"Some people have used carbon dioxide fertilization to argue that this is a boon of the fossil fuel era and that it will lead to greater agricultural yields and carbon sinks," said Richard Norby of the Department of Energy's ORNL. "Some recent experiments, however, have suggested that there will be no lasting effect of carbon dioxide fertilization. As is often the case, the truth may lie in between."
Norby is among several scientists participating in a panel discussion titled "CO2 Fertilization: Boon or Bust?" Feb. 16 at the American Association for the Advancement of Science annual meeting in Seattle.
For the last six years, Norby and colleagues at ORNL have examined the responses to elevated carbon dioxide levels in a stand of sweetgum trees a few miles from ORNL. The experiment consisted of pumping tons of carbon dioxide into the plots, raising the concentration of carbon dioxide in the tree stand from the ambient level of about 370 parts per million to 550 ppm, and studying the effects.
One of the goals of the project, called the Free-Air CO2 Enrichment (FACE) experiment, is to examine how forests will respond to the increasing level of carbon dioxide in the atmosphere and whether it will alter the development of the greenhouse effect. Among the findings is that young trees and other green plants respond favorably to elevated concentrations of atmospheric carbon dioxide. The relevance to the role of the terrestrial biosphere in the global carbon cycle, however, has long been subject to debate.
There are lots of questions, including: Do the responses of seedlings and young trees predict those of large mature trees in a closed forest? Does the
Contact: Ron Walli
DOE/Oak Ridge National Laboratory