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Ryan O'Connor
Natural Heritage Inventory Ecologist

Southern Tamarack Swamp

State Rank: S3     Global Rank: G3   what are these ranks?


Detailed Community Description from Ecological Landscapes of Wisconsin

General natural community overview

Counties shaded blue have documented occurrences for Southern Tamarack Swamp in the Wisconsin Natural Heritage Inventory database.

Also known as tamarack rich swamp, this forested minerotrophic wetland community is dominated by tamarack (Larix laricina), in some stands hardwoods such as paper birch (Betula papyrifera), red maple (Acer rubrum), black ash (Fraxinus nigra), or American elm (Ulmus americana) may be present as associates, saplings, or as subcanopy trees. The understory is more diverse and structurally complex than in the more acid spruce-dominated swamps and includes nutrient-demanding species such as speckled alder (Alnus incana), mountain holly (Ilex mucronatus), common winterberry (Ilex verticillata), and black ash (Fraxinus nigra). Poison sumac (Toxicodendron vernix) is the most abundant tall shrub in many southern Wisconsin tamarack forests. The bryophytes may include many genera other than Sphagnum.

Stands that are fed by spring seepage sometimes support plants such as marsh-marigold (Caltha palustris), cinnamon fern (Osmunda cinnamomea), royal fern (Osmunda regalis), and skunk-cabbage (Symplocarpus foetidus). Historically, southern tamarack swamps occurred extensively in parts of southeastern Wisconsin and on the eastern margin of Glacial Lake Wisconsin. Many of them were drained and cleared for agricultural purposes. Intact examples are now uncommon but occur in a wide variety of settings, such as on the margins of lakes or streams, at the base of moraines, in outwash areas, and in a few Driftless Area stream valleys.

Defining Characteristics and Similar Communities

Southern tamarack swamps are characterized by their minerotrophic soil, canopy dominated by tamarack and swamp hardwood associates, and prevalence of tall shrubs, especially poison sumac. They are most similar to bog relicts, which are also minerotrophic wetlands with a tamarack component occurring in southern Wisconsin. They can be differentiated by the degree of canopy cover-southern tamarack swamps generally have at least 25% tree canopy (often much more) and bog relicts having less than 25%. Southern tamarack swamps have many species in common with northern hardwood swamps but the latter is usually dominated by hardwoods with tamarack usually sparse to absent.

Southern tamarack swamps are also similar to northern tamarack swamps but the latter tends to be more acidic with a lower prevalence of strong calciphiles like poison sumac. Although the two communities are generally confined to the northern and southern parts of the state, they do overlap somewhat in the Central Sands region. Although this region is within and south of Wisconsin's climatic tension zone, northern tamarack swamps are common in the ancient lakebed of Glacial Lake Wisconsin where flat, acid peatlands are underlain by nutrient-poor sands. Just to the east in the hills above the ancient lakeplain, southern tamarack swamps predominate due to the more minerotrophic groundwater seeping through the calcareous glacial deposits. Thus, nutrient status and the relative abundance of calciphitic species is more useful than latitude in differentiating the two communities.

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 Southern Tamarack Swamp 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.

Four-toed SalamanderHemidactylium scutatum2
Pickerel FrogLithobates palustris2

A Predaceous Diving BeetleHydrocolus rubyae2
A Predaceous Diving BeetleHydrocolus persimilis2
A Predaceous Diving BeetleAgabus discolor2

Rusty BlackbirdEuphagus carolinus2
American WoodcockScolopax minor1
Golden-winged WarblerVermivora chrysoptera1
Long-eared OwlAsio otus1
Yellow-breasted ChatIcteria virens1

Butterflies and mothsScore
Swamp MetalmarkCalephelis muticum1

Dragonflies and damselfliesScore
Swamp DarnerEpiaeschna heros1

Grasshoppers and alliesScore
Grizzly Spur-throat GrasshopperMelanoplus punctulatus2
Bog ConeheadNeoconocephalus lyristes1
Spotted-winged GrasshopperOrphulella pelidna1

Big Brown BatEptesicus fuscus1
Little Brown BatMyotis lucifugus1
Northern Flying SquirrelGlaucomys sabrinus1
Silver-haired BatLasionycteris noctivagans1
Water ShrewSorex palustris1

Blanding's TurtleEmydoidea blandingii2
Eastern RibbonsnakeThamnophis sauritus1
Gray RatsnakePantherophis spiloides1

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
Conioselinum chinense Hemlock-parsley 1
Cypripedium parviflorum var. makasin Northern Yellow Lady's-slipper 3
Valeriana uliginosa Marsh Valerian 2


The following Ecological Landscapes have the best opportunities to manage for Southern Tamarack Swamp, 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.


