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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.

Coarse woody debris (CWD) is an important component of fluvial systems affecting in-channel hydrology and sediment storage which in turn controls channel geometry and evolution. The role of coarse woody debris in coastal geomorphology is an emerging research field and this study investigates its role on mixed sand and gravel beach systems. A case-study approach is used whereby two field areas in Wellington, New Zealand, each with two distinct beaches with differing wood accumulations, were investigated through field surveying. It is found that on gravel beaches CWD is most important during storm events where it causes the berm crests to be 0.5–1.0 m higher than on unwooded beaches, as well as making the beachface twice as steep. During calm periods the berm appears to be inactive as non-storm waves can only rework the lower beachface. A review of the literature indicates that on sandy beaches CWD is most important in the post-storm recovery of beach systems. The same wave event that causes beach erosion also deposits the CWD. During calm periods the woody material is a trap for sand being transported along the beachface and therefore aids in re-establishing foredune systems. The differing sediment composition between sandy and gravelly beaches drives their morphological response to storm events and in turn determines how CWD interacts with the beach profile.

Niue is an uplifted limestone island, which preserves an atoll morphology with a sequence of terraces around its outer margin. A modern terrace fringes much of the island and this paper examines the extent to which this terrace can be considered accretionary and constructed by coral and coralline algae, or erosional and truncated by those processes that form shore platforms. The occurrence of Pleistocene limestone outcropping across this terrace and the continuation of caves and other karst features, dissecting the sub-aerial limestones, onto the forereef indicate the overall significance of erosion. At present live coral cover is restricted to isolated colonies growing in grooves, potholes and karstic channels eroded into the modern terrace surface. Coralline algae coat the outer margin of this terrace, and also veneer prominent surf benches that occur on the windward shore, 1–2 m above the terrace surface. Terrace evolution on Niue therefore appears to be primarily erosional in origin. There is little accommodation space for reef growth and, as a result, accretional fringing reefs are absent around most of the island. Erosional processes have also dominated landscape evolution for at least the past few eustatic cycles. Fringing reef growth is absent or severely restricted during the last interglacial and occurs as sporadic small reefs on the seaward margin of an erosional terrace during the penultimate interglacial. The development of terrace features in uplifting reef settings does not necessarily originate through accretional reef processes and may in fact be entirely erosional. Although reef terraces are frequently depositional in other settings, those present on Niue indicate a predominance of erosion, indicating the need to discriminate emergent terraces in terms of the extent to which they are erosional or accretionary when using such features to reconstruct island palaeoenvironments.