Introduction to Ecology and Management of Rare Plants of the Southeast
B. Collins
P. S. White
Donald W. Imm
This issue of Natural Areas Journal focuses on ecology and management of rare plants of the southeastern United States. This region lies mostly south of the Wisconsin glacial boundary and includes sections of the Coastal Plain, Piedmont, and Appalachian Highlands Physiographic Provinces. Lack of glaciation might have helped concentrate rare plants in the Southeast; varied geology, topography, and soils contribute to diverse habitats with rare plants. Habitat loss threatens rare plants of southeastern ecosystems. Development and fire exclusion have contributed to fragmentation and rarity in once widespread longleaf pine communities and in Florida scrub. Depression wetlands, which dot the southern coastal plain and are foci for rare plants, are often ditched or drained. Urbanization has fragmented rare plant populations along river corridors. The articles in this issue focus on the distribution of southeastern rare plants and some habitats of concern, and discuss ecological and management aspects of rarity. As rare plant populations decline in the southeast, detailed information on their distributions and ecological interactions can inform monitoring and management decisions.
Population Biology and Management of Rare Plants in Depression Wetlands of the Southeastern Coastal Plain, USA
Adrienne L. Edwards
Alan S. Weakley
One of the greatest challenges for conservation biologists is how to minimize biodiversity losses in the face of staggering habitat destruction. In the southeastern United States, a majority of the depression wetlands (Carolina bays, limesinks, and other landscape depressions) have been altered or destroyed. These wetlands harbor a large proportion of the region's rare species. Surprisingly, there is no single resource from which the patterns of rarity, life history characteristics, and vegetation alliances for species can be obtained. We extracted information from natural heritage program lists, floristic manuals, and primary literature to synthesize information on rare plants in isolated, seasonally ponded depression wetlands in the southeastern coastal plain. Out of 197 species of concern listed in six states, 69 were threatened to varying degrees, occurring in a few to approximately 100 populations (G1-G3G4 species), and 128 were relatively secure with 100 or more populations but were rare in a portion of their geographical ranges. Rare species in depression wetlands were predominately perennial and clonal (120 species), which reflects the prevalence of that life form throughout southeastern wetlands. The perennial and clonal growth form can influence population demographic and genetic structure, and should influence the management of rare plants in depression wetlands. To preserve rare species, it is important to know where they occur and what aspects of their habitats and biology most limit their persistence.