The Barrens Flora of Wisconsin’s Northwest Sands Ecological Landscape

Introduction

The diversity of vascular plants in the barrens of Wisconsin’s Northwest Sands Ecological Landscape is poorly documented. Natural plant community succession and pine plantations have greatly reduced and fragmented what remains as barrens in this region. Recognizing the importance of this landscape, several management and property master plans were developed by the Wisconsin Department of Natural Resources (2015, 2016, 2017a, 2017b). In a collaborative effort, the Wisconsin Department of Natural Resources hired a Northwest Sand’s liaison in 2017 to work with national, state, county, industrial and private landowners to expand the early successional barrens. Documenting the flora of this landscape now is an important step toward creating a base line for future comparisons of vascular plant diversity and for measuring the successes of prescribed management.

The barrens of the Northwest Sands Ecological Landscape are a dynamic mosaic that shift between dry forests and woodlands to open, prairie-like communities depending on the frequency of disturbance. However, ecologically defining the barrens plant community is difficult. The historical records in the Midwest contain several instances of barrens that refer to plant communities that fall somewhere between forest and prairie (Hutchison 1994). Many terms (e.g., savanna, brush prairie, oak opening) have been used synonymously with places described as barrens (Heikens and Robertson 1994). Generally, barrens may be described as savanna-like communities dominated by grasses and low-growing shrubs and trees, with scattered larger oaks and pines (Curtis 1959, Wisconsin Department of Natural Resources 2015). Furthermore, these communities tend to be edaphic and to receive periodic disturbances, often in the form of fire (Anderson et al. 1999, Curtis 1959, Hutchison 1994).

While plant communities described as barrens have been documented throughout much of North America (Anderson et al. 1999), this study focuses on those of the Northwest Sands Ecological Landscape in northwestern Wisconsin, which covers approximately 5,066 square kilometers stretching from northwest Polk County to north-central Bayfield County (Figure 1) (Curtis 1959, Radeloff et al. 1998, Wisconsin Department of Natural Resources 2015). Most of the upland soils of this region are comprised of sand, loamy sand, and sand mixed with gravel. This combination results in quick infiltration of water into the ground and produces xeric conditions for the flora of the uplands (Wisconsin Department of Natural Resources 2015).

FIGURE 1.

The Northwest Sand Ecological Landscape of northwestern Wisconsin, indicated by the hatched area. The specific study sites are indicated by numbered, circled points. (1) Sterling Barrens State Natural Area, (2) Fish Lake Wildlife Area, (3) Crex Meadows Wildlife Area, (4) Namekagon Barrens Wildlife Area, (5) Douglas County Wildlife Area, (6) Motts Ravine State Natural Area, (7) Barnes Barrens, and (8) Moquah Barrens. Inset: location of study area in Wisconsin. The map was created in ESRI ArcGIS 9.3 using publicly available data layers and a shapefile of the Northwest Sands Ecological Landscape provided by the Wisconsin Department of Natural Resources.

The barrens flora of the Northwest Sands has been influenced by several environmental and climatic conditions arising from the end of the Pleistocene approximately eleven thousand years ago. At the peak of the Wisconsin glaciation, the survey sites of this study would have been covered with glacial ice (Anderson 2006). As the climate changed and started to warm, species more adapted to the colder climate would have followed the retreating glaciers. Grasslands would have started to migrate northward as broadleaf forest species started moving into the region from the east and south. A dynamic interaction began to form as climate and fires interacted along this prairie and forest border (Anderson 2006). Interspersed between the boreal forest along the Great Lakes to the north, the broadleaf forests to the southeast, and the grasslands and savannas to the southwest were vast open areas of outwash sands, shallow glacial lakes, and tills. It is in this confluence that the Northwest Sands’ barrens developed, resulting in the diversity of species that we see today.

Prior to European settlement in the mid-1800s, the Wisconsin barrens, described as pine barrens in the Northwest Sands region by Curtis (1959), would have covered about 930,777 hectares (2.3 million acres). This plant community was concentrated in central, northeastern, and northwestern Wisconsin. Approximately 62%, or 3,141 square km, of the Northwest Sands Ecological Landscape was described as barrens communities (Wisconsin Department of Natural Resources 2015). The land also supported sedge marshes, lowland forests, and upland pine forests. These communities were often maintained by natural and intentional wildfires (Murphy 1931). Today, maybe as little as 20,000 hectares of barrens remain in a fragmented landscape on several county, state, and federally protected public lands (Radeloff et al. 1999).

The Ojibwe are believed to have moved into the area of the Northwest Sands about 400 to 600 years ago (Milwaukee Public Museum 2023; Minnesota Historical Society 2023; Peacock 2022). They likely were using fire at varying intervals to support their communities (Loope and Anderton 1998), thus helping to maintain the openness of this barrens landscape. These intentional fires served many purposes that included regenerating and stimulating the growth of blue-berries and other fruits and nuts, clearing brush for campsites and maintaining trails and portages (Anderton 1999; Miller and Davidson-Hunt 2010; Williams 1994). During the mid-1800s, European settlers began draining wetlands and logging the pines. This led to large-scale landscape alteration, fire control, and the disappearance of wildlife, including waterfowl and cranes. Many sites were over-logged, farming was unsuccessfully attempted, and abandoned lands became tax delinquent. By the 1940s, the sandy soils were depleted of resources, and nearly two thirds of the land in the region was tax delinquent. The State of Wisconsin, with help from federal financing, began purchasing some of these tax delinquent lands to restore the original uplands and wetlands as public wildlife areas. It was also during this last period that an intensive tree planting and fire suppression program was implemented throughout the landscape. This resulted in closed canopies and forests for industrial uses. By the 1950s, managers were realizing that the early stages of barrens and prairie habitat were dependent on fire at frequent intervals (5–10 years) (Radeloff et al. 2000). As a result of this missing disturbance, the prairie and open barrens were disappearing from the landscape.

