Northern Tamarack Swamp

Definition

Detailed Community Description from Ecological Landscapes of Wisconsin

General natural community overview

Also known as tamarack poor swamp, these weakly to moderately minerotrophic conifer swamps are dominated by a broken to closed canopy of tamarack (Larix laricina) and a frequently dense understory of speckled alder (Alnus incana), mountain holly (Ilex mucronata), winterberry (Ilex verticillata), black chokeberry (Aronia melanocarpa), and bog birch (Betula pumila). The understory is more diverse than in black spruce swamps and may include more nutrient-demanding species such as black ash (Fraxinus nigra). The bryophytes include many genera other than Sphagnum. Stands with spring seepage sometimes have marsh-marigold (Caltha palustris) and skunk-cabbage (Symplocarpus foetidus) as common understory inhabitants.

Defining Characteristics and Similar Communities

Northern tamarack swamps are characterized by their moderately minerotrophic soil, canopy dominated by tamarack, and prevalence of tall shrubs, usually with at least 5% cover, often up to 25% cover or more. While tamarack may co-dominate (or even be locally dominant in) black spruce swamps, that community has more acidic soil, a sparse layer of tall shrubs (5% cover or less), and a more continuous carpet of Sphagnum moss. While Sphagnum moss occurs in northern tamarack swamps, it usually forms a discontinuous layer and is concentrated on hummocks elevated above the moderately minerotrophic groundwater or surface water. Northern tamarack swamps sometimes grade into alder thickets, which are generally classified as having fewer trees (<25% cover, usually much less) and higher coverage of tall shrubs (50% cover or more). Northern tamarack swamps also occur adjacent to central poor fens, which are also generally classified as having no more than 25% cover of trees.

Northern tamarack swamps are similar to southern tamarack swamps, but the latter tend to be more minerotrophic with a greater prevalence of calciphiles such as poison sumac (Toxicodendron vernix). Although the two communities generally occur in the northern and southern parts of the state, respectively, they do overlap somewhat in the central sands region. Although the 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

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

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 Northern Tamarack Swamp, 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

Photos

Click to view a larger version. Please considering donating your photos to the Natural Heritage Conservation Program for educational uses. Photo use

Northern Tamarack Swamp 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.