Scale-dependent perspectives on beach-dune dynamics: a decade of field research at Greenwich Dunes, Prince Edward National Park

A seminal paper by Schumm and Lichty (1965, Am. J. Sci. 263; 110-119) was instrumental in demonstrating how a comprehensive and complete understanding of geomorphic systems necessitated deep knowledge about process-response dynamics across a range of temporal and spatial scales. Nevertheless, contemporary research that integrates knowledge across scalar domains remains surprisingly uncommon, perhaps because of methodological, theoretical, logistical, and pragmatic factors that inadvertently favor myopic perspectives on landform studies. A decade-long research agenda conducted on the north shore of PEI provides insights into major uncertainties associated with deploying process-based knowledge derived from plot (micro) scale experimentation on aeolian sediment transport across the beach-dune profile for the purpose of extrapolating to landform (meso) scale outcomes that are relevant to coastal resource managers. Results from short-term, instrumented experiments can only be understood within the broader context of the landform (meso) and landscape (macro) drivers and controls that mediate the potential range of short-term processes. For example, predicting the volume of sediment delivered to the foredune system annually is, to first order, dependent largely on the wind climatology and character of the beach sediments. However, long-term monitoring demonstrates that sediment delivery is also dependent on a much wider range of variables at the micro (e.g., moisture content, wind steering, turbulence production), meso (e.g., vegetation phenology, snow cover, fetch effects, nearshore sediment supply), and macro (e.g., sea-level rise, geological framework) scales. A proposed classification of system state variables is proposed for sandy beach-dune systems, predicated on the ideas of Schumm and Lichty (1965), that makes apparent some of these contextual inter-dependencies.