The barrens of the Northwest Sands Ecological Landscape include three natural communities described by the Wisconsin Department of Natural Resources (2015). The natural communities are comprised of pine barrens, oak barrens, and sand prairies. These communities form a mosaic on the landscape that grade into one another, making firm distinctions between the community types difficult. The communities are maintained today with frequent prescribed fires by site managers (Figure 2).

FIGURE 2.

Prescribed fire is an important tool used by land managers to maintain the barrens of the Northwest Sands Ecological Landscape. The smoke from a spring fire at Crex Meadows can be seen from miles away. Photo by Richard W. Haug.

The pine barrens community of Wisconsin is savanna-like and usually comprises Pinus banksiana (jack pine) and less commonly P. resinosa (red pine) at the more northern sites. Shrubby Quercus ellipsoidalis (northern pin oak), Q. macrocarpa (bur oak), Corylus americana (American hazel), Salix humilis (prairie willow), Prunus pumila (sand cherry), and P. virginiana (chokecherry) are often common. The ground layer is dominated by prairie grasses and forbs (Wisconsin Department of Natural Resources 2022a). This type of pine barrens exists primarily in the upper Midwest, especially in Wisconsin, Michigan and Minnesota. These barrens are considered rare and globally imperiled by NatureServe (2020). Wisconsin has one of the most significant opportunities (and possibly the best opportunity) in North America to preserve, restore, and manage large-scale pine barrens communities (Wisconsin Department of Natural Resources 2017). Other similar barrens communities exist in the northeastern United States, but they are composed of a different assemblage of plant species. They often lack the prairie grasses and forbs that are present in Wisconsin’s barrens plant communities.

The oak barrens community of Wisconsin is similar to the pine barrens described above. One observable difference between the two communities is seen in the dominant trees. In the oak barrens community, Quercus macrocarpa and Q. ellipsoidalis are typically dominant. However, frequent disturbance through fire, poor nutrient levels, and low moisture levels usually leaves these trees stunted, multi-stemmed, and shrubby in appearance (thus they are occasionally referred to as grub oaks). These shrubby oaks often have an extensive root system that is much older than their above ground stems (Johnson et al. 2019). In southern and central Wisconsin, Q. velutina (black oak) often replaces Q. ellipsoidalis as a dominant oak. An additional difference from the pine barrens community is the presence of a more diverse prairie flora (Wisconsin Department of Natural Resources 2022b).

Sand prairie is the third natural community found in the surveyed sites. These areas typically lack the trees and woody shrubs seen in the pine and oak barrens communities. The sand prairie is dominated by prairie grasses such as Andropogon gerardii (big bluestem), Dichanthelium spp. (panic grasses), Hesperostipa spartea (porcupine grass), Koeleria macrantha (June grass), Schizachyrium scoparium (little bluestem) and prairie forbs (Wisconsin Department of Natural Resources 2022c). This community is found in the southern sites of our study.

One of our primary goals in this study was a thorough documentation of the flora with voucher specimens that would be accessible to future researchers. Additionally, this comprehensive study allows for site comparisons across the Northwest Sands Ecological Landscape using several different metrics. These data can be used to inform future plant community restoration efforts, invasive species monitoring, rare plant species monitoring and to serve as a point of comparison for future floristic work in the region.

Materials and Methods

Survey Sites

We selected eight sites (Figure 1) that span approximately 170 km to represent the barrens found in the Northwest Sands Ecological Landscape. We made site visits to each property throughout the growing seasons of 2017 to 2022. We followed Mladenoff (2004) for the names of the plants found in the Public Land Survey notes included in the site descriptions below.

Sterling Barrens State Natural Area (Polk County, 45° 34.0′ N, 92° 49.0′ W) (Sterling Barrens): Figure 1, Site 1. Wisconsin Department of Natural Resources (2022d)

The Sterling Barrens is the southwesternmost site of our study. It is located in northwest Polk County within the Governor Knowles State Forest approximately 12 km west of Cushing, Wisconsin on moderate to gently rolling slopes of sand outwash above the St. Croix River. While the state natural area includes extensive areas of sedge meadows and floodplain forest near the river, our efforts focused on the upland natural communities of the site. Historically, in the Public Land Survey records, Maddin (1848) describes this area as, “a sand plain covered with small scrubby pine and destitute of water.” The site is 398 hectares, of which approximately 100 hectares are barrens (Figure 3).

FIGURE 3.

A large area of sand prairie at Sterling Barrens. The prairie is dominated by Hesperostipa spartea, Andropogon gerardii, Schizachyrium scoparium, Koeleria macrantha, Dichanthelium spp., Carex siccata, and Carex pensylvanica. In the foreground Delphinium carolinianum subsp. virescens, Lithospermum caroliniense, and Phlox pilosa are in bloom. In the distance, grub oaks (Quercus ellipsoidalis and Q. macrocarpa), along with denser stands of Prunus pensylvanica and Amelanchier spp., can be seen. Photo by Derek S. Anderson.

