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

Lists of vascular plants were compiled for 22 limestone glades in nort hern Alabama, including 16 in the Moulton Valley. A total of 233 nativ e and 36 nonnative taxa were identified in the limestone glades. Famil ies 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 nonn ative) 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 strigos us, Hypericum sphaerocarpum, Isanthus bractiatus, Juniperus virginiana , Opuntia humifusa, Ruellia humilis, and Sporobolus vaginiflorus. Wood y plants with the highest presence values were Juniperus virginiana, R hus aromatica, and Ulmus alata. Each of the 16 limestone glade endemic s known to be extant in northern Alabama occurred in one or more of th e 22 glades. Endemics with the highest presence values were Dalea gatt ingeri (68.2%), Leavenworthia alabamica (59.1%), and Oxalis priceae ss p. 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. Sev enty-six and six-tenths percent of the 269 taxa are hemicryptophytes o r therophytes, and 89.2% of them have the C-3 pathway of photosynthesi s. The flora and vegetation of the limestone glades of northern Alabam a are similar to those of the Central Basin of Tennessee. Dominant vas cular plants in the vegetation of both areas are the C-4 summer annual grass Sporobolus vaginiflorus and C-3 annual and perennial dicot herb s.