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.
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.
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.
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 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.
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.
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.”
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.
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.
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).
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
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.