Prairie Fen

Prairie Fen Series – Being a Prairie Fen Steward

/ camrynbrent1 / 1 Comment

Welcome to the final post in this series! In the first post, we discussed the unique geological processes that form prairie fens. Then in the second post, we presented plant species that we can use to discover prairie fen habitats. Lastly, we will be discussing the threats prairie fens face, what we are doing on-site, and why our efforts are so important.

My time at the parks has come to a close. Having arrived in the early spring and leaving in the early fall, I have witnessed lots of change. I followed the life stages of plants as they transitioned through the seasons. From emergence to bloom to death, I got to be a part of it all. Just as amazing, this was the first position where I was able to actually see the results of our stewardship efforts.

The photo was taken of Paint Creek Heritage Area – Fen in late summer.

I personally have felt the most fulfillment from working at the prairie fen off the Paint Creek Trail. Oakland Township’s portion of this fen is only about a half-acre, but the larger fen habitat extends up and down Paint Creek. Even with its small size and history of fragmentation and disturbance, our little fen patch is resilient. We hope to restore our park’s prairie fens to their full biodiversity capacity.

Threats and restoration

Our Paint Creek Heritage Area – Fen can be used as a case study of the major threats these natural communities face. Our fen was once a part of a larger wetland complex extending to its south and west, but the connections to this wetland and the surrounding uplands have been damaged over time. Due to the parcel’s small size, there is little buffering it from encroaching development. The smaller a site, the more vulnerable it may be to changes in the surrounding landscape and threats. These threats mainly include a lack of fire, invasive species, nutrient pollution, and changes in hydrology.

Fire Suppression

Just like our oak lands and prairies, the suppression of fire on the landscape and the removal of indigenous land management practices have changed the composition of our prairie fen. The loss of fire has compacted the sedge meadow zone of the fen while increasing the woody zone (check out the previous post to learn more about fen vegetation zones).

Interestingly, the majority of our fire-dependent landscapes in Michigan that have held on after European colonization have been along railroads. In the late 19th century a railroad was built on what is now the Paint Creek Trail, cutting right through the fen. As mentioned in Cam Mannino’s previous blog post, fires sparked by passing trains spread into the surrounding landscape, maintaining natural communities like oak savanna, prairie, and prairie fen.

Photo (L) was taken in 2015 and photo (R) was taken in 2016 at the Paint Creek Heritage Area- Prairie Fen.

With the decommissioning of the railroad in the late 1970s, we now need prescribed fires to maintain the integrity of the prairie fen. We try to use controlled burns every 3-5 years to preserve the remnant prairie fen. The burns control invasive woody shrubs and remove dead stalks of Phragmites and invasive cattails after treatment. In addition, fire encourages plants to bloom more profusely and allows seeds of fen plants to germinate. The last controlled burn at the site occurred in 2019.

Invasive Species

Invasive species may proliferate due to problems, like fire suppression, nutrient pollution, or hydrology changes. Often, though, invasive species both exacerbate these problems and create new issues of their own. Both invasive cattails and Phragmites grow more vigorously in wetlands with lots of nutrients. The dense stands of Phragmites and cattail, and the thick layers of dead thatch that accumulate, crowd out fen plants. Invasive woody shrubs like glossy buckthorn and common buckthorn often invade fens that have dried out due to hydrology changes that result from building a trail, berm, or road through a fen, fo example. However, these invasive shrubs can also change conditions in a fen to facilitate their own invasion.

Photo (L) taken underneath the tamarack canopy in 2016 where Grass-of-Parnassus (Parnassia glauca) was abundant amid emerging glossy buckthorn seedlings (Frangula alnus). Photo (R) taken this season after a day spent cutting buckthorn and treating stumps.

When our Paint Creek Heritage Area – Fen was acquired over a decade ago, large areas had already been encroached by invasive woody shrubs, narrow-leaved cattails, and Phragmites. We have prioritized saving the core area of our fen by controlling invasive Phragmites and cattails over the last five years. Fen plants like shrubby cinquefoil, Kalm’s lobelia, and grass-of-Parnassus are growing again in areas that used to be dense Phragmites or cattails.