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


The following are additional considerations for Southern Tamarack Swamp in Ecological Landscapes with opportunities for protection, restoration, and/or management. For more information, see the Wildlife Action Plan.

Central Sand Hills

Changes in hydrology due to development can be detrimental to this community type here, and there are continuing effects from past hydrologic changes (e.g., ditching, dike construction, road building, etc.). Some agricultural practices can result in soil erosion and water quality problems. Habitat fragmentation and stand isolation can affect this type in central and southern Wisconsin.

Central Sand Plains

The effects of past land use (e.g., wetland drainage, dike and impoundment construction) have impacted hydrology. Some of these uses continue today, where waterfowl production is emphasized, or to meet the needs of specialized agricultural uses such as cranberry production. Fragmentation and stand isolation are issues in the eastern part of the Ecological Landscape. Recovery potential of tamarack swamps in areas where the hydrology has been significantly altered is uncertain and needs to be clarified. Large blocks of this habitat still exist in some areas, and some of them occur within extensive upland forests. Sites in the eastern part of the Ecological Landscape should be blocked and/or buffered. The best opportunities for developing blocks and connecting corridors are in the central and western parts of the Ecological Landscape, in the Black River State Forest, and on the Jackson, Wood, and Clark County Forests. Incentives, or other means of achieving conservation objectives, that meet the needs of cranberry growers and other large landowners of this type within this region should be developed. Additional vegetation sampling is needed in central Wisconsin to determine whether tamarack forests should be included with southern stands or northern stands.

Southeast Glacial Plains

Invasive non-native plants are a major problem in southern tamarack stands (e.g., glossy buckthorn). Poison sumac can be quite common in this community, making it difficult to work in this type here. Declining tamarack stands are frequently not regenerating. Fragmentation and stand isolation are significant issues in this EL. Large stands occur in Jefferson County, in the Mukwonago River watershed, and at a few other locations. Past drainage to create muck farms and pasture eliminated much of the swamp conifer community in the Ecological Landscape. Rare species include northern plants and animals at their southern range limits, but also some that are most often associated with southern "fen" habitats. Fire may have played an important role in maintaining this type historically. Some stands appear to be succeeding to hardwoods such as red maple. Restoration techniques need to be developed for this "type" (using the term broadly) in the southern part of its range.

Southern Lake Michigan Coastal

Invasives are a significant problem in southern tamarack stands. Black spruce does not occur this far south and the "northern" understory is represented by a very reduced subset of plants. Often, declining stands are not regenerating. Stand isolation and fragmentation are major issues. High deer densities, fire suppression, and succession may all be affecting species composition and stand structure. This type is extremely limited in this Ecological Landscape. Large blocks of this habitat are needed, but there are few opportunities here. Isolated sites should be embedded in other forest habitats where possible, or buffered. More survey work is needed to assess the current condition of known stands, most of which have been referred to as "bog relicts" in the past. Restoration techniques for this type in southern Wisconsin should be developed.

Western Coulee and Ridges

The known occurrences are small and impacted by agricultural runoff (e.g., excess nutrients and sediments). Often, tamarack is declining and not regenerating. Stand isolation within formerly forested lands that were cleared for agricultural uses is a significant issue, as is the spread of invasive species. This community type is of limited extent in this Ecological Landscape. Opportunities exist to manage for a limited suite of northern species. More detailed survey work is needed to clarify the significance of these sites for sensitive species. Tamarack sites should be blocked and/or buffered where possible. Community viability is questionable for some stands.


Southern Tamarack Swamp Photos

Southern Tamarack Swamp Photo

Tamarack-dominated swamps occur in some intact peatland complexes, sometimes in a wetland mosaic of sedge meadow, calcareous fen, wet prairie, shrub swamp communities.

Photo by Andy Clark.

Southern Tamarack Swamp Photo

Southern Tamarak Swamp at Goose Lake, 30% canopy of tamarack, >50% canopy of bog birch, poison sumac, red-osier dogwood, and willows.

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.

Last revised: Tuesday, August 30, 2022