Shrub-carr

Definition

Detailed Community Description from Ecological Landscapes of Wisconsin

General natural community overview

Shrub-carr is a wetland community dominated by tall shrubs such as red-osier dogwood (Cornus sericea), silky dogwood (Cornus amomum), meadowsweet (Spiraea alba), and various willows (Salix spp.). Canada bluejoint grass (Calamagrostis canadensis) is often very common. Associates are similar to those found in alder thickets and tussock-type sedge meadows. Shrub-carrs occupy areas that are transitional between open wetlands like wet prairies, calcareous fens, and southern sedge meadows, and forested wetlands such as floodplain forests and southern hardwood swamps. Shrub-carrs can persist at a given site for a very long time if natural hydrologic cycles are maintained. This type often occurs in bands around lakes or ponds, on the margins of river floodplains, or, more extensively, in glacial lakebeds. It is common and widespread in southern Wisconsin but also occurs in the north. In the south, shrub-carrs were often an integral part of prairie-savanna landscapes, though they also occurred in wetlands in more forested regions. In the north, the landscape matrix around the shrub-carr type was usually upland forest. Statewide, shrub-carrs remain quite common and have fared considerably better than many other native wetland communities in its range.

Past drainage and marsh hay mowing likely had a negative effect on shrub-carrs, whereas clearing of conifer swamps likely produced more of this habitat. Once fire was controlled and hay mowing was discontinued in lowland meadows, shrub-carrs likely increased in extent. Drainage of meadows and marshes has also allowed shrub-carr habitats to increase in some areas. As a result of wetland drainage and fire suppression, shrub-carrs now occupy many sites that formerly supported much more extensive marsh, wet meadow, prairie, and fen vegetation, and therefore, they are sometimes targeted for elimination. However, shrub-carr is an important native wetland type that has its place on our landscape and should be protected, managed, and restored at appropriate sites.

Defining Characteristics and Similar Communities

Shrub-carr is defined as having few trees and generally 50% cover of shrubs or more, often with at least 4 or 5 species that are co-dominant. It is similar to alder thicket, but can be distinguished by having several shrub species that share dominance (especially willows and dogwoods). While alder is often present in a shrub-carr (especially in northern Wisconsin), it should comprise less than half of the relative shrub cover. Shrub-carr often intergrades with southern sedge meadow (and sometimes calcareous fen). While southern sedge meadow has less than 50% cover of tall shrubs, either community can constitute the dominant matrix community, with pockets of the non-matrix community embedded within. Shrub-carrs in southeastern Wisconsin also share similarities with bog relicts, but bog relicts have a partial canopy of tamarack, high abundance of poison sumac, and prevalence of ericaceous shrubs. Shrub-carrs also border and intergrade with forested wetlands like southern tamarack swamps and floodplain forests, but can be differentiated by having, on average, less than 25% cover of trees.

Rare animals

Species of Greatest Conservation Need

The following Species of Greatest Conservation Need are listed according to their level of association with the Shrub-carr 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.

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.

Landscapes

The following Ecological Landscapes have the best opportunities to manage for Shrub-carr, based on the Ecological Landscapes of Wisconsin Handbook.

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

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 Shrub-carr in Ecological Landscapes with opportunities for protection, restoration, and/or management. For more information, see the Wildlife Action Plan.

Central Lake Michigan Coastal

Examples of this community type can be found at Duvall Swamp (Kewaunee County), Kohler-Andrae State Park (Sheboygan County), and Mud Lake (Waupaca County). Shrub-carr habitat should be maintained where it exists.

Central Sand Hills

Examples of shrub-carr can be found at the Germania Marsh State Wildlife Area, Lawrence Creek State Wildlife Area, and Harris Marsh in Marquette County. Beaver populations should be maintained at an appropriate level in this Ecological Landscape to prevent conversion of shrub-carr communities.

Central Sand Plains

Examples of this community type can be found at Quincy Bluff and Wetlands State Natural Area, Colburn State Wildlife Area, Meadow Valley State Wildlife Area, and many additional locations on other public lands. In this Ecological Landscape there is the potential to manage this community type in very large wetland complexes with northern sedge meadow, open bog, poor fen, alder thicket, and tamarack swamp. Beaver populations should be maintained at an appropriate level in this Ecological Landscape to prevent conversion of shrub-carr communities. Hydrologic alterations are pervasive in this landscape, especially ditching and impoundment construction. More care needs to be taken to ensure that many good examples of this and other native wetland communities are protected from type conversion, degradation, or outright loss.

Forest Transition

Examples of this community type can be found at Ninemile Swamp (Marathon County) and along the Wisconsin River and its tributaries.

North Central Forest

Examples of this community type can be found at locations within the Chequamegan-Nicolet National Forest, and on other public lands such as the Lincoln and Ashland County Forests. Alder thicket is the more common wet shrub community in this landscape. Invasives are not a large problem at present, but should be monitored. Beaver populations should be maintained at an appropriate level in this Ecological Landscape to prevent conversion of shrub-carr communities.

Northern Lake Michigan Coastal

Examples of this community type can be found at the Green Bay West Shores State Wildlife Area, the Lake Noquebay Wildlife Area, and at various locations on the Door Peninsula. Beaver populations should be maintained at an appropriate level in this Ecological Landscape to prevent conversion of shrub-carr communities. In the past, residential development has tended to encroach on wetlands during periods of low water. Maintenance of healthy wetland ecosystems and all of their associated communities is highly dependent on maintaining them during both high and low water. Shoreline development is an especially important land use issue here.

Southeast Glacial Plains

Examples of this community type can be found at Cedarburg Bog (Ozaukee County), Cherokee Marsh (Dane County), White River Marsh State Wildlife Area, Mullet Lake Swamp (Fond du Lac County), and at scattered locations within the Southern Unit of the Kettle Moraine State Forest. Drainage for agriculture, grazing, and conversion to reed canary grass monotypes are significant problems in this Ecological Landscape. Efforts to limit these activities would be beneficial. This is a widespread and common type here and would appropriately be featured in regional wetland protection and habitat restoration plans.

Southern Lake Michigan Coastal

Shrub-carr occurs at Chiwaukee Prairie State Natural Area (Kenosha County), at Cherry Lake Sedge Meadow (Racine County), at Bong State Recreation Area, and along the Des Plaines River. It is not a featured community at any of these locations, but exists as a component of a community mosaic.

Superior Coastal Plain

Examples of this community type can be found at Bibon Swamp State Natural Area (Bayfield County) and in the Superior Municipal Forest (Douglas County). Beaver populations should be maintained at an appropriate level in this Ecological Landscape to prevent conversion of shrub-carr communities. Most of the shrub swamp acreage in this Ecological Landscape is alder thicket.

Western Coulee and Ridges

Most occurrences of this type are associated with floodplains of the major rivers. Examples can be found at Tiffany Bottoms State Wildlife Area (Buffalo County), Upper Mississippi River Fish and Wildlife Refuge, Avoca Prairie State Natural Area (Iowa County), and along the Lower Wisconsin State Riverway.

Photos

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Shrub-carr Photos

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.