Extensive ecological research has been conducted in order to understand abiotic conditions structuring vegetative zonation, as well as succession on the coastal sand dunes. However, few studies have examined the role of this environmental gradient in shaping intraspecific plant trait variation. We investigated whether microhabitat variation drives plant trait variation in Uniola paniculata, the dominant grass species on the southeastern Atlantic and Gulf coastal dunes. Multiple interacting environmental factors, including soil salinity, soil nutrients, and sand burial, vary across dynamic to stabilized dunes. Since Uniola paniculata occurs across a range of dune habitats, we expected that plant trait variation would track variation in abiotic factors. Environmental factors, including percent cover, elevation, soil salinity, soil moisture, organic matter, macro- and micro- soil nutrients, as well as plant traits were assessed at sites on transects perpendicular to the shoreline, across the dunes on Sapelo Island, GA. Plant traits measured included height, stem diameter, leaf number, xylem water potential, and nutrient concentrations.

Results/Conclusions

We found that several abiotic factors tended to varied along the environmental gradient. Specifically, soil nitrogen and boron increased with distance from the foredune, while soil potassium, magnesium, sodium, as well as pH and soil salinity decreased at greater distances from the shoreline. Additionally, percent plant cover increased significantly away from the shoreline. Plant morphological traits varied across the environmental gradient, with height and stem diameter greatest closest to the dynamic foredunes. However, aboveground biomass did not vary across the gradient. Future studies will determine the evolutionary responses of Uniola paniculata populations to microhabitat variation.