Old trees work faster at storing carbon

Old trees contribute more to carbon storage than previously thought in a new international study that included researchers from the University of Melbourne. The study demonstrated 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. ( Editor: And that's not all that old tree do - )

The study was published in the journal Nature this week. Contributing author, Associate Professor Patrick Baker, an ARC Future Fellow at the Melbourne School of Land and Environment, University of Melbourne, said,

“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.”

Coauthor, Dr Adrian Das, an ecologist at the U.S Geological Survey said, “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. 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 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.

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

Associate Professor Baker and Will Morris a PhD student in the School of Botany were involved in providing and analysing data from the thousands of trees from Thailand.