Fish Lake Wildlife Area (Burnett County, 45° 43.0′ N, 92° 45.0′ W) (Fish Lake): Figure 1, Site 2. Wisconsin Department of Natural Resources (2016, 2022e)

Fish Lake is in southwest Burnett County approximately 8 km southwest of Grantsburg, Wisconsin. The gentle topography of the site is a mosaic of uplands dominated by barrens, while sedge meadows and marshes are characteristic of the lowlands. The landscape was created by an ancient glacial lake that covered most of the area. Our survey efforts focused on the uplands scattered throughout the property. The uplands of this area were described by Fellows (1853a) as, “gently rolling with a foundation of sandy loam soil and very thinly timbered with small pitch pine [Pinus banksiana].” The site is approximately 5,666 hectares, of which about 1,214 are barrens.

Crex Meadows Wildlife Area (Burnett County, 45° 51.5′ N, 92° 36.5′ W) (Crex Meadows): Figure 1, Site 3. Wisconsin Department of Natural Resources (2022f)

Crex Meadows is in west-central Burnett County approximately 9 km north-northeast of Grantsburg, Wisconsin. Crex Meadows sits within the same ancient glacial lake basin as Fish Lake (Wisconsin Department of Natural Resources 2016). It consists of gentle topography and is a mosaic of uplands dominated by barrens and woodlands, with lowlands dominated by sedge meadows, marshes and lakes. The landscape today remains similar to what was described by Fellows (1853b) in the public land survey records, where he said, “All of this fractional township except the river bottoms is pine barrens, rolling surface, poor sandy soil, and thinly timbered with pitch pine [Pinus banksiana].” The site is approximately 11,533 hectares, of which about 2,833 hectares are barrens (Figure 4).

FIGURE 4.

Ceanothus americanus in bloom in the barrens of Crex Meadows. It is interspersed with other shrubs such as Corylus americana, Quercus ellipsoidalis grubs, and Prunus spp. Carex pensylvanica, Andropogon gerardii, Carex siccata, Koeleria macrantha, and Dichanthelium spp. dominate the area between the shrubs. Photo by Richard W. Haug.

Namekagon Barrens Wildlife Area (Burnett & Washburn Counties, 46° 7.5′ N, 92° 4.5′ W) (Namekagon Barrens): Figure 1, Site 4. Wisconsin Department of Natural Resources (2017a, 2022g)

The Namekagon Barrens consists of two units located at the junction of Burnett, Douglas, and Washburn Counties approximately 19 km west of Minong, Wisconsin. Both units occur within a matrix of scattered jack pine and, to a lesser extent, red and white pine, which are interspersed with openings in which oak grubs (Quercus macrocarpa and Q. ellipsoidalis) are prominent, along with prairie grasses and forbs. Historically, the public land survey records describe the general area as having, “a level surface, light sandy soil and thinly timbered with black pine [Pinus banksiana]” (Fellows 1855). The north and south units comprise approximately 2,609 hectares of which about 2,183 hectares are barrens.

Douglas County Wildlife Area (Douglas County, 46° 17.0′ N, 91° 50.5′ W) (Douglas County): Figure 1, Site 5. Wisconsin Department of Natural Resources (2017a, 2022h)

The Douglas County Wildlife Area, locally known since 1935 as The Bird Sanctuary, was established in 1948. It is in southern Douglas County west of U.S. Hwy. 53 and between the towns of Solon Springs to the north and Gordon to the south. The sandy uplands of this wildlife area are a result of sandy outwash plains from the retreat of ice during the last glaciation period. Historically these lands supported jack pine, oak savannah, and barrens. Daugherty (1856) does not provide much specific detail, but his description in the public land survey records gives an impression of pine barrens: “the surface of the township is principally rolling land 3rd rate (sandy). Timber black and yellow pine [Pinus banksiana and P. resinosa respectively], birch, linden, white cedar and spruce.” The site is approximately 1,536 hectares of which about 1,451 hectares are barrens (Figure 5).

FIGURE 5.

Douglas County. The sandy uplands are a result of sandy outwash plains from the retreat of ice during the last glaciation period. The rolling topography as depicted here supports a diverse array of grassland species interspersed with pockets of scrub shrub communities. Pedicularis canadensis, Antennaria howellii, Packera paupercula, Andropogon gerardii, Bromus kalmii, Schizachyrium scoparium, and Koeleria macrantha are common. Photo by Paul S. Hlina.

Motts Ravine State Natural Area (Douglas County 46° 26.0′ N, 91° 36.5′ W) (Motts Ravine): Figure 1, Site 6. Wisconsin Department of Natural Resources (2022i)

Motts Ravine is located about 14 km south-southwest of Brule, Wisconsin on a rolling glacial outwash plain and consists of natural jack pine forest, scrubby Hill’s and bur oak thickets, and small pine barrens remnants. The condition of the state natural area is similar to the description of the township by Fellows (1856a): “This is one of those barren townships that is almost worthless for agriculture purposes. The surface is rolling excepting that section adjoining the Brule which is very broken … .” The Brule River State Forest manages for this rare community type on the watershed. As noted in the Brule River State Forest Master Plan (Wisconsin Department of Natural Resources 2017b), the extent of Motts Ravine may expand through working with landowners adjacent to the property in the future but is unlikely to be large enough to support significant population of rare plants and animals of the pine barrens ecosystem. Motts Ravine consists of 265 hectares of barrens.

