Bracken grasslands occur in northern Wisconsin on upland sites with infertile sandy soils. These communities are dominated by bracken fern (Pteridium aquilinum), Pennsylvania sedge (Carex pensylvanica), Kalm's brome grass (Bromus kalmii), and Canada bluegrass (Poa compressa). Other common herbs include poverty-oat grass (Danthonia spicata), Lindley's aster (Symphyotrichum ciliolatum), gray goldenrod (Solidago nemoralis), and common strawberry (Fragaria virginiana). Some sites have variable coverages of low shrubs such as blueberries (Vaccinium angustifolium and V. myrtilloides), sweet fern (Comptonia peregrina), prairie willow (Salix humilis), and hazelnuts (Corylus spp.). Non-native plants are often present on these sites and sometimes reach relatively high cover value, though not all are ecologically invasive.
The origin of this type is unclear, but apparently includes an interacting mixture of topographic and edaphic conditions, past disturbance history, and perhaps some degree of allelopathy due to the abundance of bracken fern. The community is fire-dependent, was probably maintained by relatively frequent ground fires, and on some landforms is associated with low-lying frost pockets where frosts occur during the growing season.
