The average levels of methane emissions in the deepest water of the wetlands over the course of the study were 6 pounds of carbon per day in the pulsing year and almost 12 pounds of carbon per day during the steady-flow year.
The researchers suggested that slightly warmer soil temperatures and less fluctuation in water levels during the steady-flow year created conditions that promoted the production of methane.
A simultaneous study of carbon collection in the wetlands showed that the different water conditions had no significant effect on how much carbon was stored by the wetlands. Many experts suggest that the benefits of wetlands' carbon storage capacity offset any damage resulting from their methane emissions.
Mitsch noted that pulses from storms not only help dissipate one negative effect of wetlands, but also serve as a reminder of how wetlands function to absorb the surge.
"If we didn't have salt marshes and mangroves in subtropical and tropical coastal areas of the United States, it's safe to say these current storms would have even more damaging effects," he said.
"When you lose wetlands, you've lost a place for floodwater to go," Mitsch noted. "Mother Nature is better at withstanding these pulses than we are. Whether it's a flooding river or a hurricane, no matter what those pulses are, if there's a natural ecosystem to absorb them, then we as humans would be safer."
|Contact: William Mitsch|
Ohio State University