Intraspecific variation in three marsh grasses in response to increased flooding and salinity

Intraspecific variation in response to moderate levels of flooding and salinity stress was identified in Spartina patens, S. alterniflora, and Panicum hemitomon. This analysis enabled genotypes of each species to be selected for desired traits to enhance their function in restored systems, such as increased belowground biomass to stabilize soil substrates or increased aboveground biomass to enhance sedimentation. It was also determined that increased flood tolerance conferred a greater advantage for plant growth at moderate stress levels than did increased salt tolerance. However, this growth advantage was overridden by high salinity stress, and was greatly reduced by excessive flooding stress. Populations identified as more flood-tolerant were characterized as having greater total biomass, better ability to maintain relatively constant concentrations of nutrients with changing stress levels, and higher nutrient use efficiencies for nitrogen and phosphorous. Therefore, the use of the more flood-tolerant populations in deteriorating marshes would potentially restore high productivity and self-sustainability, both functions which are critical to the long-term success of restoration projects.