Survey of Rare Plants Within a Calcareous Flatwoods Community and Analysis of Plant-Environmental Relationships

Abstract

ABSTRACT The Southern Ridge and Valley Calcareous Flatwoods community is represented by a diverse and unique plant association. Atypical edaphic processes may explain the presence of disjunct or nearly endemic species, including several federal/state endangered and rare species. To evaluate this community, we surveyed a 238-ha plot at Berry College (Floyd County, GA) within a known calcareous flatwoods habitat. Contiguous 30 m wide transects were surveyed for 12 focal species in 2018. Canopy photos and soil samples were taken at sites where focal plants were found, as well as at 30 random sites within the plot. Soils were analyzed for pH, lime buffer capacity (LBC), Ca, Mg, P, K, Mn, and Zn. Canopy photos were analyzed for variables related to canopy openness. Of focal species, only Asclepias hirtella (N=52) and Marshallia mohrii (N=12) were found during the survey. Contrary to expectations, this habitat was not uniformly high in Ca (mean 603 ppm) or pH (mean 4.8). Sites where focal species were found differed from random sites in LBC (lower for both species), variables related to canopy openness (higher for A. hirtella), Mg (higher for both species), and K (lower for A. hirtella). A principal components analysis supported these results; A. hirtella was associated with higher canopy openness and Mg, and lower LBC and K. We also report analogous results for nearby sites harboring target species, and demonstrate a probable effect of land cover on soil pH. Our results should inform decisions concerning management of calcareous flatwoods habitats and their characteristic species.