Exploring Peatlands in Superior National Forest

A forested peatland in Lake County, Minnesota. The tree canopy is composed of black spruce and tamarack. Labrador tea and leatherleaf compose most of the shrub vegetation. Beneath the shrubs, sphagnum mosses predominate.

Peatlands are beautiful

Among my favorite wild places to explore are peatlands, a type of wetland that includes bogs and fens. Peatlands support diverse and unusual plant communities. Many peatlands host uncommon orchids like whorled pogonia, club-spur orchid, grass pink, and dragon’s head orchid. Other unique plants also grow in peatlands, such as sundew, bladderwort, pitcher plant, bog clubmoss, Arctic raspberry, sage willow, yellow-eyed grass, and pale and sooty beak rushes.

**Sundew (*Drosera rotundifolia*) and bog clubmoss (*Lycopodiella inundata*) from a peatland in Wisconsin.**

Peatland formation

Peatlands typically develop in depressions where soils become waterlogged and lack oxygen, leading to a buildup of dead plant material that exceeds its decomposition. The slow decay of organic matter in the waterlogged soils ties up nutrients, making them less available to living plants.

Peatlands encased in granite

In the Border Lakes Region of Minnesota, peatlands have developed in basins and troughs created by glaciers that scoured the bedrock over thousands of years.

The Border Lakes Region of Minnesota is situated on the 2.7 billion-year-old Vermilion Granitic Complex, described as a “granite-migmatite terrane composed of supracrustal metasedimentary rocks, mafic rocks, tonalitic and granodioritic plutonic rocks, and granite.”

A subdivision of the Vermilion Granitic Complex is the Lac La Croix Granite, which formed “via partial fusion of calc-alkaline tonalitic material, which may have been similar to rocks of the early plutonic suite.”

What might this complex geology and mineralogy have to do with peatlands in that region? The Lac La Croix Granite, as already noted, was derived from partial fusion of calc-alkaline tonalitic material, which is rich in alkaline elements like calcium, potassium, and sodium. My thoughts are that the alkaline mineralogy buffers the pH of the water and peat soils in peatlands. This, in turn, influences the types of vegetation that will grow there and how it will grow.

The hydrology in this region is also complex. The soils are shallow, but the bedrock is deeply fractured. These fractures serve as conduits for subterranean water flow connecting one wetland with another where surface flow is not possible, and supplying dissolved minerals to the wetlands.

A floating peatland

**The floating mat of sedge and peatmoss**

The peatland in the above photo is located in northern St. Louis County, Minnesota, in the heart of the Vermilion Granitic Complex. It is part of a 4-hectare (almost 10 acres) wetland in a 4 km-long (2.5 miles) valley bordered by rock outcrops.

This peatland is a floating vegetation mat composed of peat moss, small sedges, and sundew. It is one of fifteen wetlands in the valley that have developed behind beaver dams.

**Another view of the floating mat of sedge and peatmoss.**

The valley that contains these wetlands is relatively straight and seems to have been carved from a massive fissure in the bedrock. Some parts of the valley walls are steep cliffs, but most are rounded. Small stones, cobbles, and boulders are often scattered across the outcrops.

Across the area, there are fissures, large and small, like this one. Many have sluggish streams flowing through them, blocked by beaver dams. Ponds, sedge meadows, marshes, and peatlands have developed behind each dam.

Above is the beaver dam that is holding back the water where the floating vegetation mat has formed. The dam is about 3.6 meters (12 feet) high and 73 meters (240 feet) long. A dense growth of grass and sedge holds it together. A dam this large must be ancient.

Part of the floating mat is visible in this photo. The reddish areas are sundew plants. Binoculars are helpful in situations like this when walking is not safe.

The photo below is from the same pond along the dam where the water is deeper. It is full of pondweeds (Potamogeton spp.) and other aquatic plants like common bladderwort (Utricularia vulgaris). The water’s dark brown color is caused by tannic acids leaching from the peat.

