Foredune biogeomorphology in southeast Australia

Foredunes are important coastal landscapes that provide nature-based defence against coastal hazards. Vegetation plays a crucial yet often overlooked role in shaping the morphology of foredunes globally. Along the southeastern (SE) coast of Australia, which contains a diverse range of foredune environments characterised by conspicuous horizontal zonation and latitudinal gradients in dune vegetation species, the specific influence of plant species on foredune morphology is only just becoming apparent. Extending projects commenced in the 1980's, this study examines the biophysical interactions between dune vegetation and foredune morphology in the state of New South Wales (NSW). Using a combination of airborne LiDAR, and in situ field surveys, foredune morphometrics (including dune width, height and volume) and vegetation were analysed at 45 sites along the NSW coastline. Clear relationships are apparent between foredune morphology and vegetation composition. Seven distinct morphological foredune shapes were identified, each associated with specific vegetation assemblages, indicating an interplay between vegetation dynamics and landform development. In doing so, this study also explores the relative roles of dominant plant species within the foredune setting and examines latitudinal variations along the coast. Understanding these biophysical interactions can enhance dune resilience. Invasion of weeds, such as Chrysanthemoides sp. (Bitou Bush), has been shown to completely change the biogeomorphological characteristics of a coastal dune system necessitating significant management efforts. The detailed insights provided by this research offer valuable information for coastal managers and researchers, facilitating customised approaches to dune management, modelling and conservation in SE Australia and beyond.