Soil Microbial Community Diversity Varies by Coastal Dune Successional Stage

Spaeth, M.K.; Miller, T.E.; Gornish, E.S., and Barberán, A., 2025. Soil microbial community diversity varies by coastal dune successional stage. Journal of Coastal Research, 41(5), 799–810. Charlotte (North Carolina), ISSN 0749-0208. Coastal sand dunes play a vital role in protecting inland ecosystems and urban areas against storm surges and sea-level rise, which will become increasingly important under human-induced climate change. While plant community dynamics have been found to benefit coastal dune resilience and resistance to disturbances, there has been relatively little investigation of soil microbial communities. Soil microorganisms play a vital role in coastal ecosystems by contributing to soil development, stabilization, and the mediation of plant productivity and diversity. In nutrient-poor environments like sand dunes, plant-microbe interactions are crucial due to their reliance on resource exchange. This study investigated soil microbial communities and whether they are primarily driven by abiotic or biotic conditions across successional habitats of a coastal dune system at St. George Island, Florida, southeastern United States, to help elucidate dune function and resilience. By assessing bacterial and fungal amplicon sequences across a disturbance gradient, it was found that different successional habitats harbored distinct soil communities, which varied in taxonomic diversity and microbial functional groups. Bacteria showed the greatest diversity in interdunes, whereas fungal diversity was greatest in the foredunes. Additionally, it was found that plant and soil characteristics were differentially associated with the soil microbial community based on habitat age, with pH and soil moisture as important compositional drivers. Overall, these findings highlight how coastal dune dynamics differentially influence above- and belowground biotic communities.