Now we’re starting to work on the invasive shrubs that are spreading into the fen from the edges. In one area glossy buckthorn shaded out a nice Grass-of-Parnassus patch. This year the stewardship crew started clearing the glossy buckthorn so it may return.

Nutrient Pollution

Our fen-specialist plants are adapted to growing in alkaline, low-nutrient environments. Increased nutrient inputs from farm runoff, lawn fertilizer, leaky septic tanks, or deposited from the atmosphere through rainfall really change the function of a prairie fen by favoring more generalist wetland plants and invasive plants that can take advantage of increased nutrient levels. Left unchecked, Phragmites, invasive cattails, reed canary grass, and purple loosestrife that like high nutrient levels often grow in dense stands with no other plants, patches that we describe as “monocultures.”

A cattail monoculture at the Paint Creek Heritage Area – Fen before (L) and recently after (R) treatment.

We often can’t address past or ongoing nutrient pollution issues directly if they happen off our property, so try to limit the damage from high nutrient levels. The last three years the stewardship crew has been working at selectively treating narrow leaf cattail stands. To learn more about how this treatment is done, check out a past blog post. I have hailed it as being one of the most taxing yet most rewarding stewardship tasks. I know that each treatment causes the cattails to shrink away and reveal more prairie fen habitat.

Change in Hydrology

The steady supply of cold, calcium, and magnesium-rich water in fens really is their lifeblood. Unfortunately, many property owners don’t realize how special fens are and permanently damaged them by digging ponds. In addition to scooping up valuable fen, digging ponds lowers the water table by creating a low spot in the wetland where water can collect. This creates drier areas that become establishment hotspots for invasive species like glossy buckthorn and other invasive shrubs.

A wall of glossy buckthorn creeps into a fen, slowly shading out the unique wetland plants that this class visited to observe! This photo was taken in Bakertown Fen Preserve in SW Michigan by Grant Vander Laan.

Other changes can affect fen hydrology directly or indirectly. In the past, many fens were dried out by the installation of drain tiles and ditches to “improve” them for agriculture. Building roads, driveways, and trails disrupt the flow of water through a fen by acting like a dam, creating wetter conditions above and drier conditions below. Extracting water with wells for irrigation or other uses can also deplete aquifers that feed fens. It is critical that we partner with surrounding landowners to protect the water that charges the prairie fen.

Over time the landscape around our fen has become more fragmented, more developed, and full of invasive plant species. Aerial photographs from Oakland County.

Why Put In the Effort?

Although our fen is small, it has many high-quality specialist plant species present. Fen ecosystems also support a plethora of rare insect and animal species. In fact, several insect species rely entirely on prairie fen communities and would go extinct without them. You can check out the rare plants and animals associated with prairie fens at Michigan Natural Features Inventory (MNFI).

Prairie fens are globally rare wetlands that are rich in biodiversity. This photo is of our newly acquired prairie fen at Fox Nature Preserve. It is one of our higher-quality parcels.

With our fen off the Paint Creek Trail, it only becomes increasingly difficult to buffer it from the effects of habitat fragmentation. This is especially true for prairie fens, as they often blend into surrounding uplands, wetlands, and bodies of water. However, even in the face of fragmentation, species may be able to persist if they can move between small high-quality parcels. As you might imagine, this may be more difficult for a slow-moving species like a turtle than it is for a flying insect like a butterfly.

A restored prairie fen right next to the Paint Creek Trail is also an excellent educational opportunity for trail users. Since it is only half an acre, the site is manageable and able to show the significance of our stewardship work. As with any restoration project, it is imperative that objectives are well-defined. In the case of the Paint Creek Heritage Area, our team is working to maintain high-quality habitat that trail users may be able to see and learn from. With our invasive shrub removal efforts near the trail, we hope the prairie fen will become more visible to folks passing by. We also hope that other township residents and neighboring properties join us as prairie fen stewards. The more we protect the surrounding area, and the more we get people involved to protect our fen, the greater the impact of our little half acre will have.

Each Action Makes a Difference

Baby Blanding’s Turtle (Emydoidea blandingii)
Appalachian Brown (Satyrodes appalachia)
Photos were taken at Paint Creek Heritage Area – Fen this summer.

