Common marsh plant species of the Gulf Coast area. Volume 1: Productivity.

As part of the U.S. Army Corps of Engineers Dredged Material Research Program, administered by the Environmental Effects Laboratory of the U.S. Army Engineers Waterways Experiment Station, Vicksburg, Mississippi, a study of the growth physiology of marsh plants common to the Gulf Coast area was conducted. The growth physiology study, concerned with the physiological ecology of stress, reports on several experiments on the ability of marsh plants to measure productivity over a two-year period of the following species: Distichlis spicata (salt grass), Juncus roemerianus (black rush), Phragmites communis (common reed), Spartina alterniflora (saltmarsh cordgrass), Spartina patens (saltmeadow cordgrass), and Sagittaria falcata (bulltongue). Productivity was found to be related to the growth habit and turnover rate. S. patens, J. roemerianus, and D. spicata were found to be more productive than S. alterniflora, a species that was known to be highly productive. Productivity was higher in the fresh and brackish marsh species than in the salt marsh species and was higher for species that grow throughout the winter than those that die to the ground in late fall. An evaluation was also made of several techniques for measuring productivity, including harvest, phenometric, and gasometric methods. The study showed that peak standing crop seriously underestimates production in the Gulf Coast marshes and that the Wiegert-Evans harvest techniques is the most realistic method presently available. This technique includes an estimate of mortality in addition to live biomass changes and so gives the closest estimate of true net aboveground production. The study also showed that phenometric methods have potential as a nondestructive technique that could be developed into a reliable method.