Downwind dune dynamics following Ammophila arenaria invasion

Konlechner, T.M.; Buckley, E.C.B.; Hilton, M.J., and Wakes, S.J., 2016. Downwind dune dynamics following Ammophila arenaria invasion. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 298–302. Coconut Creek (Florida), ISSN 0749-0208. The growth of large foredunes following invasion by non-native plants has been linked to changes in beach-dune sediment transfers, and the deflected evolution of transgressive dune systems. These changes have the potential to alter downwind plant communities by modifying habitats. This paper describes changes to a transgressive dune system in southern New Zealand following invasion by Ammophila arenaria and associated foredune development. Landforms were mapped using aerial imagery from 1958, when A. arenaria was present but not dominant, through to 2013. The landscape downwind of the foredune has evolved from a sparsely vegetated, sandy landscape, dominated by nebkha, to a landscape containing well-defined, long-walled parabolic dunes and stony deflation surfaces. These changes are associated with an increase in deflation surface habitat and plant species diversity, and a corresponding loss of habitat for species associated with dunal areas. The area of deflation surface has increased 18% to 31% of the study area while dune areas decreased from 74% to 51%. These results indicate species associated with transgressive dune systems are sensitive to variations in sand supply and changes in this supply may occur over decadal scales. Land managers are now restoring beach-hinterland sand exchange by destabilizing the foredune and adjacent parabolic dunes to encourage sand drift inland.