DURHAM, N.C. -- Duke University forest plots bathed in the higher carbon-dioxide atmosphere expected by the year 2050 experienced a 25 percent growth increase over the first two years of a continuing experiment, scientists from the University of Illinois at Urbana-Champaign and Duke reported Thursday.
"This study puts forests on the CO2 map," said Evan DeLucia, a U. of Ill. at Urbana-Champaign plant biologist who is the lead author of the latest report, published in the May 14 issue of the journal Science. While the potential for forests to sop up increasing human-caused carbon dioxide emissions had been only speculative, "now we have some real data that allows for global extrapolation," he added in an interview.
If the world's forests were all to be growing 25 percent faster 50 years from now, these results would suggest that woodland plant life could serve as a "sink" for about half the expected carbon dioxide emissions from fossil fuel combustion, according to estimates of DeLucia and Duke botany professor William Schlesinger, the article's other main author.
But both scientists cautioned that such a high sustained uptake is actually unlikely, for several reasons. First, the Duke Forest plots where the U.S. Department of Energy-funded study is being conducted are dominated by 13-year-old loblolly pines, among the world's fastest growing tree species, at their peak growing age. Second, open-air studies at Italian hot springs and another Duke Forest plot suggest that the carbon-dioxide inspired growth spurt will level off in a few more years or less.
"The crux of the matter is that vegetation can respond to higher CO2 and act as a carbon sink," Schlesinger said in an interview. "The 25 percent growth increase is probably an upper limit for what the world's vegetation can do. Nevertheless, it's interestingly high."