Drawing heavily on the work of J. Roger Bray, Curtis classified the cedar glades of Wisconsin as savannas–sparsely wooded communities with a ground layer that included species commonly found in dry areas. The cedar glades are named for the dominant tree, eastern redcedar (Juniperus virginiana). This species is capable of tolerating extremely poor soils and extended drought. On the pre-settlement landscape of Wisconsin, cedar glades were limited to fire-protected sites that included dry prairie flora. Such sites tend to have thin sandy soils, and the savanna character of cedar glades in Wisconsin was likely maintained by a combination of poor soil and infrequent fire. In the absence of fire, cedar glades, like many other midwestern communities, have changed due to encroachment of woody plants.
A recent (2004) comparison of the contemporary cedar glade vegetation to Plant Ecology Laboratory records from the 1950s revealed that redcedar remains the dominant woody plant, though it now forms closed canopies. Although some savanna and prairie plants can still be observed in cedar glades, canopy closure has led to the replacement of these understory species (such as big and little bluestems, bird's-foot violet, candle anemone, and lead plant) by shade-tolerant species (such as Virginia creeper, poison ivy, dandelion, and enchanter's-nightshade). Wisconsin cedar glades have become more similar in species composition to one another and adjacent upland deciduous forests. The number of exotic taxa and the abundance of exotic individuals have increased, although native species still account for ~90% of plants present in the understory.
- WI DNR webpage on Cedar Glades