Barnes Barrens (Bayfield County 46° 26.5′ N, 91° 30.5′ W): Figure 1, Site 7. (Bayfield County Forestry Department 2013)

The Barnes Barrens management area is located in Barnes Township in western Bayfield County about 13 km south-southeast of Brule, Wisconsin. Most of the area is dominated by later stages of the pine barrens community (i.e., mid- to late jack pine forests and oak scrub/pine savanna). Fellows’ (1856b) public land survey description of the township provides perspective on the area: “This is a township of barrens that is almost worthless for agricultural purposes or anything else as there is but very little timber in it and that is scrubby black pine [Pinus banksiana], and there is hardly a drop of water in the township … .” Today, the site is managed by the Bayfield County Forestry Department and is included in Wisconsin’s priority conservation opportunity areas for wildlife species. Overall, this matrix of pine forest and late successional-stage barrens communities covers roughly 4,654 hectares. A core area of about 400 hectares of early successional barrens has been created or enhanced in the past decade (Bayfield County Forestry Department 2013). Additional open barrens will be created as harvests occur around this core area. During the duration of this project, we surveyed the 162 hectares being maintained as barrens (Figure 6).

FIGURE 6.

Barnes Barrens. These are relatively young barrens, having been recently restored and managed (2012–2022) in an extensive sandy outwash plain in western Bayfield County. Most of the area is dominated by Quercus macrocarpa, Corylus americana, Salix humilis, and, to a lesser extent, Q. ellipsoidalis. Small bands of pine trees remain on the site, but the greatest diversity is found in grass-dominated communities in the western end of the site. Photo by Paul S. Hlina.

Moquah Barrens (Bayfield County 46° 37.0′ N, 91° 15.5′ W): Figure 1, Site 8. (USDA Forest Service 2004, 2009)

Moquah Barrens is about 35 km southwest of Bayfield, Wisconsin and only 19 km to Ashland and the Chequamegon Bay on Lake Superior (Figure 1, Site 8). Moquah Barrens, which is within the Chequamegon-Nicolet National Forest, was created as glaciers retreated 10,000 years ago exposing rolling to very steep topography of pitted outwash plains consisting of glacial drift (i.e., sand, gravel, and silt). The unique topography of pitted outwash plains, its proximity to Lake Superior and its climatic effects influence plant communities of these barrens. Stuntz (1858) described the township as “high rolling, without any running water in it of a sandy gravelly soil, covered with a scattering growth of black [Pinus banksiana], yellow [Pinus resinosa] and white pine, aspen, birch and maple.” While he does not specifically characterize this area as barrens, his description is representative of later successional stages of the barrens communities. Today, the Chequamegon-Nicolet National Forest manages the 8903 hectares of the Moquah Barrens.

Results

The barrens flora of the Northwest Sands Ecological Landscape was documented with 2,213 collections representing 71 families, 217 genera and 404 taxa. The largest family was the Asteraceae family with 81 different taxa. The Solidago (Figure 7) and Symphyotrichum genera were two of the most diverse genera documented in the family, each with ten taxa. Poaceae, Rosaceae, and Fabaceae were the next largest families, with 56, 30, and 22 taxa respectively. Crex Meadows had the highest species richness, with 264 taxa. The site with the lowest species richness was Motts Ravine with 140 species. Douglas County and Moquah Barrens also had a lower species richness with 159 and 157 species respectively. Table 1 compares the total and introduced species at each site. A complete list of species documented in this study is presented in Appendix 1.

FIGURE 7.

Solidago speciosa is one of the more common goldenrods observed in the barrens. This species, along with Solidago juncea, S. nemoralis, and S. ptarmicoides are documented at all of the sites we surveyed. Photo by Richard W. Haug.

We documented 78 new county records of 70 different taxa. Nineteen new records were collected from Polk County, 47 from Burnett County, six from Douglas County, and six from Bayfield County (Table 2).

Several species are nearly ubiquitous across all of the survey sites in the Northwest Sands. Many of these species are common or abundant throughout each site. They are often included in species lists and descriptions for the sites and barrens in the region. Table 3 lists taxa that were observed in at least seven of the eight survey sites. This list includes 12 graminoids, 56 forbs, and 22 shrubs and trees. One species on this list, Lilium philadelphicum (wood lily) (Figure 8), is rare and appears to be declining at these sites. Over the last decade, regional State Natural Area staff have seen substantial declines in many forbs, including L. philadelphicum. This is thought to be caused in part by increased deer herbivory and a greater reliance on herbicides for management (Magana, personal communication 2023).

FIGURE 8.

Lilium philadelphicum is found at all of the surveyed sites with the exception of the Sterling Barrens. While the species has a broad distribution across the Northwest Sands Ecological Landscape, ongoing survey work has seen this species decline at several sites. Photo by Richard W. Haug.

Site Findings

Sterling Barrens State Natural Area

While Sterling Barrens is one of the smallest sites surveyed, it is also one of the most diverse. Oak barrens and sand prairie are the dominant plant communities. Grub oaks of Quercus ellipsoidalis and Q. macrocarpa are dominant with occasional scattered Pinus banksiana. There are several large open areas of sand prairie, which are dominated by Andropogon gerardii, Carex pensylvanica, Carex siccata, Danthonia spicata, Dichanthelium spp., Schizachyrium scoparium, and Sorghastrum nutans. A number of prairie species were documented only at the Sterling Barrens. These include Bouteloua curtipendula, B. hirsuta, Packera platensis, and Phemeranthus rugospermus. A few additional prairie species, including Aristida tuberculosa, Asclepias viridiflora, Dalea villosa, and Geum triflorum, are documented here and Fish Lake.

