Trees that have been poisoned and killed by salt water emit greenhouse gases known as “tree farts,” prompting researchers to warn of a secret source of warming that could worsen if rising seas enter forests.
Drowned trees in so-called “ghost forests” have increased the amount of carbon dioxide released by these ecosystems by about 25%, according to a study published in last week Biogeochemistry.
Melinda Martinez, lead author and PhD student at North Carolina State University, said the emissions they measured from dead pines and bald cypress trees, also known as tree stumps, in five ghost forests on North Carolina’s Albemarle-Pamlico peninsula need to be considered .
“Although these standing dead trees don’t emit as much as the soil, they still emit something,” she said. “Even the smallest fart counts.”
The study reported that carbon dioxide, methane and nitrous oxide from the trees contribute “significantly” to the overall emissions.
Martinez said greenhouse gases from tree stumps are important to monitor as ghost forests spread along U.S. coastlines.
Ghost forests stretch across the southern US coast from Louisiana to Maryland. They are named for their haunted landscape – pale trunks with no leaves or telltale signs of life.
Although most ghost forests are created by rising sea levels, salt water can also infiltrate forests through canals and ditches that are used for agricultural purposes.
The effects of the death of mass trees on plants and animals can be dramatic. A study published in earlier this year Ecological applications found that more salt-tolerant shrubs and grasses moved to North Carolina’s ghost forests. This led to a major change in wildlife and endangered endangered wolf and woodpecker species.
Before conducting the new study, Martinez said some researchers believed the dead trees would act as straws to suck greenhouse gases out of the soil. When the tree dies, the remaining water is flushed from the leaves, which, in their opinion, would cause greenhouse gases to diffuse up the tree.
However, their research showed that taller tree trunks contain fewer greenhouse gases than expected.
She added that they are still not sure how greenhouse gas emissions differ between tree species and how to advise land managers on mitigation efforts. Some researchers have suggested implementing “living shorelines” made of plants and rocks to buffer saltwater surges.
“It’s a difficult question to answer because tree stumps can become a new habitat for other animals,” Martinez said. “We hope to get a better idea of how greenhouse gases change when the trees die, as well as better estimates of the emissions from living logs.”
Reprinted from E&E News with permission from POLITICO, LLC. Copyright 2021. E&E News provides important news for energy and environmental professionals.