The girth of a tree
Thank goodness human growth rates don't match that of trees. For if it did then we would tip the scales of well over a ton by the time we reach retirement! Consider this new research from the Smithsonian Tropical Research Institute (STRI) recently published in the journal Nature. According to the new study, trees put on weight faster and faster as they grow older. Because most trees' growth accelerates as they age this suggests that large, old trees may play an unexpectedly dynamic role in removing carbon from the atmosphere.
Richard Condit, staff scientist at the STRI, devised the analysis to interpret measurements from more than 600,000 trees belonging to 403 species (from both tropical and temperate climates). "Rather than slowing down or ceasing growth and carbon uptake, as we previously assumed, most of the oldest trees in forests around the world actually grow faster, taking up more carbon," Condit said. "A large tree may put on weight equivalent to an entire small tree in a year."
"If human growth would accelerate at the same rate, we would weigh half a ton by middle age and well over a ton at retirement," said Nate Stephenson, lead author and forest ecologist with the U.S. Geological Survey.
The ramifications of this study are huge because it highlights the importance of protecting the largest trees even more aggressively to take advantage of its carbon uptake in and effort to impact climate change. We have long appreciated the importance of the large tree for its habitat but this study demonstrates that a large tree can add as much carbon in one year as an entire mid-sized tree will do in its lifetime. Yet the large tree is often the first to be harvested and is also more prone to variations in climate conditions.
But with this study in hand, researchers anticipate that forest conservation and reforestation may mitigate global warming by reducing carbon dioxide in the atmosphere. Therefore they will track the growth acceleration of individual trees to determine if their growth does translate into greater carbon storage as forests age.
Olive tree via Shutterstock.