Spring phenology is thought to exert a major influence on the carbon (C) balance of temperate and boreal ecosystems. We investigated this hypothesis using four spring onset phenological indicators in conjunction with surface-atmosphere CO2 exchange data from the conifer-dominated Howland Forest and deciduous-dominated Harvard Forest AmeriFlux sites. All phonological measures, including CO2 source-sink transition dates, could be well predicted on the basis of a simple twoparameter spring warming model, indicating good potential for improving the representation of phonological transitions and their dynamic responsiveness to climate variability in land surface models.
Richardson, Andrew D.; Hollinger, David Y.; Dail, D. Bryan; Lee, John T.; Munger, J. William; O'Keefe, John. 2009. Influence of spring phenology on seasonal and annual carbon balance in two contrasting New England forests. Tree Physiology. 29: 321-331.