Northern Wet Forest

Definition

Detailed Community Description from Ecological Landscapes of Wisconsin

General natural community overview

Northern wet forest encompasses a group of weakly minerotrophic to strongly acidic, conifer-dominated peatlands located mostly north of the Tension Zone. The dominant trees are black spruce (Picea mariana) and tamarack (Larix laricina). Jack pine (Pinus banksiana) is a significant component in parts of the type's range. This community is found primarily in kettle depressions or partially filled basins, on glacial outwash landforms, moraines, and till plains, where the water table is near the surface or where drainage is somewhat impeded. The community also occurs along the margins of lakes and low-gradient streams. On the wetter side of the moisture gradient, this community tends to grade into muskeg, open bog, or poor fen. On the drier side, the spruce-tamarack swamps may grade into nutrient-rich swamp forests of northern white-cedar (Thuja occidentalis) or black ash (Fraxinus nigra), if a source of nutrient-enriched groundwater is present. In much of the type's current range the adjacent uplands are still forested, most often with second-growth stands of northern hardwoods, pine, or aspen. A minerotrophic moat (or "lagg") may occur at the upland-wetland interface, and can support a diverse assemblage of tall shrubs, swamp hardwoods, and "rich" swamp conifers such as northern white-cedar.

Northern wet forests were widespread and relatively common historically, although due to the landforms with which they were associated, they did not typically occur in large patches in Wisconsin. Northern wet forests remain relatively common in much of their range today. WDNR's Natural Heritage Inventory (NHI) Program has split northern wet forest into two types (black spruce swamp and northern tamarack swamp, described below) to better reflect community variability. Community composition and water chemistry were used as the primary factors that differentiate the types. Because the NHI Program's older inventory information did not consider those factors when classifying coniferous wetlands, northern wet forest (Curtis 1959) has been retained as a type.

Black spruce swamp represents the more acid "bog" forests. The understory is characterized by a deep, continuous carpet of sphagnum mosses. Other representative plants include ericaceous shrubs such as leatherleaf (Chamaedaphne calyculata), Labrador-tea (Rhododendron groenlandicum), creeping snowberry (Gaultheria hispidula), small cranberry (Vaccinium oxycoccos), and herbs that are adapted to or tolerant of saturated substrates and high acidity, such as swamp false Solomon's-seal (Maianthemum racemosum), three-seeded bog sedge (Carex trisperma), and boreal bog sedge (Carex magellanica). A deep accumulation of Sphagnum mosses partially isolates the plant assemblage from the influence of mineral-enriched groundwater, limiting composition to a relatively small group of specialists, and also limiting the growth of trees. Black spruce swamp is widespread in much of northern Wisconsin, locally common in the central part of the state, and occurs in disjunct outliers as far south as Columbia and Ozaukee counties.

Northern tamarack swamp is a less acid, wet conifer forest community that can support nutrient-demanding understory plants that are also tolerant of relatively high pH levels. Tamarack is the dominant tree, sometimes to the virtual exclusion of other tree species. In some stands, hardwoods such as paper birch (Betula papyrifera), red maple (Acer rubrum), black ash (Fraxinus nigra), and American elm (Ulmus americana) occur as canopy associates, saplings, or subcanopy trees. The understory may be more diverse and structurally complex than in the more acid spruce-dominated swamps, and sometimes features a well-developed tall shrub layer composed of plants with relatively high nutrient demands such as speckled alder (Alnus incana), alder-leaved buckthorn (Rhamnus alnifolia), mountain holly (Ilex mucronata), and common winterberry (Ilex verticillata). Ericaceous shrubs and many sedge species are usually present, and in the "poorer" swamps dominate their respective strata. The bryophytes may include more minerotrophic Sphagnum mosses, as well as additional genera of mosses that do not usually occur in the acid bog forests. Stands that receive groundwater seepage may support plants such as skunk-cabbage (Symplocarpus foetidus), marsh-marigold (Caltha palustris), cinnamon fern (Osmunda cinnamomea), and royal fern (Osmunda regalis).

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 Wet Forest 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.

Landscapes

The following Ecological Landscapes have the best opportunities to manage for Northern Wet Forest, 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 Northern Wet Forest in Ecological Landscapes with opportunities for protection, restoration, and/or management. For more information, see the Wildlife Action Plan.

Central Lake Michigan Coastal

More detailed surveys of the Sheboygan Marsh and several similar (though smaller) wetland basins in this Ecological Landscape are needed. Much of the forest that formerly covered this region was cleared for agricultural, residential and industrial uses. Some of the conifer swamps in this Ecological Landscape should probably be classified as southern tamarack swamp.

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). Some agricultural practices can result in soil erosion and water quality problems. Often, declining tamarack stands are not regenerating. Fragmentation and stand isolation affect this type in central 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 has been 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. Large blocks of this habitat exist, and some of them occur within extensive forests. 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. Where possible, block and/or buffer sites in the eastern part of the Ecological Landscape. Work to develop incentives, or other means to achieve conservation objectives, that meet the needs of cranberry growers and other large landowners of this type within the region.

