Warming may not spark tree growth

A bright spot in the gloomy global warming picture has been scientists’ predictions that at least some carbon dioxide will be removed from the atmosphere by a burst of growth from tropical forests.

New research from the Arnold Arboretum, however, questions that prediction, finding that trees in two forests on opposite sides of the world have been growing dramatically slower, not faster, as temperatures have risen over the past 20 years.

Kenneth Feeley, a postdoctoral fellow at the Center for Tropical Forest Science, a partnership between the arboretum and the Smithsonian Tropical Research Institute, examined tree growth data from forest plots in Panama and Malaysia.

The 50-hectare plots are part of a remarkable network of 18 scientific forest plots established by the Center for Tropical Forest Science starting in 1981. The center exhaustively studies the trees in each plot, measuring them every five years, creating a database of growth information spanning 3 million individual trees of more than 6,000 different species.

Feeley examined growth data from the two oldest plots, at Barro Colorado Island in Panama and at Pasoh, Malaysia. The results surprised him, both because they showed growth slowing, not accelerating, and because of the magnitude of the slowdown.