U.S. Department of Agriculture: Forest Service -- National Agroforestry Center



Andrew D. Richardson, Harvard UniversityFollow
Ryan S. Anderson, University of Montana - MissoulaFollow
M. Altaf Arain, McMaster University
Alan G. Barr, Science and Technology Branch, Environment Canada
G. Bohrer, Ohio State UniversityFollow
Guangsheng Chen, Auburn UniversityFollow
Jing M. Chen, University of TorontoFollow
Philippe Ciais, Orme des MerisiersFollow
Kenneth J. Davis, The Pennsylvania State UniversityFollow
Ankur R. Desai, University of Wisconsin–MadisonFollow
Michael C. Dietze, University of Illinois at Urbana-ChampaignFollow
Danilo Dragoni, Indiana University
Steven R. Garrity, Ohio State UniversityFollow
Christopher M. Gough, Virginia Commonwealth UniversityFollow
Robert Grant, University of AlbertaFollow
David Y. Hollinger, USDA Forest ServiceFollow
Hank A. Margolis, Laval UniversityFollow
Harry Mccaughey, Queen’s UniversityFollow
Mirco Migliavacca, Institute for Environment and SustainabilityFollow
Russell K. Monson, University of ColoradoFollow
J. William Munger, Harvard UniversityFollow
Benjamin Poulter, Swiss Federal Research Institute WSLFollow
Brett M. Raczka, The Pennsylvania State UniversityFollow
Daniel M. Ricciuto, Oak Ridge National LaboratoryFollow
Alok K. Sahoo, Princeton UniversityFollow
Kevin Schaefer, University of Colorado at BoulderFollow
Hanqin Tian, Auburn UniversityFollow
Rodrigo Vargas, Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE)Follow
Hans Verbeeck, Ghent UniversityFollow
Jingfeng Xiao, University of New HampshireFollow
Yongkang Xue, University of California - Los AngelesFollow

Date of this Version



Global Change Biology (2012) 18, 566–584, doi: 10.1111/j.1365-2486.2011.02562.x


Phenology, by controlling the seasonal activity of vegetation on the land surface, plays a fundamental role in regulating photosynthesis and other ecosystem processes, as well as competitive interactions and feedbacks to the climate system. We conducted an analysis to evaluate the representation of phenology, and the associated seasonality of ecosystem- scale CO2 exchange, in 14 models participating in the North American Carbon Program Site Synthesis. Model predictions were evaluated using long-term measurements (emphasizing the period 2000–2006) from 10 forested sites within the AmeriFlux and Fluxnet-Canada networks. In deciduous forests, almost all models consistently predicted that the growing season started earlier, and ended later, than was actually observed; biases of 2 weeks or more were typical. For these sites, most models were also unable to explain more than a small fraction of the observed interannual variability in phenological transition dates. Finally, for deciduous forests, misrepresentation of the seasonal cycle resulted in over-prediction of gross ecosystem photosynthesis by +160 ± 145 g C m-2 yr-1 during the spring transition period and +75 ± 130 g C m-2 yr-1 during the autumn transition period (13% and 8% annual productivity, respectively) compensating for the tendency of most models to under-predict the magnitude of peak summertime photosynthetic rates. Models did a better job of predicting the seasonality of CO2 exchange for evergreen forests. These results highlight the need for improved understanding of the environmental controls on vegetation phenology and incorporation of this knowledge into better phenological models. Existing models are unlikely to predict future responses of phenology to climate change accurately and therefore will misrepresent the seasonality and interannual variability of key biosphere–atmosphere feedbacks and interactions in coupled global climate models.