Northern Dry Forest

Definition

Detailed Community Description from Ecological Landscapes of Wisconsin

General natural community overview

Northern dry forests occur on nutrient-poor sites with excessively drained sandy or rocky soils. The primary historic disturbance regime was catastrophic fire at intervals of ten to one hundred years. Dominant trees of mature stands include jack pine (Pinus banksiana), red pine (Pinus resinosa), and northern pin oak (Quercus ellipsoidalis). Large acreages of this forest type were cut and burned during the logging of the late-19th and early-20th century. Much of this land was then colonized by paper birch (Betula papyrifera) and/or trembling aspen (Populus tremuloides) or converted to pine plantations starting in the 1920s.

Today's forests have a greatly reduced component of pines, and a greater extent of aspen, red maple, and oaks compared to historic conditions. Common understory shrubs are hazelnuts (Corylus spp.), early blueberry (Vaccinium angustifolium), and brambles (Rubus spp.). Common herbs include bracken fern (Pteridium aquilinum), starflower (Trientalis borealis), barren-strawberry (Waldsteinia fragarioides), cow-wheat (Melampyrum lineare), trailing arbutus (Epigaea repens), and members of the shinleaf family (Chimaphila umbellata, Pyrola spp.). Vast acreages of cutover land were also planted to pine or naturally succeeded to densely stocked dry forests.

Factors affecting the current abundance and condition of northern dry forests include fire suppression and the spread of invasive species. On some sites (e.g., on richer sites where better growth is expected) silvicultural practices may maintain or even increase certain cover types such as red pine. For other cover types such as jack pine, the management efforts may be to eliminate interior gaps and edges and strive to make tree spacing and size as uniform as possible, in part to lessen the probability of severe budworm damage. Such practices reduce or remove habitat for native species dependent on aspects of the patchy nature of northern Wisconsin's dry ecosystems.

Northern dry forests most commonly occur on large, continuous glacial outwash or lake plain landforms. On these extensive dry plains, historic fires were large and intense, and were less likely to be halted by wetlands, hills, or mesic soils, creating ideal conditions for establishment of northern dry forests.

Three different seral stages are described for northern dry forest, based on the progressive stages of forest regeneration following harvesting or a major natural disturbance, from young forest to mid-seral to the attainment of reference conditions as seen in a mature stand. Stands with more than 50 percent aspen by basal area fall into the aspen-birch habitat type. For stands dominated by planted conifers, refer to the conifer plantation.

• Northern dry forest--late seral: Late-seral (may also be referred to as old or old-growth) northern dry forests are dominated by trees 40 feet tall (~5-10 inches dbh) or more and are dominated by jack pine (Pinus banksiana), red pine (Pinus resinosa), white and northern pin oak (Quercus alba and Q. ellipsoidalis), and pockets of trembling aspen (Populus tremuloides). Tall shrub (e.g. hazelnut (Corylus spp.) and serviceberry (Amelanchier spp.)) density is variable, ranging from sparse to dense thickets, but is typically greater in more mature stands, which provides important habitat for some Species of Greatest Conservation Need (SGCN). In addition, forest grasses, sedges, forbs, and mosses predominate in the groundlayer. Snag density is at its highest relative to other seral stages, providing habitat for woodpeckers and cavity-nesting birds. Stands may include those on the older end of those managed as part of a shifting barrens mosaic and those managed for old-growth characteristics.
• Northern dry forest--mid-seral: Mid-seral northern dry forests are dominated by trees 16 to 40 feet tall (~3-5 inches dbh). Like other seral stages of dry forests, species are primarily jack pine (Pinus banksiana), red pine (Pinus resinosa), and northern pin oak (Quercus ellipsoidalis), but can also include components of white pine (Pinus strobus), red maple (Acer rubrum), aspen (Populus spp.), and birch (Betula spp.). Depending on stand origin, scattered grassy or shrubby openings may be present, providing important habitat components for SGCN, such as Whip-poor-will and Common Nighthawk. However, in this seral stage, herbaceous vegetation shifts significantly away from barrens associates and toward forest grasses, sedges, and forbs. Structural complexity is slightly higher than in younger forests, with multiple size classes of trees developing, particularly where both oaks and pines are present, despite still being even-aged.
• Northern dry forest--young seral: Young-seral northern dry forests are dominated by trees 16 feet tall or less (~0-3 inches dbh). Species are primarily jack pine (Pinus banksiana), red pine (Pinus resinosa), and northern pin oak (Quercus ellipsoidalis), but can also include red maple (Acer rubrum), aspen (Populus spp.), and birch (Betula spp.). Stands typically originate from stand-replacing events such as clear-cutting or fire, but can also arise from mechanical soil scarification. They are mostly even-aged stands with few or no snags and little coarse woody debris. Structurally, young northern dry forests may have similarities with pine barrens--scattered openings with native grasses, scattered wildflowers, and patches of hazelnuts (Corylus spp.), dewberry (Rubus spp.), and blueberry (Vaccinium angustifolium) providing habitat for SGCN and other wildlife. However, tree density is higher and openings smaller than in true barrens, and ground flora is highly variable depending on how the forest was established.

