Net Primary Productivity of Spartina densiflora Brong in an SW Atlantic Coastal Salt Marsh

Coastal marshes are known as organic matter producers. The goal of this work is to study tiller demography, standing biomass, and net aerial primary productivity (NAPP) in a Spartina densiflora coastal wetland, using a method applied to permanent sample plots located at two sites differing in topographic location, a regularly flooded zone [relative low marsh (LM)] and an irregularly flooded one [relative high marsh (HM)]. Measurements were made every 2 months during the 2005-2007 period. The annual NAPP was estimated to be 2,599 +/- 705 gDW m(-2) year(-1) for the HM and 2,181 +/- 605 gDW m(-2) year(-1) and 602 +/- 154 gDW m(-2) year(-1) for the first and second period of the LM populations, respectively, showing a seasonal pattern reaching maximum values in summer. The reduced NAPP values of the LM sites in the second year was associated with an extremely high precipitation period related to the 2007-2008 El Nio event.