Rock Outcrop Plant Communities (Glades) in the Ozarks: A Synthesis

Abstract

stress. Perennial grasses are largely confined to edges of openings adjacent to surrounding forest. The distinct vegetational zones of shallow soil are dominated by annual dicots, annual grasses, and perennial dicots, including some endemic species; these are called glades in the Southeast. In the Ozarks, glade areas are typically strongly sloping, so that soil erosion frequently exceeds weathering of bedrock. Soil removal rates vary greatly over short distances, producing a mosaic of soil depths and, thus, a mosaic of plant species with different depth requirements. Plants with different soil depth requirements are intermixed or distributed in small patches, rather than in distinct zones, so fire-supporting perennial grasses are interspersed among shallow soil herbs and patches of deeper soil that support cedar trees (Juniperus). Perennial grasses support periodic fires that kill most woody plants and promote continued grass abundance. Because shallow soil plants are interspersed among deeper soil plants in the glade mosaic, studies of vegetation of glades (the total vegetational mosaic) in the Ozarks find perennial grasses and cedars dominant, with shallow-soil plants, including endemics, as minor associates.