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Trees are natural ways for the planet to sequester carbon, but once trees die, they release that carbon back into the atmosphere—but that isn’t always the case.
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A new study, analyzing a 3,375-year-old log that remained remarkable preserved in clay soil, found that the old piece of Eastern red cedar lost less than 5 percent of its carbon dioxide.
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Because the log was naturally entombed in this low-permeability soil, the ravages of fungi, insects, and even oxygen couldn’t reach its woody exterior.
Planting trees is one important tool in an arsenal of techniques for combating climate change. While it’s been rigorously debunked that planting trees alone can solve this current crisis (and more research besides that, in some instances, lots of trees can absorb more heat from the Sun), generally tree-planting, especially in urban areas, helps store carbon while also lowering the temperature.
Unfortunately, whether an English oak in Central Park or a Coastal redwood in Northern California, trees have a well-known habit of releasing all that carbon when they eventually die, offsetting some of the positive benefits of its carbon-storing life—but this doesn’t have to be the case.
In a new study published last week in the journal Science, scientists from the University of Maryland detailed the analysis of a 3,375-year-old log and found that this sample of ancient Eastern red cedar (Juniperus virginiana) lost less than 5 percent of its carbon dioxide from its original state. This is a stark example of the benefits of “wood vaulting,” a technique where dead trees are purposefully buried so that low-permeability clay soils can trap greenhouse gasses in the ground.
University of Maryland Atmospheric and Oceanic Science Professor Ning Zeng, along with colleagues from McGill University in Montréal, serendipitously found the ancient log while conducting a wood vaulting pilot project in Quebec, Canada. Zeng describes the discovery as “kind of miraculous” when the log was spotted some 6.5 feet below the surface.
“When the excavator pulled a log out of the ground and threw it over to us, the three ecologists that I had invited from McGill University immediately identified it as Eastern red cedar,” Zeng said in a press statement. “You could tell how well it was preserved. I remember standing there thinking, “Wow, here’s the evidence that we need.’”
The find helped supercharge Zeng’s research as the log, and its geologic context provided ample evidence for the best techniques in burying wood and ensuring its preservation, something that isn’t quite as easy as it first seems.
“Think about how many wooden coffins were buried in human history,” Zeng said in a press statement. “How many of them survived? For a timescale of hundreds or thousands of years, we need the right conditions.”
Quebec Ministry of Agriculture, Fisheries and Food (MAPAQ) conducted carbon dating on the wood and found that its demise occurred some 3,375 years ago, or around the time peoples in Eurasia had the bright idea to tinker around with bronze (shortly before that civilization’s mysterious collapse). When scientists compared this Bronze Age sample to modern Eastern red cedars, they discovered that the log still contained nearly all of its original carbon.
The key to this extraordinary display of preservation is the local clay soils that effectively entombed the log in the earth. In fact, the clay was so impervious that fungi, insects, and even oxygen couldn’t reach the log to work their slow, decomposing magic.
Of course, this doesn’t mean that we’re suddenly going to start burying logs en masse. For one, logs in forests are vital for natural decay processes and provide much-needed habitat and resources for all kinds of critters. Also, most logs tagged “wood vaulting” are usually damaged in fires or insect infestations and serve no other secondary purpose.
Zeng stresses that burying logs—just like planting trees in the first place—is not a substitute for lowering carbon emissions, but at least this well-preserved log from the distant past proves that humanity has another valuable technique for battling the crisis at hand.
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Source Agencies
