The Relationship of Mineral Nutrients to Growth of Spartina alterniflora in North Carolina: I. Nutrient Status of Plants and Soils in Natural Stands

Abstract

Multiple regression analysis was utilized to examine relationships between nutrient concentration in the plant tissue and/or nutrient status of the soil and differences in productivity of Spartina alterniflora, among marshes and between height zones within marshes. The tall and short height zones of seven natural stands of S. alterniflora were sampled three times during the growing season. These stands were representative of variations in latitude, tide range, and type of substrate which occur along the North Carolina coast. The 48 independent variables in the original data consisted of 11 different mineral nutrients in the plant tissue at each of three sampling times, the salinity of the soil solution at each sampling time, and 12 soil chemical and physical properties. The dependent variables chosen as measures of productivity were yield (dry weight) and height. From the independent variables, the “best” regression model was selected using the maximum R2 improvement procedure, the stepwise regression procedure, and critical examination of the independent variables. Results indicated that plant tissue concentrations of several nutrients and several soil properties were significantly associated with variations in yield and height of S. alterniflora. Important variables positively associated with yield included P concentration in the plant tissue and in the soil. Variables negatively associated with yield included salinity of the soil solution, Mn concentrations in the plants and soil, and S concentrations in the plants. Regression equations for predicting standing crop of nutrients from dry weight of the grass are also presented.