Oxidation‐reduction potentials in a salt marsh: Spatial patterns and interactions with primary production1

Abstract
Spartina alterniflora oxidizes the sediments in which it grows through both passive oxygen release and active metabolic processes. Eh is higher in the root zone of this grass than in the sediment below the root zone or in unvegetated sediments. Sediments underlying the tall form of S. alterniltorrt are more oxidized than those under the short form, and sediment redox condition and S. alterniflora production are related through a positive feedback loop. Reducing conditions inhibit aboveground grass production. But also, more productive plants have a greater capacity for sediment oxidation, as shown by the increased Eh in fertilized plots. Waterlogged sediments inhibit plan growth by decreasing passive oxygen release and thereby lowering Eh.