegaard
    • RISOE
  • H. P. Schmid
    • Department of GeographyIndiana University
  • R. Valentini
    • Department of Forest Science and EnvironmentUniversita’ di Tuscia
  • K. Wilson
    • Atmospheric Turbulence and Diffusion DivisionNOAA
  • S. Wofsy
    • Department of Earth and Planetary ScienceHarvard University
  • L. Xu
    • Ecosystem Science Division, Department of Environmental Science, Policy and ManagementUniversity of California
    • Present address: LICOR
  • S. Yamamoto
    • National Institute of Advanced Industrial Science and Technology
Original Article

DOI: 10.1007/s00484-005-0256-4

Cite this article as:
Baldocchi, D.D., Black, T.A., Curtis, P.S. et al. Int J Biometeorol (2005) 49: 377. doi:10.1007/s00484-005-0256-4


We tested the hypothesis that the date of the onset of net carbon uptake by temperate deciduous forest canopies corresponds with the time when the mean daily soil temperature equals the mean annual air temperature. The hypothesis was tested using over 30 site-years of data from 12 field sites where CO2 exchange is being measured continuously with the eddy covariance method. The sites spanned the geographic range of Europe, North America and Asia and spanned a climate space of 16°C in mean annual temperature. The tested phenology rule was robust and worked well over a 75 day range of the initiation of carbon uptake, starting as early as day 88 near Ione, California to as late as day 147 near Takayama, Japan. Overall, we observed that 64% of variance in the timing when net carbon uptake started was explained by the date when soil temperature matched the mean annual air temperature. We also observed a strong correlation between mean annual air temperature and the day that a deciduous forest starts to be a carbon sink. Consequently we are able to provide a simple phenological rule that can be implemented in regional carbon balance models and be assessed with soil and temperature outputs produced by climate and weather models.


PhenologyEddy covarianceCO2 exchangeCanopy photosynthesis

Copyright information

© ISB 2005