Fish Lake Wildlife Area

The gentle topography of the Fish Lake area also supported oak barrens and sand prairie, along with small areas of pine barrens where Pinus banksiana and P. resinosa were more common (Figure 9). The more open sand prairies here are quite similar in composition to those found at the Sterling Barrens. Small populations of Calamovilfa longifolia are found here and also at the Sterling Barrens. An interesting observation of the flora of the site were small regions where the only populations of Botrychium matricariifolium, Botrychium simplex, Hypoxis hirsuta, Prenanthes racemosa, and Pycnanthemum virginianum are documented during our surveys. This site also supported the largest populations of Hudsonia tomentosa among all eight sites.

FIGURE 9.

The barrens of Fish Lake shows little topography. Much of the site is within the basin of Glacial Lake Grantsburg. In the foreground younger Betula papyrifera and Pinus resinosa are seen. On the horizon, scattered Pinus resinosa, P. banksiana, Quercus ellipsoidalis and Q. macrocarpa can be seen. Photo by Derek S. Anderson.

Crex Meadows Wildlife Area

Overall, the barren and prairie plant communities are similar to those at Fish Lake which, as noted above, is situated in the same glacial lake basin. Crex Meadows is one of the largest sites we surveyed. It also contained the highest number of taxa documented from any one site. It is at Crex Meadows where Comptonia peregrina becomes more common in the barrens landscape, increasing in abundance from here northward. Species found only at this site include Carex bicknellii, Carex foenea, Erigeron pulchellus, Liatris pycnostachya, and Spartina pectinata.

Namekagon Barrens Wildlife Area

The Namekagon Barrens is a large barrens site found within a matrix of pine plantations and pine and oak forests. Large, scattered Pinus resinosa stand tall in the matrix of shrubby Comptonia peregrina, Corylus americana, Quercus ellipsoidalis, and Q. macrocarpa grubs (Figure 10). It is also evident that many of the prairie species more common to the southwest, such as Allium stellatum, Amorpha canescens, Dalea candida, Dalea purpurea, Solidago rigida, Symphyotrichum sericeum, start to disappear before reaching this latitude. Nevertheless, the site does support several species not documented at other sites, including Polygala senega and Rosa woodsii.

FIGURE 10.

Namekagon Barrens. A small grove of about ten, large Pinus resinosa trees in the pine barrens is shown to the right. Fire charring of the bark is seen on the lower portion of the trunks. In the background, the area is dominated by grub oaks (Quercus ellipsoidalis and Q. macrocarpa), Corylus americana, Comptonia peregrina, Ceanothus herbaceous, and Prunus spp. Common graminoids include Danthonia spicata, Koeleria macrantha, Schizachyrium scoparium, and Carex pensylvanica. Photo by Derek S. Anderson.

Douglas County Wildlife Area

Pine barrens is the dominant plant community found at the Douglas County site. Pinus banksiana and P. resinosa are common. The shrub layer consists of oak grubs (Quercus ellipsoidalis and Q. macrocarpa), Comptonia peregrina, Corylus americana, and several species of Prunus. It is one of the more disturbed barren sites in our survey. The wildlife area has been a training site for horses and hunting dogs since 1935, which resulted in numerous trails, paths, and other disturbances. It is the site with the highest percentage of its flora made up of introduced species, at 21.4%. This includes large populations of the introduced Robinia pseudoacacia. However, this site and the Namekagon Barrens are the only sites in which Erigeron glabellus (a western species) is found. Hieracium longipilum is observed at this site as a new Douglas County record, expanding its known range farther northward. Also of interest, two grapeferns, Sceptridium multifidum and S. rugulosum, have been documented at the site. This is also the only site in which Juniperus communis was observed.

Motts Ravine State Natural Area

This is the second smallest of the barren sites surveyed, which likely contributes to it having the lowest species diversity among all the sites, with 140 taxa. The area is heavily managed with frequent burns to control tree dominance (Figure 11). Though it is small, many interesting finds were observed here. Comptonia peregrina, Vaccinium angustifolium, Amelanchier spicata, Prunus pumila, and Arctostaphylos uva-ursi are important small shrub species in these open areas. A healthy suite of grasses and forbs, such as Andropogon gerardii, Bromus kalmii, Liatris aspera, and Lithospermum spp. are commonly found here. Agastache foeniculum, Oenothera clelandii, and Froelichia floridana reach the northernmost limits of their ranges here. The highlight of this site occurred in 2015 during a floral study of the Brule River watershed, when Lactuca hirsuta was found, for only the second time in the state (Hlina et al. 2020; Raimond 2021). Mott’s Ravine and Barnes Barrens are the only two locations in the Northwest Sands that support small populations of this new state record.

FIGURE 11.

The gently rolling topography of Motts Ravine. In the distance, a Pinus resinosa plantation is visible. A few lone individuals of Pinus resinosa are visible to the right in the photograph. The foreground is dominated by oak grubs (Quercus ellipsoidalis). Scattered among the oaks are occasional individuals of Corylus americana, Comptonia peregrina, and Prunus spp. Andropogon gerardii, Schizachyrium scoparium, Koeleria macrantha, Danthonia spicata, and Carex pensylvanica make up the common graminoids. Photo by Derek S. Anderson.

