Patterns of early-colonising species on eroding to prograding coasts; implications for foredune plant communities on retreating coastlines

Abstract

Shoreline erosion is predicted to increase as the result of climate change, yet the effects on foredune-building species and associated dune processes remain poorly understood. To predict the response of foredune plant communities to increased erosion we examined the abundance of six early colonising dune-building species across 71 beach-foredune sites in south-east Australia. The assumption being that those species better adapted to shoreline retreat will be more frequent and have increased abundance on erosional coasts than species lacking the capacity to withstand or re-establish following periods of storm-induced erosion. All species were frequently recorded regardless of the rate of shoreline progradation or erosion, which ranged 3.8 to −2.2 m year−1. Species presence was not related to erosion rates; however, there was a significant association between the rate of shoreline change and abundance for some of the studied species. Variation in traits related to tolerance to salinity and burial and the ability to establish following erosion appear to correspond to the observed patterns of species abundance. While this study examined only six species, it appears that species that are restricted to zones closer to the spring-tide level, that have a persistent rather than opportunistic growth-history or that are limited in their ability to recolonise following erosion, are more likely to be negatively impacted by increased rates of coastal erosion. Given the association between vegetation and foredune morphology these findings have important implications for the management of sandy coasts.