Coastal dune management affects above and belowground biotic characteristics

Dune vegetation mediates dune-building through trapping wind-blown sand and reduces dune erosion by attenuating wave energy via above- and belowground biomass. Despite the role of vegetation in dune functions, the amount and distribution of biomass within a dune remains poorly quantified due to a lack of ample data. Our objectives were to determine the effects of management history and elevation on (1) dune belowground biotic structure and aboveground community composition and (2) to determine best predictors of belowground biomass. We sampled belowground biomass and sedimentology across the dune profile at sites in the Outer Banks, North Carolina, USA. Dunes were classified as either unmanaged (no anthropogenic interventions) or managed (sand fencing, vegetation planting, dune construction). Living belowground biomass was higher in unmanaged dunes and decreased with depth. Non-living belowground biomass was 50% higher than living biomass and with greater abundance in unmanaged dunes. Elevation was a significant covariate of living and non-living belowground biomass, vegetative cover and species richness. Plant community composition varied less in managed dunes and differed significantly from unmanaged dunes. Vegetative cover, species richness, elevation, sedimentology and management history were predictors of belowground biomass. These results underscore the influence of management and geomorphology on dune plant communities, which may influence erosion resistance.