Bogs and fens are wetlands that form upon layers of dead and decaying plant material called peat. Water in these "peatlands" is at or near the surface.

Physical features

Rain and snow are the only sources of water for bogs. They are low in nutrients and acidic. These conditions make it difficult for many plants to grow. Fens receive water from both precipitation and groundwater. They typically have more nutrients than bogs and are only slightly acidic. Minnesota has 20 percent of the world's calcareous fens, an extremely rare kind of fen that is rich in calcium.

Biological features

Bogs are carpeted with sphagnum moss. Usually they also have stunted black spruce and tamarack trees, and low shrubs of the heath family, which retain their leaves throughout the year. Bogs are famous for their oddities such as insect eating plants and ground that bounces when you walk upon it. Most fens are treeless, but they may be covered by shrubs. The most common plant types in fens include reeds, sedges and grasses.

Location

Bogs and fens are found primarily in the northern half of Minnesota. However, fens also occur in the prairie regions of the state.

Fun facts

With more than 6 million acres, Minnesota has more peatlands than any other state except Alaska. Because Minnesota's peatlands are rare, relatively undisturbed, and important for scientific research, more than 170,000 acres across the northern half of the state were permanently protected in 1991.

What are calcareous fens and what's special about them?

Calcareous fens are rare peat wetlands characterized by cold inflowing groundwater containing dissolved calcium and magnesium, creating ecological conditions favorable to supporting certain very rare plants. Calcareous fens are found on slopes, such as at the base of river bluffs.

Fens have special protection under the Minnesota Wetlands Conservation Act. The DNR maintains an official list of known calcareous fens , including their general location. For more information, check out the Minnesota Wetlands Conservation Plan . The Guide to Scientific and Natural Areas lists several sites maintained by the SNA program with calcareous fens.