Michigan Nature Monday: Great Lakes & Fresh Water

The State of Michigan has declared June 3-11 as Great Lakes & Fresh Water Week. So, this month’s Michigan Nature Monday will focus on one of the most important ways that we protect Michigan’s many freshwater resources: peatlands.

What are peatlands? These land-based wetland ecosystems are highly efficient carbon sinks on the landscape—formed by the water-saturated ground which prevents plant materials from fully decomposing. The resulting organic matter is called “peat” and is composed primarily of mosses, sedges, and shrubby material.

Why are peatlands important? Plants absorb carbon from the atmosphere throughout their life through photosynthesis, and when those plants reach the end of their life the process of decomposition releases that stored carbon back into the air. Because the plants that form peat are prevented from fully decomposing, much of the carbon that they have stored remains trapped in the waterlogged conditions of the peatland. It is for this reason that peatlands are known to store more carbon than any other terrestrial ecosystem on Earth, including forests!

One example of peatlands found in Michigan is fens. There are several types of fens found throughout the state and are home to many rare animals such as the yellow rail, Mitchell’s satyr, and eastern massasauga rattlesnake. Fens are extremely fragile and sensitive systems that are already being impacted by climate change. But MNA is working to protect fens all over the state including at our newest sanctuary acquisition in the Eastern Upper Peninsula.

Patterned fens are characterized by ridges and swales that can look like waves on the landscape. Photo by Jason Whalen | Fauna Creative

Fox River Wetlands hosts a variety of natural communities, but none so special as a rare, high-quality “patterned fen”, which is ranked imperiled in Michigan. There are a limited number of these types of fens found in Michigan, and of those, the quality of this complex is ranked in the top ten, making it very important in terms of biodiversity. Protecting the fen and wetlands directly contributes to the pristine water quality of the Fox River.

Patterned fens, also known as a string bog, is a groundwater-fed wetland community found on flat, ancient lakes and outwash plains. Peat forms the soil substrate, and the community displays a series of low-relief ridges (strings) and swales (flarks) that look like subtle waves across the land.

MNA’s largest land protection project in its 70-year history will secure over 5 square miles of habitat and a collection of pristine natural communities, including an incredibly rare and high-quality patterned fen. The 3,436-acre Fox River Wetlands is at the very heart of the storied Fox River watershed, made famous by Ernest Hemingway, and connects to a conservation landscape of over 1 million acres that provides habitat for rare plants and animals of concern in Michigan.

The East Branch of the Fox River, one of just two Michigan Natural Rivers in the Upper Peninsula. Photo by Jason Whalen | Fauna Creative

Comprised of the Main Branch, East Branch, and several other tributaries, the Fox River system is one of only two designated under Michigan’s Natural Rivers program in the Upper Peninsula and only one of 16 across the entire state. The program was created to preserve, protect, and enhance our state’s finest river systems for the use and enjoyment of future generations.

These rivers and the wetlands that feed them are a critical part of the state’s healthy Great Lakes ecosystem. MNA is proud to be part of protecting Michigan’s fresh water through our network of more than 180 nature sanctuaries. Learn more and join us in this work at michigannature.org.

Michigan Nature Monday: Floodplain Forests

In southern Lower Michigan, the populated landscapes of farms, homes, and towns create predictable, right-angle patterns of human settlement when viewed from above.  But winding across and through those straight-line grids, meandering corridors trace the paths of streams and rivers.

These corridors often harbor something really important, a dynamic natural community known as a floodplain forest. Floodplain forests are a vital part of Michigan’s natural heritage. Periodic flooding, scouring, erosion and sediment deposition follow the rise and fall of water levels creating diverse microhabitats that are used by a variety of wildlife.

Land meets water in a floodplain forest. When that stream or river tops its banks, it reshapes the bottom lands with tree falls, migrating river channels, new sediment deposits or erosional scour. These actions create fluvial landforms such as natural levees, backswamps, oxbow ponds, and terraces – all associated with a particular type of vegetation.

The Thornapple River flows along the banks of MNA’s Thornapple Lake Nature Sanctuary as it empties into Thornapple Lake.

The flowing waters help the soils thaw earlier in the spring, meaning these are often the places where the first wildflowers bloom. Insects, invertebrates, reptiles, and amphibians appear almost simultaneously to take advantage of the food sources provided by these wildflowers. “These forests are often very important stopover or even nesting sites for declining neotropical migratory birds as well.” “Often they are the last forested strongholds in a lot of agriculturally-dominated landscapes and are therefore valuable for a variety of plants and animals.”

Threats to these impressive habitats are an all too familiar list – invasive plants and animals, hydrological modifications (levees, impoundments, channelization, dams), including those brought by climate change, habitat loss due to industrial, residential and agricultural fragmentation, and incompatible timber management. For those reasons, floodplain forests are both globally and state-ranked as vulnerable.

Copperbelly watersnakes are one rare species that use floodplain forests and other adjacent habitats. Photo courtesy Michigan Natural Features Inventory.

For sometimes being no more than a narrow, green edge along a river, the magnitude of floodplain forest benefits outweigh their seemingly limited size. Besides important habitat, they play a critical function in Michigan’s fight against climate change. When water flows across the land to a river, the floodplain forest serves as a buffer, absorbing both the quantity and the energy of that flow while filtering pollutants. Floodplain forests therefore help to protect the water quality in many of Michigan’s watersheds.

Michigan Nature Monday – Spring Ephemerals

If you’ve spent much time in Michigan, you are likely familiar with the excitement that comes with spring—wildflowers blooming, birds migrating, trees budding. It is a time of renewal and rebirth as the drab browns of winter slowly return to green, the additional sunlight and longer days allowing the process of photosynthesis to recur.

