Strategic Planting and Nutrient Amendments to Accelerate the Revegetation of Rapidly Retreating Coastal Dunes

The increasing frequency and severity of disturbances to coastal dune ecosystems requires developing and implementing restoration strategies that rapidly accelerate re-establishment of vegetation, enhance dune accretion, and ultimately preserve dune ecosystem services. To assess how to rapidly re-establish vegetation to counter ecosystem losses, we conducted a manipulative field experiment on a created foredune crest in Northeast Florida, USA to determine what combinations of planting density, outplant species composition, and nutrient addition maximize dune revegetation rate. Above-ground biomass in densely planted plots with added nutrients was 4.7-7.3 times that of plots planted at conventional restoration densities after only 3 months. Critically, thickly vegetated, high-density plots with nutrient addition accreted 1-5 cm more sediment after 3 months and 7.5-22 cm more sediment after 15 months, demonstrating that this planting method can rapidly kickstart dune-building processes. Additionally, above- and below-ground biomass in densely planted, fertilized plots containing bitter panicum (Panicum amarum) were consistently higher and accreted more sand than similar plots planted with sea oats (Uniola paniculata), suggesting that planting schemes involving this early successional species may be most effective for rapid dune-building. Synthesis and applications. Because coupling nutrient addition with dense planting can trigger self-sustaining, reinforcing plant growth and dune-building feedbacks within only months, this planting approach may help to enhance the long-term success of dune restoration projects.