Measurements of stable carbon isotopic ratios as well as carbon (C), nitrogen (N), and phosphorus (P) contents in soils and plants were made along a chronovegetation sequence stretching from high marsh to low marsh in a coastal wetland in northwest Florida. The wetland is dominated by Juncus roemerianus , which is a C3 plant and has an average δ13C of −27‰. Lesser amounts of other species, including C4 plants, are also present in the area. The δ13C values of soil organic matter from low and middle marshes range from −24 to −27 ‰, which are consistent with the current plant community. However, the δ13C values of soil organic matter from high marsh show significant variations, from −23‰ in the surface...
