Entering this Ecosystem | Fens

Have you ever heard of a fen? Fens are pretty cool wetlands that you can find all over Michigan and especially in the Upper Peninsula. They're like nature's own mix of grasses, flowering plants, shrubs, and even some small trees. These unique spots usually pop up in places that were shaped by glaciers, like outwash plains and low dips in the land. The soil in fens tends to be pretty soggy, and it can be anywhere from a little acidic to more on the alkaline side, sometimes even having that special alkaline marl.

What makes fens stand out from other wetlands is that they actually build up peat over time and get their water from mineral-rich soils or rocks underneath. A bunch of natural things influence what plants grow there and how they interact, like how groundwater flows, changes in water levels, and even stuff like erosion and fires. Plus, you’ve got the activities of insects, wind, and beavers also shaking things up a bit. It's a wild little ecosystem!

Fens can be divided into five main types: poor fen, patterned fen, northern fen, prairie fen, and coastal fen. Each type has its own characteristics, depending on factors like the plants growing there, the community structure, the soil's chemistry, water conditions, location, and the surrounding land. It’s the unique mix of these factors that makes each fen special!

Coastal Fens

If you’re near the shores of northern Lake Huron or Lake Michigan, you might stumble upon these coastal fens. They’re often part of a bigger wetland family, adding to the beauty of the area.

Patterned Fens

These fens are like nature’s patchwork quilt, found in flat outwash or lake plains. They have a gentle slope with alternating bands of sedge-peat ridges and little dips, creating a pretty cool visual.

Prairie Fens

These fens are a bit more bushy, featuring shrubs like bog birch, dogwoods, and shrubby cinquefoil. They add a nice touch of greenery to the mix!

Northern Fens

Picture this: a cool area where a thin layer of glacial drift sits on top of limestone. You’ll find all sorts of sedges and rushes here, and if you’re lucky, you might spot some orchids, gentians, and other interesting plants hanging out too.

Poor Fens

Scattered across the Upper Peninsula, these fens don’t get as much water flowing through, and they’ve got lower mineral content. But don’t underestimate them! They’re mainly filled with tough sedges and grasses that know how to thrive.

Natural processes that happen in fens are things like groundwater seepage, fire, peat accumulation and erosion, beavers love fens and can affect the ecosystem a lot. 

Michigan's Upper Peninsula is home to a diverse array of wildlife that thrives in its fens, including amphibians, birds, insects, mammals, and reptiles. In spring, the calls of frogs and toads resonate throughout the prairie fens. The fall brings migratory songbirds and waterfowl that flock to these wetlands to feed on aquatic plants and berries, while yellow-bellied flycatchers and Nashville warblers make their homes and nests in the fens. Insects such as mosquitoes, horseflies, and tree crickets are prevalent, particularly in the summer months. The mammalian residents of these habitats include shrews, voles, and muskrats, all of which rely on the unique ecosystem. Among the reptiles, the eastern massasauga rattlesnake, Michigan's only rattlesnake, can be found in prairie fens. Additionally, butterflies and moths are drawn to fens due to the availability of their food plants, and many land snails are associated with coastal fens, further contributing to the rich biodiversity of this unique environment.

For more information on fens click these links:

https://www2.dnr.state.mi.us/publications/pdfs/huntingwildlifehabitat/landowners_guide/habitat_mgmt/Wetland/Bogs_Fens.htm

https://www.michigan.gov/-/media/Project/Websites/dnr/Documents/WLD/WAP/12_fen.pdf?rev=4ee1277ddead47d6b4faf9e6e3f6c630

https://mnfi.anr.msu.edu/communities/fen-group