Field‐grown coastal dune plants exhibit similar survival, growth, and biomass in recycled glass substrate and natural beach sand

Restoration of coastal dunes following tropical storm events often requires renourishment of sand substrate dredged from offshore sources, although dredging has well‐described negative ecological impacts and high economic costs. As a potential solution, recycled glass sand (cullet) made from crushed glass bottles has been proposed as a potential replacement for dredging. However, glass sand substrates may have limited ability to provide support to coastal plant communities due to the absence of native soil microbial communities. To explore the potential use of glass sand as a substrate for dune plants in the Northern Gulf of Mexico, we compared the growth of Sea oats ( Uniola paniculata ), Beach morning‐glory ( Ipomoea imperati ), and Railroad vine ( I. pes‐caprae ) in glass sand to growth in live beach sand. To determine if inoculation of glass sand with native soil microbial communities improved survival, growth, and biomass production, we also tested plant growth in glass sand with native microbial amendments. Overall, we found no difference in the survival of the three dune species across three soil treatments and weak differences in plant growth and biomass production across our soil substrates. Our results suggest that glass sand substrates may be a viable option for coastal dune restoration, with limited differences between live beach sand, glass sand, and glass sand inoculated with native soil microbes. Restoration and replenishment of coastal dunes using glass sand as a substrate following tropical storms or sea‐level rise may allow coastal managers to reduce the economic and ecological damage associated with offshore sediment dredging.