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Explore Wisconsin's natural communities.
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Contact information
For information on Wisconsin's natural communities, contact:
Ryan O'Connor
Natural Heritage Inventory Assistant Ecologist
608-266-7714

Great Lakes Ridge and Swale

State Rank: S2     Global Rank: G3   what are these ranks?

Definition

General natural community overview

Counties shaded blue have documented occurrences for Great Lakes Ridge and Swale in the Wisconsin Natural Heritage Inventory database.

Also known as Forested Ridge and Swale, this community complex is associated closely with Great Lakes shorelines. Series of narrow sandy ridges alternate with low swales, parallel to the lakeshore. The vegetation on the dry ridges can vary from open herbaceous or shrub communities on the semi-stabilized dunes closest to the shoreline, to dry forests dominated by pines (Pinus spp.) and oaks (Quercus spp.) farther inland, to mixed mesophytic forests of northern hardwoods or hemlock-hardwoods farthest from the shore. In a few locations, some of the ridges may support a Boreal Forest association that includes pines, white spruce (Picea glauca), balsam fir (Abies balsamea), and paper birch (Betula papyrifera). This may be at least partially due to the influence of the Great Lakes on local climate, creating conditions that are relatively cool and moist during the growing season. For additional details on associated communities, see Northern Dry Forest, Northern Dry-mesic Forest, Northern Mesic Forest, and Great Lakes Dune.

Water depth is a controlling factor in the swales, which are typically deeper and more open near the shoreline, supporting marsh or sedge meadow communities. Farther away from the lake, an alder-dominated shrub community may develop, and still farther inland forested wetlands of swamp hardwoods, bog conifers, or northern white cedar (Thuja occidentalis) may be present. Only the deepest swales closest to the shore may be in contact with Great Lakes water. Most of the swales receive water via small streams or groundwater seepage from areas upslope. The wetland communities that might be part of this complex include Submergent Marsh, Emergent Marsh, Interdunal Wetland, Alder Thicket, Northern Wet Forest, Northern Wet-mesic Forest, and Northern Hardwood Swamp.

In Wisconsin, this community complex is best developed along Lake Michigan. The parallel ridges and swales offer exceptionally complex and diverse habitats for wetland, upland, and Great Lakes shoreline plants, and support rich assemblages of amphibians, reptiles, and breeding and migratory birds. A few ridge and swale systems also occur on the Lake Superior coast.

Rare animals

Species of Greatest Conservation Need

Wisconsin Wildlife Action Plan graphic

The following Species of Greatest Conservation Need are listed according to their level of association with the Great Lakes Ridge and Swale natural community type, based on the findings in Wisconsin's 2015 Wildlife Action Plan.

Scores: 3 = high association, 2 = moderate association, and 1 = low association. See the key to association scores for complete definitions.

AmphibiansScore
Four-toed SalamanderHemidactylium scutatum3

Aquatic and terrestrial snailsScore
Dentate SupercoilParavitrea multidentata3
Appalachian PillarCochlicopa morseana2
Bright GlyphGlyphyalinia wheatleyi1
Ribbed StriateStriatura exigua1
Sculpted GlyphGlyphyalinia rhoadsi1
Six-whorl VertigoVertigo morsei1

BirdsScore
Least FlycatcherEmpidonax minimus2
Olive-sided FlycatcherContopus cooperi2
Rusty BlackbirdEuphagus carolinus2
American WoodcockScolopax minor1
Red-shouldered HawkButeo lineatus1

Dragonflies and damselfliesScore
Hine's EmeraldSomatochlora hineana2
Swamp DarnerEpiaeschna heros1

Grasshoppers and alliesScore
Delicate Meadow KatydidOrchelimum delicatum2
Blue-legged GrasshopperMelanoplus flavidus1
Scudder's Short-winged GrasshopperMelanoplus scudderi1
Stone's LocustMelanoplus stonei1

MammalsScore
Big Brown BatEptesicus fuscus2
Northern Flying SquirrelGlaucomys sabrinus2
Eastern PipistrellePerimyotis subflavus1
Woodland Jumping MouseNapaeozapus insignis1

Please see Section 2. Approach and Methods of the Wildlife Action Plan to learn how this information was developed.

Rare plants

The Natural Heritage Inventory has developed scores indicating the degree to which each of Wisconsin's rare plant species is associated with a particular natural community or ecological landscape. This information is similar to that found in the Wildlife Action Plan for animals. As this is a work in progress, we welcome your suggestions and feedback.

Scores: 3 = "significantly associated," 2 = "moderately associated," and 1 = "minimally associated."
Scientific Name Common Name Score
Anticlea elegans ssp. glaucus White Camas 1
Botrychium lunaria Common Moonwort 2
Botrychium spathulatum Spoon-leaf Moonwort 2
Carex concinna Beautiful Sedge 2
Clinopodium arkansanum Low Calamint 3
Coreopsis lanceolata Sand Coreopsis 2
Cypripedium arietinum Ram's-head Lady's-slipper 2
Equisetum palustre Marsh Horsetail 1
Galium brevipes Swamp Bedstraw 2
Geocaulon lividum Northern Comandra 2
Parnassia parviflora Small-flowered Grass-of-Parnassus 3
Primula mistassinica Bird's-eye Primrose 3
Selaginella selaginoides Low Spike-moss 2
Trichophorum cespitosum Tufted Bulrush 2
Triglochin palustris Slender Bog Arrow-grass 2
Trisetum melicoides Purple False Oats 2

Landscapes

The following Ecological Landscapes have the best opportunities to manage for Great Lakes Ridge and Swale, based on the Ecological Landscapes of Wisconsin Handbook.


Map of the Ecological Landscapes of Wisconsin.


