Study: Amazon trees older than believed

A University of California-Irvine scientist says many trees in the Amazon tropical forests are much older than previously believed.

A team of American and Brazilian researchers are using radiocarbon dating to study tree growth in the world's largest tropical region.

The team, including UC-Irvine's Susan Trumbore, found as many as half of all trees greater than four inches (10 centimeters) in diameter are more than 300 years old. Some of the trees, Trumbore said, are as much as 750 to 1,000 years old.

Trumbore, a professor of Earth system science, said since the trees are old and slow-growing, the Amazon forests, which contain about a third of all carbon found in land vegetation, might have less capacity to absorb atmospheric carbon than previous thought.

"In the Central Amazon, where we found the slowest growing trees, the rates of carbon uptake are roughly half what is predicted by current global carbon cycle models," Trumbore said. "As a result, those models ... may be overestimating the forests' capacity to remove carbon dioxide from the atmosphere."

Study results appear in the online early edition of the Proceedings of the National Academy of Sciences.