Photo by Ryan O'Connor
- WDNR
State Rank: S2 Global Rank: G3 what are these ranks?
Also known as forested ridge and swale, this community complex is closely associated 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 migrating birds. A few ridge and swale systems also occur on the Lake Superior coast.
Defining Characteristics and Similar Communities
Great Lakes ridge and swale is a community complex comprised of a series of alternating communities associated with dry ridges and wet swales. While Great Lakes dune, northern dry forest, northern sedge meadow, and alder thicket may also occur separately near the Great Lakes, the defining feature of a ridge and swale complex is the repeating series of narrow linear bands of uplands alternating with wetlands running parallel to the shoreline or following the curve of an embayment of the Great Lakes.
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.
| Amphibians | Score | |
|---|---|---|
| Four-toed Salamander | Hemidactylium scutatum | 3 |
| Aquatic and terrestrial snails | Score | |
|---|---|---|
| Dentate Supercoil | Paravitrea multidentata | 3 |
| Appalachian Pillar | Cochlicopa morseana | 2 |
| Bright Glyph | Glyphyalinia wheatleyi | 1 |
| Ribbed Striate | Striatura exigua | 1 |
| Sculpted Glyph | Glyphyalinia rhoadsi | 1 |
| Six-whorl Vertigo | Vertigo morsei | 1 |
| Birds | Score | |
|---|---|---|
| Least Flycatcher | Empidonax minimus | 2 |
| Olive-sided Flycatcher | Contopus cooperi | 2 |
| Rusty Blackbird | Euphagus carolinus | 2 |
| American Woodcock | Scolopax minor | 1 |
| Red-shouldered Hawk | Buteo lineatus | 1 |
| Dragonflies and damselflies | Score | |
|---|---|---|
| Hine's Emerald | Somatochlora hineana | 2 |
| Swamp Darner | Epiaeschna heros | 1 |
| Grasshoppers and allies | Score | |
|---|---|---|
| Delicate Meadow Katydid | Orchelimum delicatum | 2 |
| Blue-legged Grasshopper | Melanoplus flavidus | 1 |
| Scudder's Short-winged Grasshopper | Melanoplus scudderi | 1 |
| Stone's Locust | Melanoplus stonei | 1 |
| Mammals | Score | |
|---|---|---|
| Big Brown Bat | Eptesicus fuscus | 2 |
| Northern Flying Squirrel | Glaucomys sabrinus | 2 |
| Tricolored Bat | Perimyotis subflavus | 1 |
| Woodland Jumping Mouse | Napaeozapus insignis | 1 |
Please see Section 2. Approach and Methods of the Wildlife Action Plan to learn how this information was developed.
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.
| 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 |
The following Ecological Landscapes have the best opportunities to manage for Great Lakes Ridge and Swale, based on the Ecological Landscapes of Wisconsin Handbook.
| Ecological Landscape | Opportunity |
|---|---|
| Central Lake Michigan Coastal | Major |
| Northern Lake Michigan Coastal | Major |
| Superior Coastal Plain | Present |
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.
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
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.
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).
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.
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.
Click to view a larger version. Please considering donating your photos to the Natural Heritage Conservation Program for educational uses. Photo use
Long linear sedge-dominated parallel sandy ridges forested with pines. Point Beach State Forest, Manitowoc County.
Photo by Eric Epstein.
Complex ridge and swales landforms occur only along the Great Lakes coasts. Many kinds of wetlands may occupy the swales, coniferous forests often occur on the narrow sandy ridges.
Photo by Eric Epstein.
Complex landforms in the coastal areas of Lakes Michigan and Superior. Linear, usually forested, ridges are paralleled by narrow swales that harbor diverse wetlands.
Photo by Eric Epstein.
Ridge and swale complex, which are extremely rare away from Great Lakes shores. Northeast side of Kentuck Lake, Vilas County.
Photo by Eric Epstein.
Great Lakes ridge and swale showing alternating series of forested ridges and open to shrubby wetland swales at The Ridges Sanctuary.
Photo by Ryan O'Connor.
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.