Coastal dunes are highly vulnerable to global climate change because of the tight couplings among island ecological processes, geomorphological processes, and oceanic/atmospheric drivers of disturbance. Dune stabilization is influenced by vegetation with plant roots reducing erosion and aerial stems and leaves intercepting aeolian transported sediments. Recent studies have shown that the belowground structures of dune vegetation are important in reducing erosion. However, these studies primarily focus on total belowground biomass in established dunes or focus on species involved in embryonic dune building. Species-specific carbon allocation patterns to different belowground organs (roots, stems, and rhizomes) and root traits from established dunes may influence sediment capture and erosion resistance in the dune environment. Our objective is to characterize the belowground components and traits of four dominant dune grasses from established dunes. Whole plant samples of dominant dune building species along the US Atlantic coast (Ammophila breviligulata, Uniola paniculata) and secondary dune species (Panicum amarum, Spartina patens) were collected along the dune face from the US Army Corps of Engineers Field Research Facility in Duck, NC. Plants were analyzed for a variety of root traits, mycorrhizal infection, biomass, and root tensile strength.
Results/Conclusions
Analyses of root traits revealed that the four species differed significantly. Ammophila and Uniola differed significantly in specific root length. Both Ammophila and Spartina had significantly lower root surface area to volume ratios than Uniola. Ammophila and Spartia also allocated a greater percentage of total root surface area to small diameter roots than Uniola and Panicum. Roots of small average diameter (0.0-0.5 mm) exhibited the strongest root tensile strength values, suggesting that greater belowground investment in these fine roots has the potential to provide higher mechanical reinforcement to dunes. Additionally, Ammophila (2879 MPa) and Spartina (4315 MPa) exhibited greater maximum tensile strength values than Panicum (1374 MPa) and Uniola (1281 MPa). These data indicate that Ammophila and Spartina root systems are composed of smaller diameter roots which exhibit greater tensile strength than those of Uniola and Panicum. Species also differed in mycorrhizal percent infection, which may indicate different mycorrhizae-mediated erosional effects. These data may inform evaluations and models of dune erosion and assist in dune restoration companion planting methods to maximize below- and aboveground erosional resistance and ecosystem services.