Stewardship work is often laborious and ceaselessly repetitive. The blood, sweat, and tears our stewardship crew spent at the half-acre fen parcel have been rewarded time and again by our encounters with fen dwellers. Whether it is the noisy flush of a spooked woodcock or the silent presence of a butterfly, visits to the fen never felt lonesome. While treating our last group of narrow-leaf cattail for the season, fellow steward Cassie spotted a baby Blanding’s turtle. After she set the baby down, she turned to me and exclaimed how happy she was to have seen that turtle. We had been selectively hand-wicking cattails all morning. We were tired and hungry for lunch. But after releasing the prehistoric baby back into a pool of groundwater, we continued our tedious task with newfound ambition. Our work was making a difference.

Prairie Fen Series – Recognizing a Fen Neighbor

/ camrynbrent1 / 3 Comments

Welcome back to our prairie fen series! The first post took a broad look at what prairie fens are and why they exist. In this post, we will focus on key plants that act as indicator species for a prairie fen community. Using mostly pictures taken from our township’s own fens, we will also dive into the vegetation zones that characterize these unique habitats.

I have been fortunate enough to visit each prairie fen in our township parks. I am always amazed by the diversity of plants I find at each of these sites. I started this series because I had little knowledge of what a prairie fen was, and no idea that I lived among them. Unlike other wetlands, I found that prairie fens blend extremely well into the surrounding environment. Maybe this is why I and so many others were estranged from these fen communities that are my close neighbors here in southern Michigan! A fen could be right under your nose in your local natural area or even your backyard! I hope this post may guide you if you hope to get acquainted with the wondrous prairie fen.

Our prairie fens

We have three prairie fen habitats in three different parks. Each site is unique with its own plant community, land use history, and threats.

We have prairie fen habitat in three of our township parks: Draper Twin Lake Park, Paint Creek Heritage Area – Fen, and Fox Nature Preserve. The plants that have greeted me at these prairie fens ranged from recognizable prairie and wetland species to more specialized flora able to survive in difficult environments. With their unique conditions, prairie fens are biodiversity hotspots for plants, animals, and insects in Michigan.

As the book Exploring the Prairie Fen Wetlands of Michigan states, prairie fens typically support twice the plant species found in bogs. Although both fens and bogs exhibit difficult growing conditions, with pH ranges in the extremes, fens exhibit a wider diversity of vegetation types. My last post gave us an important clue to why this is: fens are fed by groundwater seeps. Not all parts of the fen get equal volumes of calcium-rich water, resulting in different growing conditions and different sets of plant species in each fen zone.

Even the topography of a fen depends on the flow and composition of groundwater. Wetlands are usually associated with depressions in the landscape. However, prairie fens can be found as domes within a wetland, on slopes, and in low-lying areas along lakes and streams. Basically, wherever calcium and magnesium-rich groundwater percolates to the surface in southern Michigan, there could be a prairie fen!

When identifying a prairie fen, do not exclude areas that form a mound or on a slope. Figure from Exploring the Prairie Fen Wetlands of Michigan

Other conditions such as peat accumulation and disturbances, both natural and human-caused, can play a role in fen vegetation types. According to Michigan Natural Features Inventory (MNFI), these zones in a fen may include wooded fen, sedge meadow, marl flat, and inundated flat. As reported by the Michigan DNR, the sedge meadow is typically the largest part of a fen, while the wooded fen is found in slightly elevated uplands around the edges. Historically, naturally-caused fires and those lit by Native Americans would burn into prairie fens and maintain a more open structure. Today, the wooded fen may occupy more of the fen and the sedge meadow less due to fire suppression throughout Michigan.

The four vegetation zones of prairie fens. Note that the prairie fens in our parks are not large enough to have all of the four vegetation zones present. All photos are from our township prairie fens except the marl flat, which was taken in Springfield Township.

