A FLORISTIC PLANT ECOLOGY STUDY OF THE LIMESTONE GLADES OF NORTHERN ALABAMA

Lists of vascular plants were compiled for 22 limestone glades in northern Alabama, including 16 in the Moulton Valley. A total of 233 native and 36 nonnative taxa were identified in the limestone glades. Families with the highest number of species were Asteraceae (34), Poaceae (29), and Fabaceae (20); genera with the highest number of species were Aster (5) and Euphorbia (5). Sixty-six of the taxa (63 native, 3 nonnative) occurred in 9 or more limestone glades (presence class 3, 4, or 5). Species present in 18 or more limestone glades (presence class 5) were Agave virginica, Arenaria patula, Diodia teres, Erigeron strigosus, Hypericum sphaerocarpum, Isanthus bractiatus, Juniperus virginiana, Opuntia humifusa, Ruellia humilis, and Sporobolus vaginiflorus. Woody plants with the highest presence values were Juniperus virginiana, Rhus aromatica, and Ulmus alata. Each of the 16 limestone glade endemics known to be extant in northern Alabama occurred in one or more of the 22 glades. Endemics with the highest presence values were Dalea gattingeri (68.2%), Leavenworthia alabamica (59.1%), and Oxalis priceae ssp. priceae (54.5%). Greater than 90% of the 36 nonnative taxa were in presence classes 1 and 2, and none was in presence classes 4 or 5. Seventy-six and six-tenths percent of the 269 taxa are hemicryptophytes or therophytes, and 89.2% of them have the C-3 pathway of photosynthesis. The flora and vegetation of the limestone glades of northern Alabama are similar to those of the Central Basin of Tennessee. Dominant vascular plants in the vegetation of both areas are the C-4 summer annual grass Sporobolus vaginiflorus and C-3 annual and perennial dicot herbs.