Coastal dunes arise from feedbacks between vegetation and sediment supply. Species-specific differences in plant functional morphology affect sand capture and dune shape. In this study, we build on research showing a relationship between dune grass species and dune geomorphology on the US central Atlantic Coast. This study seeks to determine the ways in which four co-occurring dune grass species (Ammophila breviligulata, Panicum amarum, Spartina patens, Uniola paniculata) differ in their functional morphology and sand accretion. We surveyed the biogeography, functional morphology, and associated change in sand elevation of the four dune grass species along a 320-kilometer distance across the Outer Banks. We found that A. breviligulata had dense and clumped shoots, which correlated with the greatest sand accretion. Coupled with fast lateral spread, it tends to build tall and wide foredunes. Uniola paniculata had fewer but taller shoots and was associated with similar to 42% lower sand accretion. Coupled with slow lateral spread, it tends to build steeper and narrower dunes. Panicum amarum had similar shoot densities and associated sand accretion to U. paniculata despite its shorter shoots, suggesting that shoot density is more important than morphology. Finally, we hypothesize, given the distributions of the grass species, that foredunes may be taller and wider and have better coastal protection properties in the north where A. breviligulata is dominant. If under a warming climate A. breviligulata experiences a range shift to the north, as appears to be occurring with U. paniculata, changes in grass dominance and foredune morphology could make for more vulnerable coastlines.
1.Oregon State Univ, Dept Integrat Biol, Corvallis, OR 97331 USA 2.US Army, Engineer Res & Dev Ctr, Coastal & Hydraul Lab, Field Res Facil, Duck, NC 27949 USA 3.Univ N Carolina, Dept Geol Environm & Sustainabil, Greensboro, NC 27412 USA 4.Oregon State Univ, Sch Civil & Construct Engn, Corvallis, OR 97331 USA 5.Univ N Carolina, Dept Geol Sci, Chapel Hill, NC 27514 USA 6.Oregon State Univ, Coll Earth Ocean & Atmospher Sci, Corvallis, OR 97331 USA
Recommended Citation:
Hacker, Sally D.,Jay, Katya R.,Cohn, Nicholas,et al. Species-Specific Functional Morphology of Four US Atlantic Coast Dune Grasses: Biogeographic Implications for Dune Shape and Coastal Protection[J]. DIVERSITY-BASEL,2019-01-01,11(5)