Thousand-year-old tropical soil unearthed by accelerating deforestation and agriculture land use could be unleashing carbon dioxide into the atmosphere, according to a new study from researchers at Florida State University.

In an investigation of 19 sites in the eastern Democratic Republic of the Congo, researchers discovered that heavily deforested areas leach organic carbon that is significantly older and more biodegradable than the organic carbon leached from densely forested regions.

Released from deeper soil horizons and leached by rain into waterways, that older, chemically unstable organic carbon is eventually consumed by stream-dwelling microbes, which devour the rich compounds and respire carbon dioxide back into the atmosphere. It’s a process that could jeopardize local ecosystems and further fuel the greenhouse effect, researchers said.

“In many ways, this is similar to what happened in the Mississippi River Basin 100 years ago, and in the Amazon more recently,” said study author Rob Spencer, an associate professor in FSU’s Department of Earth, Ocean and Atmospheric Science. “The Congo is now facing conversion of pristine lands for agriculture. We want to know what that could mean for the carbon cycle.”

Source: Tropical soil disturbance could be hidden source of CO2