The Distribution and Growth of Salicornia Europaea on an Inland Salt Pan

The nature of the distribution of plant species along a soil salinity gradient at Rittman, Ohio, indicates that there is a definite relationship between soil salinity concentrations and the position of plant species along this environmental gradient. Only a single species of flowering plant, Salicornia europaea, was found growing at the most extreme portion of the salinity gradient. Soil samples collected from sites dominated by S. europaea had salinity levels which yielded in situ electrical conductivities ranging from 18.9 to 142.8 mmhos/cm, Atriplex triangularis grew at sites with intermediate levels of soil salinity, 3.9 to 40.0 mmhos/cm, and Hordeum jubatum dominated the least saline sites, 1.1 to 14.0 mmhos/cm, which were directly adjacent to a nonsaline meadow. Salicornia europaea had high levels of mortality during the spring and early summer months of the growing season, with the mean number of seedlings ranging from 58 plants per 100—cm² quadrat in May to a mean value of 18 mature plants per quadrat at the end of the growing season in October. At the most highly saline sites containing S. europaea, seedling numbers ranged from a mean of 5 plants per 100—cm² quadrat in May to 1 mature individual per quadrat by October. Transplants of S. europaea had the highest standing crop biomass levels in the Atriplex and Hordeum zones, with dry weight production decreasing in zones of both higher and lower soil salinity. Laboratory investigations indicated that S.europaea reached its optimal growth in nutrient solution treatments containing 170 meq/1 and 340 meq/1 NaC1. Germination of seeds of S. europaea under field conditions occurred over an extended period of time, from February through June, when soil salinity levels were lowest. Seed germination was not stimulated by treatments with salt and maximum germination percentages occurred in distilled water controls.