EFFECT OF AN AMMONIUM NITRATE PULSE ON THE GROWTH AND ELEMENTAL COMPOSITION OF NATURAL STANDS OF SPARTINA ALTERNIFLORA AND JUNCUS ROEMERIANUS

Abstract

A nitrogen (ammonium nitrate) pulse of 200 kg ha“ 1 was added to stands of tall (1.0–1.5 m) Spartina alterniflora , short (< 0.5 m) Spartina alterniflora , and Juncus roemerianus in a Georgia salt marsh in July. The major response ten weeks later was an increase in the aerial biomass and a sharp reduction in the C/N ratio in short Spartina alterniflora. One year after the treatment the difference between the biomass in enriched and control plots was greater than ten weeks after treatment, but the C/N ratio in the plants in the treated plots had risen to that of the controls. The availability of nitrogen appears to limit growth in the middle elevation Georgia salt marsh (short S. alterniflora ), but not in the lower (tall S. alterniflora ) or higher ( J. roemerianus ) portions.