Ghost forests release greenhouse gas emissions in "tree farts"

A new study from North Carolina State University has revealed that dead trees in coastal wetlands release greenhouse gas emissions in the form of “tree farts.” The researchers explained that these emissions must be accounted for when estimating the environmental impact of ghost forests.

For their investigation, the experts compared the quantity and type of greenhouse gas emissions from dead tree snags to emissions released from the soil. The study revealed that while soil generates more emissions than dead trees, the so-called tree farts increase the overall emissions of a ghost forest by about 25 percent.

According to the researchers, the findings show that snags are important for understanding the climate effects associated with the spread of ghost forests.

“Even though these standing dead trees are not emitting as much as the soils, they’re still emitting something, and they definitely need to be accounted for,” said study lead author Melinda Martinez. “Even the smallest fart counts.”

The experts measured carbon dioxide, methane, and nitrous oxide emissions from dead pine and bald cypress snags in five ghost forests on the Albemarle-Pamlico Peninsula in North Carolina. Across this region, ghost forests are rapidly expanding as a result of sea level rise.

“The transition from forest to marsh from these disturbances is happening quickly, and it’s leaving behind many dead trees,” said Martinez. “We expect these ghost forests will continue to expand as the climate changes.”

In each forest, overall average emissions from soils were approximately four times higher than average emissions from snags in both 2018 and 2019. But while snags did not contribute as much, the researchers noted that they did contribute significantly to emissions.

The research lays the foundation for understanding the role that snags are playing in emissions. In particular, the experts want to investigate whether the forests of dead trees are preventing emissions, like corks, or releasing them, like straws.

“We started off this research wondering: Are these snags straws or corks?” said study co-author Professor Marcelo Ardon. “Are they facilitating the release from soils, or are they keeping the gases in? We think that they act as straws, but as a filtered straw. They change those gases, as the gases move through the snags.”

The study is published in the journal Biogeochemistry.

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By Chrissy Sexton, Earth.com Staff Writer