What is a Fen?

A fen is a groundwater-dependent peat layer within a wetland, which takes centuries to form (one inch every 100 years). It creates a unique watershed that is home to rare flora and fauna. There are multiple fens in the Yellowstone ecosystem, but the one we are most concerned about is right here in our backyard.

The fen, located in the north end of the Tribal Trail Scenic Pathway, is 12 inches thick, or 1200 years old. This is “young” compared to most fens in the Rocky Mountains, which are more than 6,000 years old.

Why is a fen important?

A fen is an irreplaceable ecosystem, which counteracts global warming naturally by capturing CO2, recycling nutrients, trapping eroding soil, and filtering out pollutants to create hotbeds of diverse flora and fauna
Globally, peatlands store carbon and nitrogen, retaining about one-third of the world’s soil carbon and 16 to 28 percent of the world’s soil nitrogen while occupying only 3 to 4 percent of the Earth’s surface
Dozens of rare plant and animal species are supported by fens
Fens require stable hydrological conditions which are important for their water storage and release capacities – activities that disturb the groundwater-dependent hydrological regime of a fen, causing drying or warming, can permanently damage, or destroy them

To learn more about Fens in the Rocky Mountains, read this USDA study.