**Plants in the tannin-stained water are *Potamogeton* sp (pondweed)., *Utricularia vulgaris* (bladderwort, an aquatic carnivorous plant), and a species of *Sparganium* (bur-reed).**

I’m planning to go back

It’s been a few years since I was last at this peatland. Back then, I was doing rare plant surveys in Minnesota and Wisconsin. My schedule was tight, and so I couldn’t spend much time in one place, leisurely exploring.

I have plans to revisit this wetland later this year. I won’t be rushed, trying to keep on schedule like I was when doing rare species surveys. I can take my time exploring these special places, discovering and learning new things about them. This trip will be in small doses over three days. It’s a vacation after all.

The satellite photo below shows the area of interest in the red box. Within that area are not just beaver dams, but upland forests, rock outcrops, and another large peatland that may have been a lake in the distant past.

**Zone 15 U, 554493.00 m E, 5321327.00 m N if you’d like to see this in better detail on Google Earth.**

This other peatland is 5.9 hectares (14.5 acres) and is in the lower left corner of the box. It has a large open area with creeping sedge, poor sedge, beaked sedge, white beaked rush, iris, cotton grass, fir clubmoss, bog clubmoss, sundew, and many other plants. I want to spend a long time here wandering around, taking photos, and enjoying the solitude.

The uplands around the peatlands are forested with white pines and other conifers, paper birch, and red maple. Scattered throughout the forest are many rock outcrops (the light gray areas in the photo map) with colorful, beautifully patterned lichens.

**Map lichen (*Rhizocarpon geographicum*) grows on many rock outcrops in the Vermilion Granitic Complex.**

There are peatlands even in the upland forests. These have developed in small basins in the bedrock. The largest is 0.2 hectares (0.5 aces), which is small but similar in size to forest vernal pools. There is no inflow to them or outflow from them, and there was no evidence of upwelling water. I do not know how they remain wet, but they are vegetated with sphagnum, leatherleaf, Labrador tea, pod-grass (Scheuchzeria palustris), and pitcher plants. I wonder how these small peatlands were formed and how they maintain themselves.

Polystichum braunii (Braun’s Holly Fern)

Polystichum brauni is a huge fern, but for a long time, it was barely known from Minnesota. In recent years, more discoveries have been made of this rare Minnesota species.

Description

Polystichum braunii is a large fern with shiny, leathery, arching, broadly lanceolate fronds 0.2 to 1 meter in height. These grow in a rosette from a central erect stem. The petioles are 1/8 to 1/6 the length of the blade. The petiole and blade are densely covered in light golden brown scales, which gradually become smaller distally.

The blade is broadly lanceolate, bipinnate, and narrow at the base. The pinnae are oblong-lanceolate to curved, in one plane, and not overlapping. The apex is acute. The short-falcate to oblique-rhombic pinnules are finely dentate along the margins with slender bristles.

*Polystichum braunii* upper surface of old frond

Habitat

In Polystichum brauni grows in cool, humid ravines and cool, moist forests.

Distribution

Polystichum brauni has a disjunct North American distribution. It also occurs in Eurasia.

Sources

Discovering Minnesota’s Diverse Moth Species

**Phalaenophana pyramusalis** (dark-banded owlet, Family Erebidae, Subfamily Herminiinae).

How many moth species does Minnesota have?

When I first started moth hunting in 2017, I had no idea how many species of moths live in Minnesota. My first experience with Minnesota’s moth numbers was from a moth survey report. There had been a Minnesota DNR moth survey of state parks from 2006 to 2008 along the eastern edge of the state. Its purpose was to document moth species present before LDD moth (Lymantria dispar dispar) control efforts.

Their final list, representing just a small portion of the state, was 768 species, although they believed that statewide, there are about 2,200. I wondered how many of those moths might be where I live.

So many moths are tiny

Early on in my mothing I noticed there were many tiny moth species. I found some moths the size of a thumbtack. Others are smaller than a grain of rice, like the three species below.

