Robert W. Freckmann Herbarium
University of Wisconsin - Stevens Point

Vascular Plants

Plants of Wisconsin

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Natural Communities
Keyword: Savanna


Click on community name for photo gallery.

Cedar glade
Dry sandstone, quartzite or dolomite exposures vegetated with dense thickets of red cedar (Juniperus virginiana). Red maple (Acer rubrum), Paper birch (Betula papyrifera) and black and bur oaks (Quercus velutina and Q. macrocarpa) may also be present. This community is usually if not always the result of fire suppression on dry prairies, and in pre-settlement times it may have occurred only where extensive cliffs served as firebreaks. Common herbs include bluestem and grama grasses (Andropogon spp. And Bouteloua spp.), prickly-pear cactus (Opuntia compressa), flowering spurge (Euphorbia corollata), stiff sandwort (Arenaria stricta) and gray goldenrod (Solidago nemoralis).

Great Lakes barrens
In Wisconsin, this variant of pine savanna is known from only one sandy site on Lake Superior. The dominant trees in this open stand are wind- and fire-deformed trees, red pines (Pinus resinosa) with white pine (P. strobus) also present. The understory consists of dense growths of lichens with scattered thickets of common juniper (Juniperus communis), early blueberry (Vaccinium angustifolium) and huckleberry (Gaylussacia baccata). Other common plants are hairgrass (Deschampsia flexuosa), ticklegrass (Agrostis hyemalis), false-heather (Hudsonia tomentosa), and bearberry (Arctostaphylos uva–ursi).

Oak barrens
Black oak (Quercus velutina) is the dominant tree in this fire-adapted savanna community of xeric sites, but other oaks may also be present. Common understory species are lead plant (Amorpha canescens), black-eyed susan (Rudbeckia hirta), round-headed bush clover (Lespedeza capitata), goat’s rue (Tephrosia virginiana), june grass (Koeleria cristata), little bluestem (Schizachyrium scoparium), flowering spurge (Euphorbia corollata), frostweed (Helianthemum canadense), false Solomon's-seals (Smilacina racemosa and S. stellata), spiderwort (Tradescantia ohioensis), and lupine (Lupinus perennis). Distribution of this community is mostly in southwestern, central and west central Wisconsin.

Oak opening
As defined by Curtis, this is an oak-dominated savanna community in which there is less than 50% tree canopy. Historically, oak openings occurred on wet-mesic to dry sites. The few extant remnants are mostly on drier sites, with the mesic and wet-mesic openings almost totally destroyed by conversion to agricultural or residential uses, and by the encroachment of other woody plants due to fire suppression. Bur, white, and black oaks (Quercus macrocarpa, Q. alba and Q. velutina) are dominant in mature stands as large, open-grown trees with distinctive limb architecture. Shagbark hickory (Carya ovata) is sometimes present. American hazelnut (Corylus americana) is a common shrub, and while the herblayer is similar to those found in oak forests and prairies, with many of the same grasses and forbs present, there are some plants and animals that reach their optimal abundance in the “openings”.

Oak woodland
This “forest” community is structurally intermediate between Oak Openings and Southern Dry Forest. The tree canopy cover is high, but frequent low-intensity fires and possibly (in pre-settlement times) browsing by herbivores such as elk, bison, and deer kept the understory relatively free of shrubs and saplings. Much additional information is needed but it appears that at least some plants (certain legumes, grasses, and composites among them) reached their highest abundance here.

Pine barrens
This savanna community is characterized by scattered jack pines (Pinus banksiana), or less commonly red pines (P. resinosa), sometimes mixed with scrubby Hill's and bur oaks (Quercus ellipsoidalis and Q. macrocarpa), interspersed with openings in which shrubs such as hazelnuts, (Corylus spp.) and prairie willow (Salix humilis) and herbs dominate. The flora often contains species characteristic of "heaths" such as blueberries (Vaccinium angustifolium and V. myrtilloides), bearberry (Arctostaphylos uva-ursi), American hazelnut (Corylus americana), sweet fern (Comptonia peregrina), and sand cherry (Prunus pensylvanica). Also present are dry sand prairie species such as june grass (Koeleria macrantha), little bluestem ( Schizachyrium scoparium), silky and sky-blue asters (Aster sericeus and A. azureus), lupine (Lupinus perennis), blazing-stars (Liatris asper and L. cylindracea), and western sunflower (Helianthus occidentalis). Pines may be infrequent, even absent, in some stands in northern Wisconsin and elsewhere because of past logging, altered fire regimes, and an absence of seed source.


Offsite resources:
Virginia Kline's collection of the Vegetation of Wisconsin
Michigan Natural Features Inventory Community descriptions

Vascular Plants

Plants of Wisconsin

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