Barnes Barrens

This site was newly created over the last decade (2012–2022) as open barrens. The 162 hectares of the core barren area studied was forested up through 2012. Frequent burns, chemical applications, and mechanical scarification have all been used as management tools at this site. There are several large areas with uniform vegetation of grub oaks of Quercus macrocarpa, with a lesser extent of Quercus ellipsoidalis, as well as Corylus americana, Salix humilis, and Pteridium aquilinum. Other pockets at this site are quite diverse with notable species including Lactuca hirsuta, Cynoglossum boreale, Carex houghtoniana, Zizia aptera, Ceanothus americanus, and Carex adusta.

Moquah Barrens

Moquah Barrens is the largest of the barren sites studied and is heavily influenced by the climate of Lake Superior. It also has the greatest elevation changes among the sites with dry valleys and tall hilltops (Figure 12). Hudsonia tomentosa occurs in these barrens only at this site at the windblown hilltops, which are likely part of the old Glacial Lake Duluth shorelines. Many sidehills support a mix of Quercus spp., Corylus americana, and Pteridium aquilinum. Flat areas support extensive grasslands of Carex pensylvanica, Andropogon gerardii, Danthonia spicata, Bromus kalmii, Schizachyrium scoparium, and Avenella flexuosa. The site contains more northern dry forest species than any of the other sites. These include Gaultheria procumbens, Maianthemum canadense, Uvularia sessilifolia, Melampyrum lineare, Trientalis borealis, Spiranthes lacera, and Prenanthes alba. Common throughout these barrens in the fall is the striking Liatris ligulistylis, which was also found in one small area at Fish Lake. Interestingly, Liatris aspera is absent here, but common to abundant at all of the other study sites.

FIGURE 12.

The rolling topography of the Moquah Barrens seen from a hilltop view. Small groves and isolated individuals of Pinus banksiana are visible in the distance. Graminoids in the large open swaths between the groves include Schizachyrium scoparium, Carex pensylvanica, Danthonia spicata, and occasionally Avenella flexuosa. In the foreground, Solidago speciosa, Liatris ligulistylis, Comptonia peregrina, and Prunus pumila can be seen. Photo by Paul S. Hlina.

Latitudinal Distribution of Species

As alluded to in the previous section, the ranges of several species are distributed along a latitudinal gradient within the Northwest Sands Ecological Landscape. The northern sites (Moquah Barrens, Barnes Barrens, and Motts Ravine) are more influenced by the northern forests. As a result, several species reach their southern extent here in the Northwest Sands. These include Agrostis hyemalis, Avenella flexuosa, Carex adusta, Crataegus macrosperma, Cynoglossum boreale, Dichanthelium xanthophysum, Epigaea repens, Geranium bicknellii, Geum fragarioides, and Lactuca hirsuta. Arctostaphylos-uva-ursi (Figure 13), a species that was documented at all of our study sites, has a greater presence in the northern sites, where it is sometimes locally dominant. It diminishes in abundance and presence southward to Burnett and Polk Counties.

FIGURE 13.

Arctostaphylos uva-ursi grows in large patches in Moquah Barrens, Barnes Barrens, Motts Ravine, and Douglas County and produces large amounts of berries for consumption by birds, mammals, and other wildlife. This circumpolar species reaches the northern latitudes of the arctic, but dwindles in abundance southward through the northwest sand barrens communities. Photo by Paul S. Hlina.

Similarly, the southern sites (Crex Meadows, Fish Lake, and Sterling Barrens) exhibit a floristic influence from the prairies. Species that approach their northern limits within these barren sites include Allium stellatum, Ambrosia psilostachya, Amorpha canescens, Artemisia serrata, Aristida tuberculosa, Asclepias viridiflora, Calystegia sepium, Castilleja coccinea, Celastrus scandens, Cirsium discolor, Coreopsis palmata, Dalea candida, D. purpurea, D. villosa, Delphinium carolinianum, Euphorbia corollata, Gaylussacia baccata, Geum triflorum, Hesperostipa spartea, Juniperus virginiana, Liatris cylindracea, L. pycnostachya, Lobelia spicata, Lupinus perennis, Mirabilis alba, Penstemon gracilis, P. grandiflorus, Physalis heterophylla, Phemeranthus rugospermus, Polygonatum biflorum, Ranunculus rhomboideus, Rhus glabra, Scutellaria parvula, Sisyrinchium campestre, Solidago missouriensis, Sporobolus cryptandrus, Symphyotrichum sericeum, Tradescantia occidentalis, Veronicastrum virginicum, and Viola sagittata.

The central sites (Douglas County and Namekagon Barrens) exhibit a convergence of northern and southern influences. Several species reach their northern limits in the Northwest Sands including Anemone patens, Artemisia ludoviciana, Asclepias ovalifolia, Boechera grahamii, Cornus foemina, Cycloloma atriplicifolium, Lespedeza capitata, Phlox pilosa, Selaginella rupestris, and Solidago rigida. Northern species reaching their southern limits within these sites include Capnoides sempervirens, Erigeron glabellus, Hieracium scabrum, Oryzopsis asperifolia, Sibbaldiopsis tridentata, Sisyrinchium montanum, Solidago hispida, Symphoricarpos albus, Symphyotrichum laeve, and Turritis glabra.

Rare Species

Several populations of rare plant species tracked by the Natural Heritage Program of the Wisconsin Department of Natural Resources were documented in the course of this study. Eight species (one threatened and seven species of special concern) were observed (Table 7).

TABLE 7.

Listing status and S-rank of species in the barrens sites listed by the Wisconsin Department of Natural Resources and the sites in which each occur.

