Calcareous glade

Calcareous glades are ecological communities found in areas with limestone near or at the surface, resulting in shallow soil and harsh conditions where trees cannot grow. These areas are typically sunny, dry, and hot, supporting vegetation similar to desert ecosystems, including small annuals and some perennials.

These glades occur in various regions across North America. In the Interior Low Plateau, particularly the Central Basin, calcareous glades, often referred to as cedar glades, are prominent. These areas support numerous endemic plant species, such as Echinacea tennesseensis and Leavenworthia uniflora. The Ozark Mountains also feature well-developed calcareous glades, primarily on dolomitic limestones, with indicator species like Cheilanthes feei and Oenothera macrocarpa.

In the Ridge-and-Valley Appalachians, stretching from Pennsylvania to Alabama, calcareous glades are notable for their high magnesium content in dolomitic soils. This region supports rare plant species such as Addison's leatherflower (Clematis addisonii) and Delphinium exaltatum. The southern end of this range, known as the Ketona Dolomite Outcrops in Alabama, has particularly high levels of plant endemism, with eight new species described since its recognition in 1992.

Threats to calcareous glades include urban development, but conservation efforts through protected areas and research initiatives, such as those at Middle Tennessee State University, aim to preserve these unique ecosystems.