Perhaps the most exciting of all are the ephemerals—the short-lived plants—like spring beauty, trillium, hepatica, and more that provide important food sources for pollinators. These temporary wonders are among the first to appear on the forest floor, anytime between March and June depending on the latitude and elevation. As insects emerge from under leaves where they’ve spent the winter they must go in search of food sources like nectar from these spring ephemeral wildflowers. Widespread and abundant ones like trillium are an easy source for many insects (and birds in search of an insect meal), but there are also some insects that are more particular about the plants they seek nectar from.

False rue anemone and spring beauty in bloom at MNA’s Dowagiac Woods Nature Sanctuary. Photo by Lauren Ross.

It is well-known that monarch butterflies need milkweed for the caterpillar stage of life. Milkweed is actually a toxic plant containing glycosides that would normally make them inedible to people and wildlife, but monarchs have developed a tolerance for this toxin that offers them protective benefits. Birds that eat monarch caterpillars will become sick due to the stored glycosides, and so they learn that the color pattern associated with the monarchs are not a source of food, and will move on.

Another ephemeral plant that blooms later in the summer—the Black-eyed Susan—has a less well-known benefit to Michigan’s federally endangered Poweshiek skipperling butterfly. Adult Poweshiek skipperlings feed exclusively on the nectar of Black-eyed Susan flowers, making these common wildflowers an essential part of the recovery effort for this butterfly.

Poweshiek skipperling butterfly on a black-eyed Susan. Photo by Kelly Nail, USFWS.

So, as signs of spring make their way across Michigan and you delight in the sight of wildflowers blooming, it is a good reminder that these brief encounters are just one of the many important parts of a healthy ecosystem.

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Several MNA nature sanctuaries are well-known for their wildflower displays. Dowagiac Woods Nature Sanctuary in Cass County is home to a wide variety of wildflowers including trillium, trout lily, dutchman’s breeches, and many more. Trillium Ravine Plant Preserve in Berrien County holds several different types of trillium that carpet the forest floor for an incredible display for trillium seekers.  Visit michigannature.org to plan your next visit today!

Michigan Nature Monday: Michigan’s Many Water Resources

Michigan is well-known as the “Great Lakes State” but there is much more to the state’s freshwater ecosystem than the massive inland freshwater seas that garner all the attention. There is a true “underdog” in Michigan’s freshwater systems—groundwater.

In honor of National Groundwater Awareness Week (March 5-11, 2023), the Michigan Nature Association is proud to explore a vital component of Michigan’s groundwater system, fens, written by MNA volunteer Zoë Goodrow.

What is a fen?

When the final glaciers in Michigan retreated north about 8,000-12,000 years ago, they shaped landforms that eventually became the wetlands we see today. Fens are among the rarest types of wetlands – more specifically, peatlands – found in Michigan. What differentiates fens from other wetlands is their hydrology.

Fens are fed by a continuous flow of groundwater that filters through nutrient-rich layers of sediment, like limestone, resulting in an ecosystem rich in calcium and magnesium. The steady supply of groundwater into fens means that fen soils remain saturated throughout the year. This causes a reduced abundance of bacteria that break down plant materials (compared to other wetlands), resulting in a buildup of decayed plant debris – also known as peat.

Rare species in fens

Fens have 500 times more rare plant and animal species than the average acre of land in Michigan. They support nearly 60 rare species and are the Michigan equivalent of rainforests in terms of relative biodiversity. Typical plant species that are unique to fens across Michigan include sphagnum mosses, white lady slipper, fringed gentian, edible valerian, and carnivorous plants including sundews and pitcher plants. Rare animals that habituate fens include the yellow rail, Mitchell’s satyr, and eastern massasauga rattlesnake. Fens are extremely fragile and sensitive systems that are already being impacted by climate change, which does not bode well for the rare species that are endemic to fen ecosystems. Because of this, and their significance to Michigan’s biodiversity, it is important to know the guidelines for minimizing disturbance before you visit one.

Types of Michigan fens

Michigan is home to many types of fens, including the northern, prairie, patterned, and coastal fens. These different fens are characterized by the natural processes that formed them and the climatic conditions of the regions they reside in.

Prairie fen photo by Dave Cuthrell.

Northern fens are found in the Upper Peninsula and the northern half of the Lower Peninsula. They occur where a glacial outwash meets a more textured glacial feature like a kettle lake or an end moraine.

Prairie fens, located in the southern half of the Lower Peninsula, occur in former oak-savanna prairies. As their name suggests, they are dominated by a mix of prairie and wetland sedges, grasses, and forbs. These fens were formed via the same glacial processes as northern fens.

Patterned fens, also known as string bogs, also occur in the Upper Peninsula. What differentiates these fens from northern fens is that they are a series of alternating ridges and hollows, oriented parallel to the contours of the land. The natural processes responsible for forming these unique systems are still unknown. While there are several proposed hypotheses – researchers agree that an essential factor is the direction of water movement, as the ridges and hollows are consistently oriented perpendicular to the flow of groundwater. (See more on patterned fens with MNA’s Fox River Wetlands in the video linked below)

Click on the image above to watch “The Fox and the Fen”. Photo by Jason Whalen, Fauna Creative.

Coastal fens occur along Lake Michigan and Lake Huron in the Upper Peninsula and northern Lower Peninsula. The natural processes that formed them are inextricably linked to those of the Great Lakes. The water tables that influence these systems are subjected to seasonal and multi-year lake level fluctuations, so vegetation in coastal fens changes quickly when water levels change.

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To experience a fen habitat first-hand, consider visiting MNA’s Lefglen Nature Sanctuary in Jackson County. The sanctuary is home to a prairie fen and a natural flowing well visible from the south trail. Visit our online sanctuary map for directions and more information.