Species	Listing Status	S-Rank	Sites
Asclepias ovalifolia	Threatened	S3	Sterling Barrens, Fish Lake, Crex Meadows, Namekagon Barrens
Coreopsis lanceolata	Special Concern	S2	Moquah Barrens
Dalea villosa	Special Concern	S2	Sterling Barrens, Fish Lake
Packera plattensis	Special Concern	S3	Sterling Barrens
Phemeranthus rugospermus	Special Concern	S3	Sterling Barrens
Sceptridium rugulosum	Special Concern	S2	Namekagon Barrens, Douglas County, Moquah Barrens
Scleria triglomerata	Special Concern	S2	Fish Lake, Crex Meadows
Symphyotrichum robynsianum	Special Concern	S1	Crex Meadows

Asclepias ovalifolia (dwarf milkweed) is a threatened species in Wisconsin (Figure 14). It also appears to be strongly represented at the southern sites of our study. We documented populations at Sterling Barrens, Fish Lake, Crex Meadows and the Namekagon Barrens. Anecdotally, we observed increases in flowering stems and follicle development following prescribed site management (e.g., fire and tree removal). More than ten populations of Dalea villosa (silky prairie clover) (Figure 15), are found at Sterling Barrens and Fish Lake. Several of these populations are comprised of hundreds of individuals.

FIGURE 14.

Asclepias ovalifolia is the only species found during our surveys that is listed as threatened by the Wisconsin Department of Natural Resources. We found populations at Sterling Barrens, Fish Lake, Crex Meadows, and Namekagon Barrens. The species appears to respond well to management carried out at these sites. Photo by Richard W. Haug.

FIGURE 15.

Dalea villosa is listed as special concern by the Wisconsin Department of Natural Resources. This western species reaches the eastern edge of its range in western Wisconsin. Many large populations were documented at Sterling Barrens and Fish Lake. Photo by Richard W. Haug.

Two other species listed as special concern, Packera plattensis (prairie ragwort) and Phemeranthus rugospermus (prairie fame flower), were observed only at Sterling Barrens. Phemeranthus rugospermus was previously known from the site and continues to persist in these barrens. This is the northernmost known site for the species in Wisconsin. The discovery of Packera plattensis also represents a new county record and range extension for the species in the state (Wisconsin Department of Natural Resources 2021a). This is a species more common to the prairies south and west of our survey area. It should be noted that identification of Packera paupercula and P. plattensis in northwestern Wisconsin is difficult and confounded by the tendency of P. paupercula to exist as a tetraploid in the barrens of this region. It occasionally displays a few characteristics more commonly associated with P. plattensis (Mahoney and Kowal 2008; Mahoney, personal communication 2022).

An interesting discovery made at Crex Meadows and Fish Lake was Scleria triglomerata (whip nutrush). This species is found in the oak/jack pine barrens of these sites in nearly indiscernible depressions within the barrens landscape. Associates included Bromus kalmii, Hieracium umbellatum, Juncus sp., Lespedeza capitata, Pedicularis canadensis, Solidago spp., and Sorghastrum nutans. We found two populations at Fish Lake and one population at Crex Meadows. Symphyotrichum robynsianum (long-leaved aster) was found only at one small location at Crex Meadow in a population consisting of about a dozen individuals. This aster has unusually long leaves and was growing on the edge of a remnant barren stand of jack pine and aspen.

Coreopsis lanceolata (sand coreopsis) was located at Moquah Barrens at the edge of a sandy road in the barrens, possibly an escapee or part of an earlier seeding or restoration activity at the site. Sceptridium rugulosum (rugulose grape fern) was located at three sites: Namekagon Barrens in 2020, Douglas County in 1991, and Moquah Barrens in 1929. The latter two specimens were growing in moist sandy soils, one near a relict lake and the other in an open grassy field. The 2020 collection was found in open sandy barrens with flat to gently rolling topography growing in association with Arctostaphylos uva-ursi, Comptonia peregrina, and Rosa sp.

Discussion

The barren communities of the Northwest Sands Ecological Landscape represent a diverse assemblage of species. Several trends are noted in the distribution of species along the latitudinal gradient of sites from northwestern Polk County in the south to north-central Bayfield County in the north. There is a higher diversity of species in the southwestern sites in comparison to those in the northeast. The barrens of the southern sites are marked with a greater diversity of prairie species, while the barrens of the northern sites tend to have species more characteristic of northern dry forests and woodlands.

Management in the form of fire, robust scarification or tilling, and mechanical chopping, have been critical components in maintaining these sites as early successional barrens. Much of the recent expansion of barrens in the northwest sands is a direct result of two plans, the Wisconsin Sharp-tailed Grouse: A Comprehensive Management and Conservation Strategy (Fandel and Hull 2011) and the Northwest Sands Habitat Corridor Plan (Reetz et al. 2013). Fandel and Hull (2011) discuss the plight of the Tympanuchus phasianellus (Sharp-tailed Grouse) in Wisconsin. This is a species of greatest conservation need, and there was a desire to expand and protect high quality barrens habitat in the Northwest Sands. In an earlier study, Gregg (1987) found that fewer than 2000 birds existed in Wisconsin during a census survey of the early 1980s. Gregg (1987) recommended an aggressive landscape habitat management plan for barrens habitat throughout northwestern Wisconsin to prevent extirpation of the Sharp-tailed Grouse from the region. Since 1987, Sharp-tailed Grouse populations have fluctuated, and, in good years, some hunting has resumed. However, recent trends continue to challenge these birds. There was a 26% decrease in populations between 2020 and 2021 in the Northwest Sands, resulting in the cancellation of the hunting season of Sharp-tailed Grouse (Wisconsin Department of Natural Resources 2021b). Only Namekagon Barrens and the new Barnes Barrens have provided some stability and consistency for the Sharp-tailed Grouse.

