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- For information on Wisconsin's natural communities, contact:
- Ryan O'Connor
Natural Heritage Inventory Ecologist
608-354-2383
Great Lakes Alkaline Rockshore
Photo by Eric Epstein
- WDNR
State Rank: S2 Global Rank: G3 what are these ranks?
Definition
Detailed Community Description from Ecological Landscapes of Wisconsin
General natural community overview
Great Lakes alkaline rockshore is a community that develops on creviced, wave-splashed, horizontal or gently sloping exposures of dolomite bedrock that dip toward Lake Michigan. These occur only along the Lake Michigan shoreline of the northern Door Peninsula, and on the margins of some of the Grand Traverse Islands to the north. This is the same bedrock that forms the Niagara Escarpment which forms prominent cliffs on the west side of the Peninsula. The extent of the exposed rock is dependent on Lake Michigan water levels; large expanses of this habitat may be either inundated or exposed during a given year. Characteristic members of this community include the shrubs ninebark (Physocarpus opulifolius) and shrubby cinquefoil (Dasiphora fruticosa), and the herbs silverweed (Potentilla anserina), birds-eye primrose (Primula mistassinica), grass-leaved goldenrod (Euthamia graminifolia), brook lobelia (Lobelia kalmii), gentians (Gentiana spp., Gentianopsis spp.), grasses-of-Parnassus (Parnassia spp.), Indian paint-brush (Castilleja coccinea), low calamint (Clinopodium arkansanum), and many sedges and rushes. Plants endemic to the Great Lakes shores are significant components of some stands.
Because this community type is geographically restricted to those portions of the Lake Michigan coast with dolomite shoreline, it is, and has always been, rare here. Just inland of the exposed dolomite pavement there is often a narrow zone of rank herbs and tall shrubs, sometimes occupying a ridge of cobbles, gravel, or a low ledge. On the more stable habitats beyond this zone of herbs and shrubs, a very distinctive forest sometimes develops. Mature stands are usually composed of mixtures of northern white-cedar (Thuja occidentalis), white spruce (Picea glauca), balsam fir (Abies balsamea), eastern white pine (Pinus strobus), and paper birch (Betula papyrifera).
Rare animals
Species of Greatest Conservation Need
The following Species of Greatest Conservation Need are listed according to their level of association with the Great Lakes Alkaline Rockshore 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.
| Aquatic and terrestrial snails | Score | |
|---|---|---|
| Appalachian Pillar | Cochlicopa morseana | 2 |
| Sculpted Glyph | Glyphyalinia rhoadsi | 1 |
| Six-whorl Vertigo | Vertigo morsei | 1 |
| Mammals | Score | |
|---|---|---|
| Big Brown Bat | Eptesicus fuscus | 1 |
| Eastern Pipistrelle | Perimyotis subflavus | 1 |
| Little Brown Bat | Myotis lucifugus | 1 |
| Silver-haired Bat | Lasionycteris noctivagans | 1 |
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.
| Scientific Name | Common Name | Score |
|---|---|---|
| Astragalus neglectus | Cooper's Milkvetch | 1 |
| Carex garberi | Elk Sedge | 3 |
| Clinopodium arkansanum | Low Calamint | 3 |
| Eleocharis quinqueflora | Few-flowered Spike-rush | 2 |
| Festuca occidentalis | Western Fescue | 2 |
| Iris lacustris | Dwarf Lake Iris | 3 |
| Parnassia parviflora | Small-flowered Grass-of-Parnassus | 2 |
| Trisetum melicoides | Purple False Oats | 2 |
| Trisetum spicatum | Spike Trisetum | 2 |
Landscapes
The following Ecological Landscapes have the best opportunities to manage for Great Lakes Alkaline Rockshore, based on the Ecological Landscapes of Wisconsin Handbook.
| Ecological Landscape | Opportunity |
|---|---|
| Northern Lake Michigan Coastal | Major |
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
Great Lakes Alkaline Rockshore Photos
Dolomite pavement ("Great Lakes Alkaline Rockshore") on Hog Island, part of the Grand Traverse Islands Archipelago north of the Door Peninsula.
Photo by Emmet Judziewicz.
Great Lakes Alkaline Rockshore. Moonlight Bay, Door County.
Photo by Emmet Judziewicz.
Great Lakes Alkaline Rockshore and Boreal Forest. Toft Point, Door County.
Photo by Eric Epstein.
Aerial shot of Great Lakes alkaline rockshore on Lake Michigan, NE coast of Door Peninsula. Such sites may be partially or totally inundated when water levels are high, or during severe storms.
Photo by Eric Epstein.
NE tip of the Door Peninsula supports an upland forest of mesic hardwoods mixed with boreal conifers. Lake MI shoreline is characterized by level exposures of dolomitic bedrock.
Photo by Eric Epstein.
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.
