Old trees are ‘star players’ of soaking up carbon

Although old trees can die and release carbon back into the atmosphere, the study's findings suggest while they are alive they are rapidly absorbing carbon. "It is as if the star players on your favorite sports team were a bunch of 90 year-olds," says Adrian Das. (Credit: Ben/Flickr)

Growth measurements of more than 400 species of trees on six contents show that large old trees are playing a disproportionally important role in carbon absorption.

The study shows that tree growth rates increased continuously with size, and in some cases, large trees appeared to be adding the carbon mass equivalent of an entire smaller tree each year. The significance of this study is that big, old trees are better at absorbing carbon from the atmosphere than previously thought.

“Our research shatters the long-standing assumption that tree growth declines as individuals get older and larger. However, the rapid carbon absorption rate of individual large trees does not necessarily translate into a net increase in carbon storage for an entire forest,” says Patrick Baker, assistant professor at the Melbourne School of Land and Environment, University of Melbourne.


“Old trees, after all, can die and lose carbon back into the atmosphere as they decompose. But our findings suggest that while they are alive, large old trees play a disproportionately important role in a forest’s carbon dynamics,” says coauthor Adrian Das, an ecologist at the US Geological Survey. “It is as if the star players on your favorite sports team were a bunch of 90 year-olds.”

Researchers compiled growth measurements of 673,046 trees belonging to 403 species from tropical, subtropical, and temperate regions across six continents, calculating the mass growth rates for each species and analyzing the trends. The study was published in the journal Nature.

“What makes these results so compelling is the sheer scale of the datasets that we had available to work with,” says Associate Professor Baker.

The study was a collaboration of 38 researchers from research universities, government agencies, and non-governmental organizations from the Argentina Australia, Cameroon, China, Colombia, Democratic Republic of Congo, France, Germany, Malaysia, New Zealand, Panama, Spain, Taiwan, Thailand, the United Kingdom, and the United States.

Source: University of Melbourne