Foliar release of soluble reactive phosphorus from Spartina alterniflora in a Georgia (USA) salt marsh

Foliar release of soluble reactive phosphorus (SRP) from live shoots of Spartina alterniflora (Loisel.) was investigated in a Georgia (USA) salt marsh. Average foliar SRP release rates varied from undetectable to 7.5 μg P (g dry wt)−1 h−1 with values from individual plants as high as 61.7 μg P (g dry wt)−1 h−1. Release rates of SRP generally exhibited little diel variation and were highest in midsummer. Estimates of extrafoliar SRP accumulated on leaf surfaces varied from < 1 to 41 μg P (g dry wt leaf)−1 and 0.8 to 1.7 mg P m−2 normalized to marsh area. Time course experiments revealed that SRP release was a 2-step process with a rapid solubilization of extrafoliar SRP and a constant release thereafter. Releases of SRP from creekbank stands of S. alterniflora during tidal submergence were estimated to be 3.1 to 8.2 mg P m−2 d−1, with annual releases of 1.7 g P m−2 yr−1. Foliar releases of SRP from the live plants are equivalent to 60 % of the annual production of particulate phosphorus as S. alterniflora detritus reported from Georgia salt marshes.