Crossing scales: The complexity of barrier-island processes for predicting future change

Barrier islands are heavily influenced by external drivers such as sea-level rise, storm-related disturbances, and other complex factors that affect net sediment exchange. Numerous ecological processes (e.g., dispersal, competition, and facilitation) interact with these drivers and ultimately influence barrier-island state change and therefore stability. Our synthesis of physical and ecological processes controlling barrier-island function highlights the importance of incorporating ecological factors into predictive models of barrier-island state change. We present a conceptual framework that outlines how local-scale processes contribute to broadscale patterns of barrier-island function. We have also identified specific, scale-dependent drivers and cross-scale interactions that lead to different topographic states, which vary in species composition, and generate contrasts in function between and within individual islands. This multidimensional continuum of topographic states ultimately determines island resilience in response to climate change.