CORVALLIS, Ore., Jan. 16 (UPI) -- Despite a common view of large old trees as unproductive, a study has found the world's oldest trees are growing faster and sequestering more carbon as they age.
An international research group, writing in the journal Nature, said 97 percent of 403 tropical and temperate species grow more quickly the older they get, Oregon State University researchers involved in the study reported Wednesday.
While extraordinary growth is well-known in species such as Australian eucalyptus and the coast redwood in the United States, it's not limited to just a few species, the researchers said.
"Rather, rapid growth in giant trees is the global norm and can exceed 600 kg (1,300 pounds) per year in the largest individuals," they said in Nature.
"In human terms, it is as if our growth just keeps accelerating after adolescence, instead of slowing down," study leader Nate L. Stephenson of the U.S. Geological Survey Western Ecological Research Center said. "By that measure, humans could weigh half a ton by middle age, and well over a ton at retirement."
Older trees "do not act simply as senescent carbon reservoirs but actively fix large amounts of carbon compared to smaller trees; at the extreme, a single big tree can add the same amount of carbon to the forest within a year as is contained in an entire mid-sized tree," the study authors wrote.
The study was conducted by scientists from the United States, Britain, Australia, Germany, Colombia, Argentina, Thailand, Cameroon, France, China, Taiwan, Malaysia, New Zealand and Spain.