A high-intensity fires can destroy peat bogs and cause them to emit huge amounts of their stored carbon into the atmosphere as greenhouse gases, but a new Duke University study finds low-severity fires spark the opposite outcome.
The smaller fires help protect the stored carbon and enhance the peatlands’ long-term storage of it. As peatlands are wetlands that cover only 3% of Earth’s land but store one-third of the planet’s total soil carbon.
Left undisturbed, they can lock away carbon in their organic soil for millennia due to natural antimicrobial compounds called phenolics and aromatics that earlier studies by the Duke team have shown can prevent even drier peat from decaying.
If a smouldering, high-intensity fire or other major disturbance destroys this natural protection, however, they can quickly turn from carbon sinks to carbon sources.
The flash heating of moist peat during less severe surface fires chemically alters the exterior of clumped soil particles and “essentially creates a crust that makes it difficult for microbes to reach the organic matter inside,” said Neal Flanagan, visiting assistant professor at the Duke Wetland Center and Duke’s Nicholas School of the Environment.