A 22-year study of 55 mixed hardwood forest plots has yielded unexpected results. The trees appear to have accelerated growth rates, and are probably growing faster now than they have ever done for the past 225 years (the age of the oldest trees in the study).
Geoffrey Parker, a forest ecologist at the Smithsonian Environmental Research Center in Edgewater, Md., points out that, over the course of the study, the concentration of carbon dioxide in the forest air has risen by 12 per cent, the average temperature has increased by three-tenths of a degree and the growing season has lengthened by 7.8 days.