Forest Transition

The best opportunities for northern wet forest occur in the eastern and extreme northern portions of the Ecological Landscape, where agricultural and residential development has been minimal. Forest fragmentation is a significant factor in many other locations here, and many wetlands are somewhat isolated by agricultural developments.

North Central Forest

This is the most important Ecological Landscape for managing northern wet forest, in terms of the types in abundance here and the forested condition of most local and regional watersheds. The Lost Lake Bog in Price County is a well preserved example within a wetland complex. Many good examples occur on the Chequamegon-Nicolet National Forests, the Flambeau River State Forest, and on county forests. More survey work is needed to identify sites that support sensitive species. Invasives are not a major problem now but should be monitored and controlled as needed.

Northeast Sands

Opportunities to manage for this type here have not been assessed thoroughly. This Ecological Landscape is known to contain sites that represent excellent opportunities to manage for the more minerotrophic "northern wet-mesic forest" type (white cedar swamp).

Northern Highland

Extensive acreages of relatively unmodified acid peatlands occur on the Northern Highland-American Legion State Forest and some adjoining properties. In these areas, tamarack and black spruce are regenerating well. Opportunities to manage for boreal species (e.g., birds, Lepidoptera, plants) are present. Inventory assessments targeting this type have been limited to a relatively small number of the larger stands, or to those occurring within vegetation mosaics that also contain other significant features, such as old growth forests or rare species habitats. Additional survey work is needed in this type to identify those sites that contain large, intact stands; stands of especially high value to sensitive plants and animals; and sites that are critical to the protection of water quality and flood attenuation. Rare plants, birds, and invertebrates have been documented in a number of peatlands, especially those that border the water bodies that are so abundant in this landscape. The high level of residential development in this Ecological Landscape is causing hydrologic changes, and land use planning could be an important means of limiting negative impacts. Best Management Practices and other sustainable forest management practices within and adjacent to the community should be used to limit hydrologic change.

Northern Lake Michigan Coastal

Fragmentation from road construction and the clearing of upland forest are serious issues in this Ecological Landscape. The best opportunities known for management of this type occur on the Door Peninsula. Further evaluation is needed to identify important community occurrences and associated rare species populations in the western and northern portions of the Ecological Landscape.

Northwest Lowlands

The best representatives of northern wet forest are found in the Black Lake, Mud Lake-Ericson Creek, Empire and Belden Swamps in Douglas County, where they are well preserved. This Ecological Landscape has some of the lowest road densities in the state, providing habitat for species that need large remote areas relatively free of human disturbance. Large blocks of this habitat should be protected where they exist. This type should be managed as a part of a complex that includes northern mesic forest, boreal forest, and other peatland communities, such as poor fen, open bog, and muskeg. Opportunities to manage for boreal species are outstanding in the Ecological Landscape. Management should be coordinated with Minnesota to provide connectivity for wide-ranging fauna (e.g., gray wolves). Invasives are not a large problem at present in this Ecological Landscape, but should be monitored.

Northwest Sands

Acid conifer swamps of black spruce and tamarack are widespread and quite common in areas of pitted outwash where lakes and poorly drained kettle depressions are important landscape features. More comprehensive survey work is needed to identify stands of high conservation value, especially those that are large, hydrologically intact, and of importance to sensitive species. Good opportunities for protection and management exist on the Chequamegon-Nicolet National Forests.

Southeast Glacial Plains

Invasive non-native plants are a problem in tamarack stands (e.g., glossy buckthorn). Poison sumac can be quite common in this community, making it difficult to work in this type here. Often, declining tamarack stands are not regenerating. Fragmentation and stand isolation are significant issues in this Ecological Landscape. 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. See bog relict (Section 3.3.8.2) and southern tamarack swamp (Section 3.3.3.9) for additional information regarding these related communities that are also present in the Southeast Glacial Plains Ecological Landscape.

Southern Lake Michigan Coastal

Invasives are a significant problem in 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 habitat 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. See bog relict (Section 3.3.8.2) and southern tamarack swamp (Section 3.3.3.9) for additional information regarding these related communities that are also present in the Southern Lake Michigan Coastal Ecological Landscape.

Superior Coastal Plain

Past land use practices (e.g., Cutover-era logging, intense burning) have resulted in loss and conversion (to willow and alder) of much of the type. The vast Bibon Swamp (Bayfield County) includes stands of this type. The White River corridor between Bibon Swamp and the Kakagon Sloughs of Lake Superior warrants additional protection to alleviate sedimentation and water quality issues. Sultz Swamp, a large basin perched on the spine of the northern Bayfield Peninsula, includes good examples of acid black spruce swamp. Opportunities to manage for boreal species at their southern range limits are outstanding in this Ecological Landscape because of its geographic location, the presence of significant, intact occurrences, and inherent site capability. Invasive plants are not a large problem at present, but should be monitored.

Western Coulee and Ridges

The known occurrences are small and impacted by agricultural runoff (excess nutrients, sediments). Often, tamarack is declining and not regenerating. Stand isolation within cleared agricultural lands is an 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. See southern tamarack swamp (Section 3.3.3.9) for additional information regarding this related community that is also present in the Western Coulee and Ridges Ecological Landscape.

Photos

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Northern Wet Forest 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.