Major (3 on map)
A major opportunity for sustaining the natural community in the Ecological Landscape exists, either because many significant occurrences of the natural community have been recorded in the landscape or major restoration activities are likely to be successful maintaining the community's composition, structure, and ecological function over a longer period of time.

Important (2 on map)
Although the natural community does not occur extensively or commonly in the Ecological Landscape, one to several occurrences do occur and are important in sustaining the community in the state. In some cases, important opportunities may exist because the natural community may be restricted to just one or a few Ecological Landscapes within the state and there may be a lack of opportunities elsewhere.

Present (1 on map)
The natural community occurs in the Ecological Landscape, but better management opportunities appear to exist in other parts of the state.

Threats/Actions

Wisconsin Wildlife Action Plan graphic

What are conservation actions?

Conservation actions respond to issues or threats, which adversely affect species of greatest conservation need (SGCN) or their habitats. Besides actions such as restoring wetlands or planting resilient tree species in northern communities, research, surveys and monitoring are also among conservation actions described in the WWAP because lack of information can threaten our ability to successfully preserve and care for natural resources.

Threats/issues and conservations actions for natural communities

Considerations

The following are additional considerations for Great Lakes Ridge and Swale in Ecological Landscapes with opportunities for protection, restoration, and/or management. For more information, see the Wildlife Action Plan.

Central Lake Michigan Coastal

Point Beach Ridges State Natural Area (Manitowoc County) is an exceptional example of a forested ridge and swale ecosystem. This site is partially protected by its inclusion within Point Beach State Forest and a private nature preserve. Grazing, dumping, and forest clearcutting has negatively affected parts of the larger wetland-dune complex. Another excellent example of a forested ridge and swale community occurs at Woodland Dunes State Natural Area (Manitowoc County).

Northern Lake Michigan Coastal

The Ridges Sanctuary State Natural Area (Door County) and several privately owned sites contain good examples of this community complex. The narrow ridges are forested with black spruce, white spruce, balsam fir, and eastern white pine with wet swales between the ridges. Swamp conifers occupy some of the swales; others are filled with marsh and bog flora. Sections of the forest can be classified as boreal and are similar to, but far disjunct from the northwestern Wisconsin boreal forests near Lake Superior. The cool water of Lake Michigan heavily influences the local climate, allowing many northern species to thrive. Shivering Sands (Door County) is a large, diverse complex that occurs on the eastern side of the Door Peninsula along Lake Michigan. This site, like others on the Door Peninsula, is threatened by residential development, unsustainable logging practices, hydrologic disruption, the spread of invasive plants, and road construction. The conversion of farmland to homesites and subdivisions in the upper parts of the watershed poses potential challenges to conservation efforts directed toward maintaining the quality and quantity of surface and ground water downstream.

Superior Coastal Plain

Great Lakes coastal ridge and swale systems occur near the mouth of the Bad River and in association with a coastal barrier across Chequamegon Bay.

Photos


Great Lakes Ridge and Swale Photos

Great Lakes Ridge and Swale Photo

Long linear sedge-dominated parallel sandy ridges forested with pines. Great Lakes Ridge and Swale complex. Point Beach State Forest, Manitowoc County.

Photo by Eric Epstein.

Great Lakes Ridge and Swale Photo

Long, linear, sedge-diminated swales between parallel sandy ridges forested wirh pines, oaks, and maples. Point Beach State Forest, Manitowoc County.

Photo by Emmet Judziewicz.

Great Lakes Ridge and Swale Photo

Complex ridge and swales landforms occur only along the Great Lakess coasts. Wetlands of many kinds may occupy the wet swales, while coniferous forests often occur on the narrow sandy ridges. Here a linear Northern Sedge Meadow is flanked by Boreal Forest. Baileys Harbor, Door County.

Photo by Eric Epstein.

Great Lakes Ridge and Swale Photo

Cattail dominated swale separates forested sandy ridge. Great Lakes Ridge and Swale complex, Point Beach State Forest, Manitowoc County.

Photo by Andy Clark.

Great Lakes Ridge and Swale Photo

Blowdown east of Sturgeon Bay. Note dense thickets of sapling hemlock and white cedar, a rare sight almost anywhere in Wisconsin these days.

Photo by Eric Epstein.

Great Lakes Ridge and Swale Photo

Complex landform of linear upland ridges and parallel wet swales harbors an exceptional diversity of native biota, including many rarities. Northern Sedge Meadow and Boreal Forest are the major natural communities depicted here. The Ridges Sanctuary, Door County.

Photo by Eric Epstein.

Great Lakes Ridge and Swale Photo

Wire-leaved sedges dominate this Northern Sedge Meadow at Toft Point. Boreal Forest occurs on the adjoining uplands. Door County.

Photo by Eric Epstein.

Great Lakes Ridge and Swale Photo

Wire-leaved sedges dominate this Northern Sedge Meadow at Toft Point. Boreal Forest occurs on the adjoining uplands. Door County.

Photo by Eric Epstein.

Great Lakes Ridge and Swale Photo

Ridge and swale complex. These are extremely rare away from the shores of the Great Lakes. Northeast side of Kentuck Lake, Nicolet National Forest, Vilas County.

Photo by Eric Epstein.

Great Lakes Ridge and Swale Photo

Fen grass-of-Parnassus and the WI Special Concern lesser fringed gentian are among the unusual plants growing in this semi-shaded alkaline swale near Lake Mighigan on the northeastern Door Peninsula.

Photo by Eric Epstein.

Note: photos are provided to illustrate various examples of natural community types. A single photograph cannot represent the range of variability inherent in a given community type. Some of these photos explicitly illustrate unusual and distinctive community variants. The community photo galleries are a work in progress that we will expand and improve in the future.

Last revised: Tuesday, November 28, 2017