Older trees have been found to grow just as fast as young trees do, contrary to earlier research that suggested trees lost their vigor with maturity.
The study, published in the journal Nature, found that trees' growth continued to accelerate even after their "adolescent" growth spurt.
"This finding contradicts the usual assumption that tree growth eventually declines as trees get older and bigger," said Nate Stephenson, the study's lead author. "It also means that big, old trees are better at absorbing carbon from the atmosphere than has been commonly assumed."
Researchers used growth measurements from over 670,000 trees belonging to 403 species across six continents. Although the researchers relied mostly on existing data they were able to calculate the growth of individual trees, unlike previous studies that calculated the amount of carbon absorbed by plots of trees.
Related
The findings showed that most species continued to show accelerated mass growth rates with some of the larger trees adding the carbon mass equivalent of a smaller tree. This means that older trees are better at absorbing CO2 and help balance the amount of CO2 generated by humans.
But the authors were quick to point out that this does not result in an increase in the carbon storage capacity of a forest because this CO2 did find its way back to the atmosphere.
"Old trees, after all, can die and lose carbon back into the atmosphere as they decompose," says Adrian Das, a USGS coauthor. "But our findings do suggest that while they are alive, large old trees play a disproportionately important role within a forest’s carbon dynamics.
The study will help clarify contradictions that have plagued plans for forest management, and help maximize timber yields while at the same time helping to protect older trees and increase carbon absorption.
[Nature] [USGS]