The second plan, the Northwest Sands Habitat Corridor Plan (Reetz et al. 2013) recommends the creation of corridors to connect the eight sites of our study and other barren properties in the region. The potential habitat corridors, which contain fragmented forests of various growth stages, have been identified to reconnect currently managed barrens properties. These forests can be managed as rotating barrens, which would be made up of large blocks of forest that are harvested and regenerated in a systematic way. These corridors would provide critical habitat for wildlife to move between the larger managed barrens (Reetz et al. 2013). Expansion of this work continues at a rapid pace in Crex Meadows, Fish Lake, Namekagon Barrens, Barnes Barrens and a new area called Bass Lake Barrens that will link Barnes Barrens with Moquah Barrens (Bayfield County Forestry Department 2013; Wisconsin Department of Natural Resources 2015, 2016, 2017a, 2017b; USDA Forest Service 2009).

In the southern sites of our study, the importance of these communities for wildlife is only reinforced. In addition to providing habitat for numerous birds, reptiles, and mammals, the barrens are also habitat for many invertebrates. Perhaps one of the most significant is Lycaeides melissa samuelis (Karner blue butterfly). This federally endangered species is dependent on Lupinus perennis (wild lupine), which is commonly found in the southern sites (Figure 16). Maintaining the open savanna-like nature of the barrens is critical for maintaining a strong population of L. perennis and its obligate companion, the Karner blue butterfly.

FIGURE 16.

Lupinus perennis is documented only at Sterling Barrens, Fish Lake, and Crex Meadows. Many large populations of this species are observed in the oak barrens and sand prairies of these sites. This species is the host plant for the federally endangered Karner Blue Butterfly. Photo by Richard W. Haug.

In the northern sites, graminoids, oak scrub, and other woody shrubs continue to be the dominant features in the barrens. Anecdotally, these recent observations in tandem with over 20 years of visiting these sites, suggests a decline in some flowering forbs, such as Asclepias tuberosa, Rudbeckia hirta, Lilium philadelphicum, Liatris aspera, Monarda fistulosa and Monarda punctata. Future vegetative studies and observations could provide quantitative results of the changing landscape. If our suspicions are correct, these future studies would show that the barrens is experiencing a greater biotic homogenization while diminishing habitat values for insects, pollinators, birds and wildlife, as has been shown in other forest and non-forested ecosystems in Wisconsin. Future work could examine some further causes of habitat challenges in the barrens that may include deer herbivory, habitat fragmentation, management practices or lack thereof, a warming climate, anthropogenic disturbance, and mismatches in the synchronous relationship between flowering plants and pollinators.

Deer herbivory poses a serious threat to the proper functioning of these barrens ecosystems of the Northwest Sands Ecological Landscape. One of the first Wisconsin studies on the impact of deer was conducted by Alverson et. al. (1988). This study illustrated the negative impact of elevated Odocoileus virginianus (white-tailed deer) populations on the vegetation of northern Wisconsin. Over the ensuing 30 plus years the deer problem has intensified. Rooney (2009) describes the simplification and biotic homogenization of northern natural landscapes due to high deer densities browsing on forbs and woody vegetation in forested landscapes, which in turn favor graminoid species.

The increase in deer pressure on the vegetation coupled with decades-long changes in disturbance patterns (primarily fire suppression) may be related to an increase in the presence of Carex pensylvanica in the barrens. This species is normally considered a species of dry forests, but now is seen to be abundant in many areas of the barrens. In a floristic study conducted by Thomson (1945) in the barrens of the Brule River watershed, more than 127 species were documented, although Carex pensylvanica was not noted. Additionally, the work of Curtis (1959) lacks the inclusion of C. pensylvanica as a dominant, co-dominant, or associate species on his lists for pine barrens communities. In examining the northern sites of this study, we observed areas where monoculture stands of C. pensylvanica had formed. These dense pockets provide little opportunity for the establishment of other barrens species (Abrams et al. 1985). Long-term, this condition could further the degradation of sites, thereby reducing the diversity of plant species.

Conclusion

Our documentation of the flora of the region will provide data that adds to the vast body of knowledge of the region. The floristic quality assessments can serve as a baseline in strategic management plans (Magurran et al. 2010). They can be used to re-evaluate the flora at regular intervals in the future (e.g., once every 5 to 10 years). Lower values may indicate some changes in the environmental conditions on the sites that could influence future management decisions to maintain or increase floristic quality. Surveying after the implementation of management strategies would be highly beneficial to document the resurgence and expansion of barrens species that may be dormant or in the seed bank. Additionally, these surveys should target rare species listed by the state. It will be beneficial to document their responses to management and incorporate this information into conservation efforts in the future.

The expansion of the barrens on the landscape will allow plant populations to expand their narrow ranges of present day. It appears that there is a suite of plants (e.g., Allium stellatum, Asclepias ovalifolia, and others) that may lay dormant in the shaded forest of the region that will be expressed once trees are harvested. As continued restoration activities proceed throughout the Northwest Sands Ecological Landscape, future floristic studies will continue to expand our understandings of these ecosystems.