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Ryan O'Connor
Natural Heritage Inventory Ecologist

Lake--Hard Bog

State Rank: S2     Global Rank: GNR   what are these ranks?


General natural community overview

Counties shaded blue have documented occurrences for Lake--Hard Bog in the Wisconsin Natural Heritage Inventory database.

Small lakes (<10Ac) with alkalinity of > 50 ppm and high pH.

The pH of hard bog lakes is at or slightly above neutral, due to groundwater influence. This mineral-rich environment commonly supports a genus of macroalgae called muskgrass (Chara spp.), which in turn supports diverse aquatic invertebrates. As the muskgrasses extract carbon dioxide from calcium bicarbonate, they produce calcium carbonate which precipitates on the lake bottom in the form of marl. Many muskgrass populations have a hard or crunchy texture due to the crusty layer of marl that often precipitates on the plant's surface. If nutrient levels get very high, eutrophication may occur, resulting in a muddy false bottom as the remains of poorly decomposed microscopic plants and animals accumulate. A quaking sedge mat (often Carex lasiocarpa) typically occupies the margins of the lake, providing a substrate for pioneering Sphagnum. If conditions allow (e.g., low lake levels during dry years), this sedge mat may advance into the lake and eventually transition to poor fen. Indicators of groundwater influence are present in the vegetation surrounding the lake, even during later successional stages of the bog mat. These include distinctive species such as white beak-rush (Rhynchospora alba), bogbean (Menyanthes trifoliata), pink-flowered orchids ((grass pink (Calopogon tuberosus), rose pogonia (Pogonia ophioglossoides)), dragon's-mouth (Arethusa bulbosa), and tamarack (Larix laricina). Associated fish species include central mudminnow, yellow perch, golden shiner, fathead minnow, northern redbelly dace, finescale dace, and brook stickleback.

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 Lake--Hard Bog 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.

Blanchard's Cricket FrogAcris blanchardi3
Mink FrogLithobates septentrionalis3
Pickerel FrogLithobates palustris2

A Minute Moss BeetleOchthebius lineatus2

Black TernChlidonias niger2
Common GoldeneyeBucephala clangula2
Common TernSterna hirundo1
Forster's TernSterna forsteri1
Red-necked GrebePodiceps grisegena1

A Giant Casemaker CaddisflyBanksiola dossuaria2
A Phryganeid CaddisflyBeothukus complicatus2

Dragonflies and damselfliesScore
Lake EmeraldSomatochlora cingulata3
Mottled DarnerAeshna clepsydra3
Pronghorn ClubtailGomphus graslinellus3
Spatterdock DarnerRhionaeschna mutata3
Unicorn ClubtailArigomphus villosipes3
Double-striped BluetEnallagma basidens2
Slaty SkimmerLibellula incesta2
Spangled SkimmerLibellula cyanea2
Lilypad ForktailIschnura kellicotti1
Painted SkimmerLibellula semifasciata1
Subarctic DarnerAeshna subarctica1

Redfin ShinerLythrurus umbratilis1

Big Brown BatEptesicus fuscus3
Little Brown BatMyotis lucifugus3
Northern Long-eared BatMyotis septentrionalis2
Silver-haired BatLasionycteris noctivagans2
Tricolored BatPerimyotis subflavus1
Water ShrewSorex palustris1

Blanding's TurtleEmydoidea blandingii3
Eastern RibbonsnakeThamnophis sauritus3
Wood TurtleGlyptemys insculpta2
Western RibbonsnakeThamnophis proximus1

Please see Section 2. Approach and Methods of the Wildlife Action Plan to learn how this information was developed.


The following Ecological Landscapes have the best opportunities to manage for Lake--Hard Bog, 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


Lake--Hard Bog Photos

Lake--Hard Bog Photo

Photo by Thomas Meyer.

Lake--Hard Bog Photo

Photo by Aaron Carlson.

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