Miller, D.L.; Thetford, M.; Dupree, J., and Atwood, L., 2014. Influence of seasonal changes and shifting substrate on survival of restoration plantings of Schizachyrium maritimum (Gulf bluestem) on Santa Rosa Island, Florida.

Environmental gradients on barrier islands are modified by the loss of dunes as a result of hurricane overwash. The success of restoration plantings in posthurricane landscapes is determined by abiotic conditions, including seasonal and spatial gradients of wind speed and substrate transport encountered before dune redevelopment. The response of Schizachyrium maritimum, a dominant, sand-trapping, dune-forming grass of the northern Gulf Coast to month of planting, sand manipulation, and plant spacing was investigated on Santa Rosa Island, Florida. This grass is also a valuable food for endangered beach mice. Seasonal plantings were initiated in 4 months (November 2005, February 2006, June 2006, and August 2006) at each of six sites. For each site and each planting date, plots were split by plant spacing (30 or 45 cm between plants) and again by two sand manipulation regimes (natural sand accumulation or sand level at 3 cm). Sand surface levels were determined and manipulated every 2 weeks. Plant survival and growth were recorded September 2006 and July 2007. Plant survival and growth were greatest for summer plantings, particularly June plantings. Sand burial by natural accumulation did not result in plant death. Most plant death, particularly for November and February plantings, was associated with root exposure and sand loss around transplants. Closer spacing appeared to slow sand loss and plant death for November plantings. Planting of S. maritimum should be restricted to summer months, preferably June, and where sand loss can be minimized by use of mulch or other sand stabilizing methods.