Indiscriminate, heavy-handed mining of an iron-rich peatland here at 11,500-feet elevation dried up a millennia-old mountain slope, leaving bare land and triggering erosion that carries debris into the middle fork of Mineral Creek. The creek joins the Animas River at Silverton.
“We don’t know really when or why this occurred, but the site could have been exploited for peat or for its iron pigment,” said Rod Chimner, a professor of wetlands-restoration ecology at Michigan Technological University, who is working with a team to restore the battered terrain.” It could have occurred around the turn of the (20th) century, but it was definitely pre-1950.”
The team of professionals and volunteers, with machinery and manual labor, is restoring the fen, a groundwater-sustained basin of peat that was formed 8,000 to 10,000 years ago as glaciers retreated at the end of the Ice Age.
“The peat – organic material such as leaves, flowers, grass and wood – accumulated over time,” said Marcie Demmy Bidwell, executive director of Mountain Studies Institute. “The material doesn’t degrade as long as it remains in an anaerobic state.
“Fens are important because they store clean water and they sequester carbon,” Bidwell said. “If a fen dries up, it releases greenhouse gases.”
The strata revealed by a 2-meter-deep assessment pit dug by team members chronicles how the peat basin developed over thousands of years, Bidwell said.
As a trackhoe moved and smoothed dirt, Bidwell pointed to where patches of bare earth had been exposed and where ditches used by peatland exploiters carved channels that encouraged erosion.
After the area is prepared, volunteers place wattles of wood shavings to slow runoff of precipitation. Next will come insulating mulch, and then plugs of Carex aquatilis sedge, a tufted grasslike plant, will be placed at intervals.
The fen project is funded by grants from the Colorado Water Conservation Board, the U.S. Forest Service, Purgatory at Durango Mountain Resort and the National Forest Foundation. Volunteers are from the Mountain Studies Institute, Colorado Mountain Club and San Juan Citizens Alliance.
“This project is notable for several reasons,” Bidwell said. “It’s an iron fen, it’s at high elevation and it’s steep terrain.”
An iron fen is one where the predominant mineral is iron, Bidwell said. The water in most fens is mineral-neutral, she said.
“Iron fens are rare in the world,” Bidwell said. “There are 13 iron fens in the United States and five are in the San Juan Mountains.”
Team members will return next summer when the snow is gone to plant moss, Chimner said. He expects touch-up revegetation will go on for several years.
“Fen restoration is a hot topic in Canada, Indonesia and Scandinavia in relation to climate change,” Chimner said. “When peat degrades, it releases greenhouse gases.”
The U.S. Army Corps of Engineers requires five years of monitoring conditions in fen restorations, he said.
Climatologists are particularly interested in fens because they’re storehouses of climatological data, Chimner said.
Peat holds evidence of climate change just as rocks, sediment, ice sheets, tree rings and coral do, Chimner said.
“Peat can contain diatoms, seeds and pollen that recreate past climate,” Chimner said.
Peat dries out and degrades when it’s outside its anaerobic universe, Bidwell said.
“I just hope we got here in time to save it,” Bidwell said.