Aboveground Net Primary Productivity of Three Gulf Coast Marsh Macrophytes in Artificially Fertilized Plots

Abstract

Plots (100 m2) of four tidal marsh communities (Juncus roemerianus and Spartina alterniflora in Alabama, J. roemerianus and Spartina cynosuroides in Mississippi) common in the Gulf Coast were enriched with commercial NH4NO3 (34 percent N). The fertilizer was applied once at the beginning of the 1978 growing season to simulate a farm-plantation operation at a dosage (136 g/m2) estimated to return to the soil approximately the same amount of nitrogen contained in the plants. Six 0.25 m2 quadrats were harvested monthly from each community from April through November. The annual net productivity was estimated with a maximum minus minimum standing crop technique based on a predictive periodic model (PPM). A correction for plant mortality during the sampling period is provided in the PPM technique. Annual aboveground net primary productivity increased by 59 percent in the Alabama J. roemerianus, 84 percent in the Mississippi J. roemerianus, 82 percent in the S. alterniflora and 26 percent in the S. cynosuroides. It appears that short form or high marsh macrophytes responded more to nitrogen enrichment than tall form or low marsh plants.KeywordsSalt MarshGulf CoastMarsh PlantHigh MarshMarsh CommunityThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.