Tales of island tails: biogeomorphic development and management of barrier islands

Abstract

The Frisian islands (Southern North Sea) have extensive island tails, i.e. the entire downdrift side of an island consisting of salt marshes, dunes, beaches and beach plains, and green beaches. Currently, large parts of these tails are ageing and losing dynamics, partly due to human influence. This may mean a loss of young stages on the long term, and current management is not enough to counteract this. To aid the development of new interventions aiming at (re)introducing natural dynamics, a conceptual model of island-tail development under natural and disturbed conditions was developed, based on existing data, field visits and literature. The development of an island tail follows the general pattern of biogeomorphic succession. The first phase consists of a bare beach plain. In the second phase, embryonic dunes form. In the third phase, green beaches, dunes and salt marshes form, including drainage by creeks and washovers. In the fourth phase, vegetation succession continues and the morphology stabilises. Human interference (such as sand dikes and embankments) reduces natural dynamics and increases succession speed, leading to a reduction in the diversity in landforms and vegetation types. Both for natural and human-influenced island tails, succession is the dominant process and large-scale rejuvenation only occurs spontaneously when large-scale processes cause erosion or sedimentation. Island tails cannot be kept permanently in a young successional stage by reintroducing natural dynamics through management interventions, as biogeomorphic succession is dominant. However, such interventions may result in local and temporal rejuvenation when tailored to the specific situation.

Is ‘re-mobilisation’ nature restoration or nature destruction? A commentary

“…A large dune field with a mix of mobile and fixed dunes with bare patches may be regarded as good because of the contrasting views and wide range of flora and fauna, but it is just one manifestation of natural dune landscapes and no better or worse than any other. In fact, it usually represents just one stage of several possible evolutionary stages (Hesp 2013;de Groot et al 2017;Pickart and Hesp 2019).…”

Remobilizing stabilized island dunes for keeping up with sea level rise?

“…Recently, a paradigm shift in coastal dune management is discussed (Arens et al 2013;de Groot et al 2017b;Martínez et al 2013;Oost et al 2012;Psuty and Silveira 2013). Restoring former morphodynamics should both reverse decreasing dune biodiversity and increase their adaptive capacity to adjust to an accelerating sea level rise in the future.…”

Comment on ‘Is ‘re-mobilisation’ nature restoration or nature destruction? A commentary’ by I. Delgado-Fernandez, R.G.D. Davidson-Arnott & P.A. Hesp

“…The paradigm shift in coastal dune management has been discussed for some years now (Van Boxel et al 1997;Arens et al 2004, Arens and Geelen 2006, Arens et al 2013aGeelen et al 2015;De Groot et al 2017;Martínez et al 2013;Provoost et al 2011;Psuty and Silveira 2013;Osswald et al 2019). Most of the Dutch dunes are the result of coastal erosion of an extensive barrier coast, induced by sea-level rise, resulting in the development of smaller or wider dune belts with transgressive dunes (Klijn 1990).…”