Red Banks Alvar

State Natural Area (No. 332)

Location: Brown County. T25N-R22E, Sections 29, 32. 96 acres.

Access: No direct public access at this time. Contact the State Natural Areas Program for more information.

Description: Red Banks Alvar supports Wisconsin's best example of an alvar community - a rare community type that occurs on flat limestone or dolomitic bedrock with very shallow soils. An unusual blend of boreal, southern and prairie species, relicts of the post-glacial environment and the warmer, dryer period that followed, characterize alvar ecosystems. Red Banks Alvar contains one of the most diverse snail communities known in the Midwest and is one of the most important areas in Wisconsin for land snails. Colonies of 25 different groups of glacial relict snails can be found from the base to the top of the escarpment. Of interest are the number of rare and glacial relict snail taxa that are present including the cherrystone drop (Hendersonia occulta) and the Midwest Pleistocene vertigo snail (Vertigo hubrichti). In many aspects, the thin-soiled, sparsely vegetated landscape resembles a dry oak savanna dominated by open grown bur oak and white oak. However, the trees are not especially large owing to the harsh growing conditions but looks can be deceiving, as some of the oaks are very old. The shrub and sapling layer is dense in many areas with red cedar, common juniper, and snowberry. Rare plants include cream gentian (Gentiana alba), Crawe’s sedge (Carex crawei), and Richardson’s sedge (C. Richardsonii). Butterfly collections in the early 1980s documented at least 20 species within the oak savanna community. On the talus slope below the dolomite escarpment is an old-growth mesic forest dominated by sugar maple, slippery elm and basswood, with an understory characterized by a rich flora of spring ephemerals. Several plant species are at their northeastern range limit in Wisconsin at this site including American bladdernut, glade fern, and eastern wahoo. Red Banks Alvar is owned by the DNR and was designated a State Natural Area in 2001.