Prairie fens can look different from one another depending on hydrology, topography, and fire history, so it may be tricky to determine if a wetland is a prairie fen. Luckily, we can use certain plant species as fen “indicators.” Prairie fens have high pH levels due to the calcium and magnesium carbonates in the groundwater, and some plants are only found in these calcareous conditions. Identifying these specialized “calciphile” plants would bring you to a prairie fen classification without having to identify each plant species in the community. However, the lower the habitat quality, the more difficult it is to determine if a habitat is a prairie fen remnant since cattails and other generalist wetland plants typically increase in abundance after disturbance.

The Michigan State University Extension resource on fen evaluation is helpful for all levels of habitat quality. They recommend surveying in late August and early September when many of the calciphilic species are in bloom. Some of the species listed below are calcium-loving, while others occur both in fens and a variety of other wetland types. Continue scrolling to see prairie fen indicator species found in each of the vegetation zones.

Wooded fen

Larix laricina – Tamarack

Photos taken at Paint Creek Heritage – Fen

Eastern Larch, also known as tamarack, is a conifer that breaks all the rules. It is a deciduous conifer that also prefers to grow in the toughest conditions. Tamarack trees are often indicators of all types of peatlands, no matter the pH, but can grow in other wetland types too. Soon they will be turning bright yellow and will eventually lose their needles. The clusters of needles on short shoots that form firework-like sprays from the branches distinguish tamaracks from other conifers in Michigan.

Toxicodendron vernix – Poison Sumac

Photos taken at Paint Creek Heritage Fen

Similar to tamarack, poison sumac can be found in both acidic and calcareous wetland soils, mostly in southern lower Michigan. I often find that the leaflets of the compound leaves point upwards to the sky. Poison sumac has light gray bark and is less “twiggy,” or finely branched than many other trees and shrubs after it drops its leaves. The photo above (right) shows the awesome fall colors that they will change into. Poison sumac may also be found scattered throughout the sedge meadow zone. Note that species may overlap in several vegetation zones.

Sedge meadow

Parnassia glauca – Grass-of-Parnassus

Photos taken at Paint Creek Heritage – Fen

Grass-of-Parnassus is not a grass, although the smooth stem does tend to blend in with the surrounding grasses. This flower also has nothing to do with Mount Parnassus in Greece. Grass-of-Parnassus is only found in calcareous conditions, making it an ideal fen indicator species.

Pycnanthemum virginianum – Virginia Mountain Mint

Photo taken at Paint Creek Heritage – Fen.

Not sure why the common name has mountain, however, the mint part of the name is very suitable. If you are not sure about the ID of a mint, look for the square stem and rub a few leaves between your fingers. Most mint species have that characteristic aromatic fragrance. Common mountain mint occurs in wet meadows like a prairie fen but is not specific to fens. If you look closely at the flowers they are speckled with purple.

Ohio Goldenrod and Riddell’s Goldenrod

Ohio goldenrod
Riddell’s goldenrod
Ohio goldenrod (L) and Riddell’s goldenrod (R). Photos were taken at Paint Creek Heritage – Fen.

Ohio goldenrod (Solidago ohioensis) is easy to identify by its lower, rosette leaves that get quite large, have one central vein, and are flat. The upper stem leaves do not get as big as the lower leaves. The leaves of Riddell’s goldenrod (Solidago riddellii) fold inward like a paper airplane and taper to a point at the end. They have three veins obvious near the base of the leaf blade. Both species have a flat-topped inflorescence and are calciphiles, meaning they are adapted to calcareous soils.

Marsh Bellflower and Kalm’s lobelia

Marsh bellflower
Kalms lobelia
Photos taken at Paint Creek Heritage – Fen.

Marsh Bellflower (Campanula aparinoides) on the left and Kalm’s lobelia (Lobelia kalmii) on the right are both calciphilic species that can easily be overlooked among the larger species in the sedge meadow. It is worth crouching down to see these delicate flowers.

Dasiphora fruticosa – Shrubby Cinquefoil

Photos taken at Paint Creek Heritage – Fen.

I see this shrub everywhere in residential landscaping. That being said, it is naturally found in alkaline soils and is an indicator of calcareous conditions. In Michigan, it is mostly found in high-quality wetlands.

Rhamnus alnifolia – Alder-leaved buckthorn

Photos taken at Fox Nature Preserve.

