Let’s start with the good news. There are no ghosts in ghost forests, even though the large tracts of land with lots of dead trees do give off a kind of eerie feeling.
Now for the bad news. Ghost forests are the remains of once-thriving green woodlands that stored vast amounts of carbon. And as the forests transform, that carbon is being released back into the atmosphere, making the challenge of slowing climate change even worse.
Those are the findings of new research into ghost forests conducted by researchers at NC State, who analyzed wood buried in the soil of a forested wetland in eastern North Carolina.
“These freshwater forested wetlands have been storing carbon for millennia,” said John King, professor of forestry and environmental resources at NC State and one of the authors of the study. “But now the leaves, wood and roots that have been storing carbon for thousands of years are in an area that is rapidly changing.”
Carbon dating revealed the coast site in the study was a forest almost 1,800 years ago.
“The deepest piece of wood we found was from a root system of an upland forest about 1,800 years ago, according to radioactive carbon isotope dating,” said King, “And while we found pieces of wood distributed throughout the upper layer of soil, the carbon dating also showed the accumulation of new soil slowed the closer we got to modern times.”
And that’s the key. The old forest is dying, and the ecosystem that is replacing it isn’t keeping up with what is being lost.
In the study (published in the journal Land), NC State researchers reported that pond pine forests of the region are experiencing suppressed growth and high mortality, leading to the formation of ghost forests.
And the transition is happening faster than they imagined.
“We collected our data in 2014 and 2015 in what we considered a healthy forest, and if you go down there now, it has almost completely transitioned to a ghost forest,” added King.
“At the time of our measurements, about 60% of the trees in the ghost forest were dead or dying,” said Maricar Aguilos, postdoctoral research scholar at NC State and the lead author of the study. “As of February 2022, we’re seeing that level of mortality in what we considered a healthy forest in 2015. Flooding and saltwater are invading the freshwater inland, and the ghost forest formation is an indicator of the impact.”
Researchers sampled the soil to try to quantify how much carbon was stored in the soil and to see how it has changed over time. And while the data showed a forest covered the area long ago, they also found the rate of soil accumulation can’t keep up with the pace of sea-level rise. Essentially, the soil is being submerged.
“That means all of the carbon in the dead trees will decompose and return to the atmosphere as carbon dioxide,” said King. “In addition, some of the carbon in the organic soil will likely decompose and return to the atmosphere as methane. That’s where we talk about wetlands being big sources of carbon to the atmosphere.”
The researchers say their findings suggest sea levels are rising faster than the forest can build up new soil. The trees are dying, and the forest is changing into a shrub ecosystem. However, they believe even that will change once the soil becomes too wet for shrubs and the area eventually turns into a marsh.
It’s estimated wetlands contain about 21% of terrestrial carbon. As sea levels rise, what will happen to the carbon stored there?
