Salicornia virginica in a Southern California salt marsh: Seasonal patterns and a nutrient-enrichment experiment

Salicornia virginica (common pickleweed) is the dominant vascular plant of many saline marshes of the US west coast, yet little is known about seasona l patterns or abiotic factors controlling it. In a southern California salt marsh, quarterly sampling revealed strong seasonal trends, with 2x greater S. virginica biomass in summer than in winter. Tissue nitrogen (N) and pho sphorus (P) concentrations were highest in winter and lower in spring and s ummer, suggesting a dilution of nutrients as plants accumulated biomass dur ing the growing season. Despite high sediment nutrient levels in this marsh , an experiment examining N and P effects still found strong S. virginica r esponses to N applied biweekly for > 1 year. Increases in succulent tissue biomass after N addition were first seen in April 1998 (after fertilization for 11 months); two-fold increases in biomass and the number of branches r esulted by the end of the experiment in August 1998. Addition of N increase d N concentration in the woody tissues when sampled in August. The N:P rati o increased with N addition beginning in winter (7 months after fertilizati on began) and continuing through the remainder of the experiment. Effects o f P addition were less marked, as adding P did not result in biomass respon ses; however, it did influence tissue nutrient levels. These amendments inc reased P concentrations in the woody tissue in August 1998. In contrast to N amendments, which did not affect root nutrient concentrations, P addition led to increases in P content of root tissues in the latter portion of the growing season. These data suggest that increases in nutrients (especially N, but also P) can lead to large changes in S. virginica characteristics e ven in estuaries with high sediment nutrient levels.