by Michele Byers
Some things get better with age, and that’s especially true for trees.
A recent study found old trees beat younger trees hands down — or maybe roots down — when it comes to removing carbon from the atmosphere.
That’s something to keep in mind Arbor Day — our national day for celebrating trees — on April 25.
Published in the journal, Nature, the study shows that, unlike people, mature trees don’t slow down after adolescence. They actually grow faster and absorb more carbon than younger, smaller ones. In fact, some older trees can pull in more carbon in a single year than a younger tree in all its years!
”It’s sort of like if you were paying attention to your favorite sports teams, and it turned out that the 90-year-olds were the star players,” explained researcher Nathan Stephenson of the U.S. Geological Survey. “In human terms, that doesn’t seem to make a lot of sense, but it’s what’s happening with forests.”
In the study, scientists around the world measured more than 400 temperate and tropical tree species on six continents over a period of years. They learned that, for the majority of trees, physical growth rate and ability to store carbon sped up with age.
These findings, Stephenson believes, will impact our understanding of the relationship between forests and climate change.
”If you’re interested in conserving old forests, a key piece of information is knowing which trees out there are the most important in the dynamics of the ecosystem services offered by the forests,” Stephenson said.
Other new research in the northeastern United States reveals that 120-year-old oak forests rapidly are accelerating carbon sequestration rates, not slowing down. These results take into account biomass accumulation in deep roots.
The ecology of roots has been ignored by the wood products industry, which, in modern publications, still promotes the notion young forests, created in the wake of logging, are most effective at storing carbon.
Speaking of old trees, did you know New Jersey keeps track of its own behemoths for each species? Since the 1950s, the Department of Environmental Protection’s Division of Parks and Forestry has run a Champion Trees program. The state’s Forest Service maintains the Big Tree List, a registry of the Garden State’s largest native and naturalized tree species.
The metric used to rank the state’s biggest trees is trunk circumference about 4 feet above the ground. Many of the state’s Champion Trees have huge girths, are stout and rounded, but not always extremely tall or of immense age. Open-grown, nonforest trees — like those found in old farm landscapes or next to historic structures — often attain a huge girth relatively quickly.
New Jersey’s largest red oak — our state tree — has a circumference of more than 23 feet and is located on private property in Wyckoff, Bergen County. Our biggest sycamore stands almost 100 feet tall with a circumference of more than 25 feet and is located on private property in Belvidere, Warren County.
Environmental benefits of old trees don’t end with absorbing carbon and producing oxygen. Old trees mitigate stormwater runoff with their massive root systems that absorb rainwater and hold together soil.
When in full leaf, they lower air temperature around them by up to 12 degrees by creating shade and releasing water vapor from their leaves.
Some of New Jersey’s big trees also have immense historic value, having been around for hundreds of years. With New Jersey celebrating its 350th anniversary this year, it’s amazing to think some of our old trees were there when the British claimed our state as a colony in 1664.
A white oak next to the Presbyterian Church in Basking Ridge is said to have already been 300 years at the time of the American Revolution! And the famous Salem Oak, in a cemetery in the city of Salem, is more than 500 years old and stands at the site where John Fenwick is believed to have signed a land treaty with the Lenape Indians.
Celebrate Arbor Day with a walk in an old forest. These forests are doing more for us than we can imagine!
To find out more about the international tree study, visit the Nature website at http://www.nature.com/nature/journal/v507/n7490/full/nature12914.html.
To learn more about New Jersey’s Champion Tree program — and how to measure and nominate a possible contender — go to http://www.state.nj.us/dep/parksandforests/forest/community/bigtree_intro.html.
Michele Byers is executive director of the New Jersey Conservation Foundation. For more information, contact her at [email protected] or visit NJCF’s website at www.njconservation.org.