Alder-leaved buckthorn is our only native buckthorn and is generally a calciphile found in high-quality wetlands. Although they are a good indicator of prairie fens, they can be tricky as they look similar to their invasive relative; common buckthorn. I can tell the difference as the leaf tips are more pointed than common buckthorn, and the leaf veins more prominent.

Bog Birch and Sage Willow

Bog birch
Sage willow
Photos taken at Draper Twin Lake Park.

These low-lying shrubs are great indicators as they tend to stand out and are easy to identify. Both bog birch (Betula pumila) on the left and sage willow (Salix candida) on the right prefer calcareous soils. Bog birch has small oval-shaped serrated leaves while sage willow has striking white-hoary leaves.

Inundated flat

This vegetation zone can be found on the edges of lakes or streams and is dominated by various sedges and rushes. Sedges and rushes are typical in inundated flats and are super cool, but since they are not easy to identify we won’t discuss them in detail here. The Fox Nature Preserve fen is the only prairie fen in our parks with an inundated flat.

Photos of an inundated flat at Fox Nature Preserve prairie fen. I stopped to watch the snapping turtle (right) in stealth mode.

Marl flat

Marl flats have strong groundwater seepage and are therefore highly alkaline. Due to the high pH, only species adapted to extreme conditions can survive and the flats are sparsely vegetated. Our township’s prairie fens do not contain marl flats.

Marl flat landscape was taken at Shiawassee Basin Preserve in Springfield Township.

Cypripedium candidum – White Lady’s Slipper

Marl flats contain the most radical plants from rare orchids to carnivorous species such as sundew and pitcher plants.

The most rewarding part of this season was finally being in on the secret of prairie fens. Now that you have been acquainted with some botanical residents of prairie fens, I hope these communities are no longer strangers. To protect imperiled ecosystems I believe we first need to be able to recognize them as fellow neighbors. Only by understanding its parts can we understand the needs of the community as a whole.

Stay tuned for the final post in the series! We will broaden our lens and discuss human-caused threats prairie fens are facing, and what our stewardship team is doing to help.

Prairie Fen Series – Meet our Dynamic Peatland!

/ camrynbrent1 / 1 Comment

Take some time to learn about Southern Michigan’s most underrated ecosystem, the prairie fen! In this three-part series, we will go over what a prairie fen is, how to identify this community by its plant species, and what threats they face. This first post offers a reflection on these globally rare, but locally abundant, biological treasures by comparing them to their more well-known cousin, the bog. We will start the series by looking at the geological events that formed these unique wetlands using photos and stories from Michigan’s largest prairie fen. Stay tuned for two more posts all about our Township’s own prairie fen plant species and its history of being overlooked.

Prairie Fen
Bog
Comparison of bog and fen prevalence in Michigan. The map on left shows the prairie fen range. The map on the right shows the range of bogs. Maps from Michigan Natural Features Inventory

Peatlands: Bogs and Fens

Wetlands have received a lot of hype recently due to their capacity for preserving biodiversity and mitigating climate change. According to the International Peatland Society, the majority of our world’s freshwater wetlands are composed of peatlands. Most peatlands are classified as either fens or bogs. The saturated, anaerobic (no oxygen) soils of these special wetlands do not allow rapid decomposition of plant matter, allowing net accumulation of peat over time. As a result, peatlands are the largest terrestrial storage for carbon, according to the International Union for Conservation of Nature (IUCN).

Although both peatlands are adept at producing incredible biodiversity and carbon storage, they do not receive equal attention. I’ve noticed that even among my science-driven peers, fens are not as well-known as bogs. In undergrad, I was taught more about bogs than fens. Perhaps because bogs are more widely distributed and occur more frequently in Michigan. Or possibly because the highly acidic conditions (low pH) of bogs make them a more singular group, while the fens have several different subtypes. In college, I remember briefly learning that fen wetlands were fed by alkaline (higher pH) calcium and magnesium-rich groundwater, and bogs by rainwater.