*Epermenia albapunctella* (Epermenioidea)

Identification is not so simple

Most people are familiar with the larger charismatic moths, like the luna moth or one of the sphinx moths. But for many of the moths out there, they are just moths. This is understandable. Identifying anything to species is not always easy. With moths, this task is even more challenging given their variety of sizes, colors, and often subtle differences in wing patterns. To make matters worse, some species exist in different forms or look like other species.

Acleris (Superfamily Tortricoidea, Family Tortricidae) is a good example of a genus with intraspecific variation. Some species even resemble others within the genus. I’ve included two photos of Acleris celiana showing two of the forms it exists in. There are also photos of other Acleris species, some of which resemble each other.

So, is that the final count?

By the end of 2019, I had identified 541 moth species. It seemed to me this was close to the upper limit of moth species present. After all, the DNR survey had documented 768 species in thirteen state parks. These parks range from the southeast corner of the state to the northeast corner. I am looking at only a tiny fraction of that territory. About 40 acres, to be exact.

My list surpasses the DNR’s list

Eventually, my species checklist surpassed the MN DNR survey’s list. After rechecking identifications, synonymy, and duplications, my list was at 865 species. That’s 97 species more than the DNR list. How to account for that?

Accounting for the differences

The differences in species counts are most likely due to our respective sampling methods and time available. The MN DNR survey’s list is almost entirely species from so-called macro-moth taxa. It is heavily weighted towards Geometridae and Noctuidae.

It is likely that the smaller moths, the so-called micro-moths, were not within the scope of the survey. It would have taken too much time to identify every moth. This would delay the report and critical action on Lymantria dispar dispar expansion into Minnesota.

So, while our lists overlap for most of the macros, my list also includes micro-moths. These include those from the superfamilies Gelechioidea, Nepticuloidea, Tineoidea, Tortricidae, and other taxa with mostly minute moths.

When I am mothing, I try to photograph and later identify every moth that comes to my moth light. I am not under any time constraints to complete fieldwork or produce a final report. Some unidentified moths have sat in my photo files for years before I figure them out. They needed to present the bigger picture. I am just filling in the details and have plenty of time to do it.

My checklist will continue to grow

I’ve been working on documenting the moths on my land for eight years. I don’t think I am done yet. I also don’t think annual additions to my checklist have peaked.

The rate of new species additions has been about 33 per year since 2020. As of 2025, the species checklist stands at 865 moth species with 34 new additions. This includes macros and micros. If that rate continues, the checklist will reach 1,000 species in about four years.

Mothing into the fall and even the winter

Autumn is upon us now. Soon, almost all insect life outdoors will be gone. In the meantime, I will continue to photograph right up until the snow falls and the lakes freeze. But even in winter, it is possible to find some insect life, including moths, outdoors.

*Operophtera bruceata* (hunter’s moth) flies in late October. It continues into November when night temperatures typically drop into the 30s and upper 20s.

Carynota marmorata (marbled treehopper)

*Carynota marmorata* on American hazel (*Corylus american*a) catkins

Carynota marmorata (marbled treehopper) is a treehopper in the Membracides. This one caught my attention when I was getting ready to trim back a hazel bush that was extending a little too far into the driveway. I rushed back to the house, got my camera and tripod, and began shooting away.

Description

The high and rounded pronotal (the first segment of the thorax) crest is one of the first things that stand out on this species. The coloration of Carynota marmorata is variable but always a shade of chestnut-brown mottled with irregular greenish white speckling over the pronotum (the dorsal plate of the prothorax). Individuals may vary in the amount of speckling, with some having more than others. There may also be broad, more connected pale yellow patches forming transverse bands across the pronotum.

The pronotum is sparsely pubescent and coarsely punctate. The triangular head is sparingly pubescent, finely punctate, and spotted with red and yellow patches. They have red to black eyes. The tegmina have noticeable veins and are smoky hyaline. The legs are rust-colored, while the underside of the body is chestnut. Adults measure 4 mm in width and 8 mm in length.

Habitat and host plants

Carynota marmorata feeds on trees and shrubs in the birch family (Betulaceae), including paper birch (Betula papyrifera), American hazel (Corylus americana), and tag alder (Alnus incana).