In describing these stages, it is recognized that they exist and persist on the landscape due to a marked range of conditions depending on conservation or production goals and the nature and intensity of management. Even the most basic actions of promoting natural regeneration carry the weight of this reality---in an area where the purpose is strictly forest production, the decision to harvest and replant may be relatively straightforward, but on a site managed all or in part for ecological values the prescription and stand rotation is more complex.

Some of the important site characteristics that may determine how SGCN utilize this seral stage include pocket barrens, frost pockets, or other non-forested openings that provide important habitat, the landscape mosaic of barrens and forest across landscape, structural attributes, and diversity of other woody species and herbaceous plants.

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 Dry 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.

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

Central Sand Plains

This community type is well represented, occurring mainly in Adams, Juneau, southeastern Wood, and southwestern Portage counties. Fragmentation is an issue in the Ecological Landscape, especially related to residential development and roads. The best opportunities for restoration and alternative management techniques are on the county forests, Quincy Bluff (Adams County), Robinson Creek and the Black River State Forest (both in Jackson County). Connectivity with other forested areas in this community type should be maintained and enhanced where possible, and jack pine should be maintained on appropriate sites since it is declining statewide.

Northeast Sands

Northern dry forests are well represented, mainly in northern Marinette and southern Florence counties. Fragmentation is less of an issue since population and road densities are low. The best opportunities for restoration and alternative management techniques are on the county forests, Pine and Popple Wild Rivers property, and the Peshtigo River State Forest. Connectivity with other forested areas should be maintained and enhanced where possible.

Northern Highland

Northern dry forests are of very limited extent in this Ecological Landscape, mainly occurring as patches in the southern portion. The best opportunities for restoration and alternative management techniques are on the Vilas and Oneida county forests and the Northern Highland-American Legion State Forest. Fragmentation is less of an issue in this Ecological Landscape. Invasives are becoming a problem (e.g., Asian honeysuckle); there is still potential for controlling invasives if effective measures are taken in the near future.

Northern Lake Michigan Coastal

There are a few occurrences of northern dry forest in this Ecological Landscape, generally on the west side of Green Bay near the Peshtigo River. The best sites are under private ownership. Opportunities for management or restoration are limited.

Northwest Sands

Northern dry forests are well represented in this Ecological Landscape, where outwash sand plains are more extensive and connected than in any other part of the state. Only in the far northern portion of the Ecological Landscape are other community types more dominant. Fragmentation is less of an issue since population and road densities are relatively low. The best opportunities for restoration and alternative management techniques are on the Polk, Burnett, Washburn, Douglas, and Bayfield County Forests; Governor Knowles State Forest and Crex Meadows (both in Burnett County); Brule River State Forest (Douglas County); and the Washburn District of the Chequamegon-Nicolet National Forest (Bayfield County). Connectivity with other forested areas in this community type should be maintained and enhanced where possible, and jack pine should be maintained on appropriate sites since it is declining statewide.

Superior Coastal Plain

There are a few occurrences of northern dry forest in this Ecological Landscape, mostly on sand spits on the Apostle Islands, especially on Long Island. Opportunities for management or restoration are limited.

Photos

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Northern Dry 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.