In the fen, water was constantly flowing beneath the elevated sedge tussocks. The spring water moved as sinuously as the ribbon snakes that slithered away when we walked near them.
In the bog, when we jumped up and down on the sphagnum moss it acted like a natural water bed. When not jumping the landscape feels sluggish as the soft moss absorbed each footstep.
Picture of me standing in Springfield township’s prairie fen (left). Emma (right) standing on a sphagnum moss mat in a bog at our newest park: Fox Nature Preserve! Notice the difference in vegetation.

Expanding my knowledge of the wondrous prairie fen

In Michigan, the fen group is made up of five natural communities, including prairie fen (check out coastal fen, northern fen, poor fen, and patterned fen if you’d like to learn about the other fens). Prairie fen is appropriately named since it shares many plants found in nearby tallgrass prairies. Prairie fen is found only in the Midwest, thanks to our mighty glaciers.

Map of lower Michigan’s glacier lobes in the most recent glaciation. The Wisconsin glaciation ended around 11,000 years ago. Image is taken from 2015 geomorphic study of the southern Lower Peninsula.

In Michigan, prairie fens primarily occur in the two interlobate regions of the southern Lower Peninsula. We have one interlobate region on the west side of the Lower Peninsula, and other interlobate region called the Jackson Interlobate here in the southeast region. These regions have a complex array of hills and valleys caused by the consolidation and withdrawal of glacier lobes during the Wisconsin glaciation. As noted earlier, all fens are fed by spring water. In the hilly landforms of the Jackson Interlobate, gravity pulls water down through the glacial deposits rich in calcium and magnesium. The alkaline water eventually flows down to the bases of slopes, showing up as spring-fed fens.

A figure displaying fen hydrology from Exploring the Prairie Fen Wetlands of Michigan by MNFI/Michigan State University Extension.

The calcium-rich, alkaline groundwater can be a tough environment for plants. A special set of plants that we call fen “indicator species” tolerate these harsh conditions better than general wetland plants. When we find these plants we know to look closer to see if the surrounding wetland is indeed a prairie fen. Tune into the next blog post in this series to learn more!

Map showing the distribution of prairie fens in Michigan. Circled in red is a cluster of fens that includes those in our township. The northwestern part of Oakland County is where Michigan’s largest prairie fen resides in Springfield Township. Figure from the 2009 Mitchell’s Satyr Habitat Conservation Plan.

My First Fen Visit

No amount of diagrams and reading can prepare someone for what a natural community is like until you are standing in one. I finally had the chance to experience a Michigan fen during the Eastern Massassauga Survey our crew helped with earlier this summer. The survey took place in Michigan’s largest remaining prairie fen in Springfield Township! On the drive there, my unconscious bias predicted the habitat to look similarly isolated and alien as an acidic bog.

The above photos are of the Springfield prairie fen at Shiawassee Basin Preserve. From afar, the photo on the left looks similar to an upland prairie. The photo on the right shows the river that the fen drains into.

I could not have been more naïve. In stark contrast, the landscape was alive and coherent. As I stood unstably on sedge mounds, I could hear what sounded like the thirsty noise of draining a bath. Only in the plants parted could I see where the peculiar sounds were coming from. Calcareous spring water, cold from being locked in the dark earth, ran in rivulets beneath us as we walked. There were also areas where streams flowed on top and through the vegetation. Water and earth weaved in and out of each other; I quickly realized that fens are interlaced with the rest of our sculpted landscape.

This picture depicts the seamless progression from prairie fen to oak forest.

Unlike bogs, which similarly occur in depressions caused by melted glacier ice, prairie fens are not isolated pockets of water. These fens are often part of larger wetland complexes, often occurring on the edges of lakes or along streams. Prairie fen’s plant communities often also morph into surrounding environments like oak barrens and openings, even sharing the same historical need for fire disturbance.

Leaving Springfield’s fen, I rejoiced in the never-ending surprises that come with being a student of the natural world. I had no idea a peatland could feel so energetic. I had been under the impression that all peatlands were as dead as their layers of preserved organic matter.

The next post in this series will dive deeper into the dynamic life that these fens sustain using flora and fauna snapshots from our prairie fen along the paint creek trail. In the meantime, you can check out a previous blog about the Unique Wetland Communities Along the Paint Creek Trail to get some background on the work we do there.