Vegetation of cedar glade area near Mascot, Tennessee, and observations on the autecology of three Arenaria Taxa

Cedar glade vegetation near Mascot, Tennessee, was examined with the view of characterizing the vegetation and soil. The area was sub divided into belts for sampling purposes. Plant succession follows soil development from lichen-covered bare rock, to herb dominated gravel pockets, to an herb-moss ecotone, to the cedar forest, and to the oak forest. Cover, frequency, and, for tree species, density and basal area were determined for plant taxa by community. Soil measurements showed that in the above sequence, depth to bedrock and per cent organic matter increased, but pH decreased. Exchangeable calcium and potassium occurred at maximum levels in the cedar community—magnesium concentration was greatest in the oak forest. The flora shared 19.8 per cent of its taxa with a glade flora in Middle Tennessee and 30.2 per cent with the barrens of the Oak Ridge area. Arenaria patula, Caryophyllaceae, which grows in the glade, was studied autecologically along with two relatives. Chromosome counts gave tentative diploid numbers: A. patula - 2n=30, A. groenlandica var. glabra—2n=20; Stipe's count of A. brevlfolla—2n=l4 was substantiated. Sand culture with concentrations of 2, 5, 25, 50, and 300 ppm. calcium in the nutrient solution and subsequent measurements of four plant characteristics showed that A. patula responded best of the three to high calcium concentrations, suggesting that its persistence in the glades is at least partly due to its physiological requirements met in this unique environment.