Investigations were conducted in 1971 and 1972 to characterize typical stands of sawgrass (Cladium jamaicense Crantz) in the southern Everglades. Estimates were obtained of standing crop, plant density, stem length, leaf numbers, growth rate, and nutrient relationships in plant tissue, soil, and water. Measurements were also made of daily rainfall and water depths. These various parameters were estimated monthly over a 12—18 mo period in mature stands, as well as in stands regrowing after wild fires. The mature stands showed little seasonal variation in standing crop, plant density, and concentration of most inorganic nutrients. Plant nutrient requirements were estimated to be low, because tissue levels of nutrients were low as compared to those of other species of Everglades macrophytes. Copper (Cu) and phosphorus (P) were particularly low. Levels of available nutrients in soil varied, with no seasonal pattern. Most nutrients were in adequate supply, except that available nitrogen (N), P, potassium (K) and Cu were generally very low. Reserve soil supplies of N and P were plentiful, but not of K. Accumulation of K in sawgrass leaves was more closely related to reserve supplies in soil than to available soil supplies. Waters in the marsh contained on an average 3%, 10%, and 8%, respectively, of the N, P, and K contained in a comparable area of sawgrass standing crop. Concentration of most nutrients in culms regrowing after fires was high during early growth stages, but decreased to levels found in older culms after 3—5 mo. Conenctrations of calcium (Ca), iron (Fe), and zinc (Zn) were exceptions, however. During the 1st year's growth after fires, 1 ha of sawgrass had accumulated 48 kg N, 1.8 kg P, and 38 kg K. After 18 mo growth, burned stands of sawgrass had produced only 38% of the standing crop contained in unburned mature stands. The apparent low nutrient requirements of sawgrass may partially explain the